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Biomedical subjects

D Walker

Publications and source records attributed to D Walker.

At least 379 records · Page 21Linked to original sources
PubMed1979

Pharmacokinetics and relative bioavailability of oral theophylline capsules.

The oral bioavailability of liquid-filled theophylline capsules relative to a nonalcoholic aminophylline solution was determined in normal volunteers. In addition, theophylline absorption and elimination kinetics were reexamined. There were no statistically significant differences between the bioavailability of capsules and liquid as measured by the area under the curve (AUC) from time 0 leads to infinity (p greater than 0.05). The bioavailability parameters of Cmax, tmax, and AUC were determined from actual serum theophylline concentration-time data and from a nonlinear least-squares fit of the serum concentration-time data. Theophylline absorption from the capsules was noticeably faster than from the liquid in most subjects, although the differences in absorption rates were not significantly different (p greater than 0.05). The determined apparent volume of distribution, elimination half-life, and plasma clearance of theophylline were similar to values reported by other investigators. Marked inter- and intraindividual variations in the elimination half-life were noted.

Adult↗
PubMed1979

Halothane does not inhibit human neutrophil function in vitro.

Various indices of function of neutrophils from normal healthy volunteers have been examined after in vitro exposure to halothane. Random free movement on glass was unaffected, but random migration through millipore filters was slightly increased. There was no significant change in migration in response to casein chemotaxis. Phagocytosis, degranulation and the enhanced non-mitochondrial respiration associated with phagocytosis were unaffected. Electron-microscopic appearance at 30 s after exposure to latex particles was normal in all respects.

Cell Movement↗
PubMed1979

A case of isolated primary chylopericardium.

Primary chylopericardium presented as radiographic cardiomegaly in an asymptomatic 19-year-old man. Normal findings at cardiac catheterisation and angiographic demonstration of cardiac displacement from the diaphragm suggested a collection of fluid below the heart which was confirmed by M and B mode ultrasound scanning. Thoracic blood pool isotope scanning indicated that the lumen was a pericardial effusion rather than a cyst. Lymphangiography did not indicate any direct lymphatic communication though a small pool of contrast appeared in the pericardium and the diagnosis of chylopericardium was confirmed by pericardiocentesis. Surgical treatment was undertaken after rapid reaccumulation of chyle and the patient remains well 6 months later.

Adult↗
PubMed1979

Suprapubic bladder needle aspiration in infants and children.

Suprapubic needle aspiration of the bladder represents an excellent alternative to urethral catheterization to document bladder bacteriuria. Specific indications include documentation of bacteriuria in infants, in uncircumcised male children, in myelodysplastic children, and in children with abnormal genitalia.

Adult↗
PubMed1978

Spectrum of multicystic renal dysplasia: diagnosis and management.

Multicystic renal dysplasia represents a spectrum of pathologic states, from unilateral multicystic kidney through segmental and focal multicystic dysplasia to bilateral multicystic kidney. Diagnosis can be established with low-risk procedures with reasonable accuracy. Treatment may be nonoperative in selected cases, but the physician must be responsible for long-term follow-up of the child until more is known about the natural history of this process.

Adolescent↗
PubMed1978

Inhalation toxicity studies on cigarette smoke (VI). 6-week comparative experiments using modified flue-cured cigarettes: histopathology of the lung.

Rats were exposed twice daily for 6 weeks to diluted smoke derived from cigarettes with a range of deliveries of particulate matter. The inhaled smoke reached the alveolar surface, increased the size and number of free macrophages and provoked epithelial metaplasia but did not appear to alter the lymphoid reaction to spontaneous infection. The hypertrophy of the macrophages was typically alveolar and their hyperplasia was directly proportional to the particulate delivery of cigarettes smoked. Alveolar metaplasia was incipient, developed characteristically near the respiratory bronchiole in close association with macrophage clusters and only in rats exposed to smoke from cigarettes with the highest delivery of particulate matter.

Animals↗
PubMed1978

Inhalation toxicity studies on cigarette smoke (VII). 6-week comparative experiments using modified flue-cured cigarettes: histopathology of the conducting airways.

Rats were exposed twice daily for 6 weeks to diluted smoke derived from cigarettes with a range of deliveries of particulate matter. The inhaled smoke caused squamous metaplasia and keratinising hyperplasia in the larynx and goblet cell hyperplasia in the nasal cavity, trachea and intrapulmonary bronchus. Squamous metaplasia occurred in the larynx of almost all rats exposed to smoke but never in their tracheas or bronchi. The degree of reaction observed for the other responses, except goblet cell hyperplasia in the trachea, was positively related, by quantitative microscopy, to the particulate delivery of cigarettes. These findings, together with other smoke-induced changes which occur in the pulmonary alveoli, provide a basis for the short-term bioassay of inhalation toxicity of cigarette smoke.

Animals↗
PubMed1978

Idiopathic priapism in the newborn.

Priapism in children usually results directly or indirectly from an underlying cause. Secondary priapism is extremely rare in neonates and idiopathic priapism has not been described previously.

Humans↗
PubMed1978

The effect of nicotine on fetal breathing movements in conscious pregnant ewes.

Nicotine (0.14--0.25 mg/kg), injected intravenously or intraarterially into conscious pregnant ewes, caused a decrease in fetal PaO2 within 5 minutes, persisting for up to 30 minutes. There was a significant fall in the incidence of fetal breathing movements. These changes did not occur if the ewe was treated with an alpha-blocking agent (phentolamine) or if the nicotine was infused for 30 minutes at 0.27 to 0.85 mg/minute. Nicotine crossed the placenta; fetal concentrations equaled those in the ewe 5 minutes after the injection and remained at or above maternal levels for 1 hour. Nicotine given directly to the fetus (0.005--0.03 mg/kg estimated fetal weight) stimulated fetal breathing movements in a dose-related manner. We suggest that the maternal injection of nicotine results in a fall of uterine blood flow by a sympathomimetic action, leading to transient fetal hypoxemia and a reduction of fetal breathing movements and that a similar phenomenon may occur when a pregnant woman smokes cigarettes.

Animals↗
PubMed1978

Hydantoin drugs inhibit polymerization of pure microtubular protein.

5,5-Diphenylhydantoin or 5-(4-hydroxyphenyl)-5-phenylhydantoin, 3.6 X 10(-4) M, inhibited polymerization of purified pig brain tubulin 50% as measured by viscosometric assay and estimation of tubulin length by electron microscopy. 5,5-Diphenylhydantoin did not bind to the low molecular weight fraction of tubulin or to guanosinetriphosphate; it displaced colchicine weakly from its binding site. 5,5-Diphenylhydantoin did not depolymerize established microtubules, indicating that it differs from colchicine in site and mode of action.

Animals↗
PubMed1977

Laboratory methods of equine pregnancy diagnosis.

Rectal examination is a reliable method of diagnosing pregnancy in the mare. Also, test kits are available for the simple quick detection of pregnant mare serum gonadotrophin. Nevertheless there is a considerable demand by practitioners for an independent laboratory service in equine pregnancy diagnosis, particularly during the gestational phase when placental gonadotrophin is concentrated in the blood. An initial attempt to provide a service by means of the agar gel diffusion test was disappointing and alternatives were sought. The primary requirements for an ideal alternative technique were defined as: accuracy, sensitivity, applicability to the optimum request period, elimination of subjective interpretation and a minimal inconclusive rate. Additional considerations included cost, practicality and test duration. The various tests available are summarised and their published accuracies are discussed. It was decided to reverse the current trend from biological to immunological techniques and to modify the test by which Cole and Hart announced the discovery of PMSG in 1930. The utero-ovarian response in the immature female mouse was quantified simply to produce a numerical result. The reason for this is explained, the method is described and its accuracy is evaluated. The primary requirements, defined above, were achieved.

Animals↗
PubMed1977

Five-hour renal functional evaluation.

Children with urogenital disease frequently require evaluation of glomerular and tubular functions. Herein is presented a practical method of performing glomerular and tubular functional studies requiring short time periods and utilizing readily availabe laboratory techniques.

Adult↗
PubMed1977

Delayed imaging to distinguish bone lesions from urinary tract activity.

In 28/1,400 patients examined by bone imaging two hours after injection of 99mTc-polyphosphate or diphosphonate, it was found that activity in the urinary tract obscured the bony pelvis, making assessment of this region difficult or impossible. In several patients additional images were obtained 24 hours after the injection when decreased activity in the urinary tract allowed the pelvis to be more satisfactory visualized.

Aged↗
PubMed1975

Excretion of inhibitors of calcification in urine. Part I. Findings in control subjects and patients with renal stones.

The total excretion of inhibitors of in vitro calcification was measured (in inhibiting units per day) in 24-hour urine samples of 11 control subjects and 20 patients with renal calculi. A semiquantitative method incorporating the rachitic rat cartilage technique was used. In both groups there was a significant positive correlation between the number of inhibiting units per day and the daily urine volume. The mean number of inhibiting units per day was significantly (P smaller than 0.05) higher in the stone patients than in the controls. However, the stone-formers had significantly larger (P smaller than 0.01) 24-hour urine volumes. When corrections were made for urine volume there was no significant difference between the two groups. These data suggest that the underlying abnormality responsible for renal stone formation is not a persistent decrease in the total concentration of urinary inhibitors of calcification.

Adult↗
PubMed1975

Excretion of inhibitors of calcification in urine Part II. Findings in patients with chronic renal failure.

By means of a semiquantitative method incorporating the rachitic rat cartilage technique, the total urinary inhibitory activity with respect to calcification was compared in 11 control subjects and 20 patients with renal failure. The patients had significantly lower mean values of inhibiting units per day than did the control subjects. Both groups showed a significant positive correlation between the number of inhibiting units per day and urine volume. When urine volume was taken into account in the comparison, the numbers of inhibiting units for patients continued to be lower than the numbers for controls. These findings are consistent with the hypothesis that the increase of inhibitory activity observed in uremic serum is secondary to a decrease in excretion of the responsible factor (or factors) in the urine, and that the factor (or factors) in serum responsible for the inhibition are identical to those in the urine.

Adult↗