Electrosurgery in gastrointestinal endoscopy: principles to practice

An electrosurgery generator unit is a critical piece of equipment in any therapeutic endoscopy setting. Electrosurgery generators produce high-frequency alternating electric current and differ from electrocautery units in that both cutting and coagulation effects can be achieved. This ability to cut and coagulate at the same time makes electrosurgery an ideal therapeutic tool for gastrointestinal endoscopy. Although education and familiarity with these devices are accepted as the primary avenue to the safest and most effective clinical outcomes, concise information linking the basic properties of electrosurgery directly to clinical practice is not widespread. The following are the aims of this article: (i) to relate the fundamental electrosurgical principles to commonly performed procedures such as snare polypectomy, hot biopsy, sphincterotomy, bipolar hemostasis, and argon plasma coagulation, and (ii) to provide practical suggestions for the use of these devices on the basis of an understanding of electrosurgical principles and the available clinical data.

Electrosurgery in the gastroenterology suite: principles, practice, and safety

An electrosurgery generator is a critical piece of equipment in any therapeutic endoscopy setting. Electrosurgery uses rapidly alternating current, provided by the electrosurgery generator, for both therapeutic cutting and coagulation of tissue. Basic variables important to electricity in general are also important to electrosurgery: current, voltage, circuit, and impedance (resistance). Monopolar and bipolar accessories (electrodes) are used in the endoscopy suite and these terms refer to the way in which the electric circuit is completed by the flowing current. Impedance resists current flow and changes with tissue type and degree of therapeutic coagulation. Waveforms are the high-frequency output selected by the operator when using an electrosurgery generator. Waveforms may be continuous or interrupted (modulated) and differ in voltage and degree of modulation. Certain waveforms are typically chosen for particular applications or accessories, such as polypectomy with a snare, because of predictable tissue-effect attributes of that waveform. Safe application of grounding pads, careful management of active accessories, and good care of electrosurgical equipment are crucial to patient and operator safety.

CPG 7909, an immunostimulatory TLR9 agonist oligodeoxynucleotide, as adjuvant to Engerix-B HBV vaccine in healthy adults: a double-blind phase I/II study

Oligodeoxynucleotides containing immunostimulatory CpG motifs (CpG ODN) act as potent Th1-like immune enhancers with many antigens in animal models. We have extended these observations to the first clinical evaluation of the safety, tolerability and immunogenicity of CPG 7909 when added to a commercial HBV vaccine. In a randomized, double-blind phase I dose escalation study, healthy volunteers aged 18-35 years were vaccinated at 0, 4 and 24 weeks by intramuscular injection with Engerix-B (GlaxoSmithKline). The regular adult dose of 20 microg recombinant hepatitis B surface antigen (HBsAg) adsorbed to alum was administered mixed with saline (control) or with CPG 7909 at one of three doses (0.125, 0.5 or 1.0 mg). HBsAg-specific antibody responses (anti-HBs) appeared significantly sooner and were significantly higher at all timepoints up to and including 24 weeks in CPG 7909 recipients compared to control subjects (p< or = 0.001). Strikingly, most CpG 7909-vaccinated subjects developed protective levels of anti-HBs IgG within just two weeks of the priming vaccine dose. A trend towards higher rates of positive cytotoxic T cell lymphocyte responses was noted in the two higher dose groups of CPG 7909 compared to controls. The most frequently reported adverse events were injection site reactions, flu-like symptoms and headache. While these were more frequent in CPG 7909 groups than in the control group (p<0.0001), most were reported to be of mild to moderate intensity regardless of group. In summary, CPG 7909 as an adjuvant to Engerix-B was well-tolerated and enhanced vaccine immunogenicity. CPG 7909 may allow the development of a two-dose prophylactic HBV vaccine.

Safety and immunogenicity of CPG 7909 injection as an adjuvant to Fluarix influenza vaccine

CPG 7909, a 24-mer B-Class CpG oligodeoxynucleotide (ODN), was tested for safety, tolerability and its ability to augment the immunogenicity of a commercial trivalent killed split influenza vaccine (Fluarix containing A/Beijing/262/95, A/Sydney/5/97 and B/Harbin/7/94; SmithKline Beecham) in a phase Ib blinded, randomized, controlled clinical trial. Sixty healthy volunteers were recruited in two consecutive cohorts of 30 subjects, who were randomly assigned to receive Fluarix plus 1mg CPG 7909 or Fluarix plus saline control (15 subjects each). Vaccines were administered by intramuscular injection on a single occasion with subjects in the first cohort receiving a 1/10th dose of Fluarix and those in the second cohort receiving the full-dose. All safety measures including physical evaluation, laboratory blood assays, and assays for DNA autoimmunity were within normal values except for transient and clinically inconsequential decreases in total white blood cell counts in groups receiving CPG 7909. All vaccines were found to be generally well tolerated with similar frequency and intensity for most adverse reactions for groups receiving CPG 7909 as controls. Exceptions were injection site pain and headache, which were reduced in frequency in subjects receiving the 1/10th Fluarix dose without CpG, compared to the frequency in all other groups. There was a lack of pre-existing immunity, defined as hemagglutinin inhibition (HI) activity < or =20, for all subjects to the influenza strains A/Beijing/262/95 and B/Harbin/7/94 and for some subjects to A/Sydney/5/97. Post-vaccination humoral immune responses, as determined 2 and 4 weeks later by assay of HI activity and ELISA to detect antibodies against hemagglutinin (anti-HA) were similar for both full and reduced Fluarix doses but the cellular immune responses (measured as PBMC antigen-specific IFN-gamma secretion) were reduced in the 1/10th Fluarix dose group. Humoral responses were not significantly enhanced by the addition of CPG 7909, except in individuals with pre-existing immunity to A/Sydney/5/97 strain (baseline HI activity titre >20), where there was a trend to higher HI activity with CPG 7909 (P = 0.06). The addition of CPG 7909 to the 1/10th dose of Fluarix did however result in significantly higher levels of IFN-gamma secretion from peripheral blood mononuclear cells recovered at 4 weeks and restimulated ex vivo with A/Beijing/262/95 (P = 0.048) and B/Harbin/7/94 (P = 0.0057), restoring these to the level seen with full-dose vaccine. These results suggest that addition of CPG 7909 to Fluarix may allow the use of reduced vaccine doses without reduced immunogenicity.

Development and implementation of an electrochemiluminescence immunoassay for the determination of an angiogenic polypeptide in dog and rat plasma

A quantitative method based on electrochemiluminescence immunoassay for the determination of the angiogenic agent aFGF-S117 has been developed and validated. Two polyclonal antibodies specific to aFGF-S117 and a wild-type aFGF antibody were selected for the analysis. The assay was based on the non-competitive sandwich immunoassay principle in which the drug is trapped with a biotinylated antibody that is immobilized on a streptavidin magnetic particle. The drug is then sandwiched with a ruthenium chelated second antibody. The assay demonstrates good accuracy and reproducibility at plasma concentration of 0.5 ng/ml.

The relational-interdependent self-construal and relationships

Three studies describe the development and validation of a measure of the relational-interdependent self-construal, which is defined as the tendency to think of oneself in terms of relationships with close others. Study 1 reports the development, psychometric properties, and tests of validity of this new measure. Individuals who scored high on the Relational-Interdependent Self-Construal (RISC) Scale characterized their important relationships as closer and more committed than did individuals who scored low on this measure (Study 1) and were more likely to take into account the needs and wishes of others when making decisions (Study 2). In Study 3, using a dyadic interaction paradigm with previously unacquainted participants, the partners of persons who scored high on the RISC scale viewed them as open and responsive to their needs and concerns; these perceptions were related to positive evaluations of the relationship.

Effect of membrane lipid composition on the conformational equilibria of the nicotinic acetylcholine receptor

The effects of cholesterol (Chol) and an anionic lipid, dioleoylphosphatidic acid (DOPA) on the conformational equilibria of the nicotinic acetylcholine receptor (nAChR) have been investigated using Fourier transform infrared difference spectroscopy. The difference between spectra recorded in the presence and absence of agonist from the nAChR reconstituted into 3:1:1 egg phosphatidylcholine (EPC)/DOPA/Chol membranes exhibits positive and negative bands that serve as markers of the structural changes associated with the resting to desensitized conformational change. These markers are absent in similar difference spectra recorded from the nAChR reconstituted into EPC membranes lacking both Chol and DOPA, indicating that the nAChR cannot undergo conformational change in response to agonist binding. When low levels of either Chol or DOPA up to 25 mol % of the total lipid are included in the EPC membranes, the markers suggest the predominant stabilization of a conformation that is a structural intermediate between the resting and desensitized states. At higher levels of either Chol or DOPA, the nAChR is stabilized in a conformation that is capable of undergoing agonist-induced desensitization, although DOPA appears to be required for the nAChR to adopt a conformation fully equivalent to that found in native and 3:1:1 EPC/DOPA/Chol membranes. The ability of these two structurally diverse lipids, as well as others (Ryan, S. E., Demers, C. N., Chew, J. P., Baenziger, J. E. (1996) J. Biol. Chem. 271, 24590-24597), to modulate the functional state of the nAChR suggests that lipids act on the nAChR via an indirect effect on some physical property of the lipid bilayer. The data also suggest that anionic lipids are essential to stabilize a fully functional nAChR. We propose that membrane fluidity modulates the relative populations of nAChRs in the resting and desensitized states but that subtle structural changes in the presence of anionic lipids are essential for full activity.

Internal dynamics of the nicotinic acetylcholine receptor in reconstituted membranes

The structure and 1H/2H exchange kinetics of affinity-purified nAChR reconstituted into egg phosphatidylcholine membranes with increasing levels of either dioleoylphosphatidic acid (DOPA) or cholesterol (Chol) have been examined using infrared spectroscopy. All spectra of the reconstituted nAChR membranes recorded after 72 h in 2H2O exhibit comparable amide I band shapes, suggesting a similar secondary structure for the nAChR in each lipid environment. Increasing levels of either DOPA or Chol, however, lead to an increasing intensity of the amide II band, indicating a decreasing proportion of nAChR peptide hydrogens that have exchanged for deuterium. Spectra recorded as a function of time after exposure of the nAChR to 2H2O show that the presence of either lipid slows down the 1H/2H exchange of those peptide hydrogens that normally exchange on the minutes to hours time scale. The slowing of peptide 1H/2H exchange correlates with both an increasing ability of the nAChR to undergo agonist-induced conformational change [Baenziger, J. E., Morris, M.-L., Darsaut, T. E., and Ryan, S. E. (1999) in preparation] and possibly a decreasing membrane fluidity. Our data suggest that lipid composition dependent changes in nAChR peptide 1H/2H exchange kinetics reflect altered internal dynamics of the nAChR. Lipids may influence protein function by changing the internal dynamics of integral membrane proteins.

Investigations of the taxonomy and systematics of Fusobacterium nucleatum using allozyme electrophoresis

Fusobacterium nucleatum forms part of the resident microbiota in both oral and extraoral sites in humans and animals. It is also involved in infections in such sites. Despite the genetic heterogeneity within the species, it has been divided into five subspecies, the validities of which have been questioned. In the present study, 44 F. nucleatum isolates were examined at 21 enzyme loci by using the allozyme electrophoretic technique to establish an accurate genetic framework for taxonomic purposes. Three distinct genetic clusters were identified; one cluster consisted exclusively of extraoral isolates, another cluster consisted predominantly of human oral isolates, and the third cluster consisted of a single human oral isolate. Our results highlight the urgent need for extensive biochemical, immunological, and epidemiological studies to accurately define the systematics of the genus fusobacterium based on the framework derived in this study by using 21 independent genetic characteristics.

The use of allozyme electrophoresis to assess genetic heterogeneity among previously subspeciated isolates of Fusobacterium nucleatum

Fusobacterium nucleatum has been implicated in the pathogenesis of periodontal diseases. Five subspecies have previously been proposed. The validity of these subdivisions was investigated using allozyme electrophoresis for 21 enzyme mobilities. The 18 F. nucleatum isolates tested had previously been subspeciated and included type strains as well as isolates from both oral and extraoral sites. The results showed 2 distinct genetic groups with fixed differences at 82.5% of the test loci, indicative of a species complex with a number of subspecies within each of the 2 groups. There was also evidence of a correlation between the 2 major groups of isolates and the site from which they were taken. It was concluded that there is a high degree of genetic heterogeneity within the species F. nucleatum and that its current subspeciation is of questionable validity.

The presence of an inhibitor of human skin collagenase in the roots of healthy and periodontally diseased teeth: changes that occur with age

The amount of anti-collagenase in the root has been reported in a group 18 to 35 years of age. Healthy roots had more than the diseased; and apical more than the cervical. The purpose of the present study is to determine the effect of age on these values. In a group 50 to 92 years of age, all values were markedly higher than in the younger group. In addition, all relationships between values were preserved. These include location and presence of disease. The higher levels might be due to an aging process or a protective defense against collagenase in the gingival crevice.

Praxis on verbal command and imitation

Nondysfunctional 4-year-old and 6-year-old children were administered the Praxis on Verbal Command subtest of the Sensory Integration and Praxis Tests (SIPT) (Ayres, 1989) under two conditions. One condition was administered in the standardized manner on verbal command; the other involved administration of the same items on imitation. An analysis of variance indicated that the variables of age and condition were significant, whereas sex was not significant. The Age x Condition interaction was also significant. Scheffé multiple comparisons revealed a significant difference between 4-year-olds and 6-year-olds on verbal command but not on imitation. Verbal-command scores were significantly lower than imitation scores for the 4-year-olds but not for the 6-year-olds.

Family studies of Alzheimer's dementia: results and prospects

Studies of families located through a proband with dementia of the Alzheimer type have demonstrated transmission of the disorder within families, probably through shared genes. Increasing closeness of genetic relationship and increasing severity of illness are both associated with increasing risk to relatives. Families at high risk are especially valuable for studies of the biology of dementing illness including, in particular, their molecular genetics. Associations at several levels between Down's syndrome and Alzheimer's dementia provide important clues for molecular hypotheses.

Seizures and myoclonus in patients with Alzheimer's disease

We reviewed 81 patients with dementia and autopsy findings of Alzheimer's disease (AD) to identify patients with seizures or myoclonus after onset of dementia. Eight (10%) had seizures, and eight others (10%) had myoclonus. The incidence of seizures was 10 times more than expected in a reference population. Seizures occurred in any stage of AD, but myoclonus was often a late manifestation. Both seizures and myoclonus, individually or together, are manifestations of AD and may be seen at any time in the course of the illness.

The inductive properties of human dentin and cementum

Studies of the inductive properties of human dentin and cementum have yielded differing results. Comparisons are difficult to draw because of variations in time, donor tissue, host immunologic status, implant site, decalcifying agents and degree of decalcification. Analysis of the many experiments intimates that the answers may lie in the use of citric acid and/or the degree of decalcification. The direction of future investigations is suggested.

Canine urolithiasis: diagnosis and treatment

Over 97% of all uroliths in males less than a year of age and in females are phosphate, excluding males with portosystemic shunts and male Dalmatians . Uroliths in male Dalmatians usually are composed of urate. Uroliths associated with Staphylococcus aureus urinary tract infection are phosphate. About 60% of uroliths in adult male Basset Hounds , Bulldogs , Chihuahuas , Irish Terriers and Yorkshire Terriers are cystine. In males of other breeds, as high as 60% of uroliths are phosphate. Feeding a calculolytic diet (s/d: Hill's) results in phosphate urolith dissolution in 2-20 weeks. Long-term feeding of the calculolytic diet is not recommended, nor is use after surgery and in pregnant, lactating or growing dogs and in those with heart failure, edema, ascites or pleural effusions. Uroliths recur in 20-50% of affected dogs without subsequent dietary alteration. Use of a urolith-prevention diet (u/d: Hill's) is recommended if urolithiasis recurs.

Treatment and prevention of feline struvite urolithiasis

A diet providing less than 20 mg of magnesium per 100 kcal that maintains urine pH near 6.0 3 to 5 hours after eating, or a diet providing this amount fo magnesium (see Table 2) with 1 gm of ammonium chloride or 1.5 gm of dl-methionine added daily, should be fed for 1 to 3 months to dissolve struvite uroliths (see Fig. 1). The low-magnesium diet should be fed indefinitely to prevent recurrence, because struvite urolithiasis and all of its effects (hematuria, pollakiuria, and/or complete to partial obstruction to urinary excretion) recurs repeatedly in cats that have previously experienced the condition if they are returned to regular cat food. In contrast, if a diet low in magnesium is fed, recurrence is uncommon. For cats that have never been affected, feeding a low-magnesium ration is unnecessary. For all cats, the following measures are recommended: encourage exercise, allow frequent urination, prevent obesity, decrease confinement, keep the litter box clean, and always have palatable water readily available.

The effect of marrow on the formation of "functionally" oriented collagen fibers

It has been shown that "functionally" oriented collagen fibers will attach to cementum when a healthy root fragment is implanted subcutaneously along with decalcified autogenous bone. The purpose of the present study was to test the effect of a strong bone grower (marrow) on this inductive system. Twenty-six composite grafts of healthy root, decalcified autogenous bone and marrow were implanted in thirteen 200 gm, female, white, Sherman-strain rats. Sixteen composite grafts without roots were similarly implanted, as controls, into eight animals. Postoperative periods ranged from 1 week to 8 months. With the exception of one section, the results showed that the addition of marrow prevented the formation of "functionally" oriented fibers. It is further evidence that strong bone formers do not produce a periodontium.

The effect of root decalcification on the formation of "functionally" oriented collagen fibers

It has been shown that "functionally" oriented collagen fibers will attach to cementum when a healthy root fragment is implanted subcutaneously in the rat along with decalcified autogenous bone. The purpose of the present study was to show how prior root decalcification affected this inductive action. Twenty-six pairs of bone and root were implanted in 13 200-gm, female, white, Sherman strain rats. The postoperative periods ranged from 1 week to 12 months. The results showed that root decalcification prevented formation of the "functionally" oriented fibers and inhibited bone induction by the decalcified autogenous bone. It was suggested that all roots have an inhibitor, the least amount in periodontally healthy roots and the most in periodontally diseased roots. It was suggested that the clinical successes in reattachment reported with acid treatment of roots were due to the denaturant effects rather than surface decalcification.

A new hypothesis of periodontal homeostasis

A review of the experimental evidence evidence on marrow inhibition by implanted roots has shown that an inhibitory factor is present in all root surfaces. It is most marked in periodontally diseased roots and least in periodontally healthy roots. It is hypothesized that a "marked" amount would inhibit periodontal cells to the point where they could not resist the destructive effects of plaque, calculus and bacteria. A lesser or "moderate" amount would result in a more resistant periodontium. Finally, little or no inhibitor would also create a periodontium resistant to periodontal destruction but at the same time would remove restraints on the alveolar bone; the result would be invasion of the periodontal space and ankylosis to the root.

The experimental induction of "functionally" oriented fibers attached to cementum

Decalcified autogenous bone induced the least amount of new bone yet observed. It also apparently helped to induce the formation of functionally oriented connective tissue fibers attached to cementum. Clinical trials are indicated.

The submucosal implantation of human allogeneic decalcified dentin

Decalcified human dentin was implanted into the buccal oral mucosa of 10 human volunteers and was later recovered for histologic examination. Extensive resorption took place. Bone did not form. Human dentinal matrix is not a bone inducer. Differences between the two methods of decalcification were not relevant.

The effects of root shape and biology on bone growth

A statistical study was carried out on the influence of root surfaces on adjacent cellular activity. This activity is indeed affected by both the shape and the biology of those surfaces. Flat surfaces tend to inhibit, nicked surfaces tend to stimulate bone formation in a bone-growing environment. A biologic effect is exerted by the matrix of diseases roots. They contain an inhibitory principle which is not present in healthy roots. This factor is masked by the apatite structure and is destroyed by heat.

An inhibitory principle in the matrix of periodontally diseased roots

The inhibitory influence shown by the periodontally diseased root resides in its organic component. Its nature is uncertain and it may be an etiologic factor in periodontal destruction. The apatite structures of healthy and diseased roots are alike in being more receptive to the growth of bone and marrow than are their respective matrices.