Biomedical subjects
Publications and source records attributed to R E Hooper.
The internal jugular vein is derived embryologically from the anterior cardinal veins. Developmental abnormalities may result in a cavernous venous varicosity, which may be the cause of massive primary hemorrhage during tonsillectomy. An index of suspicion is required for diagnosis, which may be confirmed by retrograde venography techniques.
We used the random amplified polymorphic DNA technique to determine last male sperm precedence (P2) in the damselfly Calopteryx splendens xanthostoma (Charpentier). We amplified DNA from mothers, putative fathers and from the embryos of individual offspring, and subsequently calculated band-matching coefficients between known first-order relatives (offspring within a clutch) and non-relatives (mothers and fathers) to estimate last-male paternity. The data indicate that, as in other Calopterygidae, P2 is high (0.98) in the bout of oviposition immediately following copulation, despite the fact that the males of this species do not completely remove the sperm of previous males (Siva-Jothy & Hooper 1995).
BACKGROUND: There is evidence that administration of higher doses of aminoglycosides given less frequently improves the bactericidal effect and reduces the potential to cause side effects. To investigate this, a prospectively randomised open label therapeutic trial was undertaken in stratified groups of patients with cystic fibrosis to examine the efficacy and toxic potential of an aminoglycoside dosing regimen designed to generate high peak drug concentrations at 12 hourly intervals compared with conventional dosing at eight hourly intervals. METHODS: Patients in group A received tobramycin eight hourly using a dose aimed at generating a peak concentration of 10 mg/l with trough concentrations below 2 mg/l, and those in group B received the total daily dose required to achieve eight hourly target concentrations administered as two equal 12 hourly doses. Clinical outcomes measured and assessed included vestibular symptoms, hearing and renal function, length of hospital stay, readmission rate, and mortality. RESULTS: Twenty nine patients were recruited during a six month period, 20 to group A and nine to group B. The average peak tobramycin level was higher in group B (12.5 (2.2) mg/l) than in group A (7.9 (1.9) mg/l), whilst the average trough level was higher in group A (0.8 (0.3) mg/l) than in group B (0.5 (0.2) mg/l). There was a difference in the number of ototoxic events between patients in group A (seven of 18, 38.9%) and group B (none of eight), but no difference was found in other outcome measures assessed. CONCLUSIONS: These results suggest that 12 hourly high peak aminoglycoside dosing may be less toxic than equivalent eight hourly dosing, without any apparent difference in efficacy.
An in-vitro model of aminoglycoside dosing was used to demonstrate that the bactericidal activity of tobramycin against Pseudomonas aeruginosa is directly related to the peak concentration of the drug. In addition, six patients who were being treated for malignant otitis externa with long-term, high dosage tobramycin were monitored for oto- and nephro-toxicity; the only adverse effects were transient increases in the serum creatinine concentration in two patients.
A two-phase study was undertaken designed to investigate the impact of computer-aided drug monitoring on tobramycin concentrations and clinical outcomes in adult patients with cystic fibrosis. In phase one, a baseline (historical control) study of drug use patterns was performed. During the second phase, patients admitted for intravenous treatment with tobramycin for acute exacerbations of pseudomonal pulmonary infections were randomly allocated to one of two schedules. Group A patients had tobramycin dosage regimens decided by clinicians based on pre-existing protocols using serum tobramycin assay data determined three times weekly. Group B patients had dosage regimens determined by a computerized pharmacokinetic predictive program using both population-based pharmacokinetic parameter estimation and fitting of serum concentration-time data using Bayesian regression. The agreed therapeutic target was a peak serum tobramycin concentration of 8-10 mg/L and a trough concentration of 1-2 mg/L. There was a major difference between the two groups comparing the number of paired trough and peak concentrations within the target concentration ranges (group A-14%; group B-34.7%, chi 2 test, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Forty-one normal humans were tested with sinusoidal harmonic acceleration. Phase lag at 0.01, 0.02, and 0.04 Hz was the most stable parameter, with less test-retest variability than gain and asymmetry. There was no significant difference between men and women for phase lag, gain, or asymmetry at any of the five testing frequencies. Gain decreased as age increased. Age had no effect on phase lag at most test frequencies or on asymmetry at any frequency.
The latency, amplitude and wave-form of the action potential were studied in a group of patients, mainly presbyacusics and a few with noise-induced hearing loss, sensorineural hearing loss of unknown etiology and conductive loss. Electrocochleographic recruitment with short latency of the AP "threshold" and very rapid increase in amplitude with increasing click intensity was seen in 22%. Partial recruitment with long latency at AP "threshold" but steep amplitude-intensity curves was present in 33%. Only 17% of the subjects showed both electrocpchleographic recruitment (or partial recruitment) and recruitment in the acoustic reflex test. Subjects with conductive loss had normal amplitude and latency intensity curves but they were shifted to the right. The action potential wave-form was normal. Broad action potentials with multiple peaks were the most common in sensorineural hearing loss.
Using the technique of electrocochleography with transtympanic electrode placement, it is possible to estimate behavioral thresholds from AP data for a acoustic stimulus. The correlation between behavioril and AP "thresholds" for the same stimulus was statistically significant and there was a better correlation for subjects with a mild hearing loss than for those with normal hearing or larger degrees of hearing loss (as determined by the pure tone average). Larger amplitudes of the AP at the maximum stimulus level tended to be associated with a more accurate threshold estimation. The AP "thresholds" showed best correlation with the pure tone audiometric thresholds at 1 000 Hz, at other tone frequencies the correlation was poorer. This agrees with the spectral contents of the click.
We report a case of radicular sensory neuropathy and deafness. The patients appears to be one of a family in whom several members were similarly afflicted. Thus, this case fits the pattern of hereditary deafness and sensory radicular neuropathy, originally described by Hicks in 1922.
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The intratest test-retest reliability in clinical electrocochleography was studied by measuring the difference between amplitude of the test and retest and latency of the test and retest. Eighty-four comparisons were made in 40 patients with different types of hearing losses. The type of hearing loss and whether test and retest were performed in sequence or not did not affect the variability of the amplitude. The test and retest correlation between amplitudes was good. Small amplitudes mainly found near the action potential (AP) "threshold" showed less absolute variability than larger amplitudes found at higher intensities. The correlation between the intratest latencies was excellent. The latency showed less variability at higher intensities than near AP "threshold".