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Biomedical subjects

D Kramer

Publications and source records attributed to D Kramer.

12 recordsLinked to original sources
PubMed1992

Paranasal echogenic mass: sonographic sign of bilateral complete cleft lip and palate before 20 menstrual weeks.

A paranasal echogenic mass identified at ultrasound performed during the second trimester was the initial and primary clue to the presence of bilateral complete cleft lip and palate in four fetuses. Referral had been for dating purposes in three cases and because of high maternal serum alpha-fetoprotein level in one. Genetic amniocentesis revealed deletion of the 15th chromosome in one case. The clefts were small and difficult to visualize; the finding of the echogenic mass (representing a premaxillary protrusion) therefore added confidence to the diagnosis.

Cleft Lip↗
PubMed1990

Applications of voxel shifting in magnetic resonance imaging.

Due to the nature of three-dimensional Fourier transform (3-DFT) data acquisition in magnetic resonance imaging (MRI), the spatial relation between a resolved volume element (a voxel) and the object can be manipulated easily. Those manipulations have practical consequences in terms of registering slice positions with respect to features of interest in producing oblique reformatted images where volume resolution is preserved, and in generating reformatted images that project the viewing plane onto a surface through the object that has an arbitrary shape.

Fourier Analysis↗
PubMed1990

A vasopressin metabolite increases attentional selectivity.

Two behavioral paradigms were used to assess the effect of a vasopressin metabolite, AVP4-9, on selectivity of attention. The effects observed in a multiple-cue task indicated that AVP4-9 treatment increased the extent to which attention was controlled by the dominant cues in the environment. When these stimuli predicted reward, the peptide treatment facilitated learning, but when these cues were nonpredictive, the treatment hindered learning. In a redundant learning paradigm, administration of the lower dose of AVP4-9 (1 microgram/kg) prevented animals from learning about an added, equally predictive (i.e., redundant) set of cues, suggesting that this treatment caused selective attending to the originally presented stimuli, whose relationship with reward had already been learned. The results of these two studies provide converging evidence that AVP4-9 treatment increases the selectivity of attention, with preferential processing of dominant information. Parallels with the putative attentional effects of increased arousal are discussed.

Animals↗
PubMed1989

Increasing empathy among medical students.

The objective of the research was to evaluate the short- and long-term effectiveness of teaching medical students interviewing skills. Methods of teaching communication skills included a workshop for clinical instructors, as an indirect approach, a workshop for medical students, as a direct approach, and a combination of both. Results demonstrated that in order to stimulate medical students to use supporting-interview skills, they themselves should participate in an interpersonal skills workshop. Being taught these skills by teachers who have participated in the workshop does not have the same positive effect.

Clinical Clerkship↗
PubMed1989

Preliminary characterization of a group of actinophages of the thermophilic actinomycete genus Saccharomonospora.

The comparison of the Saccharomonospora phages phi SaC1, phi SaG1, phi SaV1, phi SaV2, phi SaV3, and Tm1 demonstrated that they all belong to a single group of closely related actinophages: they were similar with regard to host range, virion mophology (B1 type), genome length (43-45 kb), and GC content of their genomes (63, 3% G + C). Furthermore, DNA-DNA hybridization showed that the phage genomes had a high degree of homology to each other. The phages are, therefore, proposed as representatives of a new bacteriophage species in the sense of the ICTV.

Actinomycetaceae↗
PubMed1989

Accessible magnetic resonance imaging.

The cost of magnetic resonance imaging (MRI) is driven by magnetic field strength. Misperceptions as to the impact of field strength on performance have led to systems that are more expensive than they need to be. Careful analysis of all the factors that affect diagnostic quality lead to the conclusion that field strength per se is not a strong determinant of system performance. Freed from the constraints imposed by high-field operation, it is possible to exploit a varied set of opportunities afforded by low-field operation. In addition to lower costs and easier siting, we can take advantage of shortened T1 times, higher contrast, reduced sensitivity to motion, and reduced radiofrequency power deposition. These conceptual advantages can be made to coalesce onto practical imaging systems. We describe a low-cost MRI system that utilizes a permanent magnet of open design. Careful optimization of receiving antennas and acquisition sequences permit performance levels consistent with those needed for an effective diagnostic unit. Ancillary advantages include easy access to the patient, reduced claustrophobia, quiet and comfortable operation, and absence of a missile effect. The system can be sited in 350 sq ft and consumes a modest amount of electricity. MRI equipment of this kind can widen the population base than can access this powerful and beneficial diagnostic modality.

Costs and Cost Analysis↗
PubMed1977

The metal-cement interface in total hip prostheses.

Serial radiographs of 101 total hip arthroplasties were reviewed to evaluate the clinical significance of lucent zones at the femoral metal-cement interface. Such lucent zones were identified in 19 hip prostheses, but only in four was there clinical evidence of infection loosening of the prosthesis. The remaining 14 patients (15 prostheses) were followed for periods ranging from 18 months to 5 years; none had complications despite the development of these lucent zones. Microdensitometry confirmed the existence of a true lucent zone in most cases, but in several the apparent lucency was due to the Mach effect. While progressive widening of the lucent zone or a lucency measuring greater than 2 mm in width should prompt careful clinical evaluation for evidence of infection or loosening, our data indicate that such complications need not necessarily be present.

Arthroplasty↗