High prevalence of cobalamin deficiency in elderly outpatients.

OBJECTIVE: To measure the prevalence of cobalamin (vitamin B12) deficiency in geriatric outpatients as documented by both low serum cobalamin levels and elevations of serum methylmalonic acid and homocysteine and to determine the response to cobalamin treatment. DESIGN: Prospective study screening elderly subjects for cobalamin deficiency using radiodilution cobalamin assays as well as stable isotope dilution gas chromatography-mass spectrometry methylmalonic acid and homocysteine assays. In patients with serum cobalamin levels < or = 300 pg/mL, the response to cobalamin treatment in the group with levels of methylmalonic acid and/or homocysteine > 3 standard deviations (SD) above the mean for normals was compared with that of those without such elevations. SETTING: Outpatient geriatric clinics at the VA Medical Center and University Health Sciences Center, Denver, CO. PATIENTS: One-hundred and fifty-two consecutive outpatients, ages 65 to 99, were screened. Twenty-nine subjects with serum cobalamin levels < or = 300 pg/mL were prospectively evaluated and treated with cobalamin. MAIN OUTCOME MEASURES: Cobalamin, methylmalonic acid, homocysteine, complete blood counts, neurologic examination, and neuropsychological testing. RESULTS: The prevalence of cobalamin deficiency as defined by a serum cobalamin level < or = 300 pg/mL and levels of serum methylmalonic acid and/or homocysteine elevated to > 3 SD was 14.5% of the screened outpatients. A similar proportion of patients with low normal serum cobalamin levels (between 201 and 300 pg/mL) demonstrated elevated metabolites > 3 SD (56%) compared with patients with low serum cobalamin levels (< or = 200 pg/mL) (62%). Cobalamin therapy caused a marked fall or complete correction of the elevated methylmalonic acid and homocysteine levels in each patient who was treated prospectively. Results for complete blood count, lactate dehydrogenase, bilirubin, baseline neurologic score, and baseline neuropsychologic scores did not differ in the group of patients with elevated metabolites compared with those with normal metabolites. The mean red cell volume fell significantly in the patients with elevated metabolites after 6 months of cobalamin treatment. One patient with elevated metabolites had marked improvement in his neurologic abnormalities after 6 months of cobalamin treatment. CONCLUSION: There was a high (14.5%) prevalence of cobalamin deficiency as demonstrated by elevations in serum methylmalonic acid and homocysteine in addition to low or low normal serum cobalamin levels in elderly outpatients. The serum cobalamin level was insensitive for screening since similar numbers of patients with low normal serum cobalamin levels of 201-300 pg/mL compared with patients with low cobalamin levels (< or = 200 pg/mL) had markedly elevated metabolites which fell with cobalamin treatment. Additional studies will be required to define the full clinical benefit from treatment with Cbl in elderly subjects.     

Leukemia inhibitory factor upregulates cytokine expression by a murine stromal cell line enabling the maintenance of highly enriched competitive repopulating stem cells

Attempts to maintain or expand primitive hematopoietic stem cells in vitro without the concomitant loss of their differentiative and proliferative potential in vivo have largely been unsuccessful. To investigate this problem, we compared the ability of three cloned bone marrow (BM) stromal cell lines to support the growth of primitive Thy- 1lo Sca-1+H-2Khi cells isolated by fluorescence-activated cell sorting from the BM of Ly-5.2 mice treated 1 day previously with 5-fluo- rouracil. Sorted cells were highly enriched in cobblestone area-forming cells (CAFC), but their frequency was dependent on the stromal cell lines used in this assay (1 per 45 cells on SyS-1; 1 per 97 cells on PA6). In the presence of recombinant leukemia inhibitory factor (LIF), CAFC cloning efficiency was increased to 1 per 8 cells on SyS-1 and 1 per 11 cells on PA6, thus showing the high clonogenicity of this primitive stem cell population. More primitive stem cells with competitive repopulating potential were measured by injecting the sorted cells into lethally irradiated Ly-5.1 mice together with 10(5) radioprotective Ly-5.1 BM cells whose long-term repopulating ability has been "compromised" by two previous cycles of marrow transplantation and regeneration. Donor-derived lymphocytes and granulocytes were detected in 66% of animals injected with 50 sorted cells. To quantitate the maintenance of competitive repopulating units (CRU) by stromal cells, sorted cells were transplanted at limiting dilution before and after being cultured for 2 weeks on adherent layers of SyS-1, PA6, or S17 cells. CRU represented 1 per 55 freshly sorted cells. CRU could be recovered from cocultures supported by all three stromal cell lines, but their numbers were approximately-sevenfold less than on day 0. In contrast, the addition of LIF to stromal cultures improved CRU survival by 2.5-fold on S17 and PA6 cells (approximately two-fold to threefold decline), and enabled their maintenance on SyS-1. LIF appeared to act indirectly, because alone it did not support the proliferation of Thy- 1lo Sca-1+H-2Khi cells in stroma-free cultures. Polymerase chain reaction (RT-PCR) analysis revealed that Interleukin-1beta (IL-1 beta) IL-2, IL-6, granulocyte-colony stimulating factor, granulocyte macrophage-colony stimulating factor, transforming growth factors, LIF, and Steel Factor (SLF) mRNAs were upregulated in SyS-1 within 1 to 6 hours of LIF-stimulation. To determine if increased expression of SLF by LIF-stimulated SyS-1 cells could account for their capacity to support stem cells, sorted calls were cocultured on simian CV-E cells that were transfected with an expression vector encoding membrane-bound SLF, or supplemented with soluble SLF. In both cases, SLF synergized with IL-6 produced endogenously by CV-E cells enabling CAFC growth equivalent to that on LIF-stimulated SyS-1. CAFC development on LIF- stimulated SyS-1 could also be completely abrogated by an anti-SLF antibody. These data provide evidence for a role of LIF in the support of long-term repopulating stem cells by indirectly promoting cytokine expression by BM stroma. Furthermore, we have used quantitative assays to show a maintenance of CRU numbers, with retention of in vivo function following ex vivo culture.     

Growth in Children with Steroid Sensitive Nephrotic Syndrome

Background

Nephrotic syndrome in children usually has an onset between 2-8 years of age and steroids form the mainstay of management. Therapy may affect growth in children with relapsing nephrotic syndrome. This study was carried out to correlate growth with the cumulative dose of steroids in children with steroid sensitive nephrotic syndrome (SSNS).

Methods

Data of 35 children with SSNS was analysed retrospectively. They were divided into two groups. Group I received prednisolone only and Group II received levamisole and or cyclophosphamide in addition to steroids. Their heights were recorded at the time of inclusion and again one year later. The SD scores for age were determined. Growth rate as a change in the SD score over one year (Δ SD score) was correlated to the cumulative dose of steroids over the same period using the Pearson''s correlation. Result: There were 24 (68.6 %) boys and 11 (31.4 %) girls (M:F ratio 2.18:1) in the age group of 17 months to 11 years at inclusion. Group I constituted 19 (54.2 %) and Group II, 16 (45.8 %). Pearson''s correlation coefficients for all children, Groups I and II were -0.341, -0.441 and -0.255 respectively indicating “Fair correlation”. This indicates that as the cumulative dose of steroid increases the growth retardation becomes more apparent.

Conclusion

Growth retardation is proportional to the cumulative dose of steroids in children with SSNS.Key Words: Steroids, Cumulative dose, Nephrotic syndrome, Growth     

Loss-of-function mutations in Notch receptors in cutaneous and lung squamous cell carcinoma

Squamous cell carcinomas (SCCs) are one of the most frequent forms of human malignancy, but, other than TP53 mutations, few causative somatic aberrations have been identified. We identified NOTCH1 or NOTCH2 mutations in ~75% of cutaneous SCCs and in a lesser fraction of lung SCCs, defining a spectrum for the most prevalent tumor suppressor specific to these epithelial malignancies. Notch receptors normally transduce signals in response to ligands on neighboring cells, regulating metazoan lineage selection and developmental patterning. Our findings therefore illustrate a central role for disruption of microenvironmental communication in cancer progression. NOTCH aberrations include frameshift and nonsense mutations leading to receptor truncations as well as point substitutions in key functional domains that abrogate signaling in cell-based assays. Oncogenic gain-of-function mutations in NOTCH1 commonly occur in human T-cell lymphoblastic leukemia/lymphoma and B-cell chronic lymphocytic leukemia. The bifunctional role of Notch in human cancer thus emphasizes the context dependency of signaling outcomes and suggests that targeted inhibition of the Notch pathway may induce squamous epithelial malignancies.     

B细胞能够部分自主控制命运

最近,澳大利亚和爱尔兰科学家在B细胞研究中证实B细胞可在某种程度上控制自己的命运.这一发现在很大程度上会改变科学家们对于细胞命运决定因素的理解.在淋巴结中增殖的B细胞面临着多种命运的抉择：常见的包括细胞死亡、细胞分裂、成为能够分泌抗体的细胞或是改变它们产生的抗体.过去科学界普遍认可的观点是B细胞的命运取决于例如特定激素或细胞信号分子等外部信号.而新研究发现B细胞的命运在很大程度上是由内部的程序所决定.他们开发了新型技术与图像分析方法,通过重建B细胞分化形成不同细胞类型所需的条件,对B细胞进行了追踪成像观测.结果 表明不同的细胞命运是细胞内竞争的结果.即使这些细胞获得相同的外部信号,细胞群体中发生的事件仍会出现相当大的差异.这表明激素或细胞信号分子等外部因素并非是B细胞命运的主宰因子,它们只不过能改变细胞命运选择的概率.