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Biomedical subjects

R L Cohen

Publications and source records attributed to R L Cohen.

At least 91 records · Page 5Linked to original sources
PubMed1982

Immersions of manifolds.

This paper outlines a proof of the conjecture that every compact, differentiable, n-dimensional manifold immerses in Euclidean space of dimension 2n - alpha(n), where alpha(n) is the number of ones in the dyadic expansion of n.

Journal Article↗
PubMed1982

Effects of temperature on antimicrobial susceptibility of bacteria.

The effects of variations in temperature within the physiologic range on minimal inhibitory concentrations (MICs) and on the serum bactericidal activity of 17 different antimicrobial agents for 432 strains of bacteria were studied. Comparison of 3,053 experimental MICs performed at 41.5, 40, 38.5, 37, or 35 C with duplicate standard MICs performed at 35 C showed a progressive increase in antimicrobial activity as the temperature was raised within the experimental range. At the highest temperature (41.5 C), 17.1% of MICs were four or more times lower, 7% were eight or more times lower, and 2% were greater than or equal to 16 times lower than the standard MICs performed at 35 C. Binding to proteins in serum neither accentuated nor diminished the augmenting effect of temperature on antimicrobial activity. Comparison of serum bactericidal activity determined at 35 C and 40 C revealed similar hyperthermic augmentation of antimicrobial activity.

Aminoglycosides↗
PubMed1982

Anaesthesia and cognitive functioning. Mental function in postoperative day patients at the time of their release.

Day care patients at Law Hospital, who had received either a general or a local anaesthetic in conjunction with minor surgery, were assessed by five tests of mental function before surgery and before discharge from hospital some hours after surgery. These patients did not perform differently from control patients, who were subjected to the same two testing sessions, without intervening surgery or anaesthesia. It was concluded that the day cases were quite capable of normal cognitive functioning at the time of their discharge and that the procedures followed by the hospital for the discharge of day cases are generally adequate.

Adult↗
PubMed1982

Ostensible versus actual reasons for seeking pediatric attention: another look at the parental ticket of admission.

The presentation of parental anxiety that appears excessive in view of the nature of the child's "chief complaint" is a frequent occurrence in pediatric practice. This study reviews 370 sick-patient visits in one pediatric office during a three-month period. Additional questioning in the area of parental anxieties concerning these symptoms revealed that in 125 instances (33.8%), the parent was entertaining unverbalized fears that something much more serious was wrong with the child than could be anticipated from the ostensible reason for seeking assistance. An analysis of the "actual reason for coming" reveals that the child's presenting complaint has become associated for the parent with (1) family history of serious life-threatening illness; (2) fears of loss and separation; (3) death; (4) the fears of another family member who is pressing for "answers" about the problem; (5) fears of loss of vital functions and a variety of other thought processes that have somehow become linked to the child's symptom. Techniques for recognizing and ameliorating this parenting difficulty are discussed.

Adult↗
PubMed1981

A cyanine dye distinguishes between cycling and non-cycling fibroblasts.

Cellular proliferative activity has previously been determined by measuring the incorporation of radiolabelled nucleotides or by visual inspection of cellular morphology. Although two flow cytometric methods have recently been developed which can distinguish cycling from non-cycling cells, both have serious disadvantages. One method requires uptake of a substantial amount of BUdR, limiting its usefulness for in vitro systems. The other method utilizes RNA/DNA content differences but its successful application has proved cell-type dependent. We have now used the findings that the cell membrane is more highly polarized in resting than in proliferating cells and that cyanine dyes carrying a delocalized positive charge enter live cells to an extent that depends on the cell membrane potential, to develop a method of distinguishing between cycling and non-cycling cells. The greater the membrane polarization, the greater is the concentration of dye within the cell. At high concentrations, the dye molecules aggregate and their fluorescence is quenched. Thus, for a given external dye concentration, cells of different membrane potential would accumulate different amounts of fluorescent (non-aggregated) dye. Using fibroblasts in culture conditions chosen to provide various models of cycling and non-cycling cells, we found that fluorescence intensity with the dye, 3,3'-diheptyloxycarbocyanine (Di-O-C,(3)) was consistently greater in the former than the latter.

Carbocyanines↗
PubMed1979

Strabismus in the aphakic patient.

Fifty patients with aphakia and strabismus were studied. The chief complaint was diplopia following full optical correction. Prism therapy was recommended if the diplopia persisted after 3 to 4 months. When prism therapy was ineffective or impractical, surgery was recommended. The result of therapy was not influenced by the cause of the cataract treatment was considered successful in approximately 80% of patients. Patients who had convergence insufficiency did well with prism therapy alone. Half of the patients who had divergence excess needed extraocular-muscle surgery. One fourth of the patients had esotropia, nearly half associated with lateral rectus palsy. While prism therapy resulted in fusion, a reduction in prism power was not tolerated in this group. For this reason, surgery was suggested for all patients who had esotropia.

Adolescent↗
PubMed1976

Use of low-pass noise in word-recognition testing.

This study attempted to determine whether word-recognition scores obtained in noise were more sensitive to the presence of a hearing loss than recognition scores obtained in quiet. Subjects with normal hearing, high-frequency cochlear hearing loss, and flat cochlear hearing loss were tested in quiet and in the presence of a 500-Hz low-pass noise. Two signal-to-noise conditions were employed, -4 dB and -12 dB. Words were presented at 40dB SL in one experiment and at 96 dB SPL for normal-hearing subjects in a second experiment. The results indicated that, while the word-recognition scores of groups were similar in quiet, the more negative the signal-to-noise ratio, the greater the separation of group scores, with hearing-impaired subjects having poorer recognition scores than normal-hearing subjects. When the speech and noise were presented at high SPLs, however, the normal-hearing subjects had poorer word recognition than those with flat cochlear losses. The results are interpreted as indicating greater spread of masking in normal-hearing than hearing-impaired subjects at high sound pressure levels.

Adult↗
PubMed1972

Mössbauer spectroscopy: recent developments.

In this review I have emphasized two basic points. First, Mössbauer spectroscopy has been widely used as a tool for basic research in solid-state physics, chemical structure, and magnetism. Second, the technique has been applied to many analytical and materials science problems where the nature of the sample prevents the use of more traditional approaches. Mössbauer spectroscopy research on frozen solutions, colloids, interface chemistry, and crystallographic transformations can be expected to increase rapidly in the next few years.

Magnetic Resonance Spectroscopy↗