NIH funding for biomedical research, 1990: perceptions and realities.
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Budgets↗
Biomedical subjects
D E Kelly
Publications and source records attributed to D E Kelly.
The morality of cooperation.
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Ethics, Professional↗
Transcript characterisation, gene disruption and nucleotide sequence of the Saccharomyces cerevisiae WH12 gene.
WH12 is a gene which plays a prominent role in regulating growth and proliferation in Saccharomyces cerevisiae. It is expressed as a 2.0-kb mRNA transcript. Disruption of this transcript in a WH12+ cell results in the mutant phenotype being displayed. The nucleotide sequence of the cloned gene has been determined and found to include a 487-codon long open reading frame coding for a 55.3-kDa protein. The protein showed no extensive homologies to any previously identified protein. The 5' and 3' noncoding regions contained many of the features found in other yeast genes.
Base Sequence↗
Analysis and exploitation of cytochrome P-450 in yeast.
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Animals↗
Analysis of desmosomal intramembrane particle populations and cytoskeletal elements: detergent extraction and freeze-fracture.
We have examined sections and freeze-fracture replicas of Triton X-100 detergent-extracted desmosomes from murine palatal epithelium. After extraction of lipids as well as soluble proteins, a cytoskeletal framework remained which consisted of intermediate filaments, microfilaments, and intact desmosomal skeletons. Traversing filaments, which link the intermediate filaments to large intramembrane particles of the P-face, appeared undisturbed within the desmosomal skeletons. Compared to unextracted controls, extracted specimens displayed P- and E-face desmosomal intramembrane particles which were more fully exposed. A broad range of sizes and shapes was apparent for the P-face associated particles. E-face particles, some of which were exposed for the first time, were more homogeneous and generally smaller. Statistical data gathered from a large sample of P- and E-face particle diameters disclosed significant differences among the populations of the two faces. Both fracture faces of extracted desmosomal domains displayed a residual surface upon which the exposed particles seemed to remain lodged. The newly revealed structural features are presented in an hypothetical molecular model which provides for both vertical and horizontal stabilization of desmosomal subcomponents. The model may ultimately be relatable to emerging biochemical characterization.
Animals↗
Intraorbital cerebrospinal fluid outflow and the posterior uveal compartment of the hamster eye.
An ultrastructural and tracer study was undertaken to determine normal outflow pathways of cerebrospinal fluid (CSF) at the terminal subarachnoid space (SAS) of the optic nerve. In the morphological studies, the optic nerve dura and arachnoid were found to be continuous with the sclera of the eye beyond the optic nerve SAS. The pia mater is continuous with the inner sclera and the lamina fusca of the eye. Montages and serial sections demonstrated that the distal SAS is divided into numerous tortuous channels to form an "arachnoidal trabecular meshwork". Spaces of this meshwork continue into "microcanals" which bypass the outer arachnoid barrier layers of the optic nerve meninges to reach the sclera and posterior intraorbital connective tissue. Ferritin infused into the cisterna magna entered the optic nerve SAS within 1 min and reached arachnoidal trabecular meshwork channels and the microcanals within 8 min. It then passed into intraorbital connective tissue spaces at the posterior pole of the eye. Ferritin appeared to be blocked by the lamina fusca and a newly discovered "posterior compact zone" which together prevented its entrance into the choroidal interstitium. These observations suggest that a "subarachnoidal-scleral-orbital outflow pathway" provides a route for CSF drainage from the optic nerve SAS to intraorbital connective tissue. The previously described "posterior uveal compartment" in the hamster eye (Kelly et al. 1983) appears to be relatively isolated from this subarachnoidal-scleral-orbital CSF outflow.
Animals↗
Differences in the cytochrome P-450 enzymes of sterol C-14 demethylase mutants of Saccharomyces cerevisiae.
A number of nystatin-resistant strains of S. cerevisiae have been isolated which are defective in lanosterol C-14 demethylation, a reaction normally catalysed by cytochrome P-450. In this paper two of these strains have been compared and found to have differences in their reduced-CO difference spectra indicating different distortions in the enzyme molecule. Nystatin resistance in the C-14 demethylation deficient SG1 in shown to be determined by a single gene, and a sterol 5,6-desaturase defect does not appear to be required for viability of SG1, was reported for the C-14 demethylase deficient isolate JR4 by Taylor et al. (1983). There are at least two discernable mutant phenotypes for the yeast cytochrome P-450 structural gene which give a C-14 demethylase defect.
Cytochrome P-450 Enzyme System↗
Interaction between yeast cytochrome P-450 and chemical carcinogens.
The binding of various chemical carcinogens to the glucose-inducible form of cytochrome (cyt.) P-450 in Saccharomyces cerevisiae was examined with reference to known metabolism in mammalian systems. All the carcinogens examined gave spectral interactions with the yeast cytochrome. The carcinogens benzo[a]pyrene and cyclophosphamide gave Type I binding, while benzidine and 2-naphthylamine gave Type II binding spectra indicating binding at the haem group. Dimethylnitrosamine gave undetectable binding in yeast microsomal fractions, but a Type I binding spectrum was seen with purified cyt. P-450 preparations. The demonstration that these carcinogens bind to yeast cyt. P-450 is discussed in the light of their genotoxicity.
2-Naphthylamine↗
Fibrillar and cytoskeletal substructure of tight junctions: analysis of single-stranded tight junctions linking fibroblasts of the lamina fusca in hamster eyes.
The lamina fusca of the hamster eye contains layers of flattened, slightly overlapping fibroblasts. Thin sections of the overlapping margins reveal punctate, tight-junction-like membrane appositions associated with accumulation of cytoplasmic filaments, 5-7 nm in diameter. Intermediate filaments are present in the surrounding cytoplasm. A diffuse dense substance occurs in adjacent intercellular space. Freeze-fracture replicas show that the membrane appositions are mainly single-stranded tight junctions, each composed of two fibrils (micelles), and each continuous or nearly continuous around the fibroblastic perimeter. Fracturing characteristics of these junctions offer a unique opportunity to gain further insight into tight junctional morphology. When exposed, the fibrils adhere to the P-face, measure 9.2 +/- 0.3 nm in diameter, and are accompanied by a narrow band of membrane differing in texture from non-junctional membrane. Characteristically, the junctional fibrils themselves mark the deviation line along which fracture planes pass from one membrane of the junction to the other. This pattern exposes, over long distances, the P-face of one membrane on one side of this line and E-face of the adjacent membrane on the other. Analysis of any single junction over such distances reveals that the juxtaposition of the fibrils may gradually twist or undulate over a range of at least 180 degrees within the two involved membranes. The fracture plane appears preferentially to pass between the two junctional fibrils; association of the cytoskeleton with junctional fibrils may govern this route of fracture. Cytoskeletal attachment appears to be to a single fibril and may alternate from one fibroblast to the next depending on which cytoplasmic leaflet is nearest a given fibril.
Animals↗
Uveal compartmentalization in the hamster eye revealed by fine structural and tracer studies: implications for uveoscleral outflow.
The uveal tracts of hamster eyes have been examined using electron microscopy and electron opaque tracer infusion. A heretofore undescribed intrauveal "compact zone" was detected at the level of the ora serrata. Together with extensive, sheet-like fibroblastic layers within the lamina fusca and the well-known junctional barriers of the pigment epithelium, the compact zone appears to separate anterior and posterior uveal regions into defineable compartments. To test this possibility and study potential pathways of uveoscleral outflow with special reference to these morphologic features, horseradish peroxidase or anionic ferritin was infused into the anterior chamber at physiologic pressures, in some experiments coincident with vascular rinsing and/or fixation to prevent tracer redistribution. Tracer rapidly permeated outflow and connective tissue spaces of the anterior uvea and spread into the sclera and adventitia. However, it did not appear in the inner choroid unless vascular recirculation and redistribution of tracer was allowed. Potential structural boundaries that might prevent direct choroidal penetration include the compact zone, which never contained tracer, and tight-junctioned, sheet-like fibroblastic lamellae of the lamina fusca. The choriocapillaris and internal choroidal interstitium may thus be isolated to an appreciable degree as a "posterior uveal compartment." The position of this compartment is comparable developmentally to the subarachnoid space of the brain and optic nerve. The anterior margin of the compartment (the compact zone) limits the space available for uveoscleral outflow of aqueous humor in the hamster and may provide a focus for control of that process.
Animals↗
Traversing filaments in desmosomal and hemidesmosomal attachments: freeze-fracture approaches toward their characterization.
Desmosomes and hemidesmosomes from larval newt epidermis were examined by freeze-fracture methods incorporating low osmolality fixation, short duration glycerination, complementary replica comparison, stereo imaging, and dark shadow printing. These procedures provide new evidence regarding the structure of "traversing" filaments as mediators of attachment between intermediate filaments and the cell membranes of desmosomes and hemidesmosomes. A detailed analysis of intramembranous particles and other structures in these attachments has also been possible. The relationship of this evidence to models of desmosomal structure suggested by other authors is discussed.
Animals↗
Primary mandibular neuroblastoma.
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Child↗
Subunits of the triadic junction in fast skeletal muscle as revealed by freeze-fracture.
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Animals↗
An unusual bilateral pathological fracture.
An unusual case of a bilateral pathological fracture of the mandible has been presented. The fracture of the right side of the mandible was through an area of bacteroides osteomyelitis and the fracture of the left side of the mandible was through a large cementifying fibroma, which had replaced the left body of the mandible.
Adult↗
Leiomyoma of the tongue: report of case.
An instance of leiomyoma of the tongue has been reported. The theories of origin of smooth muscle tumors within the oral cavity have been reviewed. The necessity for differentiation of leiomyomas from other spindle-cell tumors and the need for thorough examination of the specimen have been discussed. Complete surgical excision of these tumors is the preferred treatment.
Adult↗
Arteriovenous malformation of the mandible: report of case.
A case of a potentially lethal arteriovenous malformation of the right side of the mandible has been presented. Procedures that may be helpful in diagnosing the lesion have been discussed, and a protocol for treatment of these lesions in the mandible has been proposed. Research of the cause and management of these lesions is greatly needed.
Adult↗
The hemidesmosome: new fine structural features revealed by freeze-fracture techniques.
Hemidesmosomes along the dermal-epidermal junction of larval and post-metamorphic newt skin have been examined in freeze-fracture replica images correlated with electron micrographs of sectioned material. Larval hemidesmosomal sites are characterized by large (200-300 A) intramembranous granules arranged into clusters, each of which is aligned with a cytoplasmic hemidesmosomal plaque. In unfixed epidermis the granules remain attached to the A-face, while after glutaraldehyde fixation they are found on both A- and B-faces. Following metamorphosis the clusters are less distinct and localized. Replicas of unfixed B-faces and nearby cytoplasm display elongate, filamentous profiles which traverse the cytoplasmic leaflet and extend onto the B-face. The possibility that these components constitute a filamentous network serving to link tonofilaments, hemidesmosomal plaque, and basal plasmalemma is considered in view of the evidence to date. Hemidesmosomal fine structure as revealed by these studies is compared to features of desmosomes as detailed in the following report.
Animals↗
The desmosome: fine structural studies with freeze-fracture replication and tannic acid staining of sectioned epidermis.
Desmosomes of larval and post-metamorphic newt epidermis have been studied by freeze-fracture replication both with and without prior glutaraldehyde fixation. Characteristic particles of a diameter (70-130 A) similar to that of typical membrane associated particles are found clustered on the exposed internal faces of adherent desmosomal membranes. They remain attached to the B-face in unfixed material, but occupy the desmosomal A-face after fixation. Membrane associated particles of nondesmosomal surfaces are found predominantly on the A-face in both fixed and unfixed epidermis. Suitably oriented replicas of unfixed desmosomes reveal profiles of apparent fine filaments extending from the region of tonofilament loops through the desmosomal plaque to traverse the cytoplasmic leaflet of the plasmalemma. They can be traced onto the B-face. Their position correlates to fine linear profiles noted in tannic acid/glutaraldehyde-fixed and sectioned desmosomes. The possibility that these represent a mechanism for anchorage of tonofilaments to the plaque and to the membrane is discussed. These and other fine structural features are compared and contrasted to the properties of hemidesmosomes described in the preceding report.
Animals↗