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Biomedical subjects

D Walker

Publications and source records attributed to D Walker.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effects of thyroidectomy on development of skeletal muscle in fetal sheep.

The influence of the thyroid gland on the functional and histochemical development of fast- and slow-twitch skeletal muscle of fetal sheep has been studied in euthyroid fetal sheep (n = 6) and athyroid fetuses (n = 4) surgically thyroid-ectomized at 70-75 days of gestation. Two fast-twitch muscles, the medial gastrocnemius and extensor digitorum longus, and the slow-twitch soleus muscle were studied at the fetal age of 140 days gestation. The athyroid fetuses had significantly slower twitch contraction and relaxation times in both the medial gastrocnemius and extensor digitorum longus muscles compared with the euthyroid fetuses. Twitch contraction and relaxation times of the soleus were not different in the two groups. Thyroidectomy resulted in an increase in the proportion of fast (type II) muscle fibers and myosin, as shown histochemically and by gel electrophoresis of heavy-chain myosins. These results indicate that the functional maturation of the fast-twitch muscles of sheep is influenced by the presence of an intact thyroid gland from at least 70 days of gestation. In contrast, the slow-twitch soleus muscle fiber diameter and twitch contraction and relaxation times were not different in the two groups.

Animals↗
PubMed1991

Surgical mandibular advancement in adolescents: postsurgical growth related to stability.

Ten of 12 adolescents treated with surgical mandibular advancement showed postsurgical mandibular growth, as indicated by an increase in the distance from condylion to pogonion. In all cases, the growth was expressed vertically relative to the cranial base, so that the chin did not come forward. None of the patients had significant increments of anterior maxillary growth postsurgically. Several patients had vertical maxillary growth, which was compensated by vertical mandibular growth, so that the anteroposterior position of the chin was maintained. Forward growth of the maxilla is minimal after the peak of the adolescent growth spurt, and results of mandibular advancement surgery can be acceptably stable after that time.

Adolescent↗
PubMed1991

The relationship of loneliness, social isolation, and physical health to dietary adequacy of independently living elderly.

This study evaluated the dietary adequacy of elderly individuals to determine whether factors such as loneliness, social isolation, or physical health were related to nutrient intake. The participants (n = 61) were independently living individuals aged 60 to 94 years recruited through senior citizen centers, residential housing areas, and social agencies in Rutherford County, Tennessee. Three-day food records were used to collect dietary data, and nutrient intakes were compared with the 1989 Recommended Dietary Allowances. Three-day social contact diaries were used to measure frequency of interaction with others. The Physical Health Questionnaire was used to evaluate subjectively the number and severity of disease states, and the loneliness index was computed using the revised UCLA Loneliness Scale. Energy and calcium were most likely to be underconsumed, and poor physical health was related to decreased intakes of vitamin A and ascorbic acid. Loneliness was related to dietary inadequacies. We recommend emphasis on education and services to provide home-delivered meals and groceries as well as affordable convenience foods of high nutrient density to enable older individuals to achieve adequate nutrient intake while maintaining an independent life-style.

Black or African American↗
PubMed1990

A comparison of the relative sensitivity of two types of Heaf gun.

A total of 696 secondary school children were given a Heaf test in one forearm with a magnetic head Heaf gun and in the other forearm with a fixed head gun. One week later the results were read blind. In 333 (48%) children the fixed head gun gave a more strongly positive result than the magnetic head gun, while in only 27 (4%) children did the magnetic head gun gives a more strongly positive result. These findings are statistically highly significant (p less than 0.001).

Adolescent↗
PubMed1990

No effect of prostaglandin synthesis inhibition on muscle reflexes in fetal lambs.

The effects of inhibiting prostaglandin (PG) synthesis on fetal breathing movements and on the amplitude of reflex contraction of the digastric muscle (five trials) or hindlimb semitendinosus muscle (seven trials) has been studied in six fetal lambs at 123-139 days gestation. Infusion of either indomethacin (100 mg) or acetaminophen (300 mg) in 30 ml saline over 30 min resulted in an increase in the amplitude and incidence of breathing movements for 3-18 h in the different trials, but there was no change in the mean amplitude of either reflex or in the normal variation of reflex amplitude with changes in electrocortical activity. It is concluded that PGs modulate fetal breathing movements by an action on the brain stem chemoreceptors but do not alter the excitability of neural pathways subserving some cranial and spinal reflexes.

Acetaminophen↗
PubMed1990

Pertussis immunisation: professional attitudes and knowledge.

A survey in Fife found that 98 per cent of health professionals were committed to the prevention of whooping cough. Ninety seven per cent considered pertussis vaccine to be relatively safe and 98 per cent found the current immunisation guidelines satisfactory. However the survey also identified considerable misinterpretation of vaccine contra-indications which would result in many eligible children not being immunised.

Attitude of Health Personnel↗
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↗