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Biomedical subjects

D L Blank

Publications and source records attributed to D L Blank.

10 recordsLinked to original sources
PubMed1995

Decontamination procedures for drugs of abuse in hair: are they sufficient?

This paper reviews the methods for decontaminating hair exposed to external solutions of drugs of abuse. Exposure of hair to cocaine at 1 microgram/ml for 5 min is sufficient to contaminate hair, yet decontamination is a very slow process. Using externally contaminated hair, a number of decontamination procedures were attempted, and none removed all the contamination. The percentage of external contamination removed depended on the hair type, with thick black hair being the most resistant to decontamination. Hair treated by dying incorporated externally applied drugs differently, depending on the hair type. Thick black hair became more absorbent whereas thin brown hair became less absorbent. Kinetic wash criteria are evaluated for their ability/inability to determine if hair has been contaminated from external sources. A theoretical framework for the incorporation and removal of drugs from hair is discussed, and the hypothesis that inaccessible domains exist in hair which trap drugs is critically examined. The results presented in this paper strongly suggest that much more information on the decontamination of hair and the differentiation of exogenously and endogenously incorporated drugs is needed before hair analysis can be employed in most forensic applications. We propose that the radioactive tracer methods discussed herein are well suited for evaluating any new decontamination or extraction technique.

Decontamination↗
PubMed1993

External contamination of hair by cocaine: an issue in forensic interpretation.

This paper explores the variables by which hair samples may become contaminated with cocaine and thereby generate false positives during analysis of hair samples. A novel method for following the incorporation and removal of cocaine from hair was developed. This method allowed a large number of specimens to be analysed under a variety of conditions with high precision. The quantity of cocaine was carefully followed in each step of a published procedure. Regardless of washing technique, a substantial amount of cocaine could still be found in the final hair digest. Very few of our externally contaminated samples could be identified as externally contaminated by previously published criteria and washing procedures. Attempts to further decontaminate this hair were without success. Our data strongly suggest that external contamination of hair by drugs of abuse may make the interpretation of forensic results problematical.

Cocaine↗
PubMed1982

Changes in morphology and physiology of olfactory receptor cilia during development.

Ciliated olfactory receptor neurons in vertebrates turn over throughout life. We show that these neurons bear different types of cilia at different developmental stages; cilia on newly differentiating cells are short and motile; cilia on mature cells are longer and immotile; Mg2+ and adenosine 5'-triphosphate are requisite for ciliary motion; stimulation with odorants can induce synchronous motion and that this process is mediated by Ca2+. We propose that receptor neurons have two distinguishable developmental states. In the first, before the growing axon establishes synaptic connection to the brain, the cells bear motile cilia and are generally irritable. In the second, the cilia are long and immotile and the cells can distinguish between odorants.

Animals↗
PubMed1981

Olfactory receptor response characteristics: a reevaluation.

The activity of single olfactory receptor cells previously reported was reexamined using Guttman-Lingoes multidimensional scaling, cluster analysis and factor analysis. These analyses were compared and contrasted with similar analyses using another olfactory unit data set and a color vision receptor data set. Questions were raised regarding the interpretation of the results of these analyses for any of the data sets employed.

Animals↗
PubMed1976

Effect of combined reserpine and ECS on electroshock seizure thresholds in mice.

Recent evidence has suggested that electroshock seizure threshold is correlated with levels of brain biogenic amines. Reserpine, a drug that depletes serotonin and norepinephrine, has been shown to decrease seizure thresholds. ECS treatment has been shown to increase amine levels as well as seizure thresholds. Combined reserpine and ECS have been shown to produce an intermediate level of serotonin and norepinephrine, but seizure threshold data for this group is absent. It was the purpose of this study to examine the seizure thresholds for combined treatment and compare them with groups treated with reserpine alone, ECS alone, and a placebo control group. The results suggest that, if only maximal seizures are considered, the seizure threshold is lowest for the reserpine and highest for the ECS alone or control groups, with the combined treatment group falling intermediate. If both minimal and maximal seizures are considered, the reserpine and combined treatment groups do not differ from one another, but do show a lower threshold as compared to ECS or control groups.

Animals↗
PubMed1976

Electromechanical stimulator for presenting moving cutaneous stimuli.

Recent interest in the neural processing of complex cutaneous stimuli such as moving stimuli has necessitated more versatile stimulating devices. This article describes the construction and application of a relatively inexpensive instrument, utilizing equipment readily available in most neurophysiological laboratories, which provides a variety of moving cutaneous stimuli of selected velocities, excursions, and directions. The electronic portion of the instrument consists of a logically controlled varable rate integrator wired to conform to the electrical and mechanical characteristics of a Grass P5 plug-in. This circuitry operates the remainder of the instrument which consists of a P5 driver amplifier used to drive the pen motor mechanism that provides the moving cutaneous stimulus.

Electric Stimulation↗
PubMedDate not supplied

Olfactory receptor response characteristics: a factor analysis.

The responses to odor stimulation of 22 single olfactory units in the frog olfactory mucosa were recorded with metal filled micropipettes. Seven purified odorants matched in concentration and a pure air stimulus were administered. The change in firing frequency for each unit to each chemical was evaluated to determine: (1) whether the response patterns developed across all units are different from chemical to chemical and, (2) whether individual units can be grouped in terms of their similarity of their responses to all odorants. The results of a Bartlett Sphericity test suggest that each odorant produces an independent pattern of responses across units. To answer the second question, a factor analysis was employed. It examined the responses of each unit to all chemicals and yielded 7 out of a possible 22 independent factors, suggesting that there are 7 ways by which the units studied look at the odorant stimuli and an air control employed in this study. These analyses were evaluated and discussed in terms of previously published data suggesting receptor site specificity.

Animals↗