Immunohistochemistry of thyroid hormones as a functional parameter in thyroid pathology

The authors study by means of immunoperoxidase method the pattern of thyroglobulin, triiodothyronine and thyroxine distribution in 58 cases of thyroid disorders: 15 euthyroid goiters, 10 Graves' disease, 7 Hashimoto's thyroiditis, 11 folliculo-papillary carcinomas (6 primary tumors and 5 lymph node metastases), 8 follicular carcinomas, 4 anaplastic carcinomas and 3 medullary carcinomas. Thyroglobulin, triiodothyronine and thyroxine were present in most of the thyroid disorders, excepting anaplastic and medullary carcinomas. Thyroglobulin and thyroxine were localized both in the follicular epithelium and in the colloid, whereas triiodothyronine was present especially in the follicular cells. The thyroid hormones distribution in benign lesions is rather similar. In carcinomas, the pattern of thyroglobulin, triiodothyronine and thyroxine is more heterogeneous, but generally the triiodothyronine distribution is similar to that of thyroglobulin. In some carcinomas, triiodothyronine and thyroxine showed a weak or negative immunostaining. The immunoperoxidase method is a valuable tool in the study of functional disturbances in the thyroid pathology and in the diagnosis of thyroid carcinoma metastases as well. Positive thyroid hormones staining clearly indicates the thyroid origin of metastases.     

Characteristics of the neuronal reaction of the substantia nigra to nociceptive stimulation

The nature of neurone response of substance nigra (SN) to nociceptive stimulation of the cat's peroneal nerve has been studied. The recording of neurone SN firing rate revealed that the majority (71.0%) of the SN neurones responded to the nociceptive repetitive stimulation of the peroneal nerve. But the thresholds of nociceptive activation in SN neurones turned to be very high. As a result of it the number of SN neurones responding to repetitive peroneal stimulation was twice as many as the number of cells responding to single stimulation of the nerve. The intravenous injection of naloxone in dose 1.0 mg/kg changed both excitatory and inhibitory responses in majority (71.4%) of SN neurones responding to repetitive peroneal stimulation. Naloxone did not modify the firing rate of neurones nonresponsive to nociception.     

Constitutive mutations of Agrobacterium tumefaciens transcriptional activator virG.

The virulence (vir) genes of Agrobacterium tumefaciens Ti plasmids are positively regulated by virG in conjunction with virA and plant-derived inducing molecules. A procedure that utilizes both genetic selection and a genetic screen was developed to isolate mutations in virG that led to elevated levels of vir gene expression in the absence of virA and plant phenolic inducers. Mutants were isolated at a frequency of 1 in 10(7) to 10(8). Substitution mutations at two positions in the virG coding region were found to result in the desired phenotype. One mutant had an asparagine-to-aspartic acid substitution at residue 54, and the other contained an isoleucine-to-leucine substitution at residue 106. In both cases, the mutant phenotype required the presence of the active-site aspartic acid residue at position 52. Further analysis showed that no other substitution at residue 54 resulted in a constitutive phenotype. In contrast, several substitutions at residue 106 led to a constitutive phenotype. The possible roles of the residues at positions 54 and 106 in VirG function are discussed.     

Cloning, sequencing, and overexpression of a [2Fe-2S] ferredoxin gene from Escherichia coli.

Escherichia coli contains a soluble, [2Fe-2S] ferredoxin of unknown function (Knoell, H.-E., and Knappe, J. (1974) Eur. J. Biochem. 50, 245-252). Using antiserum to the purified protein to screen E. coli genomic expression libraries, we have cloned a gene (designated fdx) encoding this protein. The DNA sequence of the gene predicts a polypeptide of 110 residues after removal of the initiator methionine (polypeptide M(r) = 12,186, holoprotein M(r) = 12,358). The deduced amino acid sequence is strikingly similar to those of the ferredoxins found in animal mitochondria which function with cytochrome P450 enzymes and to the ferredoxin from Pseudomonas putida which functions with P450cam. The overall sequence identity is approximately 36% when compared with human mitochondrial and P. putida ferredoxins, and the identities include 4 cysteine residues proposed to coordinate the iron cluster. The protein was overproduced approximately 500-fold using an expression plasmid, and the holoprotein was assembled and accumulated in amounts exceeding 30% of the total cell protein. The overexpressed ferredoxin exhibits absorption, circular dichroism, and electron paramagnetic resonance spectra closely resembling those of the animal ferredoxins and P. putida ferredoxin.     

Spatial variation in phenotypic selection on floral characteristics in an epiphytic orchid

Spatial variation in twelve floral characters was examined in an epiphytic orchidLepanthes rupestris to evaluate the strength and direction of phenotypic selection in seven riparian populations along two river basins in the Caribbean National Forest “El Yunque” for a range of 18–34 months. We evaluated selection on floral characters based on male (pollinaria removal) and female fitness (fruit set). Simple linear and quadratic regressions were used to evaluate the strength of directional, disruptive and stabilizing selections. Univariate and multivariate analyses were used to estimate the total strength of the selection acting on a character. Phenotypic selection was inconsistent among characters and populations. Few of the characters appeared to be under selection and none of them was found to be consistent throughout all populations. Inconsistency in selection coefficients among populations could suggest that selection is spatially variable. We only noted one character (column length) which had some consistency in differential selection coefficients among populations. Previous studies have shown that effective population sizes inL. rupestris are small and the observed “fitness differences” among populations could as easily be explained as stochastic events at play. We argue that the observed “fitness differences” in most characters and inconsistency among populations are likely from stochastic noise and not phenotypic selection. Consequently, we propose that random selection on character state support the hypothesis of genetic drift in small orchid populations.     

碱茅(puccinellia tenuifolra)Put-Cu/Zn-SOD基因的克隆及在酵母中的表达

从碱茅根cDNA文库分离得到Put-Cu/Zn-SOD全长cDNA,其序列全长为2 700 bp,该基因的开放读码框为长615 bp,所编码的蛋白由204个氨基酸组成,其预测分子量约为20.6 kD、理论等电点约为5.63.Put-Cu/Zn-SOD氨基酸序列与水稻Cu/Zn-SOD序列有较高的同源性为87%.将Put-Cu/Zn-SOD基因构建到酵母表达载体pYES2,并转化至酵母(INVSc1).对pYES2-Put-Cu/Zn-SOD转化酵母进行盐碱、氧化胁迫实验.结果表明:重组酵母的抗盐碱、氧化能力明显高于对照(pYES2转化酵母),结果显示了碱茅的Cu/Zn-SOD基因在酵母表达中,具有提高酵母抗盐碱和耐氧化能力.     

Participation of lipopolysaccharide in hyperplasic adipose expansion: Involvement of NADPH oxidase/ROS/p42/p44 MAPK‐dependent Cyclooxygenase‐2

Obesity is a world‐wide problem, especially the child obesity, with the complication of various metabolic diseases. Child obesity can be developed as early as the age between 2 and 6. The expansion of fat mass in child age includes both hyperplasia and hypertrophy of adipose tissue, suggesting the importance of proliferation and adipogenesis of preadipocytes. The changed composition of gut microbiota is associated with obesity, revealing the roles of lipopolysaccharide (LPS) on manipulating adipose tissue development. Studies suggest that LPS enters the circulation and acts as a pro‐inflammatory regulator to facilitate pathologies. Nevertheless, the underlying mechanisms behind LPS‐modulated obesity are yet clearly elucidated. This study showed that LPS enhanced the expression of cyclooxygenase‐2 (COX‐2), an inflammatory regulator of obesity, in preadipocytes. Pretreating preadipocytes with the scavenger of reactive oxygen species (ROS) or the inhibitors of NADPH oxidase or p42/p44 MAPK markedly decreased LPS‐stimulated gene expression of COX‐2 together with the phosphorylation of p47^phox and p42/p44 MAPK, separately. LPS activated p42/p44 MAPK via NADPH oxidase‐dependent ROS accumulation in preadipocytes. Reduction of intracellular ROS or attenuation of p42/p44 MAPK activation both reduced LPS‐mediated COX‐2 expression and preadipocyte proliferation. Moreover, LPS‐induced preadipocyte proliferation and adipogenesis were abolished by the inhibition of COX‐2 or PEG₂ receptors. Taken together, our results suggested that LPS enhanced the proliferation and adipogenesis of preadipocytes via NADPH oxidase/ROS/p42/p44 MAPK‐dependent COX‐2 expression.     

Genotoxic potential of cyclosporin A in patients with renal transplantation

We analyzed the induction of sister chromatid exchange (SCE) by cyclosporin A (CsA) as a marker of genotoxic potential. In 30 patients undergoing renal transplantation, SCE induction was tested before the introduction of CsA and 3 months later. We found that SCE frequency increased significantly at the end of 3 months. To our knowledge, this is the first study demonstrating in vivo induction of SCE by CsA in humans. We conclude that CsA has a genotoxic potential on human lymphocytes.     

Homozygous mutations in fibroblast growth factor 3 are associated with a new form of syndromic deafness characterized by inner ear agenesis, microtia, and microdontia

We identified nine individuals from three unrelated Turkish families with a unique autosomal recessive syndrome characterized by type I microtia, microdontia, and profound congenital deafness associated with a complete absence of inner ear structures (Michel aplasia). We later demonstrated three different homozygous mutations (p.S156P, p.R104X, and p.V206SfsX117) in the fibroblast growth factor 3 (FGF3) gene in affected members of these families, cosegregating with the autosomal recessive transmission as a completely penetrant phenotype. These findings demonstrate the involvement of FGF3 mutations in a human malformation syndrome for the first time and contribute to our understanding of the role this gene plays in embryonic development. Of particular interest is that the development of the inner ear is completely disturbed at a very early stage--or the otic vesicle is not induced at all--in all of the affected individuals who carried two mutant FGF3 alleles.     

Histopathologic observations on thyroid carcinoma with amyloid stroma.

The authors describe histopathologic aspects in ten cases of thyroid carcinoma with amyloid stroma. This form of cancer represents 3.4% of all the thyroid cancer cases in the last five years in the Institute of Endocrinology. Microscopic examination reveals a polymorphous picture alongside with amyloid deposits. The authors attribute to the tumor cells an important role in producing thyroid amyloidosis.