Hoechst staining and exposure to UV laser during flow cytometric sorting does not affect the frequency of detected endogenous DNA nicks in abnormal and normal human spermatozoa

Controlling the sex of offspring by the separation of X and Y chromosome-bearing spermatozoa using flow cytometry has been reported as a clinical technique aiding prevention of X-linked diseases. Although this technique has resulted in several hundred normal births in animals and at least one human birth, there is still concern over its genetic safety due to the involvement of two potentially mutagenic agents: UV light and the fluorochrome dye, Hoechst 33342 (H33342). Human spermatozoa, particularly those considered abnormal, may be more likely to suffer DNA damage following exposure to mutagenic agents, compared with other mammalian species. The stability of normal fresh and decondensed human spermatozoa were examined after exposure to a range of levels of UV and H33342 staining, using an assay that detects endogenous nicks in the DNA of spermatozoa. The stability of abnormal and normal, fresh and frozen-thawed human spermatozoa was examined following UV laser, H33342 staining and flow cytometry treatments utilizing the same assay. There was an increase in the presence of endogenous nicks when spermatozoa were decondensed compared with fresh spermatozoa. There was no increase in the incidence of nicks in any group of spermatozoa after UV and fluorochrome exposure compared with controls without exposure.      

抗人甲状腺过氧化物酶抗体与其他自身抗体的关系

甲状腺过氧化物酶（ＴＰＯ）是甲状腺微粒体的抗原成分。在纯化抗原建立测定抗ＴＰＯ抗体ＥＬＩＳＡ法的基础上，并对抗ＴＰＯ与其他自身抗体的伴随关系作了研究。发现除自身免疫性甲状腺病有较高阳性率外，ＳＬＥ等患者抗ＴＰＯ检出率也很高（１０％￣５２．１％），且抗ＴＰＯ阳性者，抗核抗体等其他自身抗体的阳性率也高达３０．８％￣９５．２％。抗ＴＰＯ抗体与其他自身抗体的相关系数ｒ＝０．７４６７（Ｐ〈０．０１）。     

SARS-CoV-2 spike protein favors ACE2 from Bovidae and Cricetidae

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the recent COVID-19 public health crisis. Bat is the widely believed original host of SARS-CoV-2. However, its intermediate host before transmitting to humans is not clear. Some studies proposed pangolin, snake, or turtle as the intermediate hosts. Angiotensin-converting enzyme 2 (ACE2) is the receptor for SARS-CoV-2, which determines the potential host range for SARS-CoV-2. On the basis of structural information of the complex of human ACE2 and SARS-CoV-2 receptor-binding domain (RBD), we analyzed the affinity to S protein of the 20 key residues in ACE2 from mammal, bird, turtle, and snake. Several ACE2 proteins from Primates, Bovidae, Cricetidae, and Cetacea maintained the majority of key residues in ACE2 for associating with SARS-CoV-2 RBD. The simulated structures indicated that ACE2 proteins from Bovidae and Cricetidae were able to associate with SARS-CoV-2 RBD. We found that nearly half of the key residues in turtle, snake, and bird were changed. The simulated structures showed several key contacts with SARS-CoV-2 RBD in turtle and snake ACE2 were abolished. This study demonstrated that neither snake nor turtle was the intermediate hosts for SARS-CoV-2, which further reinforced the concept that the reptiles are resistant against infection of coronavirus. This study suggested that Bovidae and Cricetidae should be included in the screening of intermediate hosts for SARS-CoV-2.     

Prenatal presentation and diagnosis of Baraitser‐Winter syndrome using exome sequencing

Baraitser‐Winter cerebrofrontofacial syndrome (BWCFF) is a rare autosomal dominant developmental disorder associated with missense mutations in the genes ACTB or ACTG1. The classic presentation of BWCFF is discerned by the combination of unique craniofacial characteristics including ocular coloboma, intellectual disability, and hypertelorism. Congenital contractures and organ malformations are often present, including structural defects in the brain, heart, renal, and musculoskeletal system. However, there is limited documentation regarding its prenatal presentation that may encourage healthcare providers to be aware of this disorder when presented throughout pregnancy. Herein we describe a case of a pregnancy with large cystic hygroma and omphalocele. Whole exome sequencing (WES) was performed and a de novo, heterozygous, likely pathogenic mutation in ACTB was detected, c.1004G>A (p.Arg335His), conferring a diagnosis of BWCFF.     

Modulation of disease severity of dystrophic epidermolysis bullosa by a splice site mutation in combination with a missense mutation in the COL7A1 gene

Dystrophic epidermolysis bullosa (EBD) is a clinically heterogeneous skin disorder, characterized by abnormal anchoring fibrils (AF) and loss of dermal-epidermal adherence. EBD has been linked to the COL7A1 gene at chromosome 3p21 which encodes collagen VII, the major component of the AF. Here we investigated two unrelated EBD families with different clinical phenotypes and novel combinations of recessive and dominant COL7A1 mutations. Both families shared the same recessive heterozygous 14 bp deletion at the exon-intron 115 boundary of the COL7A1 gene. The deletion caused in-frame skipping of exon 115 and the elimination of 29 amino acid residues from the pro-alpha1(VII) polypeptide chain. As a result, procollagen VII was not converted to collagen VII and the C-terminal NC-2 propeptide which is normally removed from the procollagen VII prior to formation of the anchoring fibrils was retained in the skin. All affected individuals also carried missense mutations in exon 73 of COL7A1 which lead to different glycine- to-arginine substitutions in the triple-helical domain of collagen VII. Combination of the deletion mutation with a G2009R substitution resulted in a mild phenotype. In contrast, combination of the deletion with a G2043R substitution led to a severe phenotype. The G2043R substitution was a de novo mutation which alone caused a mild phenotype. Thus, different combinations of dominant and recessive COL7A1 mutations can modulate disease activity of EBD and alter the clinical presentation of the patients.      

两种塑化材料对断层解剖标本制作效果的比较

目的:研究2种不同塑化材料制作的断层解剖标本的差异.方法:分别采用硅橡胶技术和聚酯共聚体技术制备人体断层标本,并进行比较.结果:硅橡胶技术所制备的标本不透明;聚酯共聚体技术制备的断层解剖标本半透明.硅橡胶材料制备的断层标本不适于研究组织纤维走向和筋膜结构,适用于标本防腐保存;聚酯共聚体材料制备的断层标本可以清晰地显示组织的纤维走向和筋膜结构,同时标本的厚度均匀,表面平滑,硬度较高.结论:聚酯共聚体材料制备的断层标本优于硅橡胶材料,此方法将会发展成为断层解剖学研究的常用技术.     

Biodegradation of benzene and its derivatives by a psychrotolerant and moderately haloalkaliphilic Planococcus sp. strain ZD22

The potential for biodegradation of aromatic hydrocarbons simultaneously at low temperatures and under saline and alkaline conditions is not well understood, but such biodegradation would be useful for remediation of polluted sites. A psychrotolerant, moderately haloalkaliphilic pure culture using benzene as a sole source of carbon and energy was isolated by selective enrichment from alkaline and saline soils in the vicinity of the Daqing oil field in China. An analysis of the 16S rDNA gene sequence and morphological and physiological characteristics showed that this strain is a member of the genus Planococcus, and it was designated as strain ZD22. Strain ZD22 could grow at temperatures between 2 and 36 degrees C (pH 7.5-11) and salt concentrations from 0.5 to 25%. Its optimal conditions for biodegradation of benzene were 20 degrees C (pH 9.5) and 10% salt concentration. Strain ZD22 not only utilized benzene, toluene, ethylbenzene and o-xylene, but also degraded chlorobenzene, bromobenzene, iodobenzene and fluorobenzene. The kinetic model of strain ZD22 for benzene was solved to obtain mumax=0.34 h-1, Ks=0.041 mM, n=1.21, Sm=10.2 mM. To our knowledge, this is the first report of biodegradation of benzene and its derivatives simultaneously under multiple extreme conditions.     

An optimal algorithm for configuring delivery options of a one-dimensional intensity-modulated beam

The problem of generating delivery options for one-dimensional intensity-modulated beams (1D IMBs) arises in intensity-modulated radiation therapy. In this paper, we present an algorithm with the optimal running time, based on the 'rightmost-preference' method, for generating all distinct delivery options for an arbitrary 1D IMB. The previously best known method for generating delivery options for a 1D IMB with N left leaf positions and N right leaf positions is a 'brute-force' solution, which first generates all N! possible combinations of the left and right leaf positions and then removes combinations that are not physically allowed delivery options. Compared with the brute-force method, our algorithm has several advantages: (1) our algorithm runs in an optimal time that is linearly proportional to the total number of distinct delivery options that it actually produces. Note that for a 1D IMB with multiple peaks, the total number of distinct delivery options in general tends to be considerably smaller than the worst case N!. (2) Our algorithm can be adapted to generating delivery options subject to additional constraints such as the 'minimum leaf separation' constraint. (3) Our algorithm can also be used to generate random subsets of delivery options; this feature is especially useful when the 1D IMBs in question have too many delivery options for a computer to store and process. The key idea of our method is that we impose an order on how left leaf positions should be paired with right leaf positions. Experiments indicated that our rightmost-preference algorithm runs dramatically faster than the brute-force algorithm. This implies that our algorithm can handle 1D IMBs whose sizes are substantially larger than those handled by the brute-force method. Applications of our algorithm in therapeutic techniques such as intensity-modulated arc therapy and 2D modulations are also discussed.     

清除骨髓中癌细胞的磁性微球研究 II.聚苯乙烯磁性微球的研制

为制备能用于清除骨髓中癌细胞的磁性微球,首先合成了单分散、大粒径的多孔聚苯乙烯交联微球,借助微球多孔结构对其进行磁化。探讨了影响磁化效果的主要因素。为使其与单抗连接紧密,在微球表面聚合了一层聚丙烯醛膜,使其表面带上易与单抗反应的醛基。同时测定了所制微球的磁响应性。X-射线衍射证明磁性物质为γ-Fe₂O₃。     

Appl1 is essential for the survival of Xenopus pancreas,duodenum, and stomach progenitor cells

An understanding of the molecular mechanisms governing the survival of organ progenitor cells in vivo is crucial for in vitro tissue regeneration. Here, we have found that Xenopus appl1 and akt2 share a similar embryonic expression pattern, showing characteristic expression in the central nervous system as well as in the pancreas and part of the stomach/duodenum (SD) at tadpole stages of development. Specific knockdown of appl1 in endoderm or inhibition of akt activity did not affect the formation of endodermal organ primordia at tail bud stages of development, but led to a gut‐coiling defect, strong apoptosis in endodermal organs, and pancreas and SD hypoplasia or even aplasia at tadpole stages of development. Furthermore, appl1 is required for akt phosphorylation and akt2 in turn can rescue appl1 knockdown phenotypes. Together, our data suggest that appl1‐akt signaling is specifically required for the survival of pancreas and SD progenitor cells in Xenopus laevis embryos. Developmental Dynamics 239:2198–2207, 2010. © 2010 Wiley‐Liss, Inc.