Contrasting mutation rates in mitochondrial and nuclear genes of yeasts versus mammals

Summary Base substitutions have been compared in two mitochondrial and two nuclear genes from three yeasts and three mammals. In yeasts, the two mitochondrial genes, cytochrome oxidase subunit 2 (COX2) and apocytochrome b (CYB), have fewer changes on a percentage basis than the nuclear-encoded cytochrome c (CYC) gene. By contrast, in mammals, the same mitochondrial genes have more mutations than CYC on a percentage basis. Sequence comparisons of the nuclear small-subunit ribosomal RNA (nSSU) gene shows that there are more substitutions per unit length in the three yeasts than in the three mammals. This result suggests that although the yeasts are more distantly related than the mammals, their mitochondrial genes have accumulated fewer changes.     

3,5-甾二烯化合物的合成及抗早孕活性

以18-甲基-17β-羟基-17α-乙炔基-雌甾-4-烯-3-酮(18-甲基炔诺酮),17β-羟基-17α-乙缺基-雌甾-4-烯-3-酮(炔诺酮),17β-羟基-17α-乙炔基-雄甾-4-烯-3-酮(妊娠素)和17a-羟基孕甾-4-烯-3,20二酮(17α-羟基黄体酮)为原料,经NaBH,还原、脱水、双键转位和酯化等反应合成一系列3,5-甾二烯化合物,用¹HNMR和MS证明了它们的结构。动物筛选结果表明,17β-丙酰氧基-17α-乙炔基-雌甾-3,5-二烯(IV_b2有明显的抗早孕活性。中断早期妊娠的作用似与其雌激素活性有关。     

The mitochondrial genome can be altered or lost without lethal effect in the petite-negative yeast Debaryomyces (Schwanniomyces) occidentalis

The nature of mutations affecting several cytochrome-deficient mutants of Debaryomyces (Schwanniomyces) occidentalis has been characterized. The DR12 mutant, which is deficient in cytochrome b, and the B10Mn mutant, which is deficient in cytochromes b and a, a3, are deleted in the mitochondrial CYB and COX1 genes respectively. The B10 strain, which is partially deficient in cytochrome b, has no detectable change in its mitochondrial DNA and possibly carries nuclear lesion(s). These three mutants, unlike the rho(-) and rho degrees "petite" mutants of Saccharomyces cerevisiae, can still grow on non-fermentable substrates, due to the development of a salicylhydroxamic acid (SHAM)-sensitive alternative pathway linked to phosphorylation at site 1. A gly(-) mutant lacking mtDNA and respiratory capacity has been isolated. For the first time, it is demonstrated that mtDNA can be altered or even lost without lethal consequence in D. occidentalis, although this yeast was classified as a petite-negative species.     

Evaluation of encephalic ventricular volume from the magnetic resonance imaging scans of thirty-eight human subjects

Summary Accurate volume determination of the encephalic ventricles is of importance in several clinical conditions, including Alzheimer's presenile dementia, schizophrenia, and benign intracranial hypertension. Previous studies have investigated the accuracy with which magnetic resonance imaging (MRI) can be used in clinical practice to evaluate the encephalic ventricles. However, adequate evaluation of pathological conditions depends on a sufficient amount of morphometric data from normal subjects. To begin establishing this data base for normal subjects, we evaluated the MRI scans of 38 subjects found to have no apparent pathology and calculated the ventricular volume in each case by using methods previously developed in our laboratory. The results were then compared with published volumes determined from studies that used either ventricular casts or computerized tomographic scans. The average total ventricular volume for all 38 subjects was 17.4 cm³, while that for males was 16.3 cm³ and that for females was 18.0 cm³. A small but significant correlation was found between age of subject and ventricular volume, with ventricular size increasing with age.

---

Evaluation du volume des ventricules cérébraux à partir des images obtenues en résonance magnétique nucléaire chez 38 sujets humains

Résumé La détermination exacte du volume des ventricules cérébraux est importante en clinique comme par exemple dans la démence présénile d'Alzheimer, la schizophrénie et l'hypertension intracrânienne bénigne. Des études antérieures ont étudié la fiabilité de la résonance magnétique nucléaire en pratique clinique pour évaluer le volume des ventricules cérébraux. Toutefois une évaluation correcte dans les conditions pathologiques implique une bonne connaissance des données morphométriques du sujet normal. Pour établir ces données sur « le sujet normal », nous avons étudié les coupes obtenues en IRM chez 38 sujets apparemment indemnes de toute pathologie; nous avons calculé le volume ventriculaire dans chaque cas en utilisant des méthodes mises au point auparavant dans notre laboratoire. Les résultats ont été ensuite comparés avec ceux obtenus par d'autres études utilisant soit des moules ventriculaires, soit des coupes tomographiques computérisées. Le volume ventriculaire total moyen chez 38 sujets est de 17,4 cm³, mais il est chez les sujets masculins de 16,3 cm³ et chez les sujets de sexe féminin de 18 cm³. Une corrélation faible mais significative a été trouvée entre l'âge du sujet et le volume ventriculaire, étant entendu que la taille du ventricule augmente avec l'âge.

     

A mobile group II intron of a naturally occurring rearranged mitochondrial genome in Kluyveromyces lactis

Summary Mitochondrial intron content is variable in the yeast Kluyveromyces lactis. Strains can be divided into three classes depending on the structure of the cytochrome oxidase subunit 1 (COX1) gene: (1) those containing intron K1 cox1.1, (2) those containing K1 cox1.2, 3 and 4 and, (3) those that contain all four introns. In addition, strains belonging to the first class (designated Type B strains), have an altered mitochondrial gene order relative to strains from classes (2) and (3) (Type A, Hardy et al. 1989). Crossing experiments reveal that K1 cox1.1 (a group II intron) transfers at high frequency (89%) to mitochondrial genomes lacking this intron. By contrast, the mobility of the remaining introns (all group I) is of the order of 7%.     

Congenital pulmonary atresia with ventricular septal defect: angiographic and surgical correlates

Of 181 patients with severe congenital pulmonary atresia and ventricular septal defect or "type IV truncus" (an obsolete term), all but 11% had true central pulmonary arteries. These arteries were demonstrable by large serial biplane angiograms using multiple selective injections into collateral vessels, frequent photographic subtraction, and occasional pulmonary vein-wedge angiograms. These techniques are extremely important for accurate diagnosis and in planning corrective or palliative surgery, which was done in 77% of patients with pulmonary arteries.     

GD2抗体达妥昔单抗β治疗神经母细胞瘤的临床应用专家共识（2021年版）

神经母细胞瘤(neuroblastoma,NB)是儿童最常见的颅外实体肿瘤,临床表现及预后具有高度异质性。低危患儿预后较好,高危患儿即使接受化疗、放疗、手术、造血干细胞移植等多种方法的综合治疗,长期存活率仍不足50%。探索潜在的治疗靶点对于提高高危患者的生存率具有重要意义。双唾液酸神经节苷脂抗原GD2在NB细胞高表达,达妥昔单抗β可与NB细胞膜表面过表达的GD2特定靶点结合,触发抗体依赖性细胞介导的细胞毒性作用和补体依赖的细胞毒性效应,通过双重免疫机制而发挥抗肿瘤作用。通过总结国外多项关键临床研究,并结合在海南和天津医疗先行区的上市前初步应用经验,我们对达妥昔单抗β的安全性、有效性、适用人群及使用方法进行总结和推荐,提出本共识,旨在为临床医师提供指导与帮助。