Limited proteolysis of single-chain tetanus toxin by tissue enzymes,in cultured brain tissue and during retrograde axonal to the spinal cord

Summary Single-chain toxin was investigated in vitro and in vivo for limited proteolysis into the fully active two-chain toxin. Plasmin from serum, elastase and gelatinase from leucocytes, as well as clostripain from C. histolyticum cleaved single-chain toxin and increased by that way its ability to inhibit [³H]noradrenaline release in vitro. Cultured mouse brain generated fragments from ¹²⁵I-single-chain toxin which were cell-associated. Some of them comigrated in electrophoresis with light and heavy chain after mercaptolysis. When injected i. v. into rats, ¹²⁵I-single-chain-toxin disappeared from the blood with a half-life of about 11 h without signs of nicking. However, after its injection into the triceps surae muscle both single- and two-chain toxin were found in the ipsilateral ventral horn of the spinal cord. Thus single-chain toxin is subjected to limited proteolysis by enzymes involved in tissue damage, by cultured brain tissue, and during or after its retrograde axonal transport to the spinal cord. Limited proteolysis is necessary for the release of the light chain known to mediate the action of toxin on several systems.     

霍乱毒素B亚单位基因的克隆和表达

用DNA重组技术构建CT-B表达性质粒pXB1及进一步修饰的pXB2,使CT-B基因在大肠杆菌中得到较高水平的表达(280～350ng/ml),且有71.5％分泌率。表达动力学研究阐明,克隆子培养24h产物收率较高。一定浓度的Mg~(2+)、L-组氨酸和天冬酰胺能刺激CT-B的表达。GM1-ELISA、CHO细胞测毒结合间接免疫荧光检测和家兔肠段结扎试验证实,表达的CT-B能与游离的或活细胞膜上的GM1受体结合,但无细胞和肠段毒性。这种细胞测毒结合免疫荧光序贯试验,为客观证实CT-B的生物学活性开拓了新途径。     

G proteins (Gi,Go) in the medial temporal lobe in schizophrenia: preliminary report of a neurochemical correlate of structural change

Summary We have measured the amount of Gi (the inhibitory G-protein) or Go (a similar G-protein of unknown function) in 5 areas of the medial temporal lobe of control and schizophrenic brains utilizing pertussis toxin-catalyzed ADP ribosylation. The material used has previously been shown to have asymmetrical structural abnormalities of the ventricular system. The amount of Gi or Go was reduced on the left side in the hippocampus, amygdala and parahippocampal gyrus, the difference reaching significance in the hippocampus. This data is the first report of a neurochemical correlate of the structural change in the brains of patients with schizophrenia. Decreased Gi or Go in hippocampus may relate to other reported neurochemical deficits or other transmembrane signalling abnormalities. Further investigations of these indices of secondary messenger function in relation to structural changes are indicated.     

Atypical hemolytic uremic syndrome in human immunodeficiency virus-1-infected children

We describe the clinical and pathological findings of the hemolytic uremic syndrome (HUS) in two children with human immunodeficiency virus (HIV) infection. Both patients presented with microangiopathic hemolytic anemia, thrombocytopenia, and subsequently developed renal failure. The diagnosis of HUS was confirmed by renal histopathology in both patients. None of these children presented with bloody diarrhea, evidence of circulating antibody response to Escherichia coli O157 lipopolysaccharide, or other known risk factors for HUS, except for the presence of HIV infection. Each patient was treated with intravenous plasma infusion and renal replacement therapy. Their clinical course was characterized by non-oliguria and lack of significant hypertension throughout the acute phase of the disease. Despite these favorable clinical parameters, both patients developed end-stage renal failure. The etiology of this atypical HUS characterized by poor renal survival remains unknown and the role of HIV infection in its pathogenesis, although possible, is unclear. Received March 5, 1996; received in revised form and accepted October 15, 1996     

Characterization of an anti-idiotypic MoAb bearing an internal image of the receptor-binding epitope of cholera toxin.

A mouse anti-cholera toxin (CT) MoAb, mAb1, specific for the GM1-binding epitope of CT, was used to raise a syngenic anti-idiotypic MoAb, mAb2. Purified mAb2 was specific for mAb1 as shown by latex particle counting immunoassay and ELISA. Several experiments of competition between mAb2 and CT for binding to mAb1 demonstrated that mAb2 bore an internal image of the GM1-binding epitope of CT. Binding of mAb2 to GM1 unambiguously corroborated the mAb1-paratopic specificity of mAb2. Furthermore, mAb2 acted as a CT-surrogate antigen: rabbits injected with mAb2 produced some anti-CT antibodies, Ab3, which resembled mAb1 in specificity as expected. The potential use of this mAb2 as vaccine or as prophylactic agent to prevent CT from binding to its cellular receptor is discussed.     

Botulinum toxin injection in patients with hereditary spastic paraparesis

In an open label study, we analyzed the efficacy of botulinum toxin injection at the lower limbs of patients with hereditary spastic paraparesis (HSP). Fifteen patients who showed disabling spasticity with no or poor effect of oral treatment were recruited consecutively. Botulinum toxin was injected (400 U; Botox^®) into the spastic muscles identified by clinical examination (equinus, varus, and pathological hip adduction). Patients were regularly assessed from the first day to the fifth month: spasticity (Ashworth), motor strength, range of movements, Functional Ambulation Categories (FAC), gait parameter, Rivermead Motor Assessment, self-analysis of benefit and satisfaction. We observed a moderate and significant ( P  < 0.05) reduction of ankle plantar flexor and hip adductor spasticity, with a partial increase in the range of the active and passive motion at the ankle and in gait velocity. At an individual level, six of 15 patients showed an increase in gait velocity. The FAC and RMA did not change. Patients often reported partial improvement in foot position and lower limb propulsion, and fair satisfaction. In conclusion, botulinum toxin injection can be effective in HSP patients with relatively ancient spasticity. This technique can be introduced into the therapeutic panel, which also includes physiotherapy, oral treatment and baclofen pump.     

Difficult myotomy is not determined by preoperative therapy and does not impact outcome.

OBJECTIVES: The impact of preoperative endoscopic therapy on the difficulty of laparoscopic Heller myotomy and the impact of the difficulty of the myotomy on long-term outcome has not been determined. This study was undertaken to determine whether preoperative therapy impacts the difficulty of laparoscopic Heller myotomy and whether preoperative therapy or difficulty of myotomy impacts long-term outcomes. METHODS: Since 1992, 305 patients, 56% male, median age 49 years, underwent laparoscopic Heller myotomy and were prospectively followed. The difficulty of the laparoscopic Heller myotomy was scored by the operating surgeon for the most recent 170 consecutive patients on a scale of 1 (easiest) to 5 (most difficult). Patients scored their symptoms before and after myotomy using a Likert scale from 0 (never/not bothersome) to 10 (always/very bothersome). RESULTS: Before myotomy, 66% of patients underwent endoscopic therapy: 33% dilation, 11% Botox, and 22% both. Preoperative endoscopic therapy did not correlate with the difficulty of the myotomy (P=NS). Median follow-up was 25 months. Regardless of the difficulty of the myotomy, dysphagia improved with myotomy (P<0.0001). By regression analysis, the frequency and severity of post-myotomy dysphagia correlated with neither preoperative endoscopic therapy nor the difficulty of the myotomy. CONCLUSIONS: Laparoscopic Heller myotomy improves the frequency and severity of dysphagia. The difficulty of laparoscopic Heller myotomy is not impacted by preoperative therapy, and neither preoperative therapy nor difficulty of the myotomy impact long-term outcome.     

Asynchronous blepharospasm, facial and cervical dystonia, and bilateral asynchronous hemifacial spasm.

We present a patient with a facial movement disorder that has characteristics of both blepharospasm and bilateral asynchronous hemifacial spasm. Because of the increased incidence of blepharospasm in patients with hemifacial spasm, our patient's clinical presentation is probably not a chance occurrence, but rather a manifestation of some predisposition for these two movement disorders. This unusual constellation of signs and symptoms challenges the current diagnostic criteria and suggests that some of these facial movement disorders may lie on a spectrum, rather than represent distinct entities.     

Reversible reorganisation of the motor cortical representation of the hand in cervical dystonia.

Previous work has suggested that there may be a widespread disturbance of motor control mechanisms in patients with cervical dystonia. In the present study, we used transcranial magnetic stimulation to investigate the topography of the corticomotor projection to the abductor pollicis brevis (APB) muscle in 10 subjects with idiopathic torticollis. Threshold-adjusted stimuli were delivered at multiple scalp sites during a low-level voluntary contraction of the APB, and maps were generated of motor evoked potential amplitude versus scalp site. The cortical maps for the APB on the side opposite to the direction of head rotation were displaced laterally or posteriorly in all subjects and reverted to a more normal position after botulinum toxin injection of the cervical muscles in 5 subjects. The findings point to a reversible reorganisation of the corticomotor representation of the hand on the same side as the sternocleidomastoid (SCM) muscle that is involved in producing the dystonia. These results provide further evidence for the involvement of cortical centres and for a more widespread abnormality of motor control mechanisms in focal dystonia. The findings also support the notion that head turning is chiefly mediated by the hemisphere ipsilateral to the direction of the head rotation by means of a corticomotor projection to the contralateral SCM.     

Botulinum toxin injection inhibits myogenic tone and sympathetic nerve function in the porcine internal anal sphincter

Objective Botulinum toxin is an effective treatment for anal fissure, though there is a lack of agreement over the optimal site for its injection. This reflects our current ignorance of its mechanism, and whether it has any action on the nerves of the internal anal sphincter (IAS). This study set out to resolve this issue through use of a pig model. Materials and methods Eight pigs were studied in pairs: one of each pair received a botulinum toxin injection into the anal sphincter, whilst the other acted as its control. Manometry was performed every two weeks under anaesthesia. Pigs were slaughtered at between four and six weeks after injection and the properties of the IAS compared in vitro. Results Whilst maximum anal resting pressure (MARP) increased slowly in control pigs during the experimental period, reflecting weight gain, a fall was observed in treated pigs. In vitro, IAS strips from control pigs generated 400 mg of spontaneous tone per gram of tissue (± 45; standard error), compared to 250 (± 25) mg/g tissue from treated pigs (P < 0.01). Electric Field Stimulation at 50Hz produced 150 (± 22) mg contraction/gram tissue in IAS strips from control pigs compared to 53 (± 13) mg/g tissue in treated pigs (P < 0.0005). This contractile response was blocked by guanethidine. Conclusion Botulinum toxin has a significant action on the IAS. It reduces myogenic tone and contractile responses of this tissue to sympathetic nerve stimulation. Further studies are required to clarify its mechanism of action more precisely.