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Biomedical subjects

M C Hansen

Publications and source records attributed to M C Hansen.

17 recordsLinked to original sources
PubMed2002

The effects of passive smoking on olfaction in children.

The effect of passive smoking on odor identification was studied in 10 children exposed to passive smoke at home. All had at least one parent who smoked at least one pack of cigarettes a day. The control group consisted of 10 children of nonsmoking parents. Ten odorants were tested: vinegar, ammonia, peppermint, roses, bleach, vanilla, cough drops, turpentine, licorice and mothballs. Each child was presented with five test trays containing all 10 odorants in random order. Of the total of 500 odors presented, the control group correctly identified 396 (79%) and the study group, 356 (71%) (p < 0.005). This work demonstrates that children exposed to passive smoke have difficulty identifying odors in comparison to children raised in relatively smoke-free environments. Since the study group tend to misidentify four of the 10 odorants tested--vanilla, roses, mothballs and cough drops--we suggest that these four odorants should suffice in testing odor identification in children.

Adolescent↗
PubMed2001

Mutualism versus independence: strategies of mixed-species oral biofilms in vitro using saliva as the sole nutrient source.

During initial dental plaque formation, the ability of a species to grow when others cannot would be advantageous, and enhanced growth through interspecies and intergeneric cooperation could be critical. These characteristics were investigated in three coaggregating early colonizers of the tooth surface (Streptococcus gordonii DL1, Streptococcus oralis 34, and Actinomyces naeslundii T14V). Area coverage and cell cluster size measurements showed that attachment of A. naeslundii and of S. gordonii to glass flowcells was enhanced by a salivary conditioning film, whereas attachment of S. oralis was hindered. Growth experiments using saliva as the sole carbon and nitrogen source showed that A. naeslundii was unable to grow either in planktonic culture or as a biofilm, whereas S. gordonii grew under both conditions. S. oralis grew planktonically, but to a much lower maximum cell density than did S. gordonii; S. oralis did not grow reproducibly as a biofilm. Thus, only S. gordonii possessed all traits advantageous for growth as a solitary and independent resident of the tooth. Two-species biofilm experiments analyzed by laser confocal microscopy showed that neither S. oralis nor A. naeslundii grew when coaggregated pairwise with S. gordonii. However, both S. oralis and A. naeslundii showed luxuriant, interdigitated growth when paired together in coaggregated microcolonies. Thus, the S. oralis-A. naeslundii pair formed a mutualistic relationship, potentially contact dependent, that allows each to grow where neither could survive alone. S. gordonii, in contrast, neither was hindered by nor benefited from the presence of either of the other strains. The formation of mutually beneficial interactions within the developing biofilm may be essential for certain initial colonizers to be retained during early plaque development, whereas other initial colonizers may be unaffected by neighboring cells on the substratum.

Actinomyces↗
PubMed2001

Changes in rRNA levels during stress invalidates results from mRNA blotting: fluorescence in situ rRNA hybridization permits renormalization for estimation of cellular mRNA levels.

Regulation of gene expression can be analyzed by a number of different techniques. Some techniques monitor the level of specific mRNA directly, and others monitor indirectly by determining the level of enzymes encoded by the mRNA. Each method has its own inherent way of normalization. When results obtained by these techniques are compared between experiments in which differences in growth rates, strains, or stress treatments occur, the normalization procedure may have a significant impact on the results. In this report we present a solution to the normalization problem in RNA slot blotting experiments, in which mRNA levels routinely are normalized to a fixed amount of extracted total RNA. The cellular levels of specific mRNA species were estimated using a renormalization with the total RNA content per cell. By a combination of fluorescence in situ rRNA hybridization, which estimates the relative level of rRNA per cell, and slot blotting to rRNA probes, which estimates the level of rRNA per extracted total RNA, the amount of RNA per cell was calculated in a series of heat shock experiments with the gram-positive bacterium Lactococcus lactis. It was found that the level of rRNA per cell decreased to 30% in the course of the heat shock. This lowered ribosome level led to a decrease in the total RNA content, resulting in a gradually increasing overestimation of the mRNA levels throughout the experiment. Using renormalized cellular mRNA levels, the HrcA-mediated regulation of the genes in the hrcA-grpE-dnaK operon was analyzed. The hybridization data suggested a complex heat shock regulation indicating that the mRNA levels continued to rise after 30 min, but after renormalization the calculated average cellular levels exhibited a much simpler induction pattern, eventually attaining a moderately increased value.

Cell Membrane Permeability↗
PubMed2001

Effects of passive smoking on odour identification in children.

BACKGROUND AND OBJECTIVE: The effect of passive smoking on odour identification in children has rarely been reported. This study assessed the ability of such young subjects to identify a variety of odours. METHODS: The study population consisted of 20 children, 10 who were exposed to passive smoke at home and 10 with nonsmoking parents. Ten odourants were tested: vinegar, ammonia, peppermint, roses, bleach, vanilla, cough drops, turpentine, licorice, and mothballs. Each child was presented with five test trays containing all 10 odourants in random order. RESULTS: Of the total of 500 odours presented, the control group correctly identified 396 (79%) and the study group identified 356 (71%) (p < .005). The study group tended to misidentify 4 of the 10 odourants tested, namely, vanilla, roses, mothballs, and cough drops-56 of 200 (28%), compared with 96 of 200 (48%) in the control group. This was a highly significant finding (p < .0005). CONCLUSION: This work demonstrated that children exposed to passive smoke have difficulty identifying odours in comparison with children raised in relatively smoke-free environments. The identification of four odourants, vanilla, roses, mothballs, and cough drops, was particularly diminished in this study group.

Adolescent↗
PubMed2000

A method for the asymmetric hydrosilylation of N-aryl imines.

[reaction: see text] The asymmetric reduction of N-aryl imines to yield chiral amines with enantiomeric excesses above 90% was achieved. Ethylenebis(eta5-tetrahydroindenyl)titanium difluoride ((EBTHI)TiF2, 1) was employed as the precatalyst with polymethylhydrosiloxane (PMHS) as the stoichiometric reducing agent. A variety of N-aryl imines derived from nonaromatic ketones were reduced with high ee.

Imines↗
PubMed2000

Flowcell culture of Porphyromonas gingivalis biofilms under anaerobic conditions.

We have developed an anaerobic biofilm culture system. The system is inexpensive, simple to use and, unlike an anaerobic glovebox, requires no dedicated space. As a test of the system, Porphyromonas gingivalis was cultured under low oxygen (1-2 ppm) and under anaerobic conditions (</=0.1 ppm O(2)). In the presence of small amounts of oxygen, the organism attached and formed an initial biofilm over the course of 4 h, but the biofilm was unable to maintain its growth and had lost biomass after 18 h. Also, ambiguous results were obtained when the biofilm was stained with a viability stain. Under anaerobic conditions, the biofilm was able to continue growth - biomass was greater after 18 h than after 4 h, and the anaerobic biofilm had a less ambiguous staining pattern than did the low-O(2)-grown biofilm.

Anaerobiosis↗
PubMed1998

Integrating students into interdisciplinary teams: extending the caring circle.

Interdisciplinary teams are considered essential for meeting the health care delivery challenges of the 21st century. Integrating students into these teams is critical to attracting and sustaining a future workforce with the knowledge and skills to maximize health care outcomes. This article describes a caring circle approach to interdisciplinary teams that promotes student learning and benefits the team. The caring circle is based on building relationships through shared knowledge, shared practices, and shared values. Specific strategies to build the caring circle using these building blocks are discussed.

Education, Nursing, Baccalaureate↗
PubMed1998

Navigating the barrier reef: QEE to successful restructuring.

This article chronicles the barriers encountered as a multidisciplinary department undertook management restructuring. Barriers that are addressed include lack of a sense of urgency; confusion and fear regarding the changing roles of both staff and managers; insufficient development of coaching skills; and lack of alignment of performance appraisals, outcomes, and rewards. Insights gained and strategies to deal with these barriers are discussed.

Attitude of Health Personnel↗
PubMed1995

Temporal bone fractures.

The diagnosis and monitoring of patients presenting to an emergency department with blunt temporal bone fracture and complications requiring acute management were reviewed for a four-month period. Of 104 trauma patients with closed head injury, 15 patients were diagnosed with temporal bone fracture, 12 of whom survived their injuries. Four patients developed cerebrospinal fluid (CSF) otorrhea and two patients developed facial nerve paralysis; all patients had resolution of complications with conservative management. Significant shortcomings in the initial evaluation and monitoring of patients with temporal bone fracture were identified. Specific and thorough facial nerve examinations were not initially conducted on temporal bone fracture patients and subsequent inpatient monitoring for facial nerve paralysis and CSF otorrhea was incomplete. The outcome of temporal bone fracture is discussed. This article reminds the emergency physician of the importance of initial diagnosis and documentation of temporal bone fractures.

Cerebrospinal Fluid Otorrhea↗
PubMed1994

The at-risk student: a study of visits to the school nurse.

This study compared rural public school students defined as at-risk and those who were defined as not at-risk to determine if there was a significant difference in the proportion of each group who visited the school nurse. Significant differences were observed between the at-risk and not at-risk students. Implications of these results for the school nurse are discussed.

Adolescent↗
PubMed1993

An assessment of air quality impacts of fires associated with fire fighting operations.

Fire fighters in Canada's navy must undergo regular training with fires from simulated helicopter crashes. Visible emissions from these fires often create health concerns in surrounding communities. This paper presents air quality implications of plume dispersion associated with "helicopter fires." Evaluations involved measuring plume rise, estimating emissions, dispersion modeling and ambient monitoring. Results of the evaluation provided ground-level concentration estimates of plume particulate matter, oxides of nitrogen, hydrogen fluoride, carbon monoxide, 22 metals, 15 PAH and 13 VOC. The study showed that the air quality impact of the fire fighting training is much lower than the relevant time-weighted averages established to protect workers' health. This paper will be of interest to people in environmental protection agencies because it demonstrates the effects of fire fighting operations that must frequently occur as part of training exercises.

Air Pollutants↗
PubMed1983

Otosclerosis and sensorineural hearing loss. A clinical study.

A causal relationship between otosclerosis and sensorineural hearing loss is thought to exist. Forty-nine patients with unilateral otosclerosis were studied by comparing the bone conduction threshold in the otosclerotic ear to the bone conduction threshold in the uninvolved ear. This difference was analyzed using the paired Student's t test, and significant differences were found at 1,000, 2,000, and 4,000 Hz but not at 500 Hz. This effect on the higher frequencies may be due to a change in the motion mechanics of the basilar membrane and is greatest at the basal end of the cochlea.

Audiometry↗
PubMedDate not supplied

Nasopharyngeal carcinoma among the population in Jerusalem.

PURPOSE: Because the incidence of nasopharyngeal carcinoma differs in various ethnic groups, the heterogeneous population of Jerusalem was selected for an epidemiologic study. MATERIALS AND METHODS: Data from 63 consecutive patients diagnosed with nasopharyngeal carcinoma were collected in a retrospective manner. Information regarding sex, age, ethnic origin, tobacco and alcohol consumption, chronic sinusitis, and immunoglobulin (Ig)G to Epstein-Barr virus capsid antigen was tabulated and was statistically analyzed by the z test. RESULTS: The results showed an increased incidence of disease in the Sephardi Jews, especially of Moroccan origin. The histologic type was 100% poorly differentiated squamous carcinoma, and was associated with a better prognosis than is usually seen in the literature. CONCLUSION: This study identified an ethnic-related pattern of nasopharyngeal carcinoma in Jerusalem, and found a 100% incidence of poorly differentiated squamous carcinoma, and a better survival rate than the literature suggests, which may be attributable to the histologic type.

Adolescent↗
PubMedDate not supplied

Mandatory inservice offerings: implementation of an all-day method.

This article describes the development and evaluation of an alternative approach to providing mandatory inservice offerings, whereby all yearly inservice requirements are presented during a 1-day program. Results of the evaluation of the all-day method employed to meet goals of compliance with attendance, cost-effectiveness, and participant and management satisfaction are also presented. The all-day approach used to provide mandatory inservice offerings was found to be an effective method for providing quality, cost-effective mandatory staff education.

Education, Nursing, Continuing↗