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Biomedical subjects

D L Miles

Publications and source records attributed to D L Miles.

13 recordsLinked to original sources
PubMed1987

The demographics of trauma in 1995.

By 1995 population aging will decrease the size of the high-injury-risk age cohort (14-34 years) by 7.0 million (-8.2%). The reduction in the high-injury-risk age cohort should reduce the overall volume of penetrating and blunt injury nationally despite a population increase of 21 million. However, the number of, and the proportion of, elderly victims of injury will increase as there will be an additional 5.3 million (+18.5%) people age 65 years or older. Yet payments based on Medicare diagnosis-related groups (DRG's) do not provide adequate reimbursement for any, let alone the elderly, victims of injury. Moreover, Medicare and Medicaid reimbursements for the long-term care so frequently needed by the elderly victims of injury is inadequate. As our population ages, the adverse financial impact of these circumstances resultant from population aging will increasingly strain the financial resources of our trauma centers.

Age Factors↗
PubMed1979

Conformation of nucleosides: circular dichroism study on the syn-anti conformational equilibrium of 2-substituted benzimidazole nucleosides.

The solution conformations of 2-substituted derivatives of 1-(beta-D-ribofuranosyl)benzimidazole have been determined by circular dichroism spectroscopy in aqueous solutions. It is shown that analogs with methyl, amino, or methylamino substituents at position 2 of the benzimidazole ring (position 8 of the purine ring) have predominantly anti conformations, whereas analogs with chloro, aza, methoxy, or methylmercapto substituents have predominantly syn conformations. The preferred solution conformations of the benzimidazole nucleosides and analogous purine nucleosides are compared. The results demonstrate that the replacement of nitrogen by carbon at position 3 of the purine ring of purine (beta) nucleosides leads to important conformational consequences, which are strengthened or neutralized by substituents at position 8 of the purine ring.

Benzimidazoles↗
PubMed1979

Interferon induction: a conformational hypothesis.

The ability of polynucleotides or polynucleotide duplexes such as poly(I).poly(C) to induce interferon production is proposed to depend on the existence of certain stable glycosidic orientations. It appears that a slight increase in instability of 1--3 kcal/mole (1 cal = 4.184 J) in the conformational regions near 20 degrees, 80 degrees, and 160 degrees leads to a loss of potency with respect to interferon induction. Thus, it is proposed that, for a polynucleotide to exist in the overall conformation necessary for interferon induction, stability of glycosidic orientations near 20 degrees, 80 degrees, and 160 degrees may be necessary to confer flexibility and activity on polynucleotide structures. This proposed conformational triad of stable conformational regions essential to interferon induction is based on the results of conformational energy calculations of the glycoside rotational profiles of adenosine, 7-deazaadenosine, inosine, and 7-deazainosine, as well as the conformational properties of other purine nucleoside analogs, and on inferences derived from calculations about the conformational effect in polynucleotides of removing the 2'-OH group.

Adenosine↗
PubMed1978

A conformational basis for the antiviral inactivity of tetrazole ribonucleosides.

The antiviral activity of ribavirin has been associated with its inhibition of the enzyme, IMP dehydrogenase. The ability of ribavirin to inhibit this enzyme has previously been shown to be related to its stability in the high anti glycosidic conformation. The antiviral effectiveness of several analogs of ribavirin have been investigated recently. The evidence indicates their antiviral effectiveness is related to their stability in the high anti conformation. Recently the disposition of purine analogs that pass through the inosine monophosphate branch point has been investigated. The results of these studies are consistent with the concept that the conversion of IMP to XMP requires the high anti conformation and that the conversion of IMP to adenylosuccinate requires some other conformation, possibly the anti conformation.

Azoles↗
PubMed1977

Conformational basis for the activation of adenylate cyclase by adenosine.

The ability of adenosine to stimulate adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and increase adenosine 3':5'-cyclic monophosphate (cAMP) levels has important biochemical consequences. These include the suppression of immune responses and cardiovascular effects. Recent investigations involving the ability of adenosine and adenosine analogs to stimulate adenylate cyclase provided experimental data that appear to be correlated with the ability of adenosine and analogs of adenosine to exist in the glycosidic high anti conformation. 9-beta-D-Arabinofuranosyladenine, which is not stable in the high anti conformation, is inactive as a stimulator of adenylate cyclase. 2'-Deoxyadenosine is also not stable in the high anti conformation but its instability may be significantly decreased by intramolecular adjustments promoted by receptor or active site interactions. 2'-Deoxyadenosine does not activate adenylate cyclase in lymphocytes when ATP is the substrate but is able to activate adenylate cyclase when 2-fluoro ATP is the substrate. The inability of certain analogs of adenosine, with bulky groups substituted for hydrogen at the 8 position of the adenine base, to activate adenylate cyclase and increase either lymphocyte or cardiac cell cAMP levels is consistent with the designation of the high anti conformation as being the conformation required for the activation of adenylate cyclase. An understanding of the glycosidic conformation required by the extracellular adenosine receptor of the adenosine molecule provides the basis for designing nucleoside analogs of adenosine that will exert a desired effect on cAMP levels. The avoidance of unwanted immunosuppressive or cardiotoxic effects can be arranged by structural changes that prohibit the high anti conformation.

Adenosine↗
PubMed1977

Physicians, physicians' assistants, and the social characteristics of patients in southern Appalachia.

A focus on health care delivery systems and the emergence of New Health Practitioners, particularly Physicians' Assistants (PAs), represents one of the more significant nonbiomedical developments in American medicine since World War II. Much discussion about PAs revolves around the kinds of illnesses they are qualified to treat which then permits physicians to concentrate on patients with other types of illnesses. Ignored in this focus on illness characteristics is the possibility that physicians and PAs may treat patients with different social characteristics. That issue is the topic of this paper. Differences between the status characteristics of physician and PA patients are reported for a rural community where PAs and physicians work side by side in the same offices. The relationships observed in this rural community suggest that the higher a patient's socioeconomic status, the more likely (s)he is to be treated by the physician.

Age Factors↗
PubMed1977

Multiple prescriptions and drug appropriateness.

The relationship between number of prescriptions per office visit and the appropriateness of the prescribed drugs is examined, using data on more than 20,000 prescriptions purchased for a low-income rural population during 1973 and 1974. Criteria for drug appropriateness are based on an AMA evaluation of drugs. The results show that greater numbers of prescriptions per visit are associated with lower percentages of appropriate drugs prescribed and that patients whose prescriptions were written by specialists received a higher percentage of appropriate drugs than did those whose prescriptions were written by general practitioners. It is concluded, in support of other researchers, that a better knowledge of drugs leads to more conservative use of them.

Age Factors↗
PubMed1976

Rural areas pose special problems for providing social services.

For maximum effectiveness, the delivery of social services and mental health services in a rural area must accommodate certain constraints imposed by the structure of the community. Accommodation to the community can be achieved best when an established and accepted institution provides structure and legitimization for the social service and the mental health worker and when it serves as a vehicle through which services are initiated and expanded.

Alabama↗
PubMed1976

Theoretical studies of the conformational properties of ribavirin.

One of the factors required for the antiviral activity of the synthetic nucleoside, ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), is the ability of the molecule to adopt the substrate conformation specified by the enzyme for which it is a competitive inhibitor, inosine 5'-phosphate dehydrogenase (IMP:NAD+ oxidoreductase, EC 1.2.1.14). The calculated glycosidic minimum for ribavirin is the high syn conformation, which is in agreement with experimental determinations of the molecule's solution conformation. The similarity in solution between the conformation of the active ribavirin molecule and the conformation of its inactive 5-methyl and 5-chloro derivatives indicate that some other substrate conformation is specified by the enzyme. The high anti conformation, found by these calculations to be close in energy to the high syn minimum, is postulated to be the active conformation required by the enzyme. The inactivity of the 5-methyl and 5-chloro derivatives is attributed to the much greater stability of these derivatives in the inactive high syn conformation.

Binding Sites↗
PubMed1976

A study of physicians' assistants in a rural setting.

In an effort to improve the health care in a rural county in Southern Appalachia, physicians' assistants (MEDEX) have been employed in the offices of three general practitioners over a three-year period. This program was evaluated using a before-after and experimental-control (county) design, utilizing data both from physician office contracts and a continuing survey of the populations of the experimental and control counties. Results show the following: 1) utilization (average office visits per week) increased; 2) types of care (preventive versus curative) remained stable; 3) the hospitalization rate increased continuously during the three years for those physicians using physicians' assistants; and 4) the physicians' assistant functioned more as a physician substitute than as an assistant. It is concluded that although use of physicians' assistants may increase utilization rates, they may not reduce the long-range cost of medical care through providing more preventive or ambulatory (as opposed to hospital) care.

Acute Disease↗