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Biomedical subjects

G Kent

Publications and source records attributed to G Kent.

At least 91 records · Page 5Linked to original sources
PubMed1986

Migration in vitro by blood and exudate neutrophils assessed serially during an inflammatory response.

Migration in vitro by blood and inflammatory neutrophils has been compared serially during an inflammatory response. Using an experimental pig model, neutrophils are isolated from the peripheral blood and from the pleural space at hourly intervals after an intrapleural challenge with zymosan activated pig serum (ZAS). Following acepromazine sedation and halothane anesthesia, blood neutrophil migration was transiently reduced. By 1 hour random and directed migration of blood neutrophils returned to normal. Directed and random migration of exudate neutrophils was markedly decreased to both a stimulus-specific (ZAS) and an unrelated (LTB4) chemoattractant. After 3 hours, migration by exudate neutrophils was similar to migration by blood neutrophils examined in parallel. These findings emphasize the importance of performing serial evaluations of cell function during an inflammatory response.

Animals↗
PubMed1986

Patients' preferences for information.

In a study of patients' views of the type of information they would like to receive from the doctor 265 patients from four general practices were given a list of five areas of information - diagnosis, prognosis, treatment, aetiology and social effects of their illness - and asked to rank these in order of importance for that visit. In general, information on diagnosis and prognosis was the most highly valued, while the ways the illness would affect daily activities was the least preferred. Although information on treatment was rarely selected as the first preference it was often the second or third preference. Conversely, diagnosis was the first choice of the largest proportion of patients and the least valued information for 26%.

Adolescent↗
PubMed1986

A new model of tracheal stenosis and its repair with free periosteal grafts.

Stenosis of 50% to 80% of the cervical or thoracic tracheal lumen was created in 17 piglets by encircling the trachea with silicone rubber sheet for 3 to 19 days (median 14 days). In 13 animals thoracic tracheal stenosis was repaired by longitudinal incision and insertion of a free tibial periosteal graft into the defect. An omental pedicle graft was applied to the surface of the free periosteal graft to augment its blood supply in three of these animals. An endotracheal silicone rubber splint was left in place for 2 to 3 weeks after the operations. Four animals served as untreated controls. In 12 of 13 piglets respiratory obstruction was relieved. One repair failed because of graft necrosis. In two animals put to death 1 month and 2 months later, stenosis was absent and the grafts showed variable ossification. The luminal surface had epithelialized. In nine of 10 animals put to death 3 months after the operation, tracheal cross-sectional areas had doubled, stenosis and granulation tissue were absent, and all the grafts had ossified and epithelialized. A mild stenosis (24%) developed over a 2 mm length in one animal and the graft had not ossified. The omental pedicle graft did not improve vascularization of the free periosteal graft. These studies describe a model of tracheal stenosis that can be used to assess various methods of repair. The results indicate that tracheal stenosis can be successfully treated by incision and insertion of a free periosteal graft into the defect.

Animals↗
PubMed1985

Laryngeal muscle and diaphragmatic activities in conscious dog pups.

A new chronic animal preparation (i.e. puppies) for the study of respiratory laryngeal muscle activity is described. Posterior cricoarytenoid (PCA), thyroarytenoid (TA) and diaphragmatic activities were monitored in conscious puppies (13-43 days old) using chronically implanted electrodes. PCA activity was prominent during inspiration in all behavioral states. TA and post-inspiratory diaphragmatic activities were consistently high during expiration in quiet wakefulness and quiet sleep, but expiratory TA activity decreased dramatically and post-inspiratory diaphragmatic activity became highly variable in rapid eye movement sleep. There was also a tendency for these expiratory muscle activities to become less pronounced with increasing postnatal age. When a chronically implanted, low resistance T-tube tracheal cannula was suddenly opened, thus effectively eliminating the effects of upper airway resistance on airflow, respiratory frequency dramatically increased. These results indicate that the puppy exhibits muscle activities consistent with the maintenance of an elevated end-expiratory lung volume achieved by the retardation of expiratory airflow using the larynx and diaphragm.

Animals↗
PubMed1985

The successful reconstruction of thoracic tracheal defects with free periosteal grafts.

A defect was created in the thoracic trachea in nine piglets (10 kg) by excising a segment from the entire thoracic trachea proximal to the right upper lobe bronchus (3 to 3.5 cm in length) and 30% of the circumference in width (1 to 1.5 cm). The defect was repaired with a free tibial periosteal graft (FPG) and in four piglets an omental pedicle graft (OPG) was applied to the surface of the FPG. An internal tracheal splint was inserted for 12 to 16 days to support the repair and prevent air leak. The splints were removed bronchoscopically. None of the pigs developed signs of airway obstruction at any stage following the repair. Eight were killed 3 months postoperatively when four to six times their original weight. One pig died on the 18th postoperative day of unknown cause. The tracheas were removed, x-rayed, and examined grossly and histologically. The results demonstrated normal tracheal growth with absence of either stenosis, collapse, or granulation tissue. All grafts were viable, bone formation was present, and the lumenal surfaces were lined with columnar and respiratory epithelium. The OPG did not improve vascularization of the FPG. This model suggests that tracheal stenosis in children may be surgically corrected by simply incising the stenotic segment longitudinally and enlarging the tracheal diameter by inserting a FPG into the defect.

Animals↗
PubMed1985

Influence of hypothermia on the pharmacokinetics of gentamicin and theophylline in piglets.

The influence of hypothermia on gentamicin and theophylline pharmacokinetics was studied in anesthetized pigs given an iv bolus of gentamicin and theophylline during normothermia (37 degrees C) and again 1 wk later after the induction of controlled hypothermia (29 degrees C). During hypothermia, the elimination half-time for gentamicin was significantly prolonged (135 +/- 19 min at 37 degrees C vs. 187 +/- 7 min at 29 degrees C), and there were significant decreases in the volume of the central compartment (Vc) of gentamicin, the gentamicin volume of distribution (Vd), and the gentamicin total body clearance (TBC). Hypothermia was associated with a small but significant decrease in theophylline Vd and Vc, but no change in TBC. In separate experiments, cardiac output decreased during the induction of hypothermia in a temperature-dependent fashion. The changes in gentamicin Vd and TBC may be explained by the decrease in cardiac output and the associated decrease in glomerular filtration rate. This study suggests that the elimination of theophylline, which has a relatively low hepatic extraction ratio, is not influenced by the hypothermia-induced decrease in liver blood flow.

Animals↗
PubMed1985

Prevalence vs. incidence of the mandibular pain dysfunction syndrome: implications for epidemiological research.

Conclusions about the aetiology and maintenance of the Mandibular Pain Dysfunction Syndrome (MPDS) are largely based on clinic populations, but there are indications that sufferers who seek help about their symptoms are not typical of the general population of sufferers. This raises important problems in extrapolating findings from the patient population to the general one. This paper argues that future epidemiological studies should take the various influences on the decision to seek advice into account so that conclusions about MPDS can be reached. Specific additions to research designs are noted.

Epidemiologic Methods↗
PubMed1985

Cognitive processes in dental anxiety.

While waiting for treatment in a dental hospital clinic, 146 patients completed questionnaires designed to measure their anxiety and cognitions about dental treatment. Both attendance pattern (regular versus irregular) and anxiety levels were related to the patients' perceptions of the likelihood of negative events, and highly anxious patients saw positive events as being less likely than did patients with low anxiety. It also seems that irregular attenders are more anxious than regular attenders because they believe that they will require more extensive treatment and not because they have a greater fear of dentistry per se. The results indicate that a cognitive approach to dental anxiety can explain why high anxiety is maintained despite repeated pain-free experiences and suggests methods of treatment.

Anxiety↗
PubMed1985

A study of factors associated with changes in dental anxiety.

Patients were given the Dental Anxiety Scale (DAS) to complete and asked to indicate the degree of pain they expected to feel on that day's visit to a dentist. After the appointment, they indicated the degree of pain actually experienced. Three months later, the patients were contacted by mail and asked about the amount of pain they remembered having experienced and to complete the DAS again. There was considerable stability in DAS scores over the two administrations, but some of the change in scores was associated with the discrepancy between the degree of pain the patients expected and the degree of pain they actually experienced.

Adolescent↗
PubMed1985

An experimental model to study blood and inflammatory neutrophils.

We sought to develop an experimental animal model in order to study the effects of hypothermia on host defences under conditions which were similar to those used for humans. We required a large animal which could tolerate arterial and venous catheters and serial blood sampling without significantly altering its blood volume and blood pressure. The animal should be intubated and ventilated to control blood gases and fluid and electrolyte balance. Finally the model should have anatomic, metabolic and physiologic similarities to humans. We describe an experimental pig model which appears to fulfill these criteria and provide important information relevant to man.

Animals↗
PubMed1984

The effect of intrauterine esophageal ligation on growth of fetal rabbits.

Babies with pure esophageal or duodenal atresia weight less than normal babies at birth. Whether this is due to the obstruction to fetal swallowing or some other cause is not known. To determine how intrauterine interruption of swallowing affects fetal growth, we developed a model of esophageal atresia in the fetal rabbit. Twenty-five time-mated rabbits at 24 days gestation were anesthetized with halothane and ketamine. The uterus was exposed through a midline abdominal incision. The head and neck of the fetus in the distal end of one horn were isolated through a 2-cm hysterotomy. Biparietal diameter (BPD) was measured and the esophagus was isolated and ligated through a midline cervical incision. The fetus in the distal end of the opposite horn underwent sham operation. Four days later, cesarean section was done. The newborn rabbits were weighed, and crown/rump length and BPD were measured. Ligation of the esophagus was confirmed by re-exploration of the neck. Three does died under anesthesia and two aborted. From the remaining 20, 156 fetuses were recovered, of which 135 were alive. One set of operated fetuses was dead, leaving 19 pairs for analysis. There was a statistically significant reduction in weight gain (31.7 +/- 1.3 g to 29.1 +/- 0.9 g, P less than 0.05) following interruption of the esophagus but linear growth was unchanged. Obstruction to normal fetal swallowing may account for the low birth weight with normal head circumference reported in babies with esophageal and duodenal atresia.

Animal Nutritional Physiological Phenomena↗
PubMed1984

Neutrophil migration in vitro and in vivo during hypothermia.

The effect of hypothermia on pig leukocyte migration in vitro and in vivo was studied. Neutrophil chemotaxis in vitro under agarose was significantly impaired at 29 degrees C (2.7 +/- 0.6 [mean +/- standard error]; 37 degrees C, 7.1 +/- 1.1). Leukocytes isolated from hypothermic pigs and tested at 37 degrees C migrated normally (7.8 +/- 0.6). Neutrophil and monocyte migration in vivo was markedly reduced at 29 degrees C. Reduced inflammatory responses may contribute to increased infections during hypothermia.

Animals↗
PubMed1983

Effect of prosthetic airway splint on the growing trachea.

Airway splints are now used clinically to treat tracheomalacia and may also have a place in the management of tracheal stenosis. These studies in 5 to 7 Kg piglets were designed to assess the effects of prosthetic airway splints on airway growth and to establish their usefulness in the reconstruction of tracheal defects. Three experimental groups were studied: group I (n = 8). Silastic reinforced Marlex mesh or Vicryl mesh prostheses were placed around 75% of the circumference of a 3 cm segment of trachea. Pigs were sacrificed at 4 months (average weight = 78.9 +/- 9.0 Kg) and the cross-sectional area of trachea was measured. Group II (n = 5). The same prostheses were used to replace the tracheal defect created by excising three rings (50% of tracheal circumference). Tracheas were examined grossly and histologically at sacrifice. Group III (n = 5). Same as Group II except tracheal defect covered by strap muscles. Prostheses placed external to them to prevent airway collapse. Group I had 4% to 14% (mean 8%) decrease from normal cross-sectional area of trachea at site of splint. No airway obstruction and no infection was encountered. Group II, severe airway obstruction, granulation tissue, and infection at site of defect was noted. Group III showed no signs of airway obstruction, no infection, and minimal airway narrowing. Re-epithelialization of the muscle surface in contact with airway occurred in all these animals. Silastic reinforced Marlex or Vicryl splints placed around the intact rapidly growing trachea do not significantly limit its growth. In addition, these synthetic materials appear to be well-tolerated when used to reconstruct tracheal defects if placed over well-vascularized tissue such as muscle.

Animals↗