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Biomedical subjects

F Allen

Publications and source records attributed to F Allen.

11 recordsLinked to original sources
PubMed1992

Inhaled steroids in patients with bronchiectasis.

The effect of inhaled beclomethasone diproprionate (1500 micrograms day-1) on symptoms, pulmonary function and sputum production was examined in a double-blind, placebo-controlled, cross-over study in 20 patients with bronchiectasis. An 18% reduction in daily sputum production (P less than 0.003) was observed on treatment with inhaled steroid compared to placebo. A small, significant, improvement in morning peak expiratory flow rate (P less than 0.03) and forced expiratory volume in 1 s (P less than 0.03) was seen but the absolute changes are unlikely to be of clinical importance. Symptom scores for cough improved significantly (P less than 0.02). Inhaled steroids may have a role in the management of bronchiectasis by reducing cough and sputum production.

Administration, Inhalation↗
PubMed1991

Gap junctional communication during neuromuscular junction formation.

We have tested whether gap junctions form between nerve and muscle during their initial contact, before establishing the chemical synapse. Embryonic Xenopus stage 18-20 myotomes and neural tubes were permeabilized with DMSO to load appropriate reagents, dissociated, and cocultured. When myotomes, loaded with Lucifer yellow, were cocultured with unlabeled neural tube cells, 23% of the neurons contained dye after 24 hr. Affinity-purified gap junction antibodies loaded into myocytes or neurons reduced neuronal labeling significantly to 5%. [3H]uridine nucleotide transfer was observed in both directions between myocytes and neurons. Again gap junction antibodies substantially reduced recipient label. In all cases preimmune IgGs did not reduce transfer. When acetylcholine receptor clustering was examined in cultures containing gap junction antibodies, no difference in the number of neuronally induced AChR clusters was observed. This suggests that the cluster-inducing signal between nerve and muscle does not pass through gap junctions.

Animals↗
PubMed1990

The role of gap junctions in patterning of the chick limb bud.

The role of gap junctional communication during patterning of the chick limb has been investigated. Affinity-purified antibodies raised against rat liver gap junctional proteins were used to block communication between limb mesenchyme cells. Co-injection of the antibodies and Lucifer yellow into mesenchyme cultures demonstrated that communication was inhibited almost immediately. When antibodies were loaded into mesenchyme tissue by DMSO permeabilization, [3H]nucleotide transfer was prevented for at least 16 h. Polarizing region tissue from the posterior limb bud margin causes digit duplications when grafted to the anterior margin. Quail polarizing region cells were loaded with gap junction antibody and grafted into chick wing buds. The antibody had no effect on growth or survival of the grafted cells. As very few polarizing region cells are required to initiate duplications, the number of polarizing region cells in the grafts was reduced by diluting 1:9 with anterior mesenchyme tissue. When either polarizing region or anterior mesenchyme tissue in the graft was loaded separately with antibody, there was little effect on respecification of the digit pattern. However, loading both tissues in the graft caused a significant decrease in duplications. This indicates that a major role of gap junctions in limb patterning may be to enable polarizing region cells to communicate directly with adjacent anterior mesenchyme. A role for gap junctional communication between anterior mesenchyme cells cannot be excluded. The results are discussed in relation to the role of retinoic acid as a putative morphogen.

Animals↗
PubMed1986

Allele frequency distribution of two highly polymorphic DNA sequences in three ethnic groups and its application to the determination of paternity.

The allele frequency distribution of two highly polymorphic DNA sequences has been determined in three ethnic groups (American blacks, Caucasoids, and Hispanics) from the New York metropolitan area. The two loci examined were D14S1 and the flanking region of HRAS-1. The former was analyzed in EcoRI-digested DNA and the latter in TaqI-digested DNA. Approximately 700 DNA samples from unrelated individuals were digested with each of these enzymes and hybridized with the appropriate recombinant DNA probes. The size range of the DNA fragments detected for the D14S1 polymorphism varied from 14.3 to 32.5 kilobase pairs (kbp). The number of alleles identified under the experimental conditions used in this study was more than 40. For the HRAS-1 polymorphism, we have detected 18 different alleles varying in size from 1.85 to 4.5 kbp. Although the number of alleles observed in the different ethnic groups examined was very similar, the relative frequency of them varied significantly. The results presented here can be used as the basis for the utilization of DNA RFLP for the purpose of identity, such as paternity determinations or the analysis of forensic material. As an example, we have compared the results of paternity cases analyzed by HLA typing with those obtained with these two DNA polymorphisms. The values of paternity index and power of exclusion were similar by both procedures.

Alleles↗
PubMed1985

Loss of breast milk nutrients during tube feeding.

Nutrient losses from banked breast milk during tube feeding were determined from laboratory models. Large fat losses occurred, continuous feeding giving rise to significantly greater losses than bolus feeding. More fat loss occurred with low flow rates and there were also significant protein losses.

Dietary Fats↗
PubMed1976

Morphology of the ascending thick limb of Henle.

The morphologic characteristics of the medullary and cortical segments of the ascending thick limb of Henle were examined in the rat utilizing light microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The kidneys of six normal female Sprague-Dawley rats were preserved for morphological examination utilizing in vivo intravascular perfusion with 6.25% glutaraldehyde buffered in 0.1m sodium cacodylate. SEM revealed the presence of two distinctly different patterns of surface structure among the population of cells forming the epithelium of the ascending thick limb, a roughsurfaced cell with prominent microvilli (R cell) and a smoothsurfaced cell generally devoid of extensive microvilli except along the lateral cell margins (S cell). This variation in surface structure was confirmed with light microscopy and TEM. Throughout both the medullary and cortical segments of the ascending thick limb, the R cells possessed extensive lateral processes radiating form the main cell body to interdigitate with adjacent cells. Lateral processes of S cells were less common than those of the R cells in the inner stripe of the outer medulla, but increased in number and complexity in the outer stripe of the outer medulla and throughout the cortex. S cells outnumbered R cells in the inner stripe of the outer medulla. As the thick limb transversed the outer medulla and ascended toward the parent renal corpuscle, there was a marked increase in the relative number of R cells. In the cortical segment of the ascending thick limb, both the R and S cells tended to acquire a more extensive population of microvilli over their luminal surface making it increasingly difficult to establish clearcut distinctions between the two surface patterns. With the possible exception that vesicles and tubulovesicular profiles located in the apical region were more numerous in many of the S cells, additional morphological differences between the rough and smoothsurfaced cells were not evident. Whether the morphological results represent two distinct cell types or simply a variation in the structure of a single cell type, their presence must be considered in future structural-functional studies involving the ascending thick limb of Henle in the rat.

Animals↗
PubMedDate not supplied

1980 Melbourne marathon study.

Most of the 5423 entrants in the Melbourne 1980 Big M Marathon were non-elite athletes. A study of a stratified random sample of 459 entrants (which represented a 42% response rate) found that, while entrants reflected the community standards of disease, they pursued healthier lifestyles. Preparation for the marathon led to a number of positive changes in the health standard of runners. The principal negative consequence of marathon training was the high rate of musculoskeletal problems (30%). Before the race, only 4% of participants had an adequate fluid intake; 33% had pre-existing problems, mainly involving muscles and joints (63%) and viral or gastrointestinal illnesses (41%). These entrants had a 60% less chance of finishing the race. Symptoms during the race were reported by 92% of entrants, but most of these were not serious; only 6% of entrants were unable to finish the race. The pattern of symptoms after the race was similar to that during the race; 50% of these resolved within three hours. Ninety-seven entrants (2%) required medical attention during the race. Serious problems were rare (only in three entrants), and no runner required admission to hospital for longer than 24 hours. Entrants were at greater risk of requiring medical attention or experiencing problems during and after the race if they had a shorter preparation (less than two months), ran fewer kilometres per week (less than 60 km/week) in the last two or three months before the race, and had performed fewer long training runs (more than 24 km).

Athletic Injuries↗