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Biomedical subjects

C M Mann

Publications and source records attributed to C M Mann.

At least 19 recordsLinked to original sources
PubMed2006

How much do medical students know about infection control?

Changes in undergraduate medical training mean that students have direct patient contact from an early stage of their training. This study aimed to assess the knowledge of third-year medical students at the University of Birmingham Medical School, UK on infection control policy and procedures. A semi-structured questionnaire was distributed to medical students. Out of 322 students, 156 returned completed questionnaires (48%). Results showed that 58% of medical students did not know the correct indications for using alcoholic hand gel, 35% did not know the correct use of gloves, and 50% did not know the exclusion period after an episode of diarrhoea and vomiting. Sixty-four percent of medical students reported formal teaching on hand hygiene, 12% reported informal teaching, 19% reported both types of teaching and 5% reported no hand hygiene teaching at all. Forty-nine percent of medical students thought that there was insufficient emphasis on infection control in their course. These results raised concerns about medical students' knowledge about infection control. The University is currently reviewing the need for a more structured model for the teaching and assessment of infection control.

Clinical Competence↗
PubMed2001

Interactions between components of the essential oil of Melaleuca alternifolia.

AIMS: This study compared the antimicrobial activity of Melaleuca alternifolia (tea tree) oil with that of some of its components, both individually and in two-component combinations. METHODS AND RESULTS: Minimum inhibitory concentration and time-kill assays revealed that terpinen-4-ol, the principal active component of tea tree oil, was more active on its own than when present in tea tree oil. Combinations of terpinen-4-ol and either gamma-terpinene or p-cymene produced similar activities to tea tree oil. Concentration-dependent reductions in terpinen-4-ol activity and solubility also occurred in the presence of gamma-terpinene. CONCLUSION: Non-oxygenated terpenes in tea tree oil appear to reduce terpinen-4-ol efficacy by lowering its aqueous solubility. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings explain why tea tree oil can be less active in vitro than terpinen-4-ol alone and further suggest that the presence of a non-aqueous phase in tea tree oil formulations may limit the microbial availability of its active components.

Anti-Infective Agents, Local↗
PubMed2000

The mode of antimicrobial action of the essential oil of Melaleuca alternifolia (tea tree oil).

The essential oil of Melaleuca alternifolia (tea tree) exhibits broad-spectrum antimicrobial activity. Its mode of action against the Gram-negative bacterium Escherichia coli AG100, the Gram-positive bacterium Staphylococcus aureus NCTC 8325, and the yeast Candida albicans has been investigated using a range of methods. We report that exposing these organisms to minimum inhibitory and minimum bactericidal/fungicidal concentrations of tea tree oil inhibited respiration and increased the permeability of bacterial cytoplasmic and yeast plasma membranes as indicated by uptake of propidium iodide. In the case of E. coli and Staph. aureus, tea tree oil also caused potassium ion leakage. Differences in the susceptibility of the test organisms to tea tree oil were also observed and these are interpreted in terms of variations in the rate of monoterpene penetration through cell wall and cell membrane structures. The ability of tea tree oil to disrupt the permeability barrier of cell membrane structures and the accompanying loss of chemiosmotic control is the most likely source of its lethal action at minimum inhibitory levels.

Anti-Bacterial Agents↗
PubMed2000

The outer membrane of Pseudomonas aeruginosa NCTC 6749 contributes to its tolerance to the essential oil of Melaleuca alternifolia (tea tree oil).

Pseudomonas aeruginosa is less susceptible to the antimicrobial properties of tea tree oil than many bacteria and its tolerance is considered to be due to its outer membrane. Polymyxin B nonapeptide (PMBN), which has no antibacterial action, was used to permeabilize the outer membrane. The addition of PMBN to Ps. aeruginosa NCTC 6749 markedly increased this organism's susceptibility to tea tree oil and to its normally inert hydrocarbons, p-cymene and gamma-terpinene.

Anti-Infective Agents, Local↗
PubMed1998

A new method for determining the minimum inhibitory concentration of essential oils.

A new microdilution method has been developed for determining the minimum inhibitory concentration (MIC) of oil-based compounds. The redox dye resazurin was used to determine the MIC of a sample of the essential oil of Melaleuca alternifolia (tea tree) for a range of Gram-positive and -negative bacteria. Use of 0.15% (w/v) agar as a stabilizer overcame the problem of adequate contact between the oil and the test bacteria and obviated the need to employ a chemical emulsifier. A rapid version of the assay was also developed for use as a screening method. A comparison of visual and photometric reading of the microtitre plates showed that results could be assessed without instrumentation; moreover, if the rapid assay format was used, rigorous asepsis was not necessary. Accuracy of the resazurin method was confirmed by plate counting from microwells and MIC values were compared with results obtained using an agar dilution assay. The MIC results obtained by the resazurin method were slightly lower than those obtained by agar dilution.

Gram-Negative Bacteria↗
PubMed1998

Redistribution of pulmonary blood flow during unilateral hypoxia in prone and supine dogs.

We used fluorescent-labeled microspheres in pentobarbital-anesthetized dogs to study the effects of unilateral alveolar hypoxia on the pulmonary blood flow distribution. The left lung was ventilated with inspired O2 fraction of 1.0, 0.09, or 0.03 in random order; the right lung was ventilated with inspired O2 fraction of 1.0. The lungs were removed, cleared of blood, dried at total lung capacity, then cubed to obtain approximately 1,500 small pieces of lung ( approximately 1.7 cm3). The coefficient of variation of flow increased (P < 0.001) in the hypoxic lung but was unchanged in the hyperoxic lung. Most (70-80%) variance in flow in the hyperoxic lung was attributable to structure, in contrast to only 30-40% of the variance in flow in the hypoxic lung (P < 0.001). When adjusted for the change in total flow to each lung, 90-95% of the variance in the hyperoxic lung was attributable to structure compared with 70-80% in the hypoxic lung (P < 0.001). The hilar-to-peripheral gradient, adjusted for change in total flow, decreased in the hypoxic lung (P = 0.005) but did not change in the hyperoxic lung. We conclude that hypoxic vasoconstriction alters the regional distribution of flow in the hypoxic, but not in the hyperoxic, lung.

Animals↗
PubMed1997

The 're-do' chest wall deformity correction.

BACKGROUND: A small percentage of patients who undergo surgical correction of a chest wall deformity will have results so unsatisfactory that a second procedure, the so-called "re-do," will be required. CONCLUSIONS: The literature contains very little information regarding the technique and results of these procedures. Based on experience with 18 "re-do" procedures, the authors believe that recurrent deformities should be surgically corrected. Although this is a somewhat diverse group based on age at the first and second procedure, type of original operative procedure, and interval between the procedures, the operative approach is standard, and the results are predictable.

Adolescent↗
PubMed1996

Significance of chest trauma in children.

Chest trauma in children is a marker of injury severity and is associated with a high mortality rate. This retrospective study of 1,356 trauma patients from a private pediatric hospital over a 2.5-year period identified 82 patients with chest injuries and a mortality rate of 22%. Results of Injury Severity Score, Glasgow Coma Scale, and Revised Trauma Score all indicated that children with chest injuries sustained more severe injuries. The presence of any extrathoracic injury was associated with a higher mortality (29%) than chest injury alone (4.3%). The type of extrathoracic injury was important, with head and neck injuries resulting in the highest mortality. Specific chest injuries, such as rib fractures and pulmonary contusions, were not related to increased mortality unless there was an associated extrathoracic injury. Many reports have shown a high mortality associated with chest trauma. This study suggests that it is the associated extrathoracic injury, rather than the chest injury itself, that is the real cause of the high mortality.

Abdominal Injuries↗
PubMed1995

A combined hospital experience with fundoplication and gastric emptying procedure for gastroesophageal reflux in children.

BACKGROUND: Operative treatment of symptomatic gastroesophageal reflux (GER), often together with neurologic feeding disorders, is very common in infancy and childhood. Delayed gastric emptying (DGE) has been observed frequently in association with GER in children. STUDY DESIGN: A retrospective review was performed on 1,200 consecutive patients 18 years of age and younger operated upon for symptomatic GER or neurologic feeding disorders, or both, at two pediatric surgery centers in widely separated geographic areas in the United States of America, to compare the results after fundoplication with or without a gastric emptying procedure (GEP). RESULTS: Operations included gastroesophageal fundoplication (GEF) alone (871 patients), GEF plus GEP (286 patients), reoperative GEF plus GEP (30 patients), and GEP alone (13 patients). Thus, 27 percent of the total and 40 percent of the last 494 children with reflux had a GEP. Delayed gastric emptying with retention of more than 60 percent of an isotope meal appropriate for age at 90 minutes was present in 241 of the 451 children with reflux studied. Major neurologic disorders were present in 219 (25 percent) of 871 children who underwent GEF alone and in 247 (75 percent) of 329 children who had a GEP. All patients operated upon from both hospitals were relieved of recurrent emesis, and those with failure to thrive showed significant weight gain; pulmonary symptoms were relieved in 94 percent. Recurrent GER developed in 47 (5.2 percent) of 901 children who had GEF alone, but in only four (1.2 percent) of 329 patients who had a GEP. CONCLUSIONS: The excellent clinical results with low morbidity in this largest reported clinical experience with GEP in childhood suggest that a GEP should be combined with GEF for symptomatic children who have both GER and DGE. Minimal investigative studies are necessary for most neurologically impaired children who require a feeding gastrostomy.

Adolescent↗
PubMed1991

The effect of tube gastrostomy on gastroesophageal reflux in patients with esophageal atresia.

Gastroesophageal reflux (GER) occurs frequently in infants with esophageal atresia (EA). The definitive management is primary repair and often includes tube gastrostomy. The recent finding of lower esophageal sphincter (LES) pressure changes with tube gastrostomy suggests that GER might be related to gastrostomy rather than EA per se. To evaluate this thesis, two populations of patients from different children's hospitals were reviewed: EA with and without routine gastrostomy. The two populations were similar with respect to number of infants, associated anomalies, distribution in the Waterston classification, morbidity, and mortality. One hundred sixteen patients were studied. Of the 66 survivors who underwent gastrostomy and repair of EA, 30 were found to have GER (45.5%) and 12 required fundoplication (18.2%). Of 31 surviving patients who underwent repair of EA without gastrostomy, 11 had GER (35.5%) and four required fundoplication (12.9%). These data suggest that tube gastrostomy does not significantly contribute to the GER associated with EA.

Esophageal Atresia↗
PubMed1987

Validation of a colorimetric method for determination of atmospheric formaldehyde.

Aqueous formaldehyde was stabilized in pH 7 phosphate buffer with excess sodium bisulfite of fixed and known concentration. The 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) procedure described previously was used to determine excess bisulfite colorimetrically. The slope of the calibration line (absorbance at 412 nm vs. formaldehyde concentration) is -0.350 A.U./ug CH2O/mL (correlation coefficient: 0.9995). The precision of the method at the 95% confidence level is indicated by the mean percentage relative error (1.81 +/- 1.67) and mean percentage standard error (0.42 +/- 0.39). Gaseous formaldehyde of known concentrations (ppm) in air was absorbed from air samples in pH 7 buffer and determined by the DTNB method. For the determination of formaldehyde in air, the precision and accuracy were demonstrated at the 95% confidence level by the mean percentage relative error (5.04 +/- 3.2), the mean percentage standard error (1.72 +/- 1.0), the mean percentage recovery (99.9 +/- 2.7), and the mean percentage absolute error (1.86 +/- 1.6). The graphic comparison of air concentration found vs. air concentration calculated shows a slope of 0.993 ppmfound/ppmcalcd (correlation coefficient: 0.9993).

Air Pollutants↗
PubMed1981

Voiding abnormalities in children: methods of evaluation and results of treatment.

Recent advances in technology have fueled interest in the field of urodynamics and have made possible accurate diagnosis of voiding abnormalities in children. A thorough understanding of the underlying physiology and institution of the appropriate pharmacologic agents and/or teaching techniques results in correction of the underlying problems in 90% of the cases. Symptoms, techniques of diagnosis, therapeutic regimens, and results of therapy are presented.

Adolescent↗