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S E Reynolds

Publications and source records attributed to S E Reynolds.

32 records · Page 2Linked to original sources
PubMed1990

Alveolar epithelial cell keratin expression during lung development.

Defining the expression and organization of keratins has provided insight into epithelial cell differentiation during tissue development and remodeling. We have used monoclonal antibodies to examine keratin distribution in lung epithelial cells in the rat from the preglandular phase of gestation to the adult. Of particular interest were the distributions of keratin No. 18 and keratin No. 19, since previous results have suggested these keratins may be important in alveolar epithelial cell transitions occurring in adult remodeling lung and in cultured type II cells. The epithelial tubes at 15 days of gestation do not react with 24A3 monoclonal antibody to keratin No. 18, nor is this antigen apparent by gel or immunoblot analysis. Staining is apparent at day 16, however, showing a light punctate pattern at the basal edge of the cells, and becomes prominent by day 17, with intensity greatest in the larger airway tubes. The intensity and number of cells in the parenchyma staining with 24A3 peaks at postnatal days 5 to 10, when proliferation and cytodifferentiation of type I and type II cells is most active. In the adult, staining of type II cells is present mainly at the cell periphery, and occasional reactive attenuated type I-like cells can be observed. Keratin No. 19 immunoreactivity is not present in the primitive epithelial tube until 19 days' gestation but predominantly stains type II pneumocytes in the adult rat lung throughout the entire cell. AE3 antibody to basic keratins stains similarly to keratin No. 19. We conclude that keratin No. 18 is expressed at high levels in type II cells during development in periods of intense proliferation and alveolarization. This correlates with our previous observations on keratin expression following bleomycin lung injury.

Animals↗
PubMed1990

Smooth muscle cell markers in developing rat lung.

We employed a panel of antibodies directed against cytoskeletal and contractile proteins in a developmental study to follow the differentiation and distribution of smooth muscle-like cells in the rat lung. We observed that, in the mesenchyme around developing airways and vessels, desmin replaces vimentin as the predominant intermediate filament as specialization toward smooth muscle occurs. Normally, desmin and smooth muscle myosin were expressed together in the cells and their acquisition appeared indicative of terminal differentiation of smooth muscle. In this regard, the maturation of vascular smooth muscle is delayed in the lung relative to that surrounding the developing air passages. alpha-smooth muscle actin-containing cells form a thicker coat around the primitive airway tubes and extend farther down the tree than desmin or smooth muscle myosin-positive cells. This suggests that the alpha-actin is a marker for initial differentiation of smooth muscle cells and that these cells arise from the enveloping mesenchyme. In the pseudoglandular and canalicular lung, alpha-actin-containing cells were also found in regions of epithelial tube cleft formation, suggesting an association with the process of branching morphogenesis. In addition, a large complement of alpha-actin-positive but smooth muscle myosin-negative cells were observed in the saccular interstitium during the period of secondary saccule formation and capillary reorganization that leads to final alveolarization. In summary, we note an association of smooth muscle-like, alpha-actin-containing cells with areas and periods of remodeling during normal pulmonary development. This observation may have relevance to the repair process in the adult lung.

Actins↗
PubMed1984

Explosive nephrolithopaxy: reality or fiction?

The use of silver and lead azide explosive charges for the percutaneous distintegration of renal calculi has been investigated. Charges of 10 mg or more reliably reduced calculi to fragments of extractable size; however, the concomitant tissue effects would preclude the use of such charges clinically. Smaller charges require multiple applications. High-speed flash photography demonstrated the unfocussed nature of these discharges. Considerable improvements are anticipated when the shock waves are focused. The use of Nonel tubing is described, and future developments are discussed.

Azides↗
PubMed1975

The mechanical properties of the abdominal cuticle of Rhodnius larvae.

1. The mechanical properties of loops of cuticle cut from the abdomens of 5th instar Rhodnius have been investigated. The cuticle shows pronounced viscoelastic behaviour. 2. Stress-relaxation tests show a continuously falling modulus over a wide range of times after the imposition of a strain. 3. Plasticized samples of cuticle show stress-relaxation curves which are shifted along the time axis towards earlier times by up to times 10-3. The modulus at any particular time after the imposition of strain is about 10 times lower than that of the unplasticized cuticle. 4. It is concluded that the mechanical properties of this cuticle are determined, at least for maintained stresses, largely by the matrix material. Chitin microfibrils may act as a reinforcing filler for short-term, rapid stresses. The cuticular macromolecules are probably not extensively cross-linked by primary bonds, though secondary interactions between them are probably important in the viscoelastic properties of the cuticle. 5. Plasticization probably involves a change in either the number or the strength of secondary interactions between the cuticle macromolecules, or both.

Abdominal Muscles↗
PubMed1975

The mechanism of plasticization of the abdominal cuticle in Rhodnius.

1. The mechanism of plasticization of the abdominal cuticle in Rhodnius larvae has been investigated, using the properties of loops of cuticle under varying test conditions as a model for the behaviour of the cuticle in vivo. 2. It is supposed that plasticization is effected by a change in the intracuticular environment. A number of model mechanisms for plasticization may be proposed, which suppose that the epidermis is capable of regulating (a) pH, (b) ionic strength,(c) Ca and/or Mg, (d) urea, within the cuticle. 3. Analyses of cuticle ash show that models(b) and (c) are not responsible for plasticization in vivo. The levels of inorganic ions within the unplasticized cuticle are not sufficiently high to allow plasticization upon their removal. 4. No evidence for model (d) has been found; urea does not occur in the cuticle in detectable quantities. 5. Exact measurements of the intracuticular pH have not been achieved but straining experiments strongly suggest that a change in pH occurs within the cuticle on plasticization. This pH change is probably large enough to account for the increased extensibility shown by plasticized cuticle.

Abdominal Muscles↗
PubMedDate not supplied

Degradation of adipokinetic hormone family peptides by a circulating endopeptidase in the insect Manduca sexta.

The hemolymph (blood) of the Lepidopteran insect Manduca sexta contains an endopeptidase that metabolizes the nonapeptide Manduca adipokinetic hormone. In contrast to the situation in other insects, where the major site of inactivation is the Malpighian tubules (excretory organs), in Manduca the capacity of the hemolymph to metabolize adipokinetic hormone is comparable to that of the Malpighian tubules. The hemolymph enzyme cleaves Manduca adipokinetic hormone (pGlu-Leu-Thr-Phe-Thr-Ser-Ser-Trp-Gly-NH2) to give the fragment pGlu-Leu-Thr-Phe-Thr. Other fragments were not positively identified. The enzyme is present in the plasma and not in hemocytes, and occurs at similar levels in the hemolymph of larvae, pupae and adults. The enzyme is inactivated by boiling, has a neutral pH optimum (7.0-7.5), and an estimated molecular weight of 66 kDa. The enzyme was strongly inhibited by inhibitors of metalloprotease activity (EGTA and 1,10-phenanthroline), but not by serine protease inhibitors. The enzyme was capable of metabolizing a number of AKH family peptides with varying sequences around the presumed site of cleavage. An accurate assessment of enzyme kinetics was not possible with the assay method used, but the enzyme was not saturated at a substrate concentration of 10 microM, and the value of Km must be at least 1 microM. It is possible that the enzyme may represent a low affinity system of peptide removal rather than the principal means of inactivation.

Amino Acid Sequence↗
PubMedDate not supplied

Intra- and intermodal discrimination transfer in auditory and visual discrimination training.

The purpose of this study was to investigate intra- and intermodal discrimination generalization-transfer in auditory and visual "same-different" discrimination training. Two subjects were trained in an auditory discrimination task, two in a visual discrimination task and two received no training. Discrimination performance was assessed on 12 visual and 12 auditory stimulus conditions at pre- and posttraining intervals for all subjects. The 4 subjects receiving training also were probed for performance at three intervals during the training. Results indicate that subjects trained to a task in one sensory modality demonstrate improved discrimination performance on untrained stimulus discrimination within (intra-) and between (inter-) sensory modalities, whereas, untrained subjects tended to show less improved performance.

Auditory Perception↗
PubMedDate not supplied

Misleading presentation of breast cancer in popular magazines.

CONTEXT: Women commonly misunderstand their risk for breast cancer, overestimating both their risk for developing the disease at a young age and their lifetime risk. OBJECTIVE: To determine whether age bias occurs in popular media coverage of breast cancer. SELECTION STRATEGY: The search term breast cancer was used to identify 389 articles in U.S. magazines with a circulation of at least 500,000 published between January 1, 1993, and June 30, 1997. MAIN OUTCOME MEASURES: Presence of age-related themes and age of patients with breast cancer who were described in vignettes. RESULTS: Age-related themes included breast cancer as a cause of premature death, breast cancer in mothers of young children, and the impact of a breast cancer diagnosis on dating and marriage. Factual information about age as a risk factor for breast cancer was presented in only 14% of articles, and age was often included in vignettes describing a woman with breast cancer. Thirty-four percent of the articles included one or more breast cancer vignettes. These articles included 172 unique vignettes in which patient age was described. In 84% of the vignettes (144 of 172), women were diagnosed with breast cancer before 50 years of age; in 47% (80 of 172), women were diagnosed before 40 years of age. On the basis of the age-specific incidence of breast cancer in the United States, the expected percentages would be 16% and 3.6%, respectively. CONCLUSIONS: Stories about breast cancer in popular U.S. magazines misrepresent the age distribution of the disease, emphasizing atypical cases of early-onset breast cancer and their social consequences. This presentation of breast cancer may contribute to women's fears of breast cancer and to overestimates of personal risk.

Adult↗