Biomedical subjects

R de Iongh

Publications and source records attributed to R de Iongh.

5 recordsLinked to original sources

PubMed2004

Scintigraphic measurement of tracheal mucus velocity in vivo.

Mucociliary clearance (MCC) is an important mechanism for removing inhaled particles, secretions and cellular debris from the respiratory tract. Here, a direct measurement of tracheal mucus velocity (TMV) for assessment of MCC, suitable for clinical and research use, is reported, and a comparison is made of TMV in normal subjects and patients with chronic obstructive pulmonary disease (COPD). A 0.1-mL bolus of radiolabelled (2-5 MBq), technetium-labelled macroaggregated human albumin (99mTc MAA) was injected through the cricothyroid membrane into the trachea of 20 young (< 50 yrs) and 12 older (> 50 yrs) normal subjects and 34 patients with COPD. Repeat studies were carried out in 13 normal subjects and 16 COPD patients. Movement of the bolus in the trachea was recorded (15 min) using a gamma camera interfaced to a computer. Data were analysed using specifically designed software. The test was well tolerated by subjects and patients, and no significant adverse events were reported. No significant differences were observed between data recorded from different regions of the bolus (leading edge, peak, trailing edge) by analysis of variance (ANOVA). Bland-Altman plots of the repeat studies indicated that data were more variable in normal subjects (coefficient of repeatability (COR) 10.3 mm.min-1) than in COPD patients (COR 5.5 mm.min-1). TMV (mean +/- SD) in young normal subjects (n = 20) was 10.7 +/- 3.5 mm.min-1. TMV was reduced in older normal subjects (n = 12; 6.5 +/- 2.6 mm.min-1) and further reduced in COPD (n = 34; 2.1 +/- 2.7 mm.min-1). In conclusion, this technique can be used to measure tracheal mucus velocity rapidly and safely in healthy subjects and patients with respiratory tract disease. This study has confirmed that tracheal mucus velocity declines with age and is further impaired in patients with chronic obstructive pulmonary disease.

Adult↗

PubMed1993

Spatio-temporal distribution of acidic and basic FGF indicates a role for FGF in rat lens morphogenesis.

As part of an investigation into the role of FGF in lens development, we have studied the distribution of both aFGF and bFGF during eye morphogenesis from embryonic days 10 to 18 (E10-E18) in the rat. For aFGF, reactivity was found only in ectoderm at E10, prior to contact between the optic vesicle and presumptive lens ectoderm. During lens placode formation (E11) there was a transient, diffuse reactivity for aFGF in anterior optic vesicle cells directly apposed to the labelled ectoderm of the lens placode. At E12 the diffuse reactivity of the lens placode had changed to a discrete localisation along the basolateral surfaces of differentiating cells in the lens pit. Similar reactivity was associated with neuroblasts along the inner margin of the optic cup. At the early lens vesicle stage (E13) the baso-lateral aFGF-like reactivity associated with elongating lens cells was more intense and extensive. From the late lens vesicle stage (E14) to E18, reactivity in the lens was increasingly restricted to the equatorial regions which incorporate the germinative and transitional zones. From E16 to E18, aFGF-like reactivity in the retina was predominantly localised in the peripheral regions corresponding to the developing ciliary body and iris and in the central retina associated with ganglion cell axons. For bFGF, weak reactivity was detectable as early as E13 in the developing lens capsule and increased in intensity during lens development with the posterior capsule reacting more intensely than the anterior capsule. Retinal bFGF-like reactivity was first detected at E14, associated with differentiating ganglion cells in the central retina. From E16 to E18 the retinal ganglion cells showed increasing reactivity and the pattern of reactivity followed the centro-peripheral pattern of retinal development. Thus reactivity for aFGF is first detected in presumptive lens ectoderm and subsequently in optic vesicle cells which are closely associated with lens ectoderm. This raises the possibility that aFGF may be involved in inductive interactions between presumptive lens ectoderm and optic vesicle. Furthermore the localisation patterns established for both aFGF and bFGF during lens and retina morphogenesis suggest an important role for FGF in regulating their morphogenesis and growth.

Animals↗

PubMed1992

Mucociliary function, ciliary ultrastructure, and ciliary orientation in Young's syndrome.

BACKGROUND: Mucociliary clearance is impaired in patients with Young's syndrome (obstructive azoospermia with recurrent sinobronchial disease), cystic fibrosis, and primary ciliary dyskinesia. No defect of cilia or mucus has been detected in Young's syndrome. METHODS: Ciliary function and ultrastructure, including ciliary orientation, were studied quantitatively in 20 patients with Young's syndrome and 20 normal subjects to determine the incidences of ciliary defects. Nasal ciliated epithelium was obtained from each subject and used for measurement of ciliary beat frequency and ultrastructural analyses. Ciliary orientation was determined by measuring ciliary deviation in electron micrographs; ciliary deviation is a measure of the relative orientation of cilia in relation to each other in which high values indicate ciliary disorientation. RESULTS: Ciliary beat frequency and the incidence of microtubular defects and numbers of dynein arms did not differ between patients with Young's syndrome and control subjects. In patients with Young's syndrome basal ciliary deviation (16.0 degrees) was similar to that in control subjects (14.1 degrees), but at the ciliary tip ciliary deviation (21.9 degrees) was greater than in healthy subjects (14.5 degrees). CONCLUSION: The relative disorientation of the distal ciliary axoneme in patients with Young's syndrome compared with normal subjects may be due to a structural defect but is more likely to be a consequence of abnormal mucus.

Adult↗

PubMed1992

Distribution of acidic and basic fibroblast growth factors (FGF) in the foetal rat eye: implications for lens development.

Previously we reported that, in vitro, lens cells proliferate, migrate or differentiate in response to low, medium and high concentrations of FGF respectively. To examine further the role of FGF in lens development we used immunohistochemistry to study the distribution of aFGF and bFGF in the eye of the 20 day rat foetus. Strong aFGF-like reactivity was localised in a band of cells near the lens equator which included the germinative zone where most cell proliferation occurs and the transitional zone where epithelial cells differentiate into fibres. The closely apposed inner epithelial layer of the ciliary and iridial retina also reacted strongly. Reactivity for aFGF was also found in the epidermis and in the corneal and conjunctival epithelia. In the neural retina, reactivity was found in the nerve fibre layer and in isolated cells of the inner plexiform layer. bFGF-like reactivity was found in the retinal ganglion cell layer, extra-ocular muscles and associated with endothelial cells of the hyaloid, lenticular and choroid vasculatures. Pre-digestion of sections with hyaluronidase caused loss of cell-associated reactivity but revealed strong bFGF-like reactivity in ocular basement membranes, in particular, the lens capsule. The sensitivity of this capsular bFGF localisation to heparinase indicates that bFGF in the extracellular matrix is complexed with heparan sulphate proteoglycans. The results of this study are consistent with the hypothesis that FGF plays an important role in lens development via both autocrine and paracrine mechanisms.

Animals↗

PubMed1984

Thalidomide deformities and their nerve supply.

The aim of this study was to test the hypothesis that thalidomide acts upon the embryonic peripheral nervous system rather than upon mesenchyme. Pregnant rabbits were given oral thalidomide (150 mg/kg/day) on Days 7-11 of gestation. Fetuses were removed at laparotomy, under anaesthesia, on Day 29 of gestation. Seven fetuses with partial or total absence of the tibia, five treated fetuses without deformities, and four untreated controls were photographed, radiographed, killed and fixed for histological examination. Sciatic nerves were dissected and transverse sections were taken from an identical site. Total fascicular area, myelinated fibre number, fibre density and diameter distribution were obtained. There was a significant reduction in total fascicular area, and in the number of large diameter fibres in all treated animals. There was a significant depletion of total fibre numbers in deformed fetuses compared with controls. These findings are similar to the quantitative changes described in human adult subjects with thalidomide polyneuropathy, and are consistent with primary axonal degeneration in both instances. It is concluded that thalidomide acts upon embryonic nerves rather than on mesenchyme, and that dysmelic deformities of the limbs are secondary to toxic embryonic neuropathy. It is suggested that skeletal defects result when irreversible damage to the nerves reduces the transverse fascicular area below a critical minimum threshold.

Abnormalities, Drug-Induced↗