Is there a double pathway for the secretion of thyroglobulin: a "short circuit" weakly glycosyl-iodinated and a "long circuit" strongly glycosyl-iodinated?

Intact rat thyroid lobes incubated in vitro release recently synthesized thyroglobulin (Tg) into the media at a faster rate than they release thyroglobulin stored in follicular structures. Differential release of this Tg fraction cannot be explained by morphological alterations in thyroid architecture during incubation. This rapidly excreted fraction exhibits a low density on rubidium chloride gradients characteristic of poorly sialylated and poorly iodinated thyroglobulin, comigrating on rubidium chloride gradients with thyroglobulin isolated from tunicamycin treated glands. This poorly sialylated and poorly iodinated thyroglobulin is itself unaffected in its density or release into the media by tunicamycin treatment. Tg isolated from the media of tunicamycin treated glands has nearly the same low iodine and low sialic acid content as rat serum thyroglobulin and does not incorporate radiolabelled glucosamine. This fraction thus appear to duplicate properties of low glycosylated-low iodinated thyroglobulin released from thyroid cells in organisms that have no follicular structures and no follicular storage process as well as from thyroid tissue in patients with thyroid disease states, particularly thyroid tumors. Thus it is proposed a "short loop" pathway of low-glycosylated low-iodinated thyroglobulin directly into circulation, that bypasses and is not stored in the follicular lumen, the "long loop".     

Rosehip -- a "new" source of lycopene?

Lycopene, an efficient antioxidant and singlet oxygen quencher, is mainly delivered within the human diet out of tomatoes and tomato products. Processing liberates this carotenoid from complexes with proteins and thus makes it more bioavailable. Rosehip, a wild fruit which is used more often recently to produce mark, jams and juices, showed remarkable contents of lycopene (12.9–35.2 mg/100 g) with an unexpected isomer pattern.     

Can there be a "cultural epidemiology"?

A brief excursion through the history of social medicine suggests that, at least in principle, epidemiology and anthropology are natural allies in the study of disease in human populations. In practice, however, this alliance has been limited and remains problematic. This article examines the possibilities for interdisciplinary research, taking cancer epidemiology as a case in point. I argue, on the basis of participant-observation over a period of nearly two years in the epidemiology department of a medical research institute in Catalonia (Spain), that bioscientific uses of the concept of culture have led, disappointingly, to its reification as "beliefs" and its incorporation into the naturalist epistemology of Western institutional medicine. The unfortunate consequence is the medicalization of culture understood as "difference," which often stands in for social class.     

Is the doubly deleted alpha-thalassemia gene a "fugitive" allele?

The alpha-thalassemias (particularly in Asia) can be considered as a three-allele system, with one "normal" allele (N) consisting of a pair of closely linked alpha-chain loci, a second "single" allele (S) in which one of the loci has been lost by deletion, and a third "double" allele (D) in which both have been lost. Representatives of all the sets of fitnesses leading to the maintenance of this condition by selection for malaria resistance have been explored, and after the discarding of unlikely sets of fitnesses, it is found that there will be three outcomes: (1) the S chromosome is fixed, (2) the S and N chromosomes form a stable polymorphism, and (3) the N and D chromosomes form a stable polymorphism, but this can be lost and the population forced to fixation by the introduction of sufficiently large number of S chromosomes. Some Melanesian populations appear to have reached outcome (1), while frequencies in African, Mediterranean, and Middle Eastern populations are not incompatible with outcome (2). Southeast Asian populations, however, which carry S and D chromosomes in high frequency, may be in a state of flux. The D chromosome may form a polymorphism with N locally, but it can be driven from the local population by the introduction of large numbers of S chromosomes. The D chromosome would thus be somewhat analogous to a fugitive species, which can only exist in certain transient environments and is displaced as the environment changes. The possibility that N, S, and D are coexisting as a stable polymorphism can almost certainly be ruled out by a consideration of fitness sets required.     

Is the osteoclast calcium "receptor" a receptor-operated calcium channel?

Elevated extracellular calcium levels ([Ca2+]e) inhibit osteoclast function by elevating cytosolic free calcium levels ([Ca2+]i), presumably via the activation of a surface Ca2+ "receptor". It is unclear whether or not Ca(2+)-induced [Ca2+]i elevation involves the direct gating, by the putative "receptor", of a divalent cation channel. The results show that [Ca2+]i elevation in response to elevated [Ca2+]e comprises a distinct component of Ca2+ influx, the magnitude of which can be decreased and increased, respectively, by depolarising (100 mM-[K+]) and hyperpolarising (1 microM-[valinomycin]) the osteoclast membrane. In addition, activation of the putative Ca2+ "receptor" by elevated [Ca2+]e causes influx of the related divalent cation, magnesium (Mg2+). We suggest that Ca2+ influx induced by Ca2+ "receptor" activation is a major component of the observed [Ca2+]i response.     

Is a "color effect" demonstrated for hair analysis of carbamazepine?

Psillakis et al. have reported on the concentration of carbamazepine recovered from hair samples collected from patients receiving this anti-seizure medication under medical supervision and determined that their was a high correlation between dose and quantitation of recovered analyte. The analyte was identified by two techniques, FPIA (Abbott TDx) and HPLC and the correlation was high for both procedures. In the literature on hair analysis some have suggested that analyte concentration in hair is critically dependent on hair color. In reporting their data Psillakis et al. reported the hair color of each patient but made no attempt to analyze their results in relation to color. This article performs a secondary analysis of the Psillakis et al. data in order to determine whether there is a hair color effect discernible in the recovery of carbamazepine from hair. Analysis of this data set for both the FPIA and HPLC by one-way analysis of variance fails to identify a color effect at p = .05. Weighting the data for per-patient dosage values fails to discern a color effect. Examination of all possible two-color comparisons also fails to identify a statistically significant effect for any subset of combinations. These data suggest that carbamazepine does not exhibit a color effect when using either FPIA or HPLC assay methods.     

Nature:CD32a蛋白暴露艾滋病病毒"藏身地"

正《自然》杂志近日发表了法国研究人员的一项最新成果:他们通过实验室研究发现,潜藏艾滋病病毒(HIV)的T细胞表面特定表达着一种名叫CD32a的蛋白,这种蛋白在未感染HIV的T细胞中却没有被检测出来。这意味着,CD32a蛋白可以作为一种生物靶标,用来开发出针对"隐身"状态HIV的全新药物。由于HIV将部分免疫、淋巴甚至肠道等细胞当作"隐身之地",现有药物和免疫系统都无法辨明它们的"身份",导致艾滋病多年来无法得     

How normal is a "normal" flora in animal or man?

When investigating different disturbances of the normal intestinal flora causing disorders and/or diseases in man and animal, these studies include comparisons of results with control materials, i.e., materials from conventional laboratory animals or healthy human beings. However, how "normal" is the control group’s flora? In this paper two different examples will be discussed; one investigation with laboratory animals and one from a human study.