Peak velocities of visually and nonvisually guided saccades in smooth-pursuit and saccadic tasks

 Smooth pursuit typically includes corrective catch-up saccades, but may also include such intrusive saccades away from the target as anticipatory or large overshooting saccades. We sought to differentiate catch-up from anticipatory and overshooting saccades by their peak velocities, to see whether the higher velocities of visually rather than nonvisually guided saccades in saccadic tasks may be found also in saccades in pursuit. In experiment 1, 12 subjects showed catch-up, anticipatory, and overshooting saccades to comprise 70.4% of all saccades in pursuit of periodic, 30°/s constant-velocity targets. Catch-up saccades were faster than the others. Saccadic tasks were run as well, on 19 subjects, including the 12 whose pursuit data were analyzed, with target-onset, target-remaining (saccade to the remaining target when the other three extinguish), and antisaccade tasks. For 17 of the 19 subjects, antisaccade velocities were lower than for either target-onset or target-remaining tasks. Velocities for the target-remaining task were near those for target onset, indicating that target presence, not its onset, defines visually guided saccades. Error and reaction-time data suggest greater cognitive difficulty for target remaining than for target onset, so that the cognitive difficulty of typical nonvisually guided saccade tasks is not sufficient to produce their lowered velocity. To produce reliably, in each subject, catch-up and anticipatory saccades with comparable amplitude distributions, nine new subjects were asked in experiment 2 to make intentional catch-up and anticipatory saccades in pursuit, and were presented with embedded target jumps to elicit catch-up saccades, all with periodic target trajectories of 15°/s and 30°/s. Velocities of intentional anticipatory saccades were lower than velocities of intentional catch-up saccades, while velocities of intentional and embedded catch-up saccades were similar. Target-onset and remembered-target saccadic tasks were run, showing the expected higher velocity for the target-onset task in each subject. Both experiments demonstrate higher peak velocities for catch-up saccades than for anticipatory saccades, suggesting that cortical structures preferentially involved in nonvisually guided saccades may initiate the anticipatory and overshooting saccades in pursuit. Received: 1 December 1995 / Accepted: 25 February 1997     

人心房肌细胞特殊颗粒的电镜酶细胞化学和免疫电镜研究

本研究应用电镜CMP酶细胞化学和心钠素免疫电镜胶体金,分别标记人心房肌细胞中初级溶酶体和心钠素,进行鉴别定位观察和定量分析。心钠素颗粒数量居多,占78.7～79.3％,大小均一,直径0.20±0.05μm(x±s),分布于整个细胞质内,多成簇,尤以肌膜下,核极区多见。而溶酶体大小不一,直径0.30±0.19μm(x±s),显著大于心钠素颗粒(P<0.001),一般在核极区成簇分布,也见肌原纤维之间和肌膜下单个散在分布。     

外源性p21WAF1/CIP1基因转染对人胶质瘤细胞生长和细胞周期的影响

目的：探讨外源性p21^WAF1／CIP1基因对胶质瘤细胞生长和细胞周期的影响．方法：采用脂质体介导法将p21^WAF1／CIP1基因质粒转导人人胶质瘤细胞系SHG44细胞，然后用电镜、流式细胞仪等技术对细胞形态、生长及细胞周期进行观察。结果：酶切电泳和斑点杂交显示p21^WAF1／CIP1基因成功的转染至SHG44细胞。转染p21^WAF1／CIP1基因的细胞光镜及电镜下可见凋亡产生；生长速度明显慢于亲代细胞，其倍增时间约是对照细胞的二倍；细胞周期发生明显改变，G1期明显增多，S期明显减少．结论：外源性p21^WAF1／CIP1基因对SHG44细胞的生长和细胞周期有明显的抑制作用，并可诱导细胞凋亡产生。     

Decreased expression of DMPK: correlation with CTG repeat expansion and fibre type composition in myotonic dystrophy type 1

Abstract Myotonic dystrophy type 1 (DM1) is an autosomal dominant disease caused by a trinucleotide repeatexpansion, cytosine-thymine-guanine (CTG)_n, in the 3′ untranslated region of a gene encoding the myotonic dystrophy protein kinase (DMPK). To correlate CTG expansion and protein expression, we studied muscle specimens from 16 adult DM1 patients using three anti-DMPK antibodies for immunoblotting. We estimated the amount of the full-length DMPK (85 kDa) in muscle biopsies from normal controls and from DM1 patients carrying different (CTG)_n expansions. We found that DMPK concentration was decreased to about 50% in DM patients’ muscles; the protein decrease did not seem correlated with the CTG repeat length. However, the fibre type composition in skeletal muscle seemed somehow to affect DMPK decrease, as the lowest level of the enzyme was found in patients with the lowest content of type 1 fibre.     

Child with a tail

An interesting case of a child with a tail is reported. The child had a tail like structure in the back since birth, increasing with age. It was 20 cm. long, the longest tail so far described in the English literature. There was no functional complain. The result was excellent after excision as the problem was only cosmetic.     

The thymus in seronegative myasthenia gravis patients

Summary In 5–10% of all patients with typical generalised myasthenia gravis (MG), serum antibody to the acetylcholine receptor (AChR) is undetectable. To determine whether these represent a distinct subgroup, we have compared the thymuses of 14 seronegatives, 70 seropositives and 12 non-myasthenic controls. By quantitative immunohistology on coded sections, the 7 seronegative samples were clearly distinguishable from the controls by the pronounced lymph node-type T-cell areas in the medulla. While these closely resembled those in the seropositive cases, germinal centres were significantly sparser, and total in vitro IgG production was disproportionately low (per B cell) in the 12 cases tested. Furthermore, specific anti-AChR production was never detected in any of these cultures. The data support the view that the medullary T-cell areas are the most consistent abnormalitiy in the MG thymus (though it may not be primary), and they strongly imply that seronegative and seropositive MG are distinct entities.     

Demonstration of human papillomavirus types 6 and 11 in juvenile laryngeal papillomatosis by in-situ DNA hybridization

A study is reported in which an in situ hybridization technique for the demonstration of human papillomavirus (HPV) employing a biotin--streptavidin polyalkaline phosphatase complex has been successfully applied to formalin-fixed paraffin-processed tissue obtained from ten patients with juvenile laryngeal papillomatosis. In all cases, positive results were obtained for either HPV type 6 or 11. Normal vocal cord epithelium was negative.     

三氧化二砷脂质体的制备及其对鼠脑胶质瘤的影响

目的研究三氧化二砷（As2o3）脂质体注射液对大鼠体内C6胶质瘤细胞凋亡的影响。方法采用超声薄膜分散法制备As籼脂质体，将126只成瘤大鼠分为As2O3脂质体组、As2O3组、生理盐水组。原子荧光法检测注射As2O3脂质体和As2O3后大鼠脑组织中As2O3浓度。从电镜、TUNNEL和大鼠生存时间等方面研究As2O3脂质体对C6胶质瘤的影响。结果As203，脂质体提高了As2O3的血-脑屏障通过。电镜和TUNEL检测显示：As203脂质体组细胞凋亡率给药后3d为（13．53±1．68）％，7d为（20．03±0．79）％，多于As2O3组和盐水组。动物生存时间亦优于其他两组。结论超声薄膜分散法是制备As2O3脂质体的较好方法。As203脂质体可较As203更明显地诱导鼠脑胶质瘤细胞凋亡，延长载瘤鼠的生存期。     

Leptomeninges as a site of relapse in locally controlled,diffuse pontine glioma with review of literature

Case report Leptomeningeal involvement in diffuse intrinsic brain stem gliomas is rarely diagnosed clinically and in majority of the instances diagnosed only on postmortem examination. We report two cases of diffuse pontine glioma diagnosed clinicoradiologically and treated with conventional radiotherapy.Observations On follow-up, both patients showed clinical features suggestive of meningeal spread although imaging for pontine tumor showed stable disease. Leptomeningeal disease in the spine was confirmed on imaging and in one case by cerebrospinal fluid examination also. During the follow-up of patients with pontine glioma, the possibility of leptomeningeal involvement must be borne in mind.