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Biomedical subjects

R A Nicholson

Publications and source records attributed to R A Nicholson.

At least 55 records · Page 3Linked to original sources
PubMed1992

Laser onychology.

Laser techniques for nail pathology have existed for over a decade. Published reports concerning onychologic techniques and results are growing along with other medical laser literature. In this article, the author has presented techniques with which he and podiatric colleagues at Wenske Laser Center have operational familiarity. Preoperative concerns have been emphasized and potential complications and prevention are discussed. Widely variant results are identified. Laser onychologic procedures are technique intensive. Research is needed, therefore, to identify factors that might lead to technical improvements so that results may be enhanced. Perhaps in the future laser onychology shall exist as a subspecialty to podiatry and dermatology, much as endodontics is to dentistry. It is hoped that this work might contribute in some small way to that development.

Foot Diseases↗
PubMed1991

Characteristics and outcomes of insanity acquittees in Oklahoma.

The insanity defense is perhaps the most vigorously debated topic at the interface of the legal and mental health systems. This article addresses the need for empirical evidence by providing data on insanity acquittees and their later outcomes in Oklahoma, a jurisdiction not previously studied. Information was obtained on the demographic, legal, psychiatric, hospitalization, and post-hospitalization characteristics of all 61 defendants acquitted not guilty by reason of insanity (NGRI) and treated on the state forensic unit during a 5-year period. Insanity acquittees had few resources, significant psychopathology, and extensive involvement with the legal and mental health systems prior to the NGRI offense. Follow-up of three groups of discharged patients--those released at an initial court review, those who completed the NGRI treatment program, and those who absconded from the forensic unit--revealed that those who escaped from the unit had significantly more arrests and subsequent legal charges than regularly discharged patients.

Adolescent↗
PubMed1991

The dopamine and 5-hydroxytryptamine content of locust and cockroach salivary neurones.

The salivary glands of the cockroach and locust are innervated primarily from two pairs of motoneurones, designated SN1 and SN2, in the suboesophageal ganglion. Intracellular cobalt fills and subsequent silver intensification were used to reveal the morphology of these cells in both species. Fluorescent microscopy, following treatment of the ganglion with glyoxylic acid, showed that in both species only the SN1 neurones contained catecholamines. A radioenzymatic assay for dopamine, performed on the locust SN1 neurones, confirmed that this catecholamine was present. A radioenzymatic assay for 5-hydroxytryptamine (5-HT), performed on both pairs of salivary neurones in the locust, revealed small quantities of this amine in the SN2 neurones, but no significant amount in the SN1 neurones. In the cockroach, 5-HT was assayed in the SN2 neurones only. In contrast to the locust, however, the 5-HT content of these cells was not significantly above that of control cells taken from other ganglia. These observations demonstrate that only the SN1 neurones are the source of the catecholaminergic fibres investing the locust and cockroach salivary glands. The difference in neurotransmitter content between the SN1 and SN2 neurones suggests that these neurones have separate functions in the control of salivary secretion.

Animals↗
PubMed1991

Absorption, degradation and excretion of benzo(a)pyrene in the cricket (Acheta domesticus).

1. The absorption, degradation and excretion of 3H-benzo(a)pyrene (3H-BP) was examined in the cricket (Acheta domesticus). 2. After 3H-BP injection, extractable 3H-BP declined in the internal compartment over a 48 period. 3. When 3H-BP was deposited on the surface of the insect it penetrated through the cuticle, as evidenced by decrease in 3H-BP recovered in surface rinses and accumulation of 3H-BP internally. 4. Administration of 3H-BP by topical application or injection resulted in a progressive association of radioactivity with tissue debris and low-level metabolism to highly polar compounds. Both parent compound and highly polar metabolites were detected in excreta. 5. Treatment of insects with piperonyl butoxide decreased accumulation of polar products in excreta after injection of 3H-BP.

Absorption↗
PubMed1990

The effect of in vivo stimulation on the cytology of neuromuscular junctions of locust flight muscles.

The ultrastructure of neuromuscular junctions in dorsoventral (tergosternal) flight muscle no. 113 and dorsolongitudinal flight muscle no. 112 of the locust Schistocerca gregaria is described. Following in vivo stimulation by enforced flight, morphological and statistical analyses reveal cytological changes at these junctions suggestive of vesicular release of neurotransmitter and membrane recycling. Flight periods from 30 min to 3 h produced a progressive decrease in the density of terminal synaptic vesicles, an increase in terminal surface area and circumference, increases in the occurrence of membranous cisternae, increases in mitochondrial numbers, and increases in the frequency of coated pits.

Animals↗
PubMed1990

Effects of colchicine on central and peripheral nerve terminals of the locust Schistocerca gregaria.

The treatment of locusts (Schistocerca gregaria) with colchicine leads to various changes in the ultrastructure of both central and peripheral nerve terminals. These changes include a marked reduction in synaptic vesicle density, which is further enhanced following stimulation. There are also increased numbers of coated pits and membraneous cisternae together with enlarged terminal areas and disruption of mitochondrial ultrastructure. The capacity of isolated central nerve terminals (synaptosomes) to take up the radiolabelled transmitter precursor [3H]-choline is enhanced following in vivo treatment of locusts with colchicine, whilst in vitro treatment leads to a reduction in choline uptake. The results are discussed with regard to the postulated effects of colchicine on axoplasmic transport.

Animals↗
PubMed1988

Effect of taurine on neurotransmitter release from insect synaptosomes.

The effect of taurine on the release of [3H]acetylcholine ([3H]ACH) and [3H]gamma-aminobutyric acid ([3H]GABA) from preloaded locust synaptosomes has been studied. Veratridine (100 microM) and K+ (100 mM) both evoked [3H]ACh release and this was reduced in a concentration-dependent manner by taurine (5, 10, and 20 mM). In contrast to this, veratridine induced no observable release of [3H]GABA, and the response to K+ was slight. In the presence of taurine, however, a concentration-dependent enhancement of [3H]GABA release was observed. Since nipecotic acid (1 mM), an inhibitor of neuronal GABA uptake, also revealed [3H]GABA release induced by veratridine, it is suggested that both this effect and that of taurine are due to prevention of GABA reuptake. These results suggest that taurine may act as a neuromodulator in insects.

Acetylcholine↗
PubMed1988

Effect of taurine on calcium accumulation in resting and depolarised insect synaptosomes.

The effect of taurine (2-aminoethanesulphonic acid) on 45Ca2+ accumulation in resting and depolarised synaptosomes obtained from the locust Schistocerca americana gregaria was studied. Taurine reduced 45Ca2+ accumulation in resting synaptosomes, and this effect was more pronounced when synaptosomes were depolarised with either high [K+] or veratridine. Veratridine-induced 45Ca2+ accumulation was not affected by either gamma-aminobutyric acid or leucine, but was reduced by both verapamil and tetrodotoxin.

Animals↗
PubMed1988

Characteristics associated with change in the legal status of involuntary psychiatric patients.

Patients initially admitted to a state hospital under an emergency commitment procedure were studied to identify the variables associated with their later change to voluntary status, release, or judicial commitment, and to compare the hospitalization and outcome patterns of voluntary and committed patients. Compared with committed or voluntary patients, released patients were younger and better educated; were more likely to be employed at admission, to contribute to family income, and to have had previous outpatient treatment; and were less likely to have serious organic or psychotic disorders or to receive government assistance. Voluntary patients were hospitalized twice as long as committed patients and were less frequently considered to have received maximum benefits from hospitalization. In view of the association between voluntary status and longer hospitalization, periodic review may be needed to safeguard these patients from unnecessary confinement.

Adult↗
PubMed1988

Validation of a brief form of the Competency Screening Test.

This study investigated the predictive validity of a brief, five item version of the Competency Screening Test (CST). Subjects were 140 defendants admitted to the forensic unit of a state hospital for evaluation of competency to stand trial. Scores on the brief version of the CST were used to predict competency decisions made by a multidisciplinary treatment team. In addition, the predictive validity of the brief version was compared with that of the standard CST. Both versions of the test exhibited significant relationships with staff decisions. However, the reliability of the brief version was lower than that of the standard CST because of the smaller number of items involved. Although the brief CST should not provide the sole basis for a decision about competency, it may be a useful component of a comprehensive program of competency evaluation, particularly when a rapid, preliminary screening instrument is needed.

Adult↗
PubMed1987

Theoretical and empirical issues in the treatment of post-traumatic stress disorder in Vietnam veterans.

This article reviews the current status of research on the treatment of combat-related post-traumatic stress disorder (PTSD) in Vietnam veterans. Dynamic, behavioral, and biochemical models of treatment are presented, along with the findings of relevant treatment outcome studies. Examination of the treatment procedures employed in available studies revealed that direct therapeutic exposure to the memories of trauma emerged as the PTSD treatment technique common to all three theoretical models. The need for controlled investigations of the clinical efficacy of exposure-based interventions for combat-related PTSD is discussed. In addition, several other issues relevant to PTSD treatment research are presented and discussed, including the potential utility of studying untrained coping behavior in combat veterans; the effects of using heterogeneous subject samples in PTSD treatment research; and issues related to the measurement of treatment outcome.

Behavior Therapy↗
PubMed1979

The metabolism of cholecalciferol in the liver of Japanese quail (Coturnix coturnix japonica) with particular reference to the effects of oestrogen.

1. Studies were carried out in vitro with the livers of Japanese quail that had been fed from hatching on diets supplying their full requirements for vitamin D. 2. 25-Hydroxycholecalciferol was the major metabolite when liver homogenates of egg-laying female and oestrogen-treated quail of both sexes were incubated with [3H]cholecalciferol. 3. Very little 25-hydroxycholecalciferol was generated from liver homogenates of adult male and immature quail. Instead the cholecalciferol was converted into one or more compounds less polar than 25-hydroxycholecalciferol and into a number of highly polar metabolites, some of which were water-soluble. 4. Oestrogen not only stimulated the 25-hydroxylation of cholecalciferol but also protected both cholecalciferol and 25-hydroxycholecalciferol from degradation by the enzymic pathways active in immature and male birds. 5. These actions of oestrogen may be of physiological significance in relation to the high requirements of laying birds for 1,25-dihydroxycholecalciferol to support the intense metabolism of calcium associated with egg-shell calcification.

Aging↗