An inexpensive ex-vivo porcine laparoscopic Nissen fundoplication training model.

BACKGROUND: We recently implemented the use of an ex-vivo porcine model to teach residents the fundamentals of performing a laparoscopic Nissen fundoplication. METHODS: Residents were trained using intact porcine esophagus, stomach, and spleen placed in a standard video-trainer. They were later asked to complete a survey containing a course evaluation. RESULTS: Sixteen residents (R1-R4) completed the survey. They agreed that (1) the exercise was a valuable use of their limited time, (2) repeating the exercise will be of additional benefit, (3) it will improve their ability to perform or assist in an actual case in the OR, and (4) the surgical principles learned using the model will transfer to other laparoscopic cases. Significant subjective improvements were reported in resident comfort level in assisting in or performing a laparoscopic Nissen fundoplication. CONCLUSIONS: The use of an inexpensive ex-vivo porcine training model increases resident comfort level in performing a Nissen fundoplication in the operating room.     

Retraction pockets in the tympanic membrane — aetiology and management — our view point

Retraction pockets of the tympanic membrane are believed to be due to eustachian tube obstruction or malfunction. Our observations based on intraoperative findings suggest that the presence of a large sized mastoid antrum along with chronic eustachian tube obstruction plays an important role in the causation of retraction pockets. Granular myringitis may also occur in these circumstances when there is a recurrent eustachian tube blockage due to infection especially if the patient has received frequent and inadequate courses of antibiotics. The use of chromic catgut to create a healed air-filled middle ear space along with a canal wall down tympanomastoidectomy is discussed for their effective treatment.     

Cap formation in a B-lymphocyte cell line is inhibited by pertussis toxin and phorbol ester.

We have examined concanavalin A (Con A)-induced cap formation in a B-lymphocyte derived cell line, LAZ-559. Treatment with pertussis toxin (PT) or phorbol-12-myristate-13-acetate (PMA) prior to exposure of the cells to Con A abolished the capping reaction. The possible role of calcium mobilization was tested using cells pre-loaded with the fluorescent dye Quin2. Both PT and PMA caused inhibition of calcium mobilization at concentrations similar to those observed for the inhibition of capping. The possible identity of the substrate for pertussis toxin was examined by carrying out ADP-ribosylation of the isolated plasma membranes using [alpha-32P]NAD and pertussis toxin. Several bands were observed at molecular weights of 109,000, 43,000, 34,000 and 22,000. Comparative labelling with cholera toxin revealed a separate band at 42,000. The bands at 43,000 and 34,000 are PT specific. Of these, the 43,000 band comigrated with the PT substrate that has been shown to regulate capping in human neutrophils (Lad et al., 1985a, 1986b). PMA-induced phosphorylation was examined in 32P-loaded cells, and multiple bands were observed to be labelled in a dose-dependent manner, at least two of which were very similar in mobility to the PT substrate. Our results suggest that regulation of calcium mobilization and the control of capping via a PMA-sensitive, GTP-binding protein are probably general phenomena observable in multiple cell systems.     

Identification and characterization of CS20, a new putative colonization factor of enterotoxigenic Escherichia coli.

An enterotoxigenic Escherichia coli (ETEC) strain producing a previously undescribed putative colonization factor was isolated from a child with diarrhea in India. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of bacterial heat extracts revealed a polypeptide band of 20.8 kDa when the bacteria were grown at 37 degrees C which was absent after growth at 22 degrees C. A specific rabbit antiserum raised against the purified 20.8-kDa protein bound specifically to the fimbriae, as shown by immunoelectron microscopy, and inhibited bacterial adhesion to tissue-cultured Caco-2 cells. Transformation with a recombinant plasmid harboring the cfaD gene, which encodes a positive regulator for several ETEC fimbriae, induced hyperexpression of the 20.8-kDa fimbrial subunit and a substantial increase in the proportion of bacterial cells that were fimbriated. The N-terminal amino acid sequence of the polypeptide showed 65 and 60% identity to the PCFO20 and 987P fimbriae of human and porcine ETEC, respectively. We propose the term CS20 for this new putative colonization factor of human ETEC.     

Simplified and accurate nonradioactive polynucleotide gene probe assay for identification of enterotoxigenic Escherichia coli.

The present study describes a colony hybridization setup for identification of enterotoxigenic Escherichia coli obviating the need for advanced equipment and radioactive isotopes. With a modest laboratory arrangement, polynucleotide gene probes were produced in large quantities. The probes were labeled with digoxigenin and, after hybridization, detected with an antidigoxigenin alkaline phosphatase conjugate. With an established isotope-based oligonucleotide hybridization assay as reference, a blinded study on a large battery of enterotoxigenic and nonenterotoxigenic bacteria revealed a satisfactory sensitivity and specificity of the nonradioactive assay.     

The Cd40 ligand

For several years, the primary function of CD40 ligand (CD40L) has been believed to be in regulation of contact-dependent, CD40-CD40L-mediated signals between B-and T-cells, which are essential for the regulation of thymus-dependent (TD) humoral immune responses. Recently, a flurry of reports indicate that CD40 is expressed by variety of cell types other than B-cells that include dendritic cells, follicular dendritic cells, monocytes, macrophages, fibroblasts, and endothelial cells. These studies show that CD40-CD40L interactions are important in inflammatory process. For the past few years, through the availability of CD40L-knockout mice, new data have emerged to support the belief that CD40L has many more functions than its role in TD humoral immunity. CD40L-deficient mice have provided significant information towards our understanding of the in vivo role of CD40L. The current picture that emerges indicates that CD40-CD40L interactions mediate many cell-mediated immune responses and T-cell-mediated effector functions that are required for proper functioning of the host defense system. This article focuses on the in vivo role of the CD40L in regulation of cell-mediated effector functions.     

The intron 4c allele of the NOS3 gene is associated with ischemic stroke in African Americans

Background  

Ischemic stroke is the most common cause of disability in North America and in addition to the generally accepted risk factors, there is increasing evidence for the potential pathophysiological role of genes. One of these genes, the endothelial nitric oxide synthase gene (NOS3) has been reported as a genetic risk factor for ischemic stroke. To independently confirm and extend the results of these previous reports, we investigated this gene as a risk factor for stroke in an ethnically diverse study population.     

Genetic relationship of putative colonization factor O166 to colonization factor antigen I and coli surface antigen 4 of enterotoxigenic Escherichia coli.

Plasmid DNA from two strains of enterotoxigenic Escherichia coli harboring genes encoding coli surface antigen 4 (CS4) and from seven Indian enterotoxigenic E. coli isolates cross-hybridized at low stringency but not at high stringency with two polynucleotide probes derived from the colonization factor antigen I (CFA/I) operon. Low-stringency Southern blot hybridization of PstI-digested plasmid DNA from the seven Indian isolates yielded characteristic restriction fragment patterns, distinct from those of CS4- and CFA/I-associated plasmid DNA. Two of the Indian strains were transformed with a recombinant plasmid harboring the cfaD gene, which encodes a positive regulator of CFA/I and CS4 genes. The cfaD transformants produced large amounts of putative colonization factor O166 (PCFO166) irrespective of whether the nutrient agar contained bile salts, a growth factor otherwise required for adequate PCFO166 expression. A considerable interstrain variation in the level of PCFO166 production could be explained by differences in the proportion of bacteria that were fimbriated, as visualized by electron microscopy. The N-terminal amino acid sequence of PCFO166 fimbrial protein showed a high degree of homology with the corresponding sequences of CFA/I and CS4.