Does feeding regime affect physiologic and thermal responses during exposure to 8, 20, and 27° C?

Summary When the loss of body heat is accelerated by exposure to low environmental temperatures, additional substrates must be oxidized to provide energy to sustain temperature homeostasis. Therefore, the present investigation examined the relation between feeding regime [pre-experimental carbohydrate feeding (FED) vs a fast (FAST)], during 120 min of exposure to 8, 20, and 27° C in well-nourished men. The following were examined: tissue insulation (I; °C · m² · W^–1), rectal temperature (T _re; °C), and oxygen consumption ( O₂; ml · kg^–1 · min^–1). O₂, T _re, and I revealed no significant differences between treatments (FED vs FAST) at any temperature. At 27° C, I was less (P < 0.05) than at 20 and 8° C, and decreased (P < 0.05) as exposure time increased. At 8° C, O₂was higher (P < 0.5) than at 20 or 27°C, and O₂increased as time increased (P < 0.05). T _re decreased (P < 0.05) as time increased for all conditions. Respiratory exchange ratio (R) differed (P < 0.05) between treatments (FED vs FAST), temperature (8 vs 20° C), and across time. Values for R suggests that carbohydrate accounted for 56% and 33% of caloric utilization during the FED vs FAST conditions, respectively. At 8 vs 20° C, R represented 54% vs 30% of cabohydrate utilization. Across time, R demonstrated that in both conditions (FED vs FAST) there was a decreased reliance on carbohydrate utilization for energy provision. From these data it appears that while substrate utilization differed between dietary treatment and across time this did not differentially affect O₂or T _re during protracted exposure to 8, 20, and 27° C. The higher R in the 8° C condition for both dietary treatments demonstrates that carbohydrate utilization is increased in shivering cold-exposed humans. However, the reduction in R across time suggests that fat oxidation is also involved in metabolic heat production and core temperature maintenance during shivering in the cold.     

Study of CYP2D6 gene in children with autoimmune hepatitis and P450 IID6 autoantibodies.

Cytochrome P450 IID6 is an autoantigen recognized by the sera of children affected with a subtype of autoimmune hepatitis. It was hypothesized that a mutation in the CYP2D6 gene could explain the autoimmune response in these patients. To examine this question, genomic DNA from peripheral lymphocytes (n = 9) and liver (n = 1) of 10 patients with anti-LKM-1 antibody was analysed by Southern blot for genetic association studies between a particular CYP2D6 haplotype and autoimmune hepatitis. In addition, a region of CYP2D6, from the same genomic DNA, was amplified by polymerase chain reaction (PCR) and digested by BstNI, in a search for the most prevalent 29B mutation, described in subjects who do not express the P450 IID6. Total RNA and proteins, prepared from the liver of an anti-LKM-1+ patient, were analysed by Northern and Western (immunoblot) blots respectively. Our results do not reveal any major structural change in the DNA of this patient at the CYP2D6 locus that could explain their autoimmune response. Corroborating this observation, no changes were noted either in P450 IID6 mRNA size or in the corresponding protein. However, these data do not exclude the possibility of subtle changes in the protein due to point mutations in critical regions that might trigger an autoimmune response.     

API2-MALT1融合基因变异体在粘膜相关淋巴组织结外边缘区B细胞淋巴瘤中的分布及凋亡的关系

目的探讨API2-MALT1融合基因变异体在粘膜相关淋巴组织结外边缘区B细胞淋巴瘤(extranodal marginal zone B—cell lymphoma of mucosa—associated lymphoid tissue，MALT)中的分布特点及其转录与肿瘤凋亡的关系。方法将逆转录-聚合酶链反应和巢式聚合酶链式反应结合，检测62例不同部位MALT淋巴瘤中API2-MALT1融合基因的多种变异体；通过TdT介导脱氧核苷酸缺口末端标记技术进行肿瘤细胞的原位凋亡检测；通过逆转录-聚合酶链反应和免疫组化染色检测API2的mRNA和蛋白水平。结果62例MALT淋巴瘤中28例检出API2-MALT1融合基因(45．16％)，为变异体A1446-M1123或A1446-M814，但未检出A1446-M541和A1446-M1150。A1446-M1123(18／28)的检出明显多于A1446-M814(10／28)。融和基因转录在甲状腺MALT淋巴瘤中检出最低，在其它部位的分布无差异。在API2-MALT1^ 组(API2-MALT1mRNA表达阳性组)肿瘤凋亡水平明显高于API2-MALT1^-组(API2-MALT1mRNA表达阴性组)，API2的mRNA和蛋白水平低于阴性组。A1446-M1123^ 与A1446-M814^ 病例之间凋亡和API2的变化无差异。结论MALT淋巴瘤中t(11；18)(q21；q21)的发生有部位差异，A1446-M1123可能是中国人MALT淋巴瘤中API2-MALT1融合基因变异体的主要类型。API2-MALT1融合基因转录与MALT淋巴瘤的凋亡水平和API2的变化有关。     

Encomium: Theodore puck,a life in biophysics applied to medicine

The dopamine hypothesis of schizophrenia proposed that dopaminergic pathways are involved in the etiology of the disease. In particular, interest among psychiatrists has focused on the D₂ receptor because of its affinity to antipsychotic drugs. Recently a new dopamine receptor gene has been cloned, and named the dopamine D₃ receptor. The D₃ receptor is a potential site for antipsychotic drug action and may be involved in the pathophysiology of schizophrenia. We have carried out a linkage study between the susceptibility gene for schizophrenia and polymorphism of the dopamine D₃ receptor gene in two Japanese pedigrees. The LOD scores were negative for, all genetic models and for all affective status at a recombination fraction θ = 0. Linkage of DRD₃ has been excluded for the model 1 (dominant model) and the model13 (recessive model). The LOD score was - 3.43 at θ = 0 for model 1 (dominant model) and broad definition of affected status. These results were consistent with previous studies. © 1994 Wiley-Liss, Inc.     

Fine structure of the carotid body of the midterm human fetus

Summary The human fetal carotid body was studied using both histochemical and electron microscopic methods. The glomus cells of a mid term fetal carotid body evidently contain catecholamines. This was demonstrated both by formaldehyder-induced fluorescence of the cells and by the presence of typical dense-cored vesicles (diameter 1430–3200 Å) in the cytoplasm of the chief cells. The glomus cells were densely innervated and the synapses found on their surface were probably cholinergic in type, containing agranular synaptic vesicles measuring 400–700 Å in diameter with a few dense-cored vesicles measuring 900 to 1300 Å. Synapses were not found in any other cell type within the glomus caroticum. The prominent feature of the glomus cell cytoplasm was the presence of the dense-cored vesicles. The density of the vesicular core varied only slightly from cell to cell. There were no perceptible differences in vesicular size between the different cells. The glomus cells were mostly surrounded by the processes of the sustentacular cells, which usually also surrounded the capillary walls. No glomus cells were ever found in direct contact with the capillary wall. The capillaries were wide and very numerous over the restricted area of the organ. They formed sinusoidal loops, probably anastomosing with each other. Finally, the features of the fine structure are discussed, correlating the present findings with our knowledge about the adult functional carotic body.     

Feasibility of simultaneous fluorescence immunophenotyping and fluorescence in situ hybridization study for the detection of estrogen receptor expression and deletions of the estrogen receptor gene in breast carcinoma cell lines

For the first time, combined immunophenotyping and fluorescence in situ hybridization (FISH) technique according to the ”fluorescence immunophenotyping and interphase cytogenetics as a tool for investigation of neoplasms” (FICTION) technique have been successfully applied in solid tumors. Thus, we were able to visualize the antigen expression of cells with chromosomal deletions of a tumor suppressor region directly. In six breast carcinoma cell lines, we investigated the correlation between estrogen receptor (ER) expression status and deletions of the estrogen receptor gene (ESR). To screen for deletions of the ESR gene, dual-color FISH was performed with a YAC (yeast artificial chromosome) probe containing the ESR gene and, as internal control, with a centromeric probe of chromosome 6. Deletions of the ESR gene were detected in four of six cell lines. For direct comparison of ER expression with the copy number of the ESR gene at the single cell level, immunophenotyping with mouse anti-human ER antibody was combined with FISH with the YAC probe containing the ESR gene according to the FICTION technique. There was no correlation between lack of or reduced ER expression and deletions of the ESR gene. One cell line with deletions of the ESR gene did express ER on the protein level, while another cell line without a deletion did not. Cells with deletions of the ESR gene were either ER expression positive or negative. The staining intensity of ER expression was not associated with the copy number of the ESR gene. Thus, this FICTION study unequivocally shows that deletions of the ESR gene are not the major cause of absent or reduced ER expression in breast carcinoma cell lines. Received: 6 September 1999 / Accepted: 14 September 1999     

Isolation of a Trichoderma reesei cDNA encoding GTP: a-d-mannose-1-phosphate guanyltransferase involved in early steps of protein glycosylation

A cDNA coding for GTP: α-d-mannose-1-phosphate guanyltransferase (MPG1 transferase) (EC 2.7.7.13) was isolated from a cDNA library of the Trichoderma reesei RutC-30 strain by suppression of the yeast Saccharomyces cerevisiae mutation in the DPM1gene encoding mannosylphosphodolichol (MPD) synthase. The nucleotide sequence of the 1.6 kb-long cDNA revealed an ORF which encodes a protein of 364 amino acids. Sequence comparisons demonstrate 70% identity with the S. cerevisiae guanyl transferase gene (MPG1) and 75% identity with the Schizosaccharomyces pombe homologue. No similarity was found with the MPD synthase encoded by the S. cerevisiae DPM1 gene. The possibility that cloned cDNA encodes a product with a MPD synthase activity was also excluded by transforming a heterozygous S. cerevisiae dpm1::LEU2/DPM1 diploid, which did not lead to the restoration of viability of the dpm1 spores. Simultaneously, a significant increase in MPG transferase activity, as compared with the wild-type yeast, was observed in cellular extracts when the mpg1 cDNA from Trichoderma was expressed in the S. cerevisiae dpm1-6 mutant. Received: 21 July 1997 / 24 April 1998     

Ellis‐van Creveld syndrome in a patient from Tanzania

We report an African infant with Ellis‐van Creveld (EVC) syndrome. EVC syndrome is a chondral and ectodermal dysplasia with autosomal recessive transmission. The baby presented with polydactyly, short limbs and atrioventricular septal defect, but was withdrawn from clinical follow up for the first year of life. Initial hematological abnormalities could not be explained and normalized later. EVC syndrome was confirmed by genetic analysis that showed two pathogenic mutations in the EVC2 gene, c.653_654del, p.Val218Glyfs*12 in exon 5, and c.2710C>T, p.Gln904* in exon 16. The variant c.653_654del; p.Val218Glyfs*12 in exon 5 has not been described before. Our review of medical literature suggested this is the first molecularly confirmed case of EVC syndrome in sub‐Saharan Africa.     

Gene Therapy: The Potential Applicability of Gene Transfer Technology to the Human Germline

The theoretical possibility of applying gene transfer methodologies to the human germline is explored. Transgenic methods for genetically manipulating embryos may in principle be applied to humans. In particular, microinjection of retroviral vector appears to hold the greatest promise, with transgenic primates already obtained from this approach. Sperm-mediated gene transfer offers potentially the easiest route to the human germline, however the requisite methodology is presently underdeveloped. Nuclear transfer (cloning) offers an alternative approach to germline genetic modification, however there are major health concerns associated with current nuclear transfer methods. It is concluded that human germline gene therapy remains for all practical purposes a future possibility that must await significant and important advances in gene transfer technology.     

抑癌基因PTEN与食管癌

PTEN是近年发现的一种与细胞信号传导途径有关的具有双特异性磷酸酶活性的新型抑癌基因。研究表明,该基因的突变与人类多种恶性肿瘤的发生发展密切相关。近年来国内外的学者在食管癌组织中发现,虽然该基因发生突变的频率较低,但其蛋白表达却普遍下降,表达程度与食管癌的恶性程度及预后密切相关。因此,PTEN的低表达可能参与了食管癌的发生发展过程。