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Biomedical subjects

D Stokes

Publications and source records attributed to D Stokes.

30 records · Page 2Linked to original sources
PubMed1985

ABH secretor status in cystic fibrosis--a negative report.

In adults, the inability to secrete ABH blood group substances in water-soluble form has been recognized as an independent risk factor for the development of chronic obstructive lung disease. We studied 50 patients (mean age 12.1 years) with cystic fibrosis and identified 33 ABH secretors and 17 non-secretors. There was no correlation between secretor status and clinical status, spirometry measurements, salivary and serum lysozyme levels or rates of respiratory tract colonization with P. aeruginosa and S. aureus.

ABO Blood-Group System↗
PubMed1984

Perfluorocarbon emulsions in cancer therapy: preliminary observations on presently available formulations.

Perfluorocarbon (PFC) emulsions, due to their favorable oxygen transporting properties, have been proposed as tumor sensitizers for application in both radiotherapy and chemotherapy. While this application is a very promising one it is by no means simple, and presently available formulations are inadequate. Intravenous administration of these emulsions can produce a severe hemodilution which tends to offset the desired effect; these emulsions can alter the pharmacokinetics of simultaneously administered drugs. Unless these variables are taken into account the risk of false negative and false positive results will be excessive. Of more serious concern are the profound disturbances produced by these emulsions in the reticuloendothelial system. Using two of the more popular PFC, Fluosol-DA and DMA/NONANE, we have shown that daily administration of these emulsions can produce 9-fold increases in liver size and 27-fold increases in spleen size. This problem appears to involve the surfactant used in both emulsions, pluronic F-68. It will be necessary to circumvent this problem before further study of their potential application can proceed.

Animals↗
PubMed1983

Indications for flexible fiberoptic bronchoscopy in pediatric patients.

Although the availability of flexible fiberoptic bronchoscopy (FFB) has been a major advance in adult pulmonary medicine, the role of FFB in pediatrics has remained less well defined. Therefore, a two-year retrospective study was undertaken to determine the indications for FFB in 95 pediatric patients (mean age, 6.9 years) who underwent 129 FFB procedures. Indications for FFB included stridor (41/129), abnormal chest roentgenogram (38/129), airway evaluation in patients with tracheostomy (13/129), airway obstruction (11/129), hoarseness (9/129), recurrent pneumonia (7/129), chronic cough (4/129), failed extubation (3/129), tracheal injury (2/129), and hemoptysis (1/129). Overall, a specific diagnosis was made in 88% of cases, of which 48% involved a lower airway disorder. A minor complication rate of 2% was observed with no major complications.

Adolescent↗
PubMed1982

Effects of posture on flow-volume curve configuration in normal humans.

Tien et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 46: 565-570, 1979) found reproducible details in the configuration of averaged maximal expiratory flow-volume curves and suggested that these details may correspond to sudden relocations of airway choke points. The occurrence of choke points depends on factors affecting local airway pressure-diameter behavior. We postulated that changes in posture as they affect the distribution of lung recoil on airways might change the locations of choke points and thereby alter flow-volume configuration. Twenty normal adults performed five flow-volume curves in each of four postures (standing, supine, right, and left lateral recumbent). Volume was measured with a Krogh spirometer and airflow with a Fleisch No. 4 pneumotachometer. Curves were digitally filtered and plotted relative to upright total lung capacity. Five curves in each posture were averaged at increments of 0.1 l/s of flow and average volumes at given flows were compared using the Student's t test. Significant differences (P less than 0.01) in mean volumes at given flows occurred in all subjects from standing to supine and/or right to left lateral postures. Large changes in configuration were apparent in one of the two postural pairs in eight subjects. We conclude that changes in posture result in significant changes in flow-volume configuration in most normal adults. These findings are consistent with the wave-speed theory of flow limitation and suggest that small changes in local airway stresses can significantly alter the location and motion of airway choke points during forced expiration.

Adult↗
PubMed1978

Unilateral hyperlucent lung (Swyer-James syndrome) after severe Mycoplasma pneumoniae infection.

An 11-year-old girl contracted pneumonia with consolidation of the left lower lobe, infiltrates in the lingula and left upper lobe, and a large left pleural effusion, accompanied by a Mycoplasma complement-fixation titer increasing to 1:16,384. Serial chest radiographs demonstrated resolution of the pneumonia and effusion, followed by development of a hyperlucent left lower lobe. This diagnosis was supported by abnormalities discovered by chest cinefluoroscopic examination and lung scans of ventilation and perfusion. Unilateral hyperlucent lung should be considered as a possible sequel to severe Mycoplasma pulmonary infection.

Acute Disease↗
PubMedDate not supplied

Capillary electrophoresis as a method to study DNA reassociation.

To develop analytical methodology to assess the genetic complexity of a DNA sample, capillary electrophoresis with laser-induced fluorescence detection is used to monitor the annealing process of DNA samples. Coated columns are filled with an entangled polymer solution shown to optimally separate DNA through size-selective capillary electrophoresis. DNA samples are denatured by heating in a boiling water bath for approximately 10 min and then cooled to approximately 25 degrees C below the melting point of the DNA sample to initiate the reassociation process. The DNA is detected by means of the laser-induced fluorescence of intercalated ethidium bromide, which produces a substantially greater signal for double- versus single-stranded DNA. The rate of reassociation is dependent upon the rate at which complimentary strands of DNA encounter each other and the degree of repeating base sequences in the sample (hence, the diversity of the DNA). Experimental parameters also influence the reassociation rate. The effects of salt concentration and incubation temperature are presented. Traditional plots of C(o)t (C(o) = DNA concentration and t = reassociation time) versus % recovery of double-stranded DNA signal are generated for PhiX 174 Hae III digest and 50 bp stepladder DNA, individually and combined, to calculate the reassociation rate constants for these samples. Because reassociation of individual fragments is observed by the CE-LIF method, more information about the samples is available than with less specific and time-consuming traditional methods of investigating DNA reassociation.

DNA↗