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Biomedical subjects

R A Nicholson

Publications and source records attributed to R A Nicholson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Detecting feigned depression and schizophrenia on the MMPI-2.

Increasingly, investigations evaluating the effectiveness of the MMPI-2 in the assessment of malingering employ methodologies whereby research participants are asked to feigned specific disorders rather than just to "fake bad." Yet there is little research addressing the issue of whether different validity scales and indicators work differently in the detection of different feigned disorders. In this study the comparative effectiveness of a number of validity scales and indicators on the MMPI-2 to assess feigned depression and feigned schizophrenia were evaluated. Overall, the validity scales and indicators were better at detecting feigned schizophrenia than they were in detecting feigned depression, attributable, most likely, to closer familiarity with depressive experiences. The validity scales F, Fb, and F(p) best distinguish patients with schizophrenia from participants feigning schizophrenia, and F and Fb best distinguish patients with depression from participants feigning depression.

Adult↗
PubMed1997

Training phantom for ultrasound guided biopsy.

Commercial phantoms designed for radiologists to practise the skills needed to biopsy lesions under ultrasound guidance can be prohibitively costly, and do not have an indefinite shelf-life. A gelatin-based in-house model has been developed to recreate the conditions found in human tissues, using materials which are cheap and in everyday use. This phantom remains useful for several weeks, although tears produced by the biopsy needle take progressively longer to bond when the reconstructed gelatin is older than a month. However, new phantoms can be built quickly and easily using fresh gelatin while recycling other components.

Biopsy, Needle↗
PubMed1995

Metallothionein expression in human breast cancer.

Metallothioneins are ubiquitous low molecular weight proteins characterised by high cysteine content and affinity for binding heavy metals. Abnormal metallothionein function and expression have been implicated in various disease states, including neoplasia. The aim of this study was to investigate metallothionein expression in human breast carcinoma. Sections of routinely fixed and processed blocks of tumour from 100 consecutive cases of primary operable breast carcinoma were stained for metallothionein using a recently developed monoclonal antibody and a standard immunohistochemical technique. Expression was scored on the basis of microscopical assessment of percentage of tumour cells staining. One patient was lost to follow-up and excluded from the study. A significant association (P < 0.0001) was observed between metallothionein expression and tumour type, with low levels being observed in tumours of good prognostic type. There was also a significant association with local recurrence (P < 0.02) and a significant difference (P < 0.02) in both survival and disease-free interval between tumours showing low and high levels of expression, the latter indicating a poor prognosis. No relationship was observed with patient age, tumour size, lymph node stage, histological grade, vascular invasion, menopausal status or oestrogen receptor status. The assessment of metallothionein expression in human breast cancer appears to provide prognostic information and may have important implications for understanding its development.

Breast Neoplasms↗
PubMed1995

Interrater reliability of ratings of delusions and bizarre delusions.

OBJECTIVE: The authors evaluated the interrater reliability of ratings of bizarre delusions, addressing limitations of previous studies. METHOD: Fifty randomly selected psychiatrists rated bizarre delusions in 30 case vignettes adapted from a previous study by Spitzer and associates. Estimates of reliability were obtained for definitions of bizarre delusions in the DSM-III, DSM-III-R, and draft DSM-IV criteria for schizophrenia and for the clinicians grouped according to their current and previous experience with psychotic patients. RESULTS: The kappas for ratings of bizarre delusions according to the different definitions and among clinicians with different levels of experience were in the moderate to fair range. CONCLUSIONS: The reliability of ratings of bizarre delusions appears to be less than satisfactory for clinical practice, and the increased weight given to this symptom in modern diagnostic systems does not seem justifiable.

Delusions↗
PubMed1995

Radiation dose reduction in paediatric fluoroscopy using added filtration.

Studies on a water phantom indicate that the insertion of extra tube filtration combined with the removal of the antiscatter grid can reduce the total energy imparted from paediatric fluoroscopy by a factor of more than four when automatic exposure control is used. The omission of the grid is responsible for up to 40% of the reduction while the addition of 0.7 mm steel filtration is found to account for a further reduction in energy imparted of between 57% and 70%, for depths of water simulating small patients of 6-16 cm thickness. For all contrast paediatric examinations the reduction in image quality was considered to be small and the diagnostic information unimpaired with the filter in place.

Child↗
PubMed1995

Technical note: the relationship between TV position and the effectiveness and comfort of protective spectacles in fluoroscopic procedures.

Although interventional radiological procedures can result in significant eye doses to an operator, protective measures are often rejected because screens are found to impede manipulations, and 0.5 mm lead equivalent spectacles are heavy and uncomfortable. With many units the TV monitors are positioned so that the operator needs to turn his head through 80 degrees or more to view the image while screening. The aim of this study was to determine the distribution of the shielding in protective spectacles which will combine maximum dose reduction for different TV positions with minimum weight. Thermoluminescent dosimeters were used to assess the effectiveness of various spectacles in shielding the lens of the eye when a skull phantom was orientated at different angles in a large area beam of X-rays generated at a tube potential typical of diagnostic energies. The beam was tilted upwards at an angle of 20 degrees as though originating from the irradiated volume of a patient. The results showed that if weight was a consideration, and the head was turned away from the image intensifier through an angle greater than 80 degrees, the shielding was most effective when concentrated in the side-panels of the spectacles. The shape of the side-panels, however, was critical to the adequate shielding of this radiation.

Eye↗
PubMed1994

Excitatory actions of dehydroabietic acid on mammalian synaptosomes.

The presynaptic effects of dehydroabietic acid were investigated using mouse brain synaptosomes as the in vitro model. At concentrations ranging from 10 to 100 microM, dehydroabietic acid depolarises the synaptosomal membrane and causes pronounced release of the neurotransmitters gamma-aminobutyric acid, acetylcholine and L-glutamate. The effects on membrane potential and transmitter release occur predominantly at concentrations below which any lytic actions of this compound can be detected. Dehydroabietic acid-induced depolarisation and release of neurotransmitters are not influenced by tetrodotoxin and are associated with only marginal inhibition of membrane-associated ATPase activity. When synaptosomes are challenged with dehydroabietic acid in calcium-free saline, a partial reduction in the stimulated release of transmitters is observed. These results provide clear evidence that dehydroabietic acid is neuroactive and capable of causing substantial increases in the release of both excitatory and inhibitory neurotransmitter substances. The mechanism which underlies the neuroexcitatory effects of dehydroabietic acid remains to be resolved however it is proposed that release of transmitters from central nerve endings may be a contributory factor in the toxicity of resin acids.

Abietanes↗
PubMed1994

Predicting treatment outcome for incompetent defendants.

This study examined the prediction of outcome in a sample of defendants hospitalized for treatment of incompetency. Defendants' demographic characteristics and scores on 18 scales of the Computer-Assisted Determination of Competency to Proceed instrument (CADCOMP) were used to predict competency restoration and length of stay (LOS). During the period of study, almost 90 percent of the defendants were restored to competency after a mean stay of over 280 days. Demographic characteristics were unrelated to outcome. Several CADCOMP scales, including two scales measuring psycholegal ability and one measuring psychopathology, were correlated with both outcome criteria. Discriminant analysis using the CADCOMP scales accurately classified 76.7 percent of the defendants into short and long stay groups. Although promising, the findings are nevertheless consistent with prior research in suggesting that examiners should exercise caution in providing feedback to the courts concerning competency restoration and the period of time needed for treatment.

Adolescent↗
PubMed1994

RH-3421, a potent dihydropyrazole insecticide, inhibits depolarization-stimulated rises in free [Ca2+] and 45Ca2+ uptake in mammalian synaptosomes.

The dihydropyrazole RH-3421 inhibits veratridine- and K(+)-induced rises in synaptosomal free Ca2+ with IC50s of 0.2 and 1 microM, respectively. The K(+)-induced rise in free synaptosomal Ca2+, which requires external Ca2+, is also blocked by RH-3421 in the presence of tetrodotoxin. The K(+)-stimulated 45Ca2+ uptake by synaptosomes is unaffected by tetrodotoxin, blocked by cobalt ions and inhibited by RH-3421 both alone (IC50 = 11 microM) and in the presence of tetrodotoxin. RH-3421 does not influence the level of free Ca2+ or basal 45Ca2+ uptake in non-depolarized synaptosomes. The results suggest RH-3421 inhibits voltage-sensitive calcium channels in nerve endings.

Animals↗
PubMed1993

Sub-chronic administration of ethanol to mice does not modify the inhibitory effects of dieldrin, abamectin and the dihydropyrazole RH-3421 at their respective sites of action in the nervous system.

1. The potential influence of sub-chronic ethanol treatment on the ability of three chemical classes of insecticide to interact with their neuronal sites of action has been investigated in mouse brain. 2. Ethanol administration did not influence the inhibitory effects of either the cyclodiene dieldrin or the avermectin abamectin as determined by inhibition of GABA-stimulated chloride uptake. 3. Likewise there was also no discernable change in the sensitivity of sodium channels to inhibition by dihydropyrazole RH-3421 with sub-chronic ethanol treatment as assessed indirectly using a membrane potential assay. 4. The results of this study indicate that short term dietary exposure to ethanol fails to cause functional changes to the primary target sites of cyclodienes, avermectins and dihydropyrazoles in the mammalian central nervous system.

Animals↗
PubMed1992

Outcome of hospitalization for defendants found incompetent to stand trial.

This study assessed the outcome of hospitalization for incompetent criminal defendants admitted to the forensic unit of a state hospital for treatment during a 4-year period. Findings suggested that the overwhelming majority of the defendants were restored to competency. The defendants also showed significant improvement in overall severity of psychopathology during hospitalization. Further, the duration of hospitalization for these defendants was relatively short. Although these results are promising with regard to treatment of incompetent defendants, predicting the outcome of hospitalization for these defendants was problematic. Prediction of competency restoration was precluded because persistent incompetence was so infrequent. Moreover, multiple regression analyses suggested limited predictive ability with regard to defendants' discharge level of functioning or length of hospitalization. These findings are consistent with the view that examiners should exercise caution in making recommendations to the courts concerning treatability of incompetent defendants.

Adult↗
PubMed1992

Itemmetric and scale analysis of a new computer-assisted competency assessment instrument (CADCOMP).

Male defendants (n = 99) who had been court ordered to a forensic treatment facility as incompetent to stand trial were tested using the Computer-Assisted Determination of Competency to Proceed (CADCOMP) instrument soon after admission (median days = 15). Shortly thereafter, competency was assessed by a forensic psychiatrist and by a majority decision of three mental health professionals who viewed a videotape of the forensic psychiatrist's interview. From the CADCOMP item pool, 18 scales were constructed on conceptual grounds. Internal consistency analyses revealed that most scales had reasonable item homogeneity and scale reliability. In addition, item and scale analyses, with few exceptions, followed predicted patterns of intercorrelation and association with competency as determined by both criteria. Scales and items measuring serious psychopathology, psycholegal ability, and criminal history demonstrated the strongest associations with competency. These findings suggest that additional research on CADCOMP is warranted. The instrument shows promise for use in forensic research and assessment.

Adult↗
PubMed1992

p53 protein expression in human breast carcinoma: relationship to expression of epidermal growth factor receptor, c-erbB-2 protein overexpression, and oestrogen receptor.

The expression of p53 protein, oestrogen receptor protein, epidermal growth factor receptor (EGFR) and overexpression of the c-erbB-2 oncoprotein was examined in a series of 149 primary symptomatic breast carcinomas. Expression of p53 was present in 62 of 146 cases (42.5%) of the invasive carcinoma and one of three cases (33.3%) of ductal carcinoma in situ (DCIS) examined. Statistical associations of tumour oestrogen receptor positivity and lack of p53 protein expression, chi 2 = 19.78 (d.f. = 1), P less than 0.001, positive tumour p53 status and poor tumour grade; chi 2 = 14.1 (d.f. = 2), P less than 0.001, EGFR expression chi 2 = 7.07, (d.f. = 1), P less than 0.01 and tumour c-erbB-2 protein overexpression; chi 2 = 4.61 (d.f. = 1), P = 0.032 were identified. Expression of p53 is rare in invasive lobular carcinoma of classical type (8.3% of cases examined) in contrast to other common types of mammary carcinoma. Non-significant trends of p53 protein expression and increased regional tumour recurrence; chi 2 = 3.20 (d.f. = 1), P = 0.074 and also poorer patient survival; chi 2 = 3.76 (d.f. = 1), P = 0.053 were identified. p53 protein expression is a common event in human breast cancer and is present in both DCIS and invasive mammary carcinoma. Abnormal expression of p53 protein is a feature of both in situ and invasive breast carcinoma, implying that the abnormal p53 protein expression may be implicated in the early stages of mammary carcinoma progression.

Biomarkers, Tumor↗