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Biomedical subjects

D Downey

Publications and source records attributed to D Downey.

At least 37 records · Page 2Linked to original sources
PubMed1996

Porphyria: a new perspective.

Recently, Medical Hypotheses has published two papers on fatigue syndromes and their relationship to porphyrin metabolism (1,2). This article continues the exploration of how many diseases may have abnormal porphyrin metabolism playing a role in their pathogenesis. Another issue is the need to expand our concepts of the frequencies of these genetic enzyme deficiencies in this pathway. Over time and the development of better tests, the identification of porphyric patients has increased (3). Now that more enzymes are becoming available for testing, the use and interpretation of those tests becomes critical and the selection of control populations could greatly affect results.

Acute Disease↗
PubMed1993

A technique for magnetic resonance imaging of the temporomandibular joint.

T1-weighted Magnetic Resonance Imaging (MRI) of 72 temporomandibular joints (TMJs) of symptomatic patients and normal subjects was performed after they had been clinically classified. The images were then interpreted by two radiologists, blinded to the clinical classification. The technique of imaging used a head coil for bilateral imaging, allowing a 3-position study in under 1 h. Correlation between MRI and clinical classification at the level of normal vs abnormal was achieved in 61/72 joints, giving a sensitivity of 79% and a specificity of 91% for MRI relative to the clinical assessment. True coronal images were of no added value. The addition of supplemental gradient-echo images was helpful in 12/15 joints. Osseous condylar abnormalities were present in 15 joints, all of which had otherwise identifiable disc abnormalities. Diminished condylar translation was a useful indirect sign of non-reducing disc displacement. We conclude that MRI is a very useful and reliable technique in TMJ imaging. The technique described is applicable to any MR unit, without the need for dedicated coils.

Adolescent↗
PubMed1993

The role of colour flow Doppler ultrasonography in the investigation of disease in the eye and orbit.

Colour flow Doppler ultrasonography is a relatively new technique in which colour-encoded representations of flowing blood are imposed over a conventional grey-scale ultrasound image. This allows interrogation of a relatively large volume of tissue to determine the presence and direction of blood flow. The waveform tracings are then evaluated by means of conventional Doppler imaging. We demonstrate examples of normal vascular structures in the orbit and describe the application of this technique in the investigation of vascular disease, such as carotid-cavernous fistula and ischemic disease. The technique can also be used to evaluate ocular membranes and masses. Colour flow Doppler imaging promises to be an important advance in ophthalmic ultrasonography.

Blood Flow Velocity↗
PubMed1992

Ultrasonographic findings in the anterior segment of the eye obtained with a nondedicated unit.

Many abnormalities of the anterior segment of the eye can be detected by ultrasonography (US), and associated anomalies of the posterior segment that are difficult to detect clinically may also be demonstrated by this modality. A total of 48 patients with ultrasonographically detectable abnormalities in the anterior segment were examined with real-time high-resolution US; 51 abnormalities were demonstrated. The most common problems were cataract (19 cases), intraocular lens implant (10), dislocated lens (9) and tumour (8). In addition, 23 abnormalities of the posterior segment of the eye were found. Six of the lesions in the posterior segment were obscured by those in the anterior segment and could be detected only by US.

Adult↗
PubMed1992

Colour-flow Doppler imaging of a carotid-cavernous fistula.

The authors describe a case of carotid-cavernous fistula evaluated with both conventional carotid angiography and colour-flow Doppler ultrasonography. The findings in the colour-flow Doppler images correlated well with those from angiography; in addition, Doppler imaging supplied extra information about the direction and the velocity of flow. After embolization, colour-flow Doppler imaging demonstrated a marked decrease in the flow. The authors conclude that colour-flow Doppler imaging may be useful for noninvasively detecting and evaluating a carotid-cavernous fistula, as well as for monitoring the patient's progress after therapy.

Aged↗
PubMed1988

Ischemic injury to enteric free flaps: an experimental study in the dog.

Enteric free flaps have proven to be useful for reconstructing the cervical esophagus. Although jejunum is favored, the rationale for this is not at all clear. We have postulated that resistance to warm ischemia varies in different regions of the gut. An experiment was carried out in 10 mongrel dogs in which 10-cm segments of proximal, middle, and distal small bowel were isolated on single vascular pedicles. In each portion of the gut there were three segments: a control, a segment subjected to 60 minutes of warm ischemia, and a segment subjected to 120 minutes of warm ischemia. The following day each animal was reexplored, and the viability of bowel segments was assessed visually and with fluorescein. All control segments were viable at 24 hours. Twenty segments were subjected to 1 hour of warm ischemia, and all but two were viable. Nineteen gut segments were subjected to 2 hours of warm ischemia. Seven of eight proximal segments were viable, two of five midsegments were viable, and zero of six distal segments were viable. Survival in the distal portion compared to the proximal portion was significantly less (p less than 0.01). It appears from this study that isolated distal small bowel segments are less resistant to warm ischemia than proximal segments.

Adult↗
PubMed1988

Staphylococcal colonization in atopic dermatitis and the effect of topical mupirocin therapy.

Forty-nine patients with atopic dermatitis entered a double blind placebo controlled cross-over study of mupirocin, a new topical antistaphylococcal antibiotic. Forty-five patients were evaluable. Quantitative bacteriological assessment before treatment showed that heavy colonization of the skin with Staphylococcus aureus was present in nearly all patients even in the absence of overt infection. However, the bacterial count was significantly reduced by 2 weeks' treatment with topical mupirocin, but not by the placebo. Moreover, a significant reduction of clinical severity was also observed after treatment with mupirocin, which was maintained over the following 4 weeks, although recolonization occurred during this period, with bacterial counts rising to pre-treatment levels. Despite recolonization, clinical deterioration was not observed during the trial period. No serious side-effects were observed. Phage typing showed that 50% of patients carried more than one bacterial phage type. Recolonization in eight patients (17%) was with a 'new' strain that had not previously been isolated.

Administration, Topical↗
PubMed1988

Somatosensory projections to the superior colliculus of the anaesthetized cat.

1. Experiments in anaesthetized cats have shown that the superior colliculus receives deep afferent input from the forelimb and hindlimb, but not from the large superficial neck muscles. 2. Neuronal activity in the superior colliculus is readily elicited by electrical stimulation of C2 and C3 cutaneous nerves. A significant proportion of neurones so activated have multiple receptive fields and some with no identifiable receptive fields in regions innervated by C2 and C3 nerves have receptive fields elsewhere on the body surface. Many collicular neurones activated by C2 and C3 stimulation had no identifiable receptive fields. 3. Natural stimuli to the limbs, hitherto believed to activate only cutaneous receptors, are sufficient to activate deep receptors which contribute to the neuronal responses in the superior colliculus elicited by the natural stimulus. These same natural stimuli set up transmitted vibration adequate to excite receptors some distance from the applied stimulus. 4. No evidence was found for a rigorous somatotopy in the superior colliculus. The great majority of neurones received trigeminal input which is widely distributed throughout the superior colliculus. 5. Tactile stimuli to the face are most effective in eliciting unit activity in the superior colliculus and many neurones activated by these stimuli were shown to be tectospinal neurones. In particular, the specialized receptors of the face, including the glabrous skin of the snout (the planum nasale) and the vibrissae, are major sources of input to collicular neurones including tectospinal neurones. 6. It is suggested that a major role of the superior colliculus is in the organization of head movements associated with the use of the specialized receptor organs of the face in exploratory behaviours. The superior colliculus may also be involved in the organization of aversion movements of the head.

Action Potentials↗
PubMed1987

Morphology, distribution, and density of sensory receptors in the glabrous skin of the cat rhinarium.

The sensory organization of the cat rhinarium has been investigated. Individual rete pegs were found to contain a triad of receptors comprising free nerve endings ascending in the peg to terminate in close proximity to the skin surface, a basally situated layer of Merkel corpuscles, and an abundance of encapsulated receptors lying at the base and to one side of the rete peg. Neither the Merkel corpuscles nor the encapsulated receptors were evenly distributed. Merkel corpuscles were more abundant dorsally; ventrally they were fewer and asymmetrically arranged within individual rete pegs. The encapsulated corpuscles were more evenly distributed, but dorsally they were consistently present as encapsulated clusters of up to nine corpuscles.

Animals↗
PubMed1986

Salmonella typhi infection in adults is not limited to travellers returning from the tropics.

We reviewed the case notes of 23 adult patients infected with Salmonella typhi and admitted to the infectious disease unit, Auckland Hospital between January 1977 and December 1984. Fifteen had typhoid fever and eight were chronic carriers of S typhi. All isolates were sensitive to amoxycillin, chloramphenicol and cotrimoxazole. Ten of those with typhoid fever had recently been in tropical countries, predominantly Pacific Islands. The remaining five all lived in South Auckland and had not travelled out of New Zealand: we suspect that contaminated shellfish collected from the Manukau Harbour in South Auckland were the source. Typhoid fever should be suspected in young travellers returning to New Zealand with fever, diarrhoea, abdominal pain and headache. Similarly this diagnosis should be suspected in Polynesians and Maoris from South Auckland who have not travelled. All but one patient with typhoid fever responded clinically to the initial regimen which was usually oral amoxycillin given for a median 18 days. One other patient relapsed. Cholescystectomy and subsequent oral antibacterials eradicated S typhi from five biliary carriers with abnormal gallbladders. Prolonged high dose oral amoxycillin alone was effective in one of two carrier patients with normal gallbladders. The role of the Department of Health in identifying carriers of S typhi remains important.

Adolescent↗
PubMed1985

Early clinical experience with imipenem-cilistatin.

We treated 15 patients with 16 proven bacterial infections with imipenem-cilistatin. Nine isolates were gram positive cocci, the remaining ten being gram negative bacilli and all had MICs less than or equal to 2.0 mg/l. Eight patients had respiratory tract infections, four urinary tract infections and there were three others. Twelve of 16 infections were microbiologically cured. There were no important drug side effects or toxicity. Imipenem-cilistatin is a potentially useful formulation.

Adolescent↗