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Biomedical subjects

B S Turner

Publications and source records attributed to B S Turner.

33 records · Page 2Linked to original sources
PubMed1990

Different high-frequency ventilator strategies: effect on the propagation of tracheobronchial histopathologic changes.

To assess the role of high-frequency ventilator strategy in the propagation of airway injury, we compared the tracheobronchial histologic alterations in 20 newborn piglets ventilated for 8 hours with high-frequency flow interruption (HFFI). Ten animals were assigned to HFFI with a strategy of continuous pulsations at a frequency of 10 Hz and a mean airway pressure of 16 cm H2O. Ten piglets were treated at identical settings except for 10 one-second baseline pauses per minute to a positive end-expiratory pressure of 5 cm H2O. A semiquantitative scoring system was used to grade light microscopic tissue alterations in the trachea, carina, and mainstem bronchi. Ultrastructural changes were evaluated with scanning electron microscopy. The HFFI-continuous-treated piglets had significantly more damage in all areas than the HFFI-baseline pause group (P less than .001). The upper tracheas of animals in both groups were altered to a greater extent than the lower tracheas (P less than .007). In addition, numerous "skip" areas of injury were noted throughout the tracheas. High-frequency ventilator strategy is a determinant of the severity of airway histologic changes. Factors that adversely affect tissue oxygenation or cause direct mechanical trauma may also influence the degree of injury. Optimal operating characteristics and limitations of different high-frequency devices must be assessed before their use in human neonates.

Animals↗
PubMed1990

Meconium aspiration syndrome: have we made a difference?

Meconium aspiration syndrome (MAS) and its associated complications are reviewed from the period before the routine use of intubation and suctioning to the present (1973 through 1987). Of the 176,790 neonates born during this period, the amniotic fluid was stained in 21,472 (12.15%). Subsequently, MAS developed in 1162 (5.41%) of the meconium-stained neonates. Male neonates were more prone to the disorder than female neonates (P = .022). There were no racial predilections for MAS. The incidence of MAS significantly decreased during the 15 years (P = .043). Of the neonates with MAS, 49 (4.22%) died as a direct consequence of the disorder. The death rate significantly declined during the study period (P = .041). Of the neonates with MAS, 345 (29.7%) required mechanical ventilation, and 134 (11.53%) had pneumothoraxes. Among neonates with MAS, the requirement for mechanical ventilation, as well as the incidence of pneumothoraxes, did not decrease from 1973 through 1987. The incidence of MAS has declined since the advent of combined obstetric and pediatric suctioning of the oropharynx and trachea. Furthermore, there are significantly fewer deaths from the disorder. These declines were likely influenced by other improvements in perinatal care, which have occurred since the early 1970s. The results do not support the contention that severe MAS and resultant deaths can be prevented altogether.

Apgar Score↗
PubMed1989

Ageing, status politics and sociological theory.

As a feature of social change and as an aspect of social stratification, ageing and age groups have been seriously neglected by sociological theory. This article attempts to conceptualize age groups in a multi-dimensional model of stratification which considers ageing in relation to economic class, political entitlement, or citizenship, and cultural life-styles. This multi-dimensional model provides an analytical basis for rejecting functionalist theories of ageing, which emphasize the positive functions of social disengagement, activity theories, which show that self-esteem in ageing is an effect of continuing social involvement, and Marxist social gerontology, which argues that retirement is determined by labour-market requirements in capitalism. The article concludes by developing a reciprocity-maturation curve of ageing which explains age stigmatization through exchange theory as an effect of declining social reciprocity. Both young and elderly social groups in a period of economic recession are perceived to be socially dependent, and become the targets of 'the politics of resentment'. The processes of social ageing can be located in the core of sociological theory, because they are connected fundamentally to the conditions of social solidarity.

Aging↗
PubMed1989

Determinants of tracheobronchial histologic alterations during conventional mechanical ventilation.

It was hypothesized that diverse mechanisms may influence upper airway injury during mechanical ventilation. To assess the roles of several factors in the propagation of such injury, the tracheobronchial histologic changes in 53 newborn piglets were compared following conventional positive pressure ventilation. Eight animals were assigned to each of four positive pressure ventilation groups at "low" settings (an FiO2 of 0.25, a frequency of 10 breaths per minute, a peak inspiratory pressure of 20 cm H2O, a positive end-expiratory pressure of 4 cm H2O, a flow rate of 10 L/min, and an inspiratory time to expiratory time ratio of 1:2): (1) positive pressure ventilation with no hypotension or hypoxemia; (2) positive pressure ventilation with hypotension; (3) positive pressure ventilation with hypoxemia; and (4) positive pressure ventilation with both hypotension and hypoxemia. In addition, eight piglets were assigned to each of two positive pressure ventilation groups at "high" settings (greater frequency [40 breaths per minute], higher peak inspiratory pressure [40 cm H2O], and greater flow rate [17 L/min]): (1) positive pressure ventilation with no hypotension or hypoxemia; and (2) positive pressure ventilation with both hypotension and hypoxemia. The changes were mild and similar among the first three positive pressure groups at low settings. However, the injury scores of the combined hypotension and hypoxemia group (group 4) were greater than those of the former three positive pressure ventilation groups (P less than .004). The piglets receiving positive pressure ventilation at high settings with no hypotension or hypoxemia (group 5) had no more injury than those in the first three groups receiving positive pressure ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Pulmonary mechanics during rapid mechanical ventilation in rabbits with saline-lavaged lungs.

Infants with respiratory failure are frequently mechanically ventilated at rates exceeding 60 breaths/min. We analyzed the effect of ventilatory rates of 30, 60, and 90 breaths/min (inspiratory times of 0.6, 0.3, and 0.2 s, respectively) on the pressure-flow relationships of the lungs of anesthetized paralyzed rabbits after saline lavage. Tidal volume and functional residual capacity were maintained constant. We computed effective inspiratory and expiratory resistance and compliance of the lungs by dividing changes in transpulmonary pressure into resistive and elastic components with a multiple linear regression. We found that mean pulmonary resistance was lower at higher ventilatory rates, while pulmonary compliance was independent of ventilatory rate. The transpulmonary pressure developed by the ventilator during inspiration approximated a linear ramp. Gas flow became constant and the pressure-volume relationship linear during the last portion of inspiration. Even at a ventilatory rate of 90 breaths/min, 28-56% of the tidal volume was delivered with a constant inspiratory flow. Our findings are consistent with the model of Bates et al. (J. Appl. Physiol. 58: 1840-1848, 1985), wherein the distribution of gas flow within the lungs depends predominantly on resistive factors while inspiratory flow is increasing, and on elastic factors while inspiratory flow is constant. This dynamic behavior of the surfactant-depleted lungs suggests that, even with very short inspiratory times, distribution of gas flow within the lungs is in large part determined by elastic factors. Unless the inspiratory time is further shortened, gas flow may be directed to areas of increased resistance, resulting in hyperinflation and barotrauma.

Animals↗
PubMed1984

Hydrocortisone inhibits mucin secretion from guinea pig gallbladder.

We studied the effects of hydrocortisone, an inhibitor of phospholipase A2, on the secretion of mucin and release of prostaglandins from guinea pig gallbladder explants. We measured mucin using [3H]glucosamine as a precursor and prostaglandins by radioimmunoassay of 6-keto-prostaglandin F1 alpha. Mucin secretion and prostaglandin release were studied under basal conditions and after arachidonate stimulation. Hydrocortisone sodium succinate reversibly inhibited basal secretion of mucin by 24% at 10(-5) M (P less than 0.05 compared with control) and 34% at 10(-4) M (P less than 0.01). Hydrocortisone, 10(-4) M, also reversibly inhibited arachidonate-stimulated secretion of mucin (P less than 0.01 compared with controls incubated with arachidonate alone). Release of prostaglandin F1 alpha was significantly inhibited by hydrocortisone under basal (P less than 0.01) and arachidonate-stimulated (P less than 0.01) conditions. The inhibitory effect of hydrocortisone was mediated by inhibition of hydrolysis of arachidonate from membrane phospholipids, suggesting that exogenous arachidonate is incorporated into membrane phospholipids prior to conversion to prostaglandins.

Animals↗
PubMed1983

Arachidonic acid stimulates mucin secretion in prairie dog gallbladder.

Mucin glycoprotein secretion from prairie dog gallbladder explants was studied in 24-h organ culture using [3H]glucosamine as a precursor. Indomethacin caused a reversible dose-dependent inhibition of both mucin release (50% inhibition between 10(-6) and 10(-5) M indomethacin) and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) release (66% inhibition at 10(-7) M). Sepharose 4B chromatography of secreted [3H]-glucosamine-labeled glycoproteins revealed that indomethacin inhibited release of a high-molecular (greater than 10(6) daltons) mucin-type glycoprotein. Addition of sodium arachidonate (10(-4) M) to organ culture medium caused an approximate two- to fivefold increase (P less than 0.02) in mucin release compared with control and an increase in the secretory component of total glycoprotein synthesis from 37.5% in control explants to 75.2% (P less than 0.01). The stimulatory effect of arachidonate on mucin secretion was blocked by indomethacin. We incubated explants for 1 h with [14C]arachidonate and studied prostaglandin and thromboxane products in medium by high-performance liquid chromatography. The only conversion product identified was 6-keto-PGF1 alpha, the stable breakdown product of prostacyclin. Release of gallbladder mucin is significantly inhibited by indomethacin and increased by arachidonate. Mucin secretion may be regulated in part by endogenous levels of prostacyclin, the major cyclooxygenase product in prairie dog gallbladder epithelium.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Gallbladder glycoprotein secretion in mice with hemolytic anemia and pigment gallstones.

The nb/nb mouse with hereditary hemolytic anemia provides an animal model for the study of pigment gallstone disease. We measured glycoprotein synthesis and secretion in gallbladder neck and fundus of 6-month-old mice without stones, and in 12-month old mice with and without stones in order to determine the effect of age and presence or absence of stones on mucin release. We observed that the gallbladder necks of 12-month-old nb/nb mice with pigment stones secreted more 3H-glucosamine-labeled glycoprotein (68.2 dpm per microgram protein) than did the gallbladder necks of mice without pigment stones (31.1 dpm per microgram protein). When expressed as a percentage of total glycoprotein synthesis in the gallbladder neck, secretion of glycoprotein was 23.4% in 6-month-old hemolytic mice and 28.7% in 12-month-old hemolytic mice without pigment stones. However, in the presence of pigment stones, the percentage of secreted glycoprotein rose to 4.08%, which differed significantly from both 6-month-old (p < 0.02) and 12-month-old mice without stones (p < 0.05). Our results suggest that the presence of gallstones in nb/nb mice was associated with a localized increase in glycoprotein release from gallbladder neck. The mechanism for this increase may be precipitation of pigment-mucin concentrations in the gallbladder neck glands which has been previously described in this animal model.

Aging↗
PubMedDate not supplied

Effect of short-duration hyperventilation during endotracheal suctioning on intracranial pressure in severe head-injured adults.

A repeated measures randomized within-group design was used to determine the effectiveness of controlled short-duration hyperventilation (HV) in blunting the increase of intracranial pressure (ICP) during endotracheal suctioning (ETS). A multimodal continuous real-time computerized data acquisition procedure was used to compare the effects of two HV ETS protocols on ICP, arterial pressure, cerebral perfusion pressure (CPP), heart rate, and arterial oxygen saturation in severe head-injured adult patients. The results indicated that short-duration HV for 1 minute, which decreases the PaCO2, reduced ETS-induced elevations in ICP while maintaining CPP. However, it is not clear whether short-duration HV is neuroprotective, particularly in ischemic regions of the brain. Therefore, before a change in practice is implemented on the use of short-duration HV as a prophylactic treatment against ETS-induced elevations in ICP, additional questions on cerebral oxygen delivery and uptake need to be answered.

Adolescent↗
PubMedDate not supplied

Amniotic band syndrome.

Amniotic band syndrome results from a tear in the amnion, due to unknown etiology, which allows amniotic fluid and fetal parts to escape from the amnion into the chorion. Defects resulting from amniotic band syndrome are described. Management of the infant by a multidisciplinary, team approach is advised. Areas for further research are recommended.

Amniotic Band Syndrome↗
PubMedDate not supplied

Left handedness.

Explore the source record for details and available documents.

Functional Laterality↗
PubMedDate not supplied

Maintaining the artificial airway: current concepts.

Artificial airways are a common treatment modality in neonatal and pediatric critical care units. Maintaining the integrity of artificial airways in infants and children requires accurate assessment of endotracheal tube (ETT) position and patency, adequacy of oxygenation and ventilation, and the identification and treatment of potential complications.

Child↗