Biomedical subjects

P Alden

Publications and source records attributed to P Alden.

5 recordsLinked to original sources

PubMed2002

Gradient separation of polymers at critical point of adsorption.

Theoretical and experimental analysis of interaction polymer chromatography revealed a new mode of polymer separation: gradient elution at the critical point of adsorption (the eluent composition where size-exclusion and adsorption interactions completely compensate each other). This mode allows for molecular-mass-independent separation by chemical composition and/or other structural differences between macromolecules. The isocratic and gradient elution of narrow polydispersity polystyrenes and poly(methylmethacrylates) on reversed- and normal-phase columns confirmed all basic theoretical assumptions and conclusions. The gradient separation of poly(alkylmethacrylate) and poly(alkylacrylate) blends, as well as styrene-butadiene copolymers provided further experimental verification of the theory.

Adsorption↗

PubMed1998

Hypnotic pain control: some theoretical and practical issues.

Pain management programs assist patients to use their behavioral and cognitive skills for the purpose of rendering their experience of pain as more tolerable in some way. Hypnotic procedures may be included in this perspective. Thus, hypnosis may be best conceived as a set of skills to be deployed by the individual rather than as a state. The authors contend that such an emphasis is more compatible with the approaches of some pain management practitioners who have been generally slow to acknowledge the value of hypnosis and to incorporate hypnosis in their range of treatment skills. In this article, the authors present a minimal and atheoretical definition of hypnosis, and they list the basic properties of hypnosis that may be used in the treatment of pain. For a number of reasons, it is suggested that undertaking hypnosis as though the individual were indeed being placed into a special trance state may in some cases promote an effective outcome. However, it should be acknowledged that there may be instances when the relevant skills may be more effectively engaged at the expense of a strict special trance state by targeting the specific skills that are to be used for therapeutic benefit.

Cognitive Behavioral Therapy↗

PubMed1993

Analysis of cationic nutrients from foods by ion chromatography.

This paper describes the feasibility of combining two relatively new technologies to generate data on the cationic nutrient content of foods. Single-column ion chromatography was used to monitor several analytes following the use of a microwave digestion scheme aimed at rapid, multiple sample digestion. The result is a more streamline and productive approach to multi-sample preparation and multi-analyte determination when investigating the cation content of foods. Linearity and limits of detection for the chromatographic procedure were established. Sample size as well as digestion acid type and amount were investigated during the microwave process. The method was applied to a variety of food matrices to evaluate its scope. Results generated with this method compare favorably to those from atomic absorption. Finally, capillary ion electrophoresis (Waters' trade name: Capillary Ion Analysis), a subset of capillary electrophoresis which has been optimized for ion analysis, was applied to the sample digests to investigate the usefulness of this technology to the analysis of mono-/divalent cations from foods.

Cations↗

PubMed1988

Aldose reductase inhibition in diabetic neuropathy: clinical and neurophysiological studies of one year's treatment with sorbinil.

In a double-blind placebo-controlled trial the effect of Sorbinil (250 mg daily) on diabetic neuropathy was examined. After a 2-month run-in placebo period (with three major assessments) 21 patients were randomized to Sorbinil and 10 to placebo, and all were studied for a further 12 months with neurophysiological measurements at 3-month intervals of nerve conduction velocity in multiple nerves, autonomic function tests, vibration thresholds as well as clinical examination and an extensive self-assessment of symptoms. Two subjects on Sorbinil treatment developed a hypersensitivity reaction and were withdrawn. Metabolic control and severity of neuropathy was not significantly different between groups. There were no changes in symptoms as judged by self-assessment scores. No patient entered the trial with neuropathic ulcers but ulceration developed in 4 patients during Sorbinil treatment and in 1 of the placebo group. No beneficial effect of Sorbinil was demonstrated on either the clinical manifestation or on the neurophysiological measurements made in these neuropathic diabetic patients over 12 months of treatment.

Aldehyde Reductase↗

PubMed1985

Alterations in amino acid clearance during ischemia predict hepatocellular ATP changes.

Although decreases in hepatic adenosine triphosphate (ATP) levels during ischemia are thought to reflect loss of hepatic energy reserves and decreased viability, such changes have not been correlated with a clinically relevant index of hepatic function or viability. Ability to clear amino acids from plasma has been shown to correlate with function of the allograft in hepatic transplantation and survival after portal decompression in patients with hepatic cirrhosis. The effects of 60 minutes of warm ischemia in two groups of mongrel dogs were studied to assess the relationship between loss of ATP and amino acid clearance. One group (shunted) had portal decompression during the ischemic period and the other (portal stasis) did not. There was a significant correlation between loss of ATP and amino acid clearance after ischemia. Although the effects of ischemia on the liver were similar in both groups, the portal stasis group demonstrated significantly elevated SGOT levels during reperfusion that were related to impaired net adenine monophosphate synthesis and suggestive of ongoing injury. These data support the contention that loss of ATP during ischemia is associated with reduced functional capacity. In addition, they suggest that portal stasis produces toxic products that can impede hepatic recovery from ischemia.

Adenosine Triphosphate↗