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Biomedical subjects

M T Kelly

Publications and source records attributed to M T Kelly.

At least 19 recordsLinked to original sources
PubMed1992

Analysis of terbutaline in human plasma by high-performance liquid chromatography with electrochemical detection using a micro-electrochemical flow cell.

A high-performance liquid chromatographic method is described for the determination of terbutaline in human plasma in the range 1-35 ng/ml. Detection was achieved using a carbon fibre micro-electrochemical detector and a column-switching system. The microelectrode cell has advantages over conventional glassy carbon electrode-based detection systems in that it is easy to prepare, flexible in its operation and suffers less trouble from problems such as air bubbles and leaks. Furthermore, it has a better detection limit for terbutaline (0.8 ng/ml) to that obtained using a conventional glassy carbon electrode flow detector (2 ng/ml). Sample clean-up was by on-line solid-phase extraction with column switching, providing a method which was sensitive and reproducible, where the mean overall coefficient of variation was 5.60% and drug recovery in excess of 86% at the concentration levels studied.

Calibration↗
PubMed1992

Sodium hypochlorite disinfection of irreversible hydrocolloid impression material.

Alginate impression material is one of the most frequently used in dentistry. However, this material is susceptible to dimensional distortion during disinfection because of its hydrophilic nature. This study examined the effects of alginate disinfection using a sodium hypochlorite spray or impression immersion. Spray disinfection of an alginate impression did not cause dimensional differences of the poured stone casts when compared with casts from water-rinsed controls. Immersion disinfection created dimensional distortion of the anterior, posterior, and interarch model segments. Both the spray and immersion treatments equally decreased the surface detail reproducibility. The antimicrobial effects of the spray treatment were similar to those of the immersion treatment, while mere water rinsing resulted in inadequate disinfection.

Aerosols↗
PubMed1992

Thermal properties of a methyl methacrylate-based orthodontic bonding adhesive.

Methyl methacrylate-based (MMA-based) bonding resins have been used in orthodontics because they offer easy removal of both the bonded bracket and the residual adhesive at case completion. However, these materials are not cross-linked, and the brackets bonded with this type of product may undergo drifting when subjected to temperatures slightly higher than those in the mouth. This research investigated the influence of heat on the debonding characteristics of a MMA-based bonding resin compared with those of a BIS-GMA-based system. The temperature of initial bracket movement, as well as of final bracket displacement, was noted for a variety of applied loads (141, 226, 425, 934, and 1727 gm) with stainless steel brackets bonded to etched bovine enamel. The results showed that the MMA-based material underwent a glass transition near 47 degrees C in which the initiation of bracket drift resulted on the tooth surface. This temperature proved independent of the applied load. Further heating resulted in the release of heat from the resin as a result of further curing. The extent of bracket drift associated with this secondary heat release was dependent on the applied load. The debonding temperature of the BIS-GMA-based system was three to six times greater than that of the MMA-based product. Practitioners should be aware that brackets bonded with MMA-based resins have the potential for drifting when subjected to temperatures within the normal range of hot fluids consumed by their patients. Bracket drift could result in deactivation of orthodontic force and could prolong the treatment time.

Adhesives↗
PubMed1992

Comparison of a direct fecal Shiga-like toxin assay and sorbitol-MacConkey agar culture for laboratory diagnosis of enterohemorrhagic Escherichia coli infection.

A direct fecal Shiga-like toxin assay (DSLTA) was used to prospectively screen 9,449 unselected stool samples, received at the British Columbia Provincial Health Laboratories and the Metropolitan Laboratories of Vancouver, for Shiga-like toxin I and Shiga-like toxin II. The results were compared with results of routine stool culture on sorbitol-MacConkey agar (SMAC) for Escherichia coli O157:H7. Of 80 specimens positive by either method, 59 (74%) and 74 (93%) were positive by SMAC and DSLTA, respectively; 53 (66%) were positive by both methods, 21 (26%) were positive by DSLTA only, and 6 (7%) were positive by SMAC only. On further screening, Shiga-like toxin-producing E. coli were detected in 8 (38%) of the 21 stools positive by DSLTA only, including serotypes O157:H7 (1 stool), O26:K60 (5 stools), O128:K67 (1 stool), and O103:H2 (1 stool). For the remaining 13 stools in which no SLTEC was found but DSLTA was positive, clinical information revealed that 11 of 12 patients had diarrheal illnesses, and 4 of these 11 had bloody diarrhea or hemolytic-uremic syndrome. Stools positive only by SMAC were collected earlier in the illness than stools positive by DSLTA, suggesting that free fecal toxin levels may be too low to detect at this time. Overall we found that DSLTA detected 19% more positive specimens than SMAC and that Shiga-like toxin-producing E. coli serotypes other than E. coli O157:H7 are causing disease in the province of British Columbia, Canada.

Bacterial Toxins↗
PubMed1992

Evaluation of the Autoscan Walkaway system for rapid identification and susceptibility testing of gram-negative bacilli.

We evaluated the performance of the Autoscan Walkaway (W/A) system (MicroScan, Sacramento, Calif.) in conjunction with the fluorometric Neg Combo panels for rapid identification and susceptibility testing of gram-negative bacilli. Fermentative and nonfermentative gram-negative bacilli were tested in parallel with the W/A system and the Cathra Repliscan replicator (C/R) system (Cathra, St. Paul, Minn.). Conventional biochemical testing and agar dilution testing were used to resolve the identification and susceptibility testing discrepancies. Of 495 clinical isolates tested, 445 (90%) were correctly identified by the W/A system and 483 (98%) were correctly identified by the C/R system. Repeat testing by using updated versions of the W/A system's computer identification software failed to demonstrate improved identification accuracy. For susceptibility testing, the W/A system demonstrated 5.6% total interpretative category errors, including only 0.9% major and very major errors. The comparative C/R system produced only 1% errors overall, including 0.2% major and very major errors. Although the W/A system is highly automated and is capable of producing results rapidly, our findings suggest that additional identification and susceptibility testing refinements are needed before the system will be suitable for routine use.

Anti-Bacterial Agents↗
PubMed1992

Characterization of a DNA probe for detection of Mycobacterium tuberculosis complex in clinical samples by polymerase chain reaction.

We cloned and sequenced a DNA fragment from Mycobacterium tuberculosis for use in the identification of members of the M. tuberculosis complex. The DNA probe for culture confirmation had a sensitivity and a specificity of 100%. By using primers developed from this probe, the polymerase chain reaction detected 20 mycobacteria by ethidium bromide staining. This polymerase chain reaction system demonstrated 98% sensitivity and 100% specificity for detection of the M. tuberculosis complex in 200 sputum specimens.

Bacteriological Techniques↗
PubMed1991

Biochemical characteristics and plasmids of clinical and environmental Plesiomonas shigelloides.

The biochemical characteristics of 68 clinical and 5 environmental Plesiomonas shigelloides isolates were determined. The reactions for ONPG, phenylalanine deaminase, motility, lactose fermentation and salicin fermentation were different from previously published findings. The reactions of the clinical and environmental isolates were very similar. The isolates were also tested for the presence of plasmids, and 40% of the strains were found to harbor between one and seven plasmids. The findings of this study will be useful for the identification and characterization of this recently recognized enteric pathogen.

Animals↗
PubMed1991

High-performance liquid chromatographic determination of nifedipine, nicardipine and pindolol using a carbon fibre flow-through amperometric detector.

The electrochemical properties of the calcium-channel blockers, nifedipine and nicardipine, and the beta-blocking agent, pindolol, have been exploited for the determination of their concentrations in plasma samples. High-performance liquid chromatography (HPLC) separation was carried out on a cyanopropyl modified column and the drugs were detected in a flow-through carbon fibre microelectrode cell. The chromatographic system was coupled to a column-switching arrangement in order to perform on-line solid-phase extraction of the drugs from spiked human plasma. Preliminary investigations showed the response of the method to be linear over a range of 20-500 ng ml-1 in plasma with a limit of detection of approximately 15 ng ml-1 for each compound.

Carbon↗
PubMed1991

Etiology of childhood diarrhea in Beijing, China.

To determine the role of recently recognized enteropathogens in childhood diarrhea in China, 221 children with diarrhea and 108 controls seen at the Beijing Children's Hospital were studied during April and May 1989. Stools were examined for ova, parasites, and rotavirus, cultured for bacterial pathogens, and probed for enterotoxigenic Escherichia coli (ETEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC), and enteropathogenic adherence factor-positive (EAF+) E. coli. Pathogens were identified in 56.5% of children with diarrhea and 43.5% of controls (P = 0.04). Detection of enteropathogens was significantly greater in patients examined within 1 week of symptom onset (65%) than in patients examined later (39%; P = 0.01). ETEC was the most frequently detected pathogen in children with diarrhea, accounting for 20% of the cases. Other agents identified in patients included the following: salmonellae, 12%; rotavirus, 7%; EIEC, 7%; EHEC, 7%; members of the Aeromonas hydrophila group, 6%; EAF+ E. coli, 5%; Ascaris lumbricoides, 3%; shigellae, 3%; campylobacters, 2%; and Vibrio spp., 0.5%. The isolation rates of salmonellae (P = 0.02), EAF+ E. coli (P = 0.04), and mixed pathogens (P = 0.05) were significantly greater for diarrhea patients than for controls. Resistance to multiple antimicrobial agents occurred in 39% of the Salmonella isolates, 22% of the Aeromonas isolates, and 17% of the Shigella isolates. Multiresistant salmonellae (P = 0.05) and shigellae were recovered from diarrheal stools only. Ciprofloxacin, cefotaxime, and imipenem were the only agents tested to which all bacterial isolates were susceptible in vitro. These results suggest that both traditional and newly recognized agents are important causes of childhood diarrhea in Beijing and that therapy may be complicated by indigenous antimicrobial resistance.

Child, Preschool↗
PubMed1990

High-performance liquid chromatographic method for the comparison of tanning capacity of tannic acid batches used in the manufacture of pregnancy testing kits.

A high-performance liquid chromatographic (HPLC) method was developed for the quantitative comparison of various batches of tannic acid from the same manufacturer used to aid the binding of human chorionic gonadotropin to sheep erythrocytes in the manufacture of pregnancy testing kits. The tannic acids were separated by reversed-phase HPLC on a C18 column using gradient elution with aqueous methanolic eluents at low pH. A portion of the chromatogram corresponding to the compounds involved in the tanninisation process was integrated and a linear relationship was established between this peak area and tannic acid concentration. The correlation coefficient was greater than 0.993 even in the absence of an internal standard. Tanning capacity was evaluated on the basis of the amount of tannic acid which remained following incubation with a known quantity of erythrocytes. The application of this procedure to three batches of tannic acid is demonstrated.

Chromatography, High Pressure Liquid↗
PubMed1990

Evaluation of drug-free plasma profiles by high-performance liquid chromatography following on-line solid-phase extraction.

The effect of varying the type of column and eluent composition on drug-free plasma profiles was investigated. The study was based on a C18 and a CN column; methanol and acetonitrile were the organic modifiers used. The plasma profiles were evaluated quantitatively by measuring the number of interfering peaks greater than 8 . 10(-4) absorbance units in the area of interest along the chromatogram. Results were subjected to statistical treatment using a three-factor analysis of variance design. The three factors were the column, the type of organic modifier and either the percentage organic modifier, the pH or the ionic strength. Analysis of the data revealed that significant effects were seen with changing eluent composition, particularly with regard to the percentage of organic modifier, and that the observed effects were strongly dependent on the type of column and the type of organic modifier under consideration.

Acetonitriles↗
PubMed1990

Clinical comparison of isolator and BACTEC 660 resin media for blood culture.

The 10-ml Isolator system (E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.) was compared with the BACTEC 16A-17A nonradiometric resin system (Johnston Laboratories, Inc., Towson, Md.) for isolation of organisms from 6,839 paired blood cultures. Equal volumes of blood (6 to 10 ml for each Isolator and 3 to 5 ml for each BACTEC bottle) were cultured in parallel in the two systems, and 600 isolates that were judged to be clinically significant by chart review were recovered during the study. The BACTEC resin system detected 510 (85%) and the Isolator system detected 435 (72%) of the clinically significant isolates (P less than 0.001). Of 45 polymicrobial blood cultures, the BACTEC system detected 32 (71%) and the Isolator system detected 21 (47%) (P less than 0.05). Of 253 gram-negative bacilli isolated during the study, 30% were detected only in the BACTEC system and 16% were detected only in the Isolator system (P less than 0.001), and of 56 nonfermentative or fastidious gram-negative bacilli detected, 46% were recovered only in the BACTEC system, while 14% were detected only in the Isolator system (P less than 0.001). Of 86 streptococci isolated during the study, 30% were detected only in the BACTEC system, and 4% were detected only in the Isolator system (P less than 0.001). Recoveries of anaerobic bacteria, staphylococci, and yeasts were equivalent in the two systems. Organisms judged to be contaminants were detected in approximately 1% of the cultures in each system. The results suggest that use of resin media renders the BACTEC nonradiometric system equivalent or superior to the Isolator system for detection of clinically significant organisms in blood cultures.

Blood↗
PubMed1989

Retention characteristics in high-performance liquid chromatography of basic drugs and plasma extracts on an alumina column.

The retention characteristics of 35 drugs on an alumina column using buffered aqueous methanolic mobile phases have been investigated. It has been shown that the effect of pH on retention depends on the pKa of the drug and the type of buffer ion used; that there is an inverse relation between ionic strength and solute retention; and that a decrease in the amount of methanol in the mobile phase causes the drugs to be held longer on the column. The chromatographic system was also coupled to an on-line column-switching assembly to facilitate extraction of the drugs from plasma, and results are presented which indicate that the alumina column lends itself well to this convenient method of plasma clean-up.

Chromatography, High Pressure Liquid↗
PubMed1989

A comparison of silica and alumina columns for high-performance liquid chromatographic separations of basic drugs and plasma constituents following on-line solid-phase extraction with column switching.

A comparison has been made of a silica and an alumina column with respect to retention behaviour in high-performance liquid chromatography of pure drug solutions and plasma profiles following on-line solid-phase extraction. Using methanol-ammonium nitrate buffer (80:20, v/v) as eluent, it was found that these systems lend themselves well to the column switching technique. Increasing the pH of the mobile phase produced similar shifts in retention for basic drugs on both columns, but fewer plasma interferents are retained on the alumina column as compared to the silica column under the same operating conditions.

Aluminum Oxide↗
PubMed1989

Antimicrobial susceptibility of Plesiomonas shigelloides from patients with diarrhea.

Antimicrobial susceptibility testing was performed on 72 fecal isolates of Plesiomonas shigelloides from patients with diarrhea by using a standard agar dilution technique. All isolates were obtained from a single geographic location. Based on the in vitro activities demonstrated in this study, norfloxacin, ciprofloxacin, and trimethoprim may be effective as oral agents in the treatment of P. shigelloides diarrheal disease. For the parenteral treatment of extraintestinal infection, netilmicin and the cephalosporins had the best in vitro activity.

Anti-Bacterial Agents↗
PubMed1989

Urease-positive, Kanagawa-negative Vibrio parahaemolyticus from patients and the environment in the Pacific Northwest.

We previously reported the occurrence of Vibrio parahaemolyticus in patients and the environment in the Pacific Northwest. The present studies compare the biochemical characteristics, Kanagawa hemolysin reactions, and plasmid profiles of 13 patient and 221 environmental isolates of the organism. Classical biochemical testing of the isolates revealed similar reactions for the clinical and environmental strains, and analysis in agarose gels revealed that 13 to 15% of the isolates had plasmids. The strains were tested for production of Kanagawa hemolysin on Wagatsuma agar, and 1.4% of environmental isolates and 23% of clinical isolates were positive. Clinical isolates from locally acquired extraintestinal infections were urease negative and Kanagawa hemolysin negative, isolates from locally acquired gastroenteritis cases were urease positive and Kanagawa negative, and isolates from traveler's diarrhea were urease negative and Kanagawa positive. Eight percent of the local environmental isolates were also urease positive and Kanagawa hemolysin negative. These findings suggest that expression of the Kanagawa hemolysin is not essential for the pathogenesis of V. parahaemolyticus infections. In addition, our findings suggest that V. parahaemolyticus gastroenteritis in the Pacific Northwest is associated with a urease-positive, Kanagawa-negative biotype of the organism.

Animals↗
PubMed1989

Clinical features, epidemiology, and treatment of Plesiomonas shigelloides diarrhea.

Recent studies have suggested that Plesiomonas shigelloides is a cause of diarrhea. The present study addresses the clinical features, epidemiology, and response to antimicrobial therapy of P. shigelloides diarrhea. Thirty cases of P. shigelloides infection were defined by isolation of the organism from stool specimens, and 30 age-matched control patients were identified by detection of other enteric pathogens. Clinical and epidemiological information was obtained by interviewing the referring physicians and the patients. Of the P. shigelloides-infected patients, 71% had a history of recent tropical travel, but 29% acquired their infections locally in association with the consumption of seafood or untreated water or both. Seventy-eight percent of the P. shigelloides-infected patients had findings suggestive of colitis, and P. shigelloides-infected patients had a history of tropical travel, acute illness, abdominal pain, and prolonged symptoms significantly more often than did the control patients. Antimicrobial therapy significantly reduced the duration of illness in patients with Plesiomonas diarrhea. These results suggest that P. shigelloides is a significant cause of both locally acquired and traveler's diarrhea that may respond to antimicrobial therapy.

Adolescent↗