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Biomedical subjects

A J Parker

Publications and source records attributed to A J Parker.

At least 19 recordsLinked to original sources
PubMed1992

Analysis of walking locomotion in adult female rats undernourished as sucklings.

Suckling rats were undernourished from birth by underfeeding their mothers. They were refed from 3 weeks of age. Detailed analyses were made of the walking locomotion of previously undernourished and well-fed control female rats at 10 weeks, using electronic, computer, and TV techniques. Previously undernourished rats were found to deploy shorter stride times resulting in greater forward velocities. The shorter stride times were attained by reductions in stance time, while swing time was unaffected. No changes in stride length or width were observed, and the relationships between stride time and velocity, swing, or stance times were unaffected.

Animals↗
PubMed1992

The Groningen valve voice prosthesis in Sheffield: a 4-year review.

The Groningen valve was first used in Sheffield in 1986 in a patient who underwent laryngectomy for malignant disease. Since then a further 21 patients have made use of this device, 17 of whom underwent insertion at the time of surgery. All patients were male, two patients have since died and the median length of follow-up to date has been 22.0 (range 2-41) months. Prostheses were replaced mainly under general anaesthesia if they leaked or resulted in difficult phonation. A total of 73 valve insertions have been performed with a median time of 4.0 (range 0.25-27) months between each. Of the 15 men in whom the prosthesis is currently in use, speech was generally good-excellent. The Groningen valve provides a highly acceptable means of obtaining vocalization after laryngectomy in the patients in this series.

Adult↗
PubMed1992

A difficult intubation--fatal respiratory arrest secondary to an oral epulis.

We report an unusual case of cardio-respiratory arrest and eventual death secondary to a benign tumour of the oral cavity obstructing the oropharynx. We review the literature of similar occurrences causing difficulty with respiration and intubation, and highlight the importance of early diagnosis and treatment.

Aged↗
PubMed1992

Characteristics of Groningen tracheo-oesophageal speaking valves prior to insertion and after removal for failure.

The Groningen valve was first used in Sheffield in 1986 in a patient who underwent laryngectomy for malignant disease. Since then it has been the main tracheo-oesophageal prosthesis used on our Unit for speech rehabilitation post-laryngectomy. This biflanged device inserted primarily or as a secondary procedure remains in situ until failure occurs either because of leakage or because increased effort is required to produce satisfactory phonation. This in vitro study we examined the differences between new valves prior to insertion and those removed for failure. The mean forward opening pressures were shown to be similar in the two populations but the mean forward resistances were increased in those valves which were defective (P less than 0.001). In addition the mean reverse opening pressure was found to be significantly lower in the defective valves when compared with their new counterparts (P less than 0.05).

Adult↗
PubMed1992

An apparatus to measure pressure, flow and speech parameters in patients producing speech using the Groningen valve prosthesis.

We present a validated method of determining in vivo pressure, flow and voice parameters from patients using tracheo-oesophageal voice prostheses post laryngectomy. This apparatus was constructed simply using equipment which should be available in most large Otolaryngology Departments. There was good agreement between measurements made over two separate sessions of in vivo opening pressure, maximum flow through the device and maximum voice amplitude and these were significant. These measurements may be useful in monitoring patient progress and also in elucidating the mechanics of prosthesis failure.

Airway Resistance↗
PubMed1992

Pharyngolaryngeal migration: a delayed complication of an impacted bullet in the neck.

We present a case of a patient who sustained a bullet wound to the mouth and face resulting in impaction of the foreign body in the neck. This was initially managed conservatively until migration into the supralaryngeal area occurred. This resulted in airway obstruction, dysphagia, and dysphonia necessitating resuscitation and per-operative intrapharyngeal removal. Bullet wounds are uncommon in this country and experience with these cases is lacking. This paper discusses the various management options and the mechanism of how the bullet became lodged in the tissues of the neck.

Adult↗
PubMed1992

Osteomyelitis of the cervical spine following laryngectomy.

Only one case of osteomyelitis of the cervical spine following laryngectomy for carcinoma of the larynx has been reported in the literature to date. We report an unusual case of osteomyelitis of the cervical spine following treatment of laryngeal carcinoma by radiotherapy (RT) and subsequent laryngectomy and discuss the relevant literature.

Carcinoma, Squamous Cell↗
PubMed1992

The effect of parental smoking on outcome after treatment for glue ear in children.

A sample of 201 children aged between 2 and 9 years with bilateral chronic otitis media with effusion (OME) were treated prospectively and at random by adenoidectomy, adenotonsillectomy, or with neither procedure. In all cases only a unilateral grommet was inserted and the contralateral unoperated ear was examined one year post-operatively for persistence or resolution of the effusion. A self-administered questionnaire was completed by the parents concerning their smoking habits. The resolution of effusion following surgery was assessed in relation to smoking by by the mother and father separately and in combination. Clearance of glue was statistically less frequent where the child's mother or where both parents smoked. This was related to the number of cigarettes smoked by the mother or both parents. The adverse effect was demonstrable whether or not adenoidectomy or adenotonsillectomy had been performed for treatment. The findings lend further support or professional and governmental opinions of a deleterious effect of passive smoke exposure on children and in this case parental smoking has been shown to have an adverse effect on the outcome of OME following surgical treatment.

Child↗
PubMed1992

The radio-opacity of fishbones.

Plain radiographs are often taken to localize fishbones which lodge in the pharynx. In this study a pig's neck was used to determine the radio-opacity of 14 different species of fishbones. Radiographs were taken with bones placed in up to four of the common sites of impaction and assessed on two occasions independently by two previously uninvolved ENT consultants. The visibility of the fishbones was scored. Inter and intra-observer agreement for species and site was determined. There was excellent interobserver agreement at both sessions for species (rs1 = 0.96, P < 0.0001, rs2 = 0.95, P < 0.0001) and site (rs1 = 0.98, P < 0.05, rs2 = 0.95, P congruent to 0.05). Intraobserver agreement for species of fish were similarly significant but not for site. The most opaque bones were cod, haddock, grey mullet and lemon sole. The site most often detected was the laryngopharynx and that most often missed was the tonsil. This study is clinically relevant because it is useful to know which species of fishbone are radio-opaque when clinical examination fails to reveal a foreign body and may clarify the decision to proceed to endoscopy.

Animals↗
PubMed1992

Efficiency of stereopsis in random-dot stereograms.

The statistical efficiency of stereopsis was investigated by measurement of the discriminability d' of a step edge in depth in a random-dot stereogram and its comparison with d' calculated for an ideal observer model. Efficiencies of approximately 20% were found for stimuli with very few (less than 30) dots. As the number of dots was increased, efficiency fell markedly to 2% and below. Over the ranges explored in this study, there was little variation in efficiency with changes in dot density (with dot number constant) or stimulus size. Efficiency loss was also found to be almost entirely due to incomplete use of the available information rather than to intrinsic observer variance. Results were compared with two simple models that implemented possible detection strategies.

Depth Perception↗
PubMed1992

Clinical, biochemical, electrophysiologic, and histologic assessment of chlorpyrifos induced delayed neuropathy in the cat.

The ability of a supralethal dose of chlorpyrifos to produce delayed neuropathy was examined using assessments of clinical signs, electromyography (EMG), motor nerve conduction velocity (MNCV), lymphocyte neuropathy target esterase activity (LNTE), and histologic changes in nervous system tissues. Cats were exposed to a single, im injection of corn oil (vehicle control), DFP (positive control) at 5.0 mg/kg, or chlorpyrifos at 300 mg/kg and observed for 60 days. Atropine and 2-PAM were administered to chlorpyrifos exposed cats one to two times a day for 14 to 24 days in response to the appearance of cholinergic signs. Anorectic cats during the acute toxicosis were force fed by hand and hydration was maintained by administering fluids sc. Onset of ataxia (mean +/- SD) for the positive control and chlorpyrifos exposed cats were 16.2 +/- 1.8 days (range of 14-19 days) and 19.0 +/- 1.4 days (range of 17-21 days), respectively. Functional deficits for both groups were confined to the hindlimbs and characterized by a crouched-waddling gait, hypermetria, and proprioceptive deficits. Maximal inhibition of LNTE activity was 96% at 24 hr postdosing in the positive control group and 46% at 7 days postdosing in the chlorpyrifos group. No EMG or MNCV abnormalities were detected in any of the treatment groups. Axonal degeneration was similar for the positive control and chlorpyrifos exposed cats. Ascending tracts of the cervical spinal cord and descending tracts of the thoracic and lumbar spinal cord were most severely affected and peripheral nerves were only mildly affected. The clinical and histologic effects produced indicate that chlorpyrifos can cause delayed neuropathy in the domestic cat. The moderate but prolonged inhibition of LNTE produced by chlorpyrifos is atypical of classic organophosphorus delayed neurotoxicants.

Animals↗
PubMed1992

Fractured-nose reduction under local anaesthesia. Is it acceptable to the patient?

This article examines patients' acceptance of fractured-nose reduction under local anaesthesia, both objectively and subjectively. At each stage of the reduction the level of the discomfort, the patients' experiences were recorded. The success rate of complete reduction of the nasal fracture was found to be 71% and this was similar to that obtained in other studies that have used general anaesthesia. An overall level of discomfort for the procedure in terms a layman can understand was obtained by comparing the manipulation with that of having a tooth filled at the dentist. Sixty-three percent of the patients said that the nasal fracture reduction was no worse or the same as a dental filling. Our study showed that 96% of patients would be willing to undergo the same local anaesthetic procedure if they fractured their nose a second time. We conclude that it is possible to reduce the majority of fractured noses adequately with little inconvenience to the patient under local anaesthesia, and so we recommend that this procedure should be considered in the first-line treatment of the displaced fractured nose.

Adolescent↗
PubMed1992

Nasal mucociliary clearance and resolution of otitis media with effusion in children following adenoidectomy.

Numerous workers have studied the relationship between nasal mucociliary clearance and adenoid removal in terms of nasal function. This study was performed to investigate the role of preoperative saccharin clearance time and velocity determination in selecting children with established otitis media with effusion (OME) for adenoidectomy. Testing was not found to be particularly reproducible and there was no statistically significant relationship between mucociliary parameters and the otoscopic resolution of effusion.

Adenoidectomy↗
PubMed1991

Vertical disparities and perception of three-dimensional shape.

The information about depth and three-dimensional shape available from the horizontal component of the stereo disparity field requires interpretation in conjunction with information about egocentric viewing distance (D). A novel computational approach for estimating D was proposed by Mayhew and Longuet-Higgins, who demonstrated that the horizontal gradient of vertical disparities uniquely specifies the viewing distance. We have now used random dot stereograms in a shape judgement task to show that changes in vertical disparities have no effect on perceived three-dimensional shape. Changes in ocular convergence do alter perceived shape, suggesting substantial changes in the subjects' scaling of horizontal disparities. We conclude that vertical disparities are not used to scale disparities for viewing distance, and that extraretinal signals must be considered when analysing human three-dimensional shape perception.

Depth Perception↗