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Biomedical subjects

D Henderson

Publications and source records attributed to D Henderson.

At least 163 records · Page 9Linked to original sources
PubMed1991

Unusual aspects of allergic bronchopulmonary fungal disease: report of two cases due to Curvularia organisms associated with allergic fungal sinusitis.

We report two cases of allergic bronchopulmonary fungal disease (ABPFD) caused by Curvularia sp and associated with allergic fungal sinusitis (AFS). Curvularia lunata was cultured in one case and Curvularia senegalensis was cultured in the other. Based on these cases and a review of the literature, we discuss unusual clinical and pathologic features that can occur in ABPFD. Unusual clinical aspects of ABPFD include associated AFS, absence of asthma, progression to Churg-Strauss angiitis and granulomatosis, concomitant hypersensitivity pneumonitis, and underlying cystic fibrosis. Atypical pathologic features that may occur in ABPFD include follicular bronchiolitis, xanthomatous bronchiolitis, limited tissue invasion, fungus balls, and association with unusual fungi. Prominent follicular bronchiolitis and xanthomatous bronchiolitis were misleading histologic features in one of our cases and led to a delay in recognition of the diagnosis. Both patients presented primarily with AFS; ABPFD was detected subsequently. This suggests that a small subset of patients with AFS may be at risk for ABPFD. The goal of this review is to increase awareness of unusual clinical and pathologic manifestations of ABPFD. It is hoped that this will result in accurate diagnosis and proper therapy, especially for patients who present with atypical features. Unusual fungal species should be considered in patients who have clinical findings compatible with ABPFD but who do not demonstrate immunologic reactivity to Aspergillus sp, especially Aspergillus fumigatus. In addition, ABPFD should be considered in patients with AFS who develop new pulmonary lesions.

Adolescent↗
PubMed1991

The effect of 'conditioning' exposures on hearing loss from traumatic exposure.

The role of 'conditioning' exposures as moderators of hearing loss produced by exposure to a higher level noise was explored using chinchillas. Monaural chinchillas were exposed to an octave band of noise centered at 0.5 kHz at 95 dB for six hours/day for ten days. The subjects were allowed to recover to pre-exposure sensitivity and at five days after the last exposure they were re-exposed to the same noise at 106 dB. Thresholds recorded at various time intervals following the second exposure were compared with those recorded in a control group exposed only to the higher level noise. The experimental animals were found to have less threshold shift at all stages of recovery. Results are discussed in the light of results of other related studies and possible mechanisms involved are hypothesized.

Acoustic Stimulation↗
PubMed1991

Development of resistance to hearing loss from high frequency noise.

The effect of interrupted exposure on the development of progressive resistance to hearing loss from exposure to high frequency noise was studied using monaural chinchillas. The animals were exposed to an octave band noise centered at 4 kHz at 85 dB SPL for 6 h a day for ten consecutive days. Hearing thresholds were measured using evoked potential recording before and after each exposure. Results indicated a reduction in threshold shift with repeated exposures. This reduction in threshold shift or 'toughening' was more rapid for the high frequency exposures than the 'toughening' from similar low frequency exposures.

Acoustic Stimulation↗
PubMed1991

The effect of exposure level on the development of progressive resistance to noise.

The effect of exposure level on the development of progressive resistance to temporary threshold shift caused by exposures to an octave band of noise centered at 0.5 kHz was explored using chinchillas. The animals were exposed to either 85, 95 or 100 dB SPL for six hours a day for ten days. Hearing thresholds were recorded electrophysiologically, prior to and after each daily exposure. A trend toward decreasing threshold shift with increase in the number of exposures was seen at all the levels. The amount of threshold shift appeared to depend upon the level as well as the test frequency. The findings are discussed in the light of results of previous studies and possible mechanisms involved in the process of 'toughening' are hypothesized.

Adaptation, Physiological↗
PubMed1991

Co-operation of progestational steroids with epidermal growth factor in activation of gene expression in mammary tumor cells.

The progesterone receptor belongs to a class of ligand binding transcription factors that regulate transcription by interacting with specific DNA sequences on hormone regulated genes. In human mammary tumor T47D cells that contain both progesterone and epidermal growth factor (EGF) receptors, the progestin-induced transactivation at various hormone regulated promoters is enhanced by EGF. The effect of EGF is rapid and does not require new protein synthesis. EGF treatment does not alter the DNA binding activity of the progesterone receptor nor does it affect the total ligand-dependent phosphorylation of this receptor. These results suggest that EGF enhances the transactivation property of the progesterone receptor through mechanisms other than those involving a direct interaction of this receptor with its cognate binding sites.

Base Sequence↗
PubMed1991

Giant cell arteritis associated with pericarditis and large vessel disease.

Giant cell arteritis is well recognised to affect branches of the external carotid artery and to cause systemic symptoms, but may also involve branches of the aorta producing a clinical syndrome that may be difficult to diagnose. A patient is described who presented with limb ischaemia, pericarditis and systemic symptoms. Treatment with corticosteroids improved the systemic manifestations but not the ischaemia. The patient died of bowel infarction four months after treatment was commenced.

Aged↗
PubMed1991

Impact noise: the importance of level, duration, and repetition rate.

The applicability of the equal energy hypothesis (EEH) to impact noise exposures was studied using chinchillas. Hearing thresholds were estimated by recording the evoked potentials from a chronic electrode implanted in the inferior colliculus. The animals were exposed to broadband impacts of 200-ms duration. The study was carried out in two parts. In experiment I, six exposure levels (107, 113, 119, 125, 131, and 137 dB SPL) and three repetition rates (4/s, 1/s and 1/4s) were employed. In the second experiment, the total duration of the exposure as well as the total energy were kept constant by trading level and rate. Results indicate that hearing loss resulting from exposure to impact noise does not conform to the predictions of the EEH. The permanent threshold shift as well as the hair cell loss are more or less equal across the lower peak exposure levels. However, both the hearing loss and the hair cell damage increase for exposures with higher peak levels. Furthermore, hearing loss and cochlear damage are dependent upon the rate of exposure. Thus the amount of hearing loss and hair cell damage appears to depend on the interaction of several factors including peak level, rate, and the susceptibility of the animal.

Animals↗
PubMed1991

The importance of "temporal pattern" in traumatic impulse noise exposures.

The equal energy hypothesis (EEH) was evaluated for impulse noise. Specifically, the experiments evaluated the importance of the temporal distribution of impulses; the trading relation between the number of impulses and peak level and the difference between continuous and impulse noise. Monaural chinchillas were exposed to one of seven conditions. Their hearing was evaluated before, immediately after, and 30 days after the exposure. Hair cell damage was reported in the form of a cochleogram. The experiments show that the EEH is more appropriate for low-level impulse (135-dB peak); for equal amounts of energy, 150-dB impulses produce more hearing loss and hair cell damage than 135-dB impulses; for equal amounts of energy, impulses presented in rapid bursts cause less damage than impulses presented at "1/s" and 50 microseconds. Pairs of impulses presented at "1/s" produce the largest amount of damage. The results are discussed in terms of implications for the EEH.

Animals↗
PubMed1991

Ocular trauma: one in the eye for safety glasses.

Over a 3-month-period, a prospective study was performed on patients presenting with eye injuries to an Accident and Emergency Department. Two hundred and forty-five patients presented, representing 3.7% of total new patients seen in that period. The majority of injuries (81%) occurred in the workplace, injuries associated with grinding (32%) being the commonest. Retained foreign body (52%) was the most common injury. Eye protection was provided in 64% of cases, but only used in 48.5% of these. Seventy-eight per cent of cases were discharged without follow-up. The use of goggles appeared to provide the greatest degree of protection.

Emergency Service, Hospital↗
PubMed1991

ASL and the family system.

This paper examines some of the sociological implications of poor interaction on families in which one of the members is deaf. When a family systems perspective is used, once a child is diagnosed as deaf the family is no longer considered "hearing"; the parents may be hearing, the other children may be, but the family system becomes "hearing and deaf." By viewing this as a hearing/deaf problem, it becomes clear that no adequate solution can be found without the participation of deaf adults and the benefit of their perspectives and insights. We suggest that attention be directed toward neutralizing the effects of the stigma associated with deafness so that American Sign Language can become a pivotal tool for facilitating functional symbolic interaction in hearing/deaf families.

Child↗
PubMed1991

Fatal airway obstruction caused by a mucous ball from a transtracheal oxygen catheter.

A 50-year-old man with pulmonary fibrosis and COPD presented with worsening cough, dyspnea, chest pain, and hypoxemia of no readily apparent etiology, approximately four weeks after insertion of a transtracheal oxygen therapy catheter. Despite vigorous bronchial hygiene therapy, the patient died. Autopsy revealed obstruction of the trachea by a large mucous ball. We point out the nonspecificity of physical and radiologic findings associated with this condition and suggest that serial flow-volume loop analysis or earlier use of fiberoptic bronchoscopy might have been of assistance in premortem diagnosis of the mucous plug.

Airway Obstruction↗
PubMed1990

Chloroplast DNA sequence from a miocene Magnolia species.

DNA has been successfully extracted from several samples of preserved tissue, the oldest so far reported originating from a 13,000-year-old ground sloth. Both severe damage to the preserved DNA, primarily due to oxidation of the pyrimidines, has prevented the acquisition of sequence data from ancient samples except in a few cases. We report here the extraction of DNA from fossil leaf samples from the Miocene Clarkia deposit (17-20 Myr old), the amplification of an 820-base pair (bp) DNA fragment from the chloroplast gene rbcL from a fossil of the genus Magnolia, and its subsequent sequencing. The sequence was verified by comparison with published and unpublished rbcL sequences. These results extend our ability to analyse ancient DNA and may open new avenues into problems in palaeobotany, biogeography, and in the calibration of mutation rates.

Base Sequence↗
PubMed1990

Cerebral palsy in multiple births in Western Australia: genetic aspects.

A study of cerebral palsy in multiple births was undertaken to test genetic involvement and assess the impact of the special conditions of pregnancy and parturition in these cases. Complete ascertainment of cerebral palsy in multiple gestations that occurred in Western Australia between 1956 and 1985 was obtained from the Western Australian Cerebral Palsy Register. There were 74 twins and 5 triplets. Data on sex, birth order, motor handicap, outcome in co-twins and triplets, zygosity, and pedigree information was obtained from the Register, hospital records, and, where possible, by interview of the parent(s) of the propositi. There was a significantly higher (P = 0.0026) concordance rate in MZ than in DZ twin pairs. However, pedigree studies showed no other relatives with a motor handicap similar to that of the propositi. This is consistent with a multifactorial cause in at least some of the cases. The sex ratio of affected twins was found to be 2.1 compared to 1.3 for singletons and all 5 affected triplets were boys. The trend of increasing sex ratio with increasing plurality was significant at the 1% level.

Birth Order↗
PubMed1990

Use of Gen-Probe and Bactec for rapid isolation and identification of mycobacteria. Correlation of probe results with growth index.

Gen-Probe culture confirmation tests (Gen-Probe, San Diego, CA) for Mycobacterium tuberculosis complex and Mycobacterium avium complex were performed on 276 mycobacterial isolates. All 138 M. tuberculosis complex isolates and 79 of 80 M. avium complex isolates were identified correctly. No falsely positive test results were obtained; 58 nontuberculous mycobacteria other than M. avium complex were negative by Gen-Probe. In a second phase of testing, Gen-Probe tests were performed using concentrates from 101 patient Bactec 12B cultures. Positive results by Gen-Probe tests were correlated with the growth index (GI) reading on the day of processing as well as the accumulated GI readings. For those 51 with high (greater than or equal to 999) final GIs, 40/40 (100%) M. tuberculosis complex isolates and 9/11 M. avium complex isolates were positive by Gen-Probe, and six other mycobacteria were negative. Of the 25 with moderate final readings (400 less than or equal to GI less than 999), 12/17 M. tuberculosis complex isolates and 1/1 M. avium complex isolates were correctly identified by Gen-Probe; seven other mycobacteria were negative. Of 25 with low readings (GI less than 400), 8/24 M. tuberculosis isolates were correctly identified by Gen-Probe, and no falsely positive test results were obtained with the other probes. All true negative tests on seven other mycobacteria (not M. tuberculosis complex or M. avium complex) had less than 2% hybridization. Of the 24 falsely negative tests on M. tuberculosis complex isolates or M. avium complex isolates, 22 had greater than 2% hybridization with their respective probes. Thus, percent hybridization greater than 2% may be a useful indicator of the need for retesting.

Algorithms↗
PubMed1990

Enhancement of mononuclear cell oxidative burst by early post-transfer sera from human patients after unsuccessful embryo transfer.

Early pregnancy sera were earlier shown to modulate T lymphocyte rosetting with sheep erythrocytes. We set out to investigate whether early pregnancy sera also modulate the state of activation of another immunologically relevant cell type, the monocyte. As an index of monocyte activation, we measured phorbol ester-triggered oxidative burst activity by a highly sensitive chemiluminescence method. Contrary to our expectations, incubation of mononuclear cells with sera taken early after embryo transfer from patients with a successfully developing pregnancy had no effect. Unexpectedly, such sera from patients from a control group of patients in whom no pregnancy developed after embryo transfer caused enhancement of mononuclear cell chemiluminescence. Stimulatory activity of these sera appeared between days 4 and 6 and was maximal between days 7 and 9 post embryo transfer. Whether this phenomenon is causally related to, or represents a consequence of the failure of embryo transfer, can currently not be decided.

Chaperonin 10↗