Search PubMed⌕ Search

Biomedical subjects

D Cameron

Publications and source records attributed to D Cameron.

At least 55 records · Page 3Linked to original sources
PubMed1991

Aerosol delivery in neonatal ventilator circuits: a rabbit lung model.

The benefits of inhaled therapy in ventilated neonates are recognized, but the reliability of drug delivery in nebulizer-ventilator circuits is uncertain. We quantified the effect of changing variables. Twenty-three freshly killed rabbits (1.15-1.9 kg) were ventilated via a tracheostomy by a pressure-limited, time-cycled ventilator (Neovent). A radioaerosol of 99Tcm pertechnetate from an Ultravent nebulizer (Mallinkrodt) was fed into the proximal ventilator tubing. Two 3-minute nebulizations at "standard settings" were followed by 2 at altered pressure, frequency, gas flow, I:E ratio, or position of the nebulizer in the circuit. Each nebulization was followed by a 3-minute gamma camera image and total deposited radioactivity was measured in excised lungs and trachea. Images demonstrated good peripheral aerosol deposition. At standard settings, lung deposition averaged 2.8% of the aerosol released. This was decreased markedly by reducing tidal volume (ventilator pressures) and residence time of aerosol (I:E ratio). Reduced gas flow decreased deposition slightly, presumably by increased particle size and marginally reduced tidal volume. Deposition did not change with increased frequency; increased minute ventilation was offset by decreased residence time of the aerosol. We conclude that the Ultravent nebulizer can be used to nebulize drugs in a standard neonatal circuit, although the dose delivered is small. Tidal volume and aerosol residence time are important determinants of aerosol delivery.

Animals↗
PubMed1991

Short report: plasma somatostatin concentrations in the irritable bowel syndrome.

The description of a patient with the irritable bowel syndrome whose symptoms were completely relieved by the administration of somatostatin raised the possibility that a deficiency of somatostatin may be involved in the pathogenesis of the disorder. We have examined this possibility by studying 11 healthy controls (35 +/- 12 years; mean +/- S.D. 8 female) and 10 irritable bowel syndrome patients (39 +/- 14 years; 7 female) complaining of frequency of defaecation of 4 or more times a day. Plasma somatostatin concentrations were determined by specific radioimmunoassay, fasting and at 15, 30, 45, 60, 90, 120 and 180 min after a standard breakfast. Irritable bowel syndrome patients and controls had similar fasting (27.4 +/- 5.1 vs. 35.2 +/- 4.3 pg/ml; mean +/- S.E.M. and integrated increment of post-prandial (5105 +/- 858 vs. 3885 +/- 793 pg.min/L) plasma concentrations of somatostatin, as assessed by student's t-test. These observations do not support the idea that a state of somatostatin deficiency exists in the irritable bowel syndrome.

Adult↗
PubMed1991

A mattress suitable for use with tilting tables in a radiology department.

It has been possible to design a comfortable, yet highly practical mattress for use in general purpose screening rooms with tilt tables. Attention has been paid to materials and fittings and because it is easy for the staff to use it is in constant use. It has become an essential part of our equipment and has considerably improved the comfort of many procedures.

Beds↗
PubMed1990

The effects of ingestion time of gliclazide in relationship to meals on plasma glucose, insulin and C-peptide levels.

The effect of altering the timing of gliclazide administration in relation to a meal was studied in ten type 2 (non-insulin dependent) chronically treated diabetics. Gliclazide was given 30 min before, at the start of and 30 min after breakfast or omitted altogether. Plasma gliclazide was present at greater than 2 mg/l throughout the study periods. Administration at 30 min after the meal significantly delayed the time to peak for plasma gliclazide. No significant difference was noted in plasma glucose, insulin or c-peptide patterns with any protocol. It is concluded that, in clinical practice, with chronically treated diabetics the timing of gliclazide ingestion in relation to meals is not critical.

Aged↗
PubMed1990

Evaluation of nebulizers for use in neonatal ventilator circuits.

The use of nebulizers in neonatal ventilator circuits offers a new and relatively uncharted route of therapy for infants in respiratory failure. We used a model lung to investigate and compare different nebulizer types and therapeutic agents and to make practical observations. Five different nebulizers (Ultravent, Acorn, MAD2, Small Particle Aerosol Generator, and Pulmosonic) were compared for efficiency of delivery of an amino-phylline aerosol to the model lung, and the particle size of aerosol produced by them was measured. A Nebulizer Efficiency Index (NEI) was created, representing the deposition rate of the original solution as aerosol upon the model lung filter. The Acorn (2.8.10(3) ml/min) and MAD2 (2.4.10(-3) scored highest NEI. When a suspension of budesonide was nebulized, minimal amounts of drug were recovered from the filter when the nebulizer producing the smallest particle size (Ultravent) was studied, suggesting that suspensions of drugs behave differently from solutions. Significant changes need to be made to a conventional circuit when jet nebulizers are used; most of these are obviated by the use of an ultrasonic nebulizer, which also avoids the potential problem of marked cooling of the gas flow produced by jet nebulizers.

Aerosols↗
PubMed1990

Effect of octreotide on mouth-to-caecum transit time in healthy subjects and in the irritable bowel syndrome.

The effect of a single subcutaneous injection of octreotide (50 micrograms) on mouth-to-caecum transit time was determined in patients with the irritable bowel syndrome who complained of bowel frequency, and in healthy volunteers. The assessment of mouth-to-caecum transit time was performed by monitoring breath hydrogen concentration and noting a sustained 10 p.p.m. rise after ingestion of lactulose 40 ml. Measurements were performed fasting, and on a separate day, after a standard breakfast which included 40 ml lactulose. The studies were performed double-blind in a pre-determined random order. Octreotide prolonged mouth-to-caecum transit time in irritable bowel syndrome patients and healthy subjects by factors of 2.4 and 2.6 after lactulose when fasting, respectively, and by factors of 2.8 and 2.6 after the breakfast which contained lactulose. The upper gastrointestinal transit rate was similar in irritable bowel syndrome patients and healthy controls.

Adult↗
PubMed1990

Clinical experience with a hypotonic oral rehydration solution for treatment of pediatric gastroenteritis in the United Kingdom.

Animal and human perfusion studies suggest that water absorption can be optimized by glucose-electrolyte solutions with low total osmolality. A new oral rehydration solution (ORS), reformulated Dioralyte (RD), containing 60 mmol/L of sodium and 90 mmol/L of glucose with an osmolality of 240 mosm/kg, was tested for safety and efficacy in children in the United Kingdom with acute gastroenteritis. In a double-blind, controlled trial, RD was compared with standard Dioralyte (SD), a widely used low-sodium, high-glucose solution containing 35 mmol/L of sodium and 200 mmol/L of glucose, with an osmolality of 310 mosm/kg. Infants and children aged 2 weeks to 3 years admitted with acute gastroenteritis of less than five days' duration and mild to moderate dehydration were randomized to receive either RD or SD. Clinical and laboratory assessments were made on admission and 12, 24, and 48 hours after treatment. Thirty-two children were enrolled in the study; 14 received RD and 18 SD. No adverse effects from either ORS were reported. Efficacy was evaluated in 24 patients, of whom eight received RD and 16 SD. Total ORS intake and intake in milliliters per kilogram were similar in both treatment groups. Mean fluid balance, mean percentage weight change, and median stool frequency did not differ between the groups at 12, 24, and 48 hours after onset of treatment. Three (12.5%) patients had greater than or equal to 0.05% reducing substances in the stool during treatment, and the incidence was similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1989

Purification and characterization of an anticonvulsant-induced human cytochrome P-450 catalysing cyclosporin metabolism.

A form of human hepatic microsomal cytochrome P-450 (P450hA7) with subunit Mr 50,400 has been purified from an epileptic who had been receiving long-term treatment with anticonvulsant drugs. P450hA7 metabolized the immunosuppressant drug cyclosporin A and the dihydropyridine calcium channel antagonist nifedipine, but did not metabolize a similar dihydropyridine drug, nicardipine, nor a series of alkoxyresorufin model substrates. The hepatic microsomal concentration of P450hA7 was higher in five individuals who had been receiving long-term anticonvulsant treatment than in any of 21 individuals who had not been similarly treated. The mean P450hA7 concentration in the treated individuals was 5-fold higher than the mean concentration in the untreated individuals. It is concluded that P450hA7 is a member of the cytochrome P450III family which is induced by anticonvulsant drugs in man.

Adult↗
PubMed1989

Factors affecting immunization rate in a cohort of elderly veterans: a retrospective pilot study of influenza vaccine compliance.

A survey of aged veterans greater than or equal to 85 years old was undertaken to determine their vaccination behaviour prior to mounting a local education campaign on influenza vaccine. A questionnaire inquiring into circumstances which may have influenced their decision to be immunized against influenza was mailed to all 300 elderly veterans (greater than or equal to 85) obtained from the register at the James A. Haley Veterans' Hospital. Ninety-two persons responded in self addressed stamped envelopes and data were analysed six months following mailing date. The most important reason for not being immunized was lack of information concerning vaccine recommendations and its availability (48%). Fear of 'shots' and side effects was the next most important reason for not taking the vaccine (19%). Amotivation and transportation difficulties played comparatively minimal roles (10%, 13%). These data suggest that health education measures may improve vaccine compliance in the elderly population who suffer from higher death rates and complications from influenza.

Aged↗
PubMed1989

Evaluation of three oral rehydration solutions designed for use in developed communities.

One hundred and sixteen children (less than 2 years old) admitted to a London hospital with acute gastroenteritis were randomized to receive either an oral rehydration solution (ORS) with low sodium and high glucose concentration (Na+ 35, glucose 200 mmol/L), an ORS with a high sodium but low glucose concentration (Na+ 60, glucose 111 mmol/L), or an ORS containing glycine and a glucose polymer (Na+ 50, glucose 50, glycine 50 mmol/L). Clinical, biochemical and haematological features of the three groups were similar on admission. Rotavirus was common (31%); the majority of children had minimal dehydration or acid-base disturbance. The clinical outcome, including ORS intake, prevention of dehydration, rehydration, and duration of hospital stay was similar in the three treatment groups. All initial electrolyte abnormalities were corrected; no child developed hypernatraemia or hyponatraemia. At 24 h, the mean serum urea was higher in those who received the ORS containing glycine than in other groups, and it had not fallen significantly since admission. Eighteen per cent of children had carbohydrate intolerance: four children with greater than or equal to 2% reducing substances in their stool had all received ORS with a high glucose content and had numerous watery green stools containing rotavirus. All ORS solutions were safe and effective for rehydration and correction of biochemical abnormalities, however carbohydrate intolerance was more prevalent in children who received the ORS with a high glucose content.

Acid-Base Equilibrium↗
PubMed1989

Caecal herniation through the foramen of Winslow.

Caecal herniation through the foramen of Winslow is a rare cause of intestinal obstruction and the preoperative diagnosis is rarely made. A patient with caecal herniation through the foramen of Winslow is presented and differentiation from caecal volvulus is stressed. In caecal herniation through the foramen of Winslow the "hilum" of the kidney shaped loop of bowel points towards the foramen of Winslow rather than the right iliac fossa.

Aged↗