Choline acetyltransferase (ChAT) immunoreactivity in paraffin sections of normal and diseased intestines

There is increasing interest in localizing nerves in the intestine, especially specific populations of nerves. At present, the usual histochemical marker for cholinergic nerves in tissue sections is acetylcholinesterase activity. However, such techniques are applicable only to frozen sections and have uncertain specificity. Choline acetyltransferase (ChAT) is also present in cholinergic nerves, and we therefore aimed to establish a paraffin section immunocytochemical technique using an anti-ChAT antibody. Monoclonal anti-choline acetyltransferase (1.B3.9B3) and a biotin-streptavidin detection system were used to study the distribution of ChAT immunoreactivity (ChAT IR) in paraffin-embedded normal and diseased gastrointestinal tracts from both rats and humans. Optimal staining was seen after 6-24 hr of fixation in neutral buffered formalin and overnight incubation in 1 microgram/ml of 1.B3.9B3, with a similar distribution to that seen in frozen sections. In the rat diaphragm (used as a positive control), axons and motor endplates were ChAT IR. Proportions of ganglion cells and nerve fibers in the intramural plexi of both human and rat gastrointestinal tracts were also ChAT IR, as well as extrinsic nerve bundles in aganglionic segments of Hirschsprung's disease. Mucosal cholinergic nerves, however, were not visualized. In addition, non-neuronal cells such as endothelium, epithelium, and inflammatory cells were ChAT IR. We were able to localize ChAT to nerves in formalin-fixed, paraffin-embedded sections. The presence of ChAT IR in non-neuronal cells indicates that this method should be used in conjunction with other antibodies. Nevertheless, it proves to be a useful technique for studying cholinergic neuronal distinction in normal tissues and pathological disorders.     

A mRNA signal for the type III secretion of Yop proteins by Yersinia enterocolitica

Pathogenic Yersinia species have a specialized secretion system (type III) to target cytotoxic Yop proteins during infection. The signals of YopE and YopN sufficient for the secretion of translational reporter fusions were mapped to the first 15 codons. No common amino acid or peptide sequence could be identified among the secretion signals. Systematic mutagenesis of the secretion signal yielded mutants defective in Yop translation; however, no point mutants could be identified that specifically abolished secretion. Frameshift mutations that completely altered the peptide sequences of these signals also failed to prevent secretion. Thus, the signal that leads to the type III secretion of Yop proteins appears to be encoded in their messenger RNA rather than the peptide sequence.     

Volkmann's ischemic contracture of the upper extremity

Upper extremity deformity of ischemic contracture usually includes elbow flexion, forearm pronation, wrist flexion, thumb flexion and adduction, digital metacarpophalangeal joint extension, and interphalangeal joint flexion. Treatment of mild contractures consists of either nonoperative management with a comprehensive rehabilitation program (to increase range of motion and strenght) or operative management consisting of infarct excision or tendon lengthening. Treatment of moderate-to-severe contractures consists of release of secondary nerve compression, treatment of contractures (with tendon lengthening or recession), tendon or free-tissue transfers to restore lost function, and/or salvage procedures for the severely contracted or neglected extremity.     

Periductal mastitis and duct ectasia: different conditions with different aetiologies

A prospective study of 14,225 patients has been undertaken to determine the inter-relationship between periductal mastitis and duct ectasia and to establish whether there is an association between smoking and either of these two conditions. Periductal mastitis affected women at a younger age than did duct ectasia. Of 139 patients with the clinical syndrome of periductal mastitis, 97 (70 per cent) had a past history of previous periductal mastitis, compared with only one (1 per cent) of 186 patients with the clinical syndrome of duct ectasia (P < 0.0001). There was a significant excess of smokers in patients with clinically (124 (89 per cent) of 139) and pathologically (71 (91 per cent) of 78) diagnosed periductal mastitis compared with age-matched controls (both P < 0.001), but there was no such excess in those with clinically (52 (28 per cent) of 186) or pathologically (15 (23 per cent) of 64) diagnosed duct ectasia. These data suggest that periductal mastitis and duct ectasia are separate conditions which affect different age groups, have different aetiologies, and should now be considered as separate entities.     

Carbon dioxide laser serial microtrapdoor flap excision of subglottic stenosis

The recent development of microspot micromanipulators for the carbon dioxide laser with 250-microns spot sizes has greatly facilitated the extension of endolaryngeal procedures to children and neonates. It is possible to accurately develop microtrapdoor flaps within the limited exposures in the pediatric subglottis. We have used serial microtrapdoor flaps in the excision of subglottic scar tissue in eight children. In five children, the stenosis was improved with relief of stridor. In three children, the flaps were used as an adjunct to laryngotracheoplasty. The surgical techniques of this procedure are detailed in this report.     

Dynamic simulation of three-dimensional rigid body systems using Vector-Network techniques

This paper describes a new approach to the problem of motion prediction. An extension of the “Vector-Network” method to rigid body systems in 3-D is introduced. This procedure, with its computational implementation, is shown to eliminate the work of analytically modelling a dynamic system in order to generate its time response. The entire procedure (Vector-Network) is a basic application of concepts of graph theory in which laws of vector dynamics are combined. The principle of orthogonality is reviewed and a specific application to the generation of equations of motion is presented. Moreover, various new terminal equations are shown to be necessary in the derivation of this algorithm. It is observed that this procedure is very attractive and may prove to be helpful due to its simplicity and basic application of Newton's law.