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Biomedical subjects

B D Cohen

Publications and source records attributed to B D Cohen.

At least 19 recordsLinked to original sources
PubMed1992

Self-structure in borderline personality disorder.

Self-structural theory is applied to the interpersonal aspects of borderline personality disorder. The notion of interpersonal contrasting, a cognitive maneuver, is introduced to account for the sharp changes between divergent self-states characteristic of the disorder. The theory and three prototypical self-states are illustrated with data from a borderline patient by means of a procedure derived from the theory.

Borderline Personality Disorder↗
PubMed1992

Effect of thermal placement techniques on some physical properties of gutta-percha.

Some clinical techniques for the placement of gutta-percha root fillings involve the application of heat. This study was undertaken to assess the effects of intracanal heating techniques on the following properties of gutta-percha: coefficient of thermal expansion, softening temperature, phase transition temperature and organic content. Samples from each of four products were prepared by three different methods. The materials were studied by thermomechanical analysis, simultaneous thermogravimetry and differential thermal analysis, and by measurement of weight loss on ashing. It was shown that the techniques of gutta-percha placement involving heating in the root canal caused reversible physical changes in the materials without any apparent change in chemical composition. The average coefficient of thermal expansion was 137 x 10(-6)/degrees C, the softening temperature was 55.5 degrees C, there were two characteristic phase changes, and the organic content was 25%.

Differential Thermal Analysis↗
PubMed1992

Orthodontic adjunctive treatment in fixed prosthodontics.

The purpose of this article has been to increase the restorative dentist's appreciation for the rationale justifying preprosthodontic orthodontic treatment. It has not been intended to identify all the specific indications for the use of orthodontic treatment to enhance prosthodontic treatment nor has it been intended as a reference to assist the restorative dentist in placing and using orthodontic appliances. Figure 12 illustrates a typical case in which the combination of orthodontic and prosthodontic treatment resulted in a more favorable outcome than prosthodontic treatment alone. When planning prosthodontic treatment, the dentist should embrace a dynamic view of tooth position and determine whether restorative treatment can be enhanced by tooth movement. Improved tooth position can eliminate potentially pathologic occlusion and create a healthier periodontal environment that is easier to maintain. In addition, it permits the dentist to place restorations that often require less natural tooth reduction during preparation, and that are more esthetic, functional, stable, and durable. Orthodontic treatment that accomplishes these benefits may be limited to a partial fixed appliance localized to one segment of an arch or require a more extensive fixed appliance. Much of this treatment can be accomplished by the interested restorative dentist. Addressing more comprehensive orthodontic problems in patients requiring prosthodontic care is best managed through a restorative dentist and orthodontist team approach to treatment.

Dental Stress Analysis↗
PubMed1991

Identification and characterization of the neurofibromatosis type 1 protein product.

The neurofibromatosis type 1 (NF1) gene responsible for von Recklinghausen neurofibromatosis is related to regulators of ras proteins, and a portion of NF1 that is homologous to the ras GTPase-activating protein (GAP) encodes a similar GTPase-stimulating activity. We have raised rabbit antisera to a bacterially synthesized 48-kDa peptide corresponding to the GAP-related domain of NF1 (NF1-GRD). These antisera immunoprecipitated the NF1-GRD peptide, and one of them specifically inhibited the GTPase-stimulating activity of NF1-GRD. The sera specifically detected a 280-kDa protein in lysates of mouse NIH 3T3 and human HeLa cells. This protein corresponds to the NF1 gene product, as shown by several criteria, including partial proteolysis. Subcellular fractionation revealed that while GAP is predominantly cytoplasmic, all of the NF1 was recovered in a pellet (100,000 x g) fraction. NF1 was present in a large molecular mass complex in fibroblast and Schwannoma cell lines and appears to associate with a very large (400-500 kDa) protein in both cell types. The relevance of these findings to cellular regulation of p21ras is discussed.

3T3 Cells↗
PubMed1991

Castable glass ceramic crowns and their reaction to endodontic therapy.

The purpose of this investigation was to determine how castable glass (Dicor) crowns would react to both cold testing and endodontic access intervention. Full crown preparations were made on six extracted maxillary teeth. The teeth were then forwarded to Dentsply International, York, Pa. Six castable glass crowns were fabricated to fit these teeth and returned to us. Subsequently the teeth were dried and the crowns were cemented. Scanning electron micrographs of the cemented crowns were made, and endodontic access openings were drilled. The teeth were also cold tested with standard methods. The teeth were then again subjected to scanning electron microscopy to determine any changes the crowns might have undergone. One crown cracked around the gingival collar as scanning electron microscopy was performed. The other crowns did not exhibit any problems such as cracking or crazing from either the access openings or the cold testing.

Ceramics↗
PubMed1977

A method for the study of lay conceptions of psychopathology: a free-response approach.

A free-response approach for identifying a lay group's conception of psycopathology is described in this paper and is illustrated with a college student population. An initial sample of individuals from the population is asked to give "reasons why someone might need to be examined by a professional person in the field of mental health." A second sample of individuals sort the problem statements on the basis of their judgements of the similarity among the statements. A measure of psychological distance for each pair of statements, based on the proportion of times the two statements are sorted together, is used as input for clustering and multidimensional scaling. A third sample contributes to the interpretation of the resulting structures by rating each problem on several psychological properties. The most relevant properties found for college students are: (a) degree of abnormality; (b) referral source--self versus others. Also disc1ssed are possible applications of the method to other lay groups in the interest of providing improved community mental health services to such groups.

Attitude to Health↗
PubMed1977

Alternate reasons for atherogenesis in uremia.

The key to symptomatology in uremia is nitrogen retention leading to amidination and transmidination of a variety of substrates. The product of this activity is a series of guanidino acids which are methyl receptors converting S-adenosylmethionine to adenosine and homocysteine. Adenosine is a potent inhibitor of the enzyme ATPase and, in this way, contributes to the anemia, the bleeding diathesis and the CNS symptoms of uremia. Homocysteine is an inhibitor of pyridoxal phosphate-induced reactions and contributes to the angiitis and thromboembolism so unexpectedly encountered in chronic uremia.

Adenosine Triphosphatases↗
PubMed1975

Uremic toxins.

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Adult↗