Production of monoclonal antibodies specific to Clostridium botulinum type B neurotoxin

Four monoclonal antibodies were produced for use in a rapid method to detect Clostridium botulinum type B neurotoxin. Cells of mouse myeloma cell line SP2/0 were fused with splenocytes of immunized BALB/c mice. An immunoblot assay of semipurified commercial neurotoxins of C. botulinum types A, B, C, D, E, and F was used to show specificity. All the monoclonal antibodies reacted with type B neurotoxin but did not cross-react with the other types. The monoclonal antibodies, separately and combined, did not neutralize the toxin in mice, and all showed specificity to the whole neurotoxin molecule and the heavy-chain component by immunoblot. No evidence of specific binding to the hemagglutinin molecule was noted. When tested against concentrated cultured supernatants of C. botulinum types A, B, E, and F, the 4 monoclonal antibodies reacted only against type B strains. They will be incorporated into a rapid assay with other specific monoclonal antibodies to detect C. botulinum neurotoxins from pure cultures or suspect foods.     

Popliteal aneurysm: surgical treatment is mandatory before complications occur

Between 1972 and 1995, surgical repair was undertaken for 94 popliteal aneurysms diagnosed in 71 patients (69 men and 2 women) with a mean age of 66 years. Ninety-one femoropopliteal bypasses, 2 lumbar sympathectomies and one primary amputation were performed. Postoperative results of 28 elective bypasses performed for asymptomatic aneurysms (AA) were compared with 63 revascularisations needed for symptomatic aneurysms (SA) secondary to thrombosis (31%), embolization (30%), venous or nerve compression (13%), or rupture (2.1%). Occlusion of at least one tibial vessel was documented angiographically in 40% of the asymptomatic aneurysms and in 80% of the symptomatic aneurysms. No significant difference was observed between 5-year graft-patency of asymptomatic aneurysms (64%, mean followup 30 months +/- 37.2) and symptomatic aneurysms (50%, mean followup 39 months +/- 40.9). Furthermore, 5-year graft patency was not influenced by the number of patent tibial vessels in either of these populations. No statistically significant difference between these two groups was observed with respect to morbidity (AA: 10.7%, SA: 19%), or early reintervention (AA: 7.1%, SA: 9.5%). However, 12 secondary amputations were needed, all of which were performed after repair of a symptomatic aneurysm (19%, p < 0.05). No postoperative mortality was observed after an elective bypass while 3 patients (4.8%) with symptomatic aneurysms died after an emergency surgery. Ischemic symptoms persisted in 56% of patients who were initially symptomatic. Surgical correction should therefore be performed once the diagnosis of a popliteal aneurysm has been established in order to prevent amputation and late sequelae.     

Innovation in clinical method: diabetes care and negotiating skills

Hepatocellular carcinoma (HCC) with extrahepatic spreading is not uncommon. In order to delineate the clinical and radiological pictures of HCC with intracranial metastasis, 33 documented cases were analysed. Eighteen had brain parenchymal metastasis without skull involvement; the other 15 cases disclosed skull metastasis with brain invasion. The underlying HCC are mainly of expanding (13/33, 39.4%) and multifocal (13/33, 39.4%) types. Eighteen cases (18/33, 54.5%) had mental changes not related to hypoglycaemia or hepatic encephalopathy. Eighteen cases (18/20, 90%) disclosed hyperdense mass lesions by non-contrast computed tomography (CT) scans and 17 cases showed homogeneous enhancement (17/22, 77.3%) by post-contrast CT images. In the non-skull involved group, five cases (5/12, 41.7%) disclosed ring-shape enhancement and 14 cases (14/16, 87.5%) had perifocal oedema, which were not seen in the skull involved group. Eight cases (8/33, 24.2%) presented as intracerebral haemorrhage. Twelve (12/33, 36.4%) died of brain herniation. Most (14/18, 77.8%) non-skull involved cases had simultaneous lung metastasis without bony metastasis, while the skull involved group often (10/15, 66.7%) disclosed extracranial bony metastasis without lung metastasis. The difference in extracranial metastasis was statistically significant (P < 0.05). The multivariate survival analysis disclosed that lower lactate dehydrogenase level (< or = 316 U/L, P = 0.029) and treatments (surgery or radiation, P = 0.001) were positively associated with longer survival. In conclusion, HCC with intracranial metastasis is symptomatic and life-threatening. Half the cases may come from pulmonary metastasis and the other half may be from bony metastasis. Brain irradiation or surgery can prolong their survival.     

Structure-based design of a potent transition state analogue for TEM-1 beta-lactamase

The structure of the plasmid-mediated beta-lactamase TEM-1 has been solved in complex with a designed boronic acid inhibitor (1R)-1-acetamido-2-(3-carboxyphenyl)ethane boronic acid at 1.7 A resolution. The boronate inhibitor was designed based on the crystallographic coordinates of the acyl-enzyme intermediate of TEM-1 bound to the substrate penicillin G. The boronate-TEM-1 complex is highly ordered and defines a novel transition state analogue of the deacylation step in the beta-lactamase reaction pathway. The design principles of this highly effective inhibitor (Ki = 110 nM) and the resulting structural and mechanistic implications are presented.     

Transumbilical use of the endovaginal probe

The endovaginal probe can be used in the umbilicus to improve fetal imaging. In 27 of 31 patients, an optimal ultrasound examination was achieved because of this added technique. The procedure is most useful in obese women and those with prior abdominal surgery.     

Alternative products in the reaction of 2-nitro-5-thiocyanatobenzoic acid with thiol groups

2-Nitro-5-thiocyanatobenzoic acid has been proposed as a reagent for converting thiol groups in proteins into their S-cyano derivatives. Evidence was obtained for formation of both the S-cyano derivative and the mixed disulphide derivative. Formation of the S-cyano derivative can be promoted by addition of excess of CN-to the reaction mixture.