Biomedical subjects
Publications and source records attributed to L F Cooper.
This article outlines those techniques and materials that will optimize the clinician's ability to obtain predictable complete denture impressions using the selected pressure philosophy. Fabrication of a custom tray is crucial to the ultimate outcome of exemplary impressions. Alternative methods for border molding the custom tray are presented.
Polymerase chain reaction amplification and sequencing of heat shock protein (HSP) 27-related transcripts present in cDNAs generated from heat-shocked osteoblast RNA revealed the expression of three related open reading frames that encode proteins of 208, 197, or 175 amino acids. Their expression as recombinant proteins in Escherichia coli demonstrated that they encode 27,000, 25,000, or 22,000 M(r) proteins. Northern blot analysis of heat shock protein 27-related transcript expression revealed that, while HSP 27 expression (850-nucleotide transcript) was induced by heat shock alone, the expression of a smaller transcript was facilitated by estrogen treatment prior to heat shock. This corresponded with the co-induction of 18,000 and 22,000 M(r) proteins by estrogen-pretreated, heat-shocked osteoblasts as revealed by fluorography. The identification of these multiple small M(r) heat shock-induced proteins demonstrated that the stress response of mammalian cells is composed of multiple, related proteins whose expression is differentially regulated. The importance of estrogen-regulation of the small M(r) heat shock protein component of the stress response may be of particular significance to osteoblast physiology.
As nursing practice becomes more complex, and patient care more variable, it will be crucial for nurse educators to teach students to think creatively and to develop a repertoire of strategies to resolve patient problems. The written nursing process has been the primary tool that nurse educators use to teach students to identify patient problems and plan for their resolution, but is it still useful? We combined a review of the literature with an informal survey of BSN nursing students to examine the usefulness of the nursing process from three perspectives: as a problem-solving tool, as a means of fostering the art and creativity of nursing, and as a method of individualizing patient care. Current nursing literature and students' comments about the nursing process suggest that this approach may no longer be realistic or germane to current practice needs.
A gene encoding the rat heat shock protein 27 protein was isolated and characterized. The gene is composed of three exons and two introns. The proximal 5' untranslated region of this gene contains consensus heat shock elements, multiple SP1 sites, and basal regulatory elements including a CCAAT box and a TATA box. Comparison of this heat shock gene with the murine heat shock protein 25 and human heat shock protein 27 genes revealed the conserved presence of a putative heat shock element in the first intron of these mammalian small M(r) heat shock protein genes. While preliminary expression studies indicate the promoter directs heat shock induced expression of heat shock protein 27, the functional significance of the intronic heat shock element to the expression of this gene remains to be determined.
Using 3H-thymidine-labeled MC3T3-El osteoblastic cells, the number of osteoblasts bound to titanium surfaces after various surface treatments and incubation periods was directly measured. MC3T3-El cell binding to titanium surfaces was saturable at a low level (approximately 10,000 cells/cm2). Although treatment of these surfaces with fibronectin, keratin sulfate, and the fibronectin-derived peptide GRGDS (glycine-arginine-glycine-glutamate-serine) increases cellular binding by 29% to 31%, the relative binding to titanium was 5 to 10 times lower than binding to collagen I gels. A collagen I matrix competed with the commercially pure titanium surfaces for cell binding from solution, suggesting that direct binding of osteoblasts to titanium surfaces present within an organic matrix may not be favored. The significance of immediate and direct bone cell attachment to titanium surfaces for osseointegration should be reevaluated.
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Despite advances in preventive dentistry, many elderly persons present with several missing teeth replaced by oral prostheses of various kinds. An increasing number of prostheses are retained and supported by oral implants. Maintaining a complete dentition with fixed, removable, or implant-retained prostheses improves function and patient self-esteem. Irrespective of the prosthesis type, periodic functional and health reassessments are necessary. Strict oral hygiene protocols must be reinforced continually and appropriate modifications (relines) and repairs should be performed to prevent possible degeneration of supporting structures. Although implants promise enhanced function and greater patient satisfaction, they too require careful maintenance. Thus, all oral prostheses require close monitoring and maintenance care. A physician can make an important contribution to a patient's health and quality of life by ensuring that he or she receives routine oral health care.
The rat submandibular gland-specific GRP-Ca gene (encoding C-terminal variant A of the glutamine/glutamic acid-rich protein) has been cloned from a male Wistar/Furth genomic library. The complete sequence, including 2.0 kb of 5' flanking and 0.5 kb of 3' flanking DNA has been determined. Electron microscopic heteroduplex analysis and sequence analysis established that transcripts coding for GRP-Ca and GRP-Cb are encoded by separate genes. The GRP-Ca gene is approx. 4.5 kb in size and is comprised of four exons and three introns. Comparison of this gene with several rodent and human salivary proline-rich protein-encoding genes (PRP) indicates that GRP-Ca shares this exon-intron structure with the rat SMR-2 gene, the hamster H29 gene, and the human PRP genes. In addition, a 28-bp element found in the proximal promoter region of GRP-Ca was found to be highly conserved among the superfamily of PRP genes.
Glutamine/glutamic-acid rich proteins (GRPs) are a family of rat submandibular gland acinar proteins which are secreted in response to beta-adrenergic agonists such as isoproterenol. Two forms of GRP transcripts have been identified by isolating plasmids containing cDNAs which code for two distinct GRPs, termed GRP-Ca and GRP-Cb. GRP-Ca and GRP-Cb have identical sequences up to nucleotide 670. This is followed by a unique 90- (GRP-Ca) or 95- (GRP-Cb) base pair element. Both forms have common 3' nucleotide sequences, although the GRP-Cb stop codon is 27 base pairs further 3' from the start site of transcription. Systemic exposure to isoproterenol results in a decrease in the relative steady-state level of GRP-Ca transcripts within 24 h, whereas GRP-Cb message increases after several days of isoproterenol treatment. The demonstration that secretagogues such as isoproterenol can modulate changes in salivary protein expression suggests that the machinery responsible for exocytosis is functionally coupled to the cellular apparatus involved in acinar protein production.
Congenitally missing teeth and poorly developed or absent alveolar ridges are signs often associated with various types of ectodermal dysplasia. Endosseous dental implants may be used to support fixed mandibular prostheses in patients with ectodermal dysplasia. Anatomical factors and age considerations require careful attention to treatment planning.
As research progresses, laser energy moves closer to acceptable usefulness. Laser application to prepare dentin creates a more retentive surface for composite bonding.
The total fluoride concentration in unstimulated whole saliva was measured before and at selected intervals after a self-applied 1.1% neutral NaF topical fluoride gel or use of a 0.05% neutral NaF fluoride mouthrinse in both normal individuals and patients with radiation-induced xerostomia. As expected, the gel resulted in higher peak fluoride values than the rinse and was retained in the mouth for longer periods of time in both groups. The xerostomic group expressed a mean oral fluoride concentration of 575 micrograms fluoride per gram of saliva within 1 min after the gel application and 150 micrograms/g following use of the mouthrinse, whereas the normal group exhibited peak concentrations of 112 and 71 micrograms/g, respectively, within 1 min after the same two treatments. The initial high levels of fluoride observed in normal subjects following the gel application decreased rapidly to less than 1 microgram/g within 2 h, whereas fluoride levels in the xerostomic subjects remained elevated above 12 micrograms/g for longer than 2 h. Similarly, following use of the mouthrinse, normal subjects' saliva fluoride levels decreased to less than 1 microgram/g within 1 h, whereas xerostomic subjects' saliva fluoride levels remained above 4 micrograms/g for longer than 2 h.
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In this study, the primary culture of bovine mandibular osteoblast cells in a microculture assay has been used to further investigate the interaction of mineralizing osteoblast cultures with implant surfaces by using correlative microscopic techniques. Rapid differentiation and mineralization of osteoblast cultures grown on titanium alloy surfaces was observed. The successful short-term culture of mineralizing mandibular osteoblasts on titanium alloy surfaces occurred without the formation of a tenacious adhesive interface between the alloplastic material and the multilayered cell culture.
Bone formation at implant surfaces may be directly influenced by effects of the implant material on osteoblast behavior. Cell culture models of osteoblast physiology may be used to investigate the interaction of osteoblastic cells with various surfaces. In this study, primary cultured fetal bovine mandibular osteoblastic cells were cultured on titanium, ceramic hydroxyapatite, and glass coverslip surfaces to allow for the comparison of the mineralizing matrix elaborated by osteoblasts grown on different implant material surfaces. Morphologic and immunohistochemical analysis revealed the similar formation of multilayered, mineralizing cultures on these three surfaces. The qualitative similarity of the matrix formed on these culture surfaces may reflect similar qualitative in vivo responses of bone to titanium and hydroxyapatite implants.
The goal of this study was to provide new data regarding levels of inflammatory and growth factor mediators and bacterial pathogens associated with failing implants, as compared to healthy implants. Twenty-one patients with failing implant sites (group 1) and 8 patients with only healthy implants (group 2) were included. Fifteen of the 21 failing implant patients (group 1) also presented with at least one stable nondiseased implant. Plaque samples were examined, using DNA oligonucleotide probes for 40 different microbes. Gingival crevicular fluid samples were collected for the analyses of catabolic bone resorbing agonists prostaglandin E2 (PGE2), interleukin-1 beta (IL-1 beta) and IL-6 and anabolic bone-forming growth factors transforming growth factor beta (TGF-beta) and platelet-derived growth factor (PDGF). Although positive trends were noted, there were no significant differences in any of the microbial, inflammatory, or growth factors mediators comparing failing to stable implants in group 1. This study found greater detection frequencies of P. nigrescens, P. micros, F. nucleatum ss vincentii, and F. nucleatum ss nucleatum, as well as significant elevations in GCF levels of PGE2, IL-1 beta, and PDGF in mouths with failing implant sites as compared to mouths with healthy control implants. Risk appears to be primarily at a patient level and secondarily at a site or implant level from a clinical, microbial (P. micros and P. nigrescens), and biochemical (PGE2 and IL-1 beta) perspective. Furthermore, the counts of P. nigrescens and P. micros were found to correlate with concentrations of PGE2 at a site level.
The tissue response of rat tibiae to the surgical placement of commercially pure titanium implants was examined at 2, 6, 10, and 28 days. The transcortical placement of 1.5-mm x 2-mm implants resulted in the apposition of threaded implant surfaces within cortical and cancellous regions of the tibia. In all regions, evidence of bone formation was obtained through pre-embedding fracture of the implant from the bone tissue interface. Scanning electron microscopy examination of early responses revealed a fibrin clot and rapid formation of a loosely organized collagenous matrix. Many extravasated blood cells contacted the implant surface. At day 6, a more organized matrix containing many blood vessels opposed the implant surfaces, and few extravasated blood cells remained in contact with the implant surface. By day 10, the surgical wound was filled with woven bone that approximated the contours of the threaded implant. Later, few cells were attached to the retrieved implants. The consolidation of the forming matrix was clearly evident at 28 days. The tissue interface was an amorphous matrix that revealed the surface characteristics of the machined implant. Light microscopic analysis of ground sections indicated that, from day 6 onward, cells morphologically consistent with the osteoblastic phenotype were predominant within the gap between the surgical margin and implant surface. Osteoblastic cells had achieved the formation of an osteoid seam upon which bone formation progressed. The matrix that had formed represented woven bone containing many osteocytes. At day 6, evidence of remodeling was observed at sites distant from the surgical site, and by day 28 osteoclastic activity was observed at trabecular sites adjacent to the implant surface. The rat tibia model provides evidence of rapid formation of bone at implant surfaces.