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Biomedical subjects

R Diamond

Publications and source records attributed to R Diamond.

At least 19 recordsLinked to original sources
PubMed1992

On the multiple simultaneous superposition of molecular structures by rigid body transformations.

A method of optimally superimposing n coordinate sets on each other by rigid body transformations, which minimizes the sum of all n (n - 1)/2 pairwise residuals, is presented. In the solution phase the work load is approximately linear on n, is independent of the size of the structures, is independent of their initial orientations, and terminates in one cycle if n = 2 of if the coordinate sets are exactly superposable, and otherwise takes a number of cycles dependent only on genuine shape differences. Enantiomorphism, if present, is detected, in which case the option exists to reverse or not to reverse the chirality of relevant coordinate sets. The method also offers a rational approach to the problem of multiple minima and has successfully identified four distinct minima in such a case. Source code, which is arranged to enable the study of the disposition of domains in multidomain structures, is available from the author.

Algorithms↗
PubMed1992

Evidence of presymptomatic cognitive decline in Huntington's disease.

Asymptomatic persons at risk for Huntington's disease (HD) (N = 28) were assessed with neuropsychological, psychiatric, and neurologic tests while undergoing genetic linkage studies to determine their probability of carrying the HD gene. Those participants who were subsequently identified as probable gene carriers did not differ on neurologic or psychiatric examination from those subsequently identified as probable noncarriers. Neuropsychological data are presented for a subset of participants free of other conditions (such as alcoholism) putting them at risk for cognitive deficits. Among these subjects, probable gene carriers were inferior to probable noncarriers on the neuropsychological battery as a whole and on several individual tests involving learning and memory. The results suggest the presence of cognitive decline prior to identifiable motor impairments in HD.

Adult↗
PubMed1992

Evaluation of new antifungal drugs for the treatment of systemic fungal infections. Infectious Diseases Society of America and the Food and Drug Administration.

These guidelines are applicable to all fungal pathogens that produce systemic infections in humans. Specific examples are provided whenever they might clarify special issues. Systemic fungal infections usually are divided into two broad categories: endemic systemic fungal diseases, which occur classically in healthy hosts, and opportunistic fungal diseases, which occur almost exclusively in patients with impaired host defenses. Both the increasing frequency of disseminated histoplasmosis and coccidioidomycosis in patients with AIDS and the occurrence of candidemia due to vascular-line infections have begun to blur this distinction. The fungi included in these guidelines are Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, Candida species, Cryptococcus neoformans, Aspergillus species, and Sporothrix schenckii. Diagnosis of infections caused by these fungi should be based on culture of infected body fluids or tissues whenever possible. Cryptococcal and coccidioidal meningitis are exceptions. Amphotericin B remains the standard comparative agent for most new agents. Further studies of the efficacy of new oral agents used alone or after a hospital course of amphotericin B are needed. The agents currently available are usually inadequate for eradication of fungal infections in patients with AIDS, who may need prolonged treatment. Final assessment for these patients may need to be classified as clinical cure with presumed microbiologic persistence.

Antifungal Agents↗
PubMed1992

The pharmacotherapy of depressive illness in adolescence: II. Effects of lithium augmentation in nonresponders to imipramine.

The antidepressant value of lithium augmentation was assessed in a 3-week open trial involving 24 adolescents who remained highly depressed after 6 weeks of treatment with imipramine hydrochloride. Two patients responded dramatically during the first week, with an additional eight patients showing partial improvement during the 3-week trial. The overall magnitude of improvement in depression ratings was significantly greater than in an historical control group of nonresponders who continued to receive imipramine monotherapy during their hospital treatment. Results suggest the potential use of this adjunctive strategy in some tricyclic resistant adolescent depressives, although it appears less efficacious overall in this age group than in adults.

Adolescent↗
PubMed1990

On the use of normal modes in thermal parameter refinement: theory and application to the bovine pancreatic trypsin inhibitor.

A method is presented whereby the amplitude coefficients of molecular normal modes of vibration are treated as independent variables in the treatment of thermal effects in X-ray diffraction, and applied to the bovine pancreatic trypsin inhibitor, form II (P2(1)2(1)2(1), a = 74.1, b = 23.4, c = 28.9 A). It is shown that the description of molecular motion furnished by 892 isotropic temperature factors may be largely reproduced using only 19 molecular thermal parameters from which anisotropic temperature factors may be synthesised for every atom. The method shows that motions and/or disorders external to each molecule are the largest single source of apparent motion, and that the internal motions are comparable to those predicted by Levitt, Sander & Stern.

Aprotinin↗
PubMed1986

Why faces are and are not special: an effect of expertise.

Recognition memory for faces is hampered much more by inverted presentation than is memory for any other material so far examined. The present study demonstrates that faces are not unique with regard to this vulnerability to inversion. The experiments also attempt to isolate the source of the inversion effect. In one experiment, use of stimuli (landscapes) in which spatial relations among elements are potentially important distinguishing features is shown not to guarantee a large inversion effect. Two additional experiments show that for dog experts sufficiently knowledgeable to individuate dogs of the same breed, memory for photographs of dogs of that breed is as disrupted by inversion as is face recognition. A final experiment indicates that the effect of orientation on memory for faces does not depend on inability to identify single features of these stimuli upside down. These experiments are consistent with the view that experts represent items in memory in terms of distinguishing features of a different kind than do novices. Speculations as to the type of feature used and neuropsychological and developmental implications of this accomplishment are offered.

Adult↗
PubMed1986

Treatment compliance in end-stage renal disease patients on dialysis.

This paper reviews the current knowledge concerning treatment compliance in patients with end-stage renal disease (ESRD). Adult hemodialysis patient noncompliance with the treatment regimen is very common. Objective and subjective measures of compliance, however, are often weakly correlated. In addition, the patients may be compliant with some aspects of the treatment regimen, but noncompliant with others. Unfortunately, no current model of predicting the degree of hemodialysis patient compliance is very accurate. In spite of this, behavioral approaches to increase regimen compliance do have at least short-term efficacy. There is a paucity of published data on compliance in adult peritoneal dialysis patients and an almost complete absence of systematic studies of compliance in children and adolescent dialysis patients. A multidimensional nosology of compliance behavior in ESRD patients is, therefore, proposed, as well as an approach to the diagnosis of noncompliance in ESRD patients and to possible interventions.

Adolescent↗
PubMed1985

Drugs and the quality of life: the patient's point of view.

Although research has established the effectiveness of antipsychotic drugs in treating schizophrenic patients, the issue of the quality of life of patients on longterm medication has not been as clearly determined. The patient's and clinician's understanding of this criterion, both objective and subjective, is discussed. Social functioning, acceptance of dose, compliance or lack of compliance, and the relative benefits of medication are factors that contribute to treatment goals. Case examples are presented to demonstrate these variables and their impact on the outcome of treatment with antipsychotic medication and on the patient's quality of life.

Adult↗
PubMed1982

Breaking force of the rabbit growth plate and its application to epiphyseal distraction.

The in vitro breaking forces of the distal femoral growth plates of young rabbits were measured as a background to the design of a bone lengthening method, using epiphyseal distraction. The mean breaking force in 16 femora was 12.98 +/- 3.48 kg and the mean strain was 0.91 +/- 0.33 mm. The mean stress in 10 femora was 14.51 +/- 3.88 kg/cm2. The procedure was repeated, after applying a 1.0 kg dead weight to 6 femora for 24 hours and the breaking force was then 15.01 +/- 4.70 kg, with a mean strain of 0.85 +/- 0.62 mm. A further 8 rabbits then underwent epiphyseal distraction for 2 days in vivo, with 1 or 2 kg forces delivered to two parallel K wires by a pair of spring devices, whereupon the femora were removed and tested as before. The breaking force on the distracted side was now only 8.91 +/- 3.71 kg, compared with 13.99 +/- 3.40 kg on the control side. Although not fractured, these plates had obviously been weakened. The clinical implication of this is discussed.

Animals↗
PubMed1979

Eye movements initiate visual-motor development in the cat.

Visually naïve kittens turn their eyes toward visual targets but lack other visual-motor coordinations. Light-reared animals were able to mediate guided behaviors with an immobilized eye, but animals with the eye immobilized before initial exposure to a lighted environment were not. Eye movement is implied to play an essential role in visual-motor development.

Animals↗