Invisible women in dentistry.
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Administrative Personnel↗
Biomedical subjects
J Fenwick
Publications and source records attributed to J Fenwick.
The effects of privet exposure on asthma morbidity.
AIM: To determine whether privet may be an important cause of asthma morbidity. METHODS: The study was conducted in two parts; (1) a longitudinal study of asthma symptoms, medication use, peak expiratory flow rate and airway responsiveness during and after the privet-flowering season, and (2) bronchial challenge of 17 subjects with two species of flowering privet. Subjects were asthmatics who attributed worsening asthma symptoms to privet exposure. All subjects were atopic and had perennial asthma symptoms requiring treatment with inhaled steroids and beta agonists. RESULTS: 1. Twenty subjects completed the longitudinal study. Airway responsiveness (PD20 histamine) was significantly greater during the privet-flowering season (0.4 mumol vs 0.73 mumol, p < 0.05). Symptom scores and bronchodilator use were higher and peak expiratory flow rates lower during the privet-flowering season, but the changes were small and not statistically significant. 2. Seventeen subjects from the longitudinal study subsequently had bronchial challenge studies performed. There were no isolated early responses, but six had late asthmatic responses. Eleven had no airway constrictor response to challenge with either of the two local varieties of privet. CONCLUSION: Although significant increases in airway responsiveness occur during the privet flowering season, only a proportion of this highly select group had a constrictor response to direct challenge. Privet exposure may cause bronchoconstriction in certain individuals, but it is unlikely to be responsible for a large proportion of asthma morbidity in New Zealand.
Adolescent↗
The chemotactic response of blood neutrophils and monocytes to strains of Escherichia coli with different virulence characteristics.
Chemotactic responses of blood neutrophils and monocytes to media conditioned by eight strains of Escherichia coli with different virulence characteristics were measured in modified Boyden assay chambers to determine if these characteristics were associated with differences in leucocyte mobility. Responding neutrophils and monocytes were prepared on conventional density gradients, and in three instances, the chemotaxis of eosinophils isolated on metrizamide gradients was also studied. Media conditioned by enteroinvasive and nonenteroinvasive E. coli strains were tested as chemo-attractants and compared to the formylated peptide standard attractant. Chemotactic activity of neutrophils was greater than that of monocytes and eosinophils, and migration by all populations was significantly greater to conditioned media than to the control medium. Chemotactic responses to media conditioned by non-enteroinvasive E. coli and strains lacking virulence factors was greater than to media conditioned by plasmid- and Sereny-positive enteroinvasive organisms. The results suggest that virulence factors of E. coli that determine invasiveness did not augment the chemotactic responses of the leucocyte populations tested in vitro, and give no support to the hypothesis that they induce mucosal inflammation by directly increasing chemotaxis in vivo.
Chemotaxis, Leukocyte↗
The effects of softwater acclimation on respiratory gas transfer in the rainbow trout Oncorhynchus mykiss
Gill O2 uptake, CO2 excretion, ventilation and blood respiratory/acid­base variables were evaluated in control and softwater-acclimated trout (Oncorhynchus mykiss) to test the hypothesis that gill chloride cell (CC) proliferation, elicited by 2 weeks of softwater exposure, impairs the diffusion of respiratory gases across the gill. The proliferation of CCs in softwater fish was verified using light microscopy, and its impact on respiratory gas transfer was assessed in vivo by continuous monitoring of arterial blood PO2 (PaO2), PCO2 (PaCO2) and pH (pHa) using an extracorporeal blood circulation under conditions of normoxia and graded hypoxia [water PO2 (PwO2) was lowered from 20.0 kPa to 5.3 kPa within 20 min]. During normoxia, ventilation frequency was significantly higher in the softwater trout (78±4 versus 57±4 breaths min-1; mean ± s.e.m.), while ventilation amplitude was similar in both groups (1.0­1.1 cm opercular displacement). PaCO2 and plasma HCO3- concentration were significantly lower in the softwater fish and the blood acid­base status was characterized by a mixed respiratory alkalosis and metabolic acidosis such that blood pH was not statistically different between the two groups. CO2 excretion (2.5­2.8 mmol kg-1 h-1) and O2 uptake rates (2.3­5.1 mmol kg-1 h-1), as measured during normoxia, were unaffected by acclimation to soft water. During hypoxia, ventilation frequency and amplitude increased in the control trout, whereas only ventilation amplitude increased in the softwater-acclimated fish. The rate of PaO2 reduction during hypoxia was significantly greater in the softwater fish (0.84±0.06 versus 0.65±0.06 kPa PaO2 kPa-1 PwO2) and, at the most severe level of hypoxia (PwO2=5.3 kPa), PaO2 was significantly lower in the softwater fish. The rate of PaCO2 reduction (caused by hyperventilation) was significantly lower in the softwater-acclimated fish (0.002±0.001 versus 0.005±0.001 kPa PaCO2 kPa-1 PwO2; mean ± s.e.m.; P<0.06) and, indeed, was not statistically different from zero. Blood pH did not change significantly during hypoxia in either group but, through much of the hypoxic period (7­15 kPa PwO2), pHa was statistically lower in the softwater-acclimated fish. These results demonstrate that exposure of trout to soft water for 2 weeks is associated with proliferation of lamellar CCs and impaired branchial gas transfer. Hyperventilation was identified as a compensatory physiological adjustment.
Journal Article↗
The effect of posture and seat suspension design on discomfort and back muscle fatigue during simulated truck driving.
Several studies have shown a relationship between low-back problems and exposure to seated whole-body vibration. The amount of vibration transmitted to the operator is influenced by the posture of the subject in the vehicle. The aim of this study was to determine whether a truck seat with a gas spring in its suspension is superior to the standard spring seat in slowing the onset of muscle fatigue and reducing the level of discomfort experienced during road vibrations while maintaining typical driving postures. The experiment used a 2 x 3 (2 seats x 3 postures) repeated measures design. It was conducted on six males free from low-back pain. Subject comfort was rated before and directly after exposure to typical vibrations. Muscle fatigue using centre frequency was determined during vibration exposure, and the magnitude and phase of acceleration transfer were calculated from the base plate to the seat pan and from the seat pan to the bite bar. None of comfort, fatigue rate or fatigue average were affected by seat type or seat suspension design in the short term, 10 min vibration exposure. Fatigue and comfort measures could continue to be used to detect postural defects, but the more sensitive measures of seat/driver interactions remain mechanical ones using motion-measuring techniques such as accelerometry and correcting for the heavily damped nature of the system. Until more sophisticated manikins are available the characteristics of vibration-attenuating seats should be confirmed using live humans.
Journal Article↗
THE EFFECTS OF BRANCHIAL CHLORIDE CELL PROLIFERATION ON RESPIRATORY FUNCTION IN THE RAINBOW TROUT ONCORHYNCHUS MYKISS
The objectives of this study were to induce chloride cell (CC) proliferation on the gill lamellae of rainbow trout Oncorhynchus mykiss and to evaluate the consequences for respiratory function. Chronic elevation of hormone levels was used to induce CC proliferation; fish were injected with a combination of cortisol (8 mg kg-1 intramuscularly every day for 10 days) and ovine growth hormone (2 mg kg-1 intraperitoneally every second day for 10 days). The extent of CC proliferation was quantified using scanning electron microscopy and a two-dimensional analysis. An extracorporeal preparation in combination with environmental hypoxia was used to assess the effects of CC proliferation on respiratory function. Arterial blood was routed from the coeliac artery through an external circuit in which pH (pHa), partial pressure of oxygen (PaO2) and partial pressure of carbon dioxide (PaCO2) were monitored continuously. Environmental hypoxia was imposed by gassing a water equilibration column supplying the experimental chamber with N2. The hormone treatment increased the average CC surface area by 2.7-fold and CC density by 2.2-fold; the combined effect was a fivefold increase in CC fractional area. While the PaO2 values of hormone-treated and control fish were similar at PwO2>12.0 kPa, the arterial O2 tensions of treated fish were significantly lower than those of the control group for PwO2¾12.0 kPa. In comparison with control fish at all environmental O2 tensions, the hormone-treated fish exhibited elevated PaCO2 values and a significant acidosis. The effects of CC proliferation on blood gas variables in hormone-treated fish were accompanied by a significantly elevated ventilation amplitude and a lowered ventilation frequency. The results of this study demonstrated (i) that impairment of respiratory gas transfer coincides with CC proliferation, (ii) that O2 and CO2 transfer are influenced differently and (iii) that partial compensation is achieved through physiological adjustments.
Journal Article↗
The effect of secondary insults on mortality and long-term disability after severe head injury in a rural region without a trauma system.
Outcome after head injury appears to be adversely affected by secondary insults such as hypoxia or hypotension. Previous work examining the influence of these secondary insults on outcome has originated from urban environments with organized systems of trauma care. We hypothesized that secondary insults would be more frequent and that outcome of severe head injury would be worse in a rural region without a trauma system. To validate these hypotheses we retrospectively reviewed the course and outcome of all patients admitted to the Medical Center Hospital of Vermont with severe head injuries between 1980 and 1985. A cohort of 170 patients was assigned to one of two groups: group I had neither hypotension nor hypoxia at the time of admission; group II had either hypotension or hypoxia at the time of admission. The groups were similar in terms of demographics, incidence of mass lesions, frequency of craniotomy, and incidence of intracranial hypertension. Only 23% of group II patients made a good recovery compared with 56% of group I patients (p < 0.01). The mortality rate of group II patients was twice that of group I patients (66% vs. 33%; p < 0.01). When compared with data provided by the National Trauma Coma Data Bank from urban areas with trauma systems, there was no difference in outcome of patients similarly grouped according to the presence or absence of secondary insults between Vermont's rural cohort and the urban cohort. We conclude that hypotension and hypoxia adversely effect the outcome of severe head injury.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Demographic characteristics of patients with severe life threatening asthma: comparison with asthma deaths.
BACKGROUND: Studies of mortality from asthma have suggested that a very severe asthma attack identifies a group at greatly increased risk of subsequent death from the disease. This study compares the demographic characteristics of asthmatic patients who required management in an intensive care unit for a severe life threatening attack between 1981 and 1987 with a group who died of asthma between 1980 and 1986. The outcome of the group admitted to an intensive care unit is described. METHODS: The groups comprised all cases aged between 15 and 49 years arising from the Auckland Area Health Board (AAHB) population who required admission to an intensive care unit for asthma between 1981 and 1987 (n = 413) and all deaths from asthma in those aged 15 to 49 years arising from the New Zealand population between 1980 and 1986 (n = 466). Details of age, sex, and information on the day and month of the attack were collected. For the group requiring admission to an intensive care unit, outcome in terms of mortality and readmission to intensive care was determined. RESULTS: The age distributions of the two groups were dissimilar, with the severe life threatening attack group having an excess of asthmatic patients under 30 years old. The distribution of events by calendar month was uniform in both groups, but there was an unexpected increase in frequency of attacks on Sundays in both groups. Over the study period, mortality fell from 5.3 per 100,000 to 3.5 per 100,000 but the admission rate to intensive care increased from 10.8 per 100,000 to 17.9 per 100,000. At least 24% of asthma deaths occurring in the AAHB region during the study period had previously experienced a severe life threatening attack. CONCLUSIONS: The similarities between the groups suggest that asthmatic patients who experience severe life threatening attacks are likely to come from the same subgroup of the asthma population as those who die. The group who experience severe life threatening attacks are at high risk of subsequent morbidity and mortality and further studies may produce information relevant to reducing mortality from asthma.
Adolescent↗
Evaluation of albumin as a reference marker of dilution in bronchoalveolar lavage fluid from asthmatic and control subjects.
BACKGROUND: Standardised expression of results of bronchoalveolar lavage (BAL) is problematical in the absence of a validated "denominator" of epithelial lining fluid dilution. The suitability of albumin in BAL fluid has been investigated in groups of clinically stable asthmatic and control subjects. METHODS: Absolute levels of albumin in BAL fluid were measured in a preliminary study of 21 asthmatic and 10 control subjects. In a more complex study designed to investigate the origin of albumin sampled at BAL in nine asthmatic and seven control subjects, radiolabelled albumin was injected intravenously five minutes before BAL. RESULTS: In the preliminary study levels of albumin in BAL fluid were very similar, with a geometric mean value of 44 (95% CI 35-54) micrograms/ml BAL supernatant for the asthmatic subjects and 41 (95% CI 33-52) micrograms/ml for the controls. The majority of control and asthmatic subjects in the radiolabel study exhibited minimal flux of albumin from the circulation into the BAL aspirate. This finding was not uniform, however, and in a third of the asthmatic subjects an albumin flux equivalent to > 20% of the measurable albumin was found in two or more aliquots of a 3 x 60 ml lavage. CONCLUSIONS: The results of this investigation into the source of albumin sampled at BAL suggest that, in general, albumin would be a reasonable reference solute for normalising the degree of dilution of BAL fluid in the groups studied. The origin of albumin was not always restricted to the bronchopulmonary segment under investigation, however, with significant leakage from the blood compartment in some individuals despite the consistency of absolute levels observed in the preliminary study.
Adult↗
Baseline risk for asthma deaths.
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Administration, Oral↗
Pneumatosis intestinalis in patients with Crohn's disease.
The prevalence, predictors, and significance of pneumatosis were determined in 50 patients with Crohn's disease who had abdominal CT scans to rule out abscess. The presence or absence of six CT descriptors and 17 clinical descriptors was documented. CT scans of a control group of 50 subjects without inflammatory bowel disease were also examined. Data was analyzed by two-sample t tests and Fisher's exact test. Pneumatosis was found in six of 50 patients with Crohn's disease and in none of the controls. Corticosteroid treatment was the single clinical variable relating significantly (P = 0.025) to pneumatosis, although trends toward absence of resection, short duration of illness, and more severe anemia were also evident in this group. This study suggests that the presence of pneumatosis alone does not dictate a specific course of treatment, but when pneumatosis is present, careful monitoring is required and therapy is based on the overall clinical picture.
Adult↗
The origin of water and urea sampled at bronchoalveolar lavage in asthmatic and control subjects.
Bronchoalveolar lavage (BAL) urea has been advocated as a denominator that might allow for the dilution of the pulmonary epithelial lining fluid sampled at BAL, and so provide a meaningful method of expressing BAL data. We investigated the origin of water and urea sampled at BAL in five asthmatic and five control subjects using radiolabeled urea injected intravenously 5 min before BAL. Labeled BAL urea was found to be fully equilibrated with that in the bloodstream. A strong relationship was found between influx of radiolabeled water and radiolabeled urea from blood to BAL fluid, suggesting that urea sampled at BAL may be derived predominantly from an acute movement from the bloodstream into the BAL aspirate. We conclude that urea is an inappropriate denominator for the expression of BAL results, and that the fluid and solute dynamics that occur during BAL are both complex and variable.
Adult↗
Clinical versus instrumented knee testing on autopsy specimens.
The accuracy, reliability, and reproducibility of the Genucom Knee Analysis System and Knee Signature System (KSS) for anteroposterior knee laxity evaluations were compared. The devices detected the same relative change in laxity between normal and anterior cruciate ligament-deficient specimens during Lachman and drawer testing; however, the absolute values differed. In a clinical study, two examiners performed three independent Lachman and drawer tests using the Genucom, KSS, and a subjective clinical examination on ten patients. The Genucom demonstrated interexaminer differences during the Lachman test. The clinical examination proved to be more reliable than either instrumented device for both Lachman and drawer testing. The intraexaminer variability of the Genucom and KSS was large, with the average 95% confidence limits about the mean for the Genucom and KSS equal to +/- 4.2 and +/- 2.8 mm, respectively. These findings question the accuracy, reliability, and reproducibility of the instrumented methods.
Adolescent↗
Prescribing for asthma and severity markers.
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Asthma↗
Foot growth in children age one to five years.
As part of the protocol on the Development of the Child's Arch, foot growth studies were monitored prospectively in 107 children from 1 year of age till 5 years of age. Under 15 months of age, growth necessitated a 1/2 size footwear change in less than 2 months; from 15 months to 2 years of age, 1/2 size increase occurred every 2 to 3 months; from 2 to 3 years of age, 1/2 size change every 3 to 4 months; and from 3 to 5 years of age, 1/2 size change every 4 months. Although foot growth in boys and girls is parallel, boys' feet tend to average one size longer and one size wider. Width growth remained proportional to length growth throughout the study.
Age Factors↗
Development of the child's arch.
The purposes of the project were to monitor the development of the lower extremities and the longitudinal arch of the foot and to determine whether or not arch support footwear (three types) affected development of a neutral arch in toddlers 11 to 14 months of age until age 5 years. A total of 125 beginner walkers were recruited through the pediatrics department during a period of 1 1/2 years and divided by lot into four different footwear groups (one nonarch supportive). The group was studied for 4 years by physical examinations, x-ray films, and pedotopography (a Moire fringe technique of photography). At initial examination all of the apparently normal toddlers had pes planus by all clinical, roentgenographic, and photographic measurements. There were no cavus feet at that time or at 5 years of age. Arches developed regardless of the footwear worn but development was faster during the first 2 years (until age 3 years) with arch support footwear. The rapidity of arch development until 5 years of age continued in those children who wore longitudinal arch cookies. Ossification of the sustentaculum tali begins at approximately 5 years of age but is not complete for at least another 1 to 2 years. Hyperpronation was present in 77.9% and genu valgum in 92.3% of the 5-year-old children. These conditions are apparently the norm at this age in both boys and girls.
Child, Preschool↗
Isokinetic trunk and lifting strength measurements: variability as an indicator of effort.
This study examines the hypothesis that force/distance curve variability distinguishes submaximal from maximal efforts in isokinetic trunk and lifting strength tests. Thirty normal subjects were tested on the Cybex Trunk Extension/Flexion (TEF) and Liftask (LT) machines during maximal (100%) and submaximal (50%) efforts. Considering each test separately, visual assessments of curve variability were indeterminate of degree of effort in 28% of TEF and 34% of LT tests. Measurement models of curve variability were more clearly discriminating. When a given subject's test curves were considered together, scaled visual assessments identified the degree of effort in 91% of TEF and 86% of LT results. The measurement models were accurate 90-92% of TEF and 79-92% of LT results. Clinical judgment is required in evaluating effort during tests of isokinetic trunk and lifting strength.
Adult↗
75 deaths in asthmatics prescribed home nebulisers.
The circumstances surrounding the deaths of 75 asthmatic patients who had been prescribed a domiciliary nebuliser driven by an air compressor pump for administration of high dose beta sympathomimetic drugs were investigated as part of the New Zealand national asthma mortality study. Death was judged unavoidable in 19 patients who seemed to have precipitous attacks despite apparently good long term management. Delays in seeking medical help because of overreliance on beta agonist delivered by nebuliser were evident in 12 cases and possible in a further 11, but these represented only 8% of the 271 verified deaths from asthma in New Zealanders aged under 70 during the period. Evidence for direct toxicity of high dose beta agonist was not found. Nevertheless, the absence of serum potassium and theophylline concentrations and of electrocardiographic monitoring in the period immediately preceding death precluded firm conclusions whether arrhythmias might have occurred due to these factors rather than to hypoxia alone. In most patients prescribed domiciliary nebulisers death was associated with deficiencies in long term and short term care similar to those seen in patients without nebulisers. Discretion in prescribing home nebulisers, greater use of other appropriate drugs, including adequate corticosteroids, and careful supervision and instruction of patients taking beta agonist by nebuliser should help to reduce the mortality from asthma.
Adolescent↗