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Biomedical subjects

L M Allen

Publications and source records attributed to L M Allen.

At least 19 recordsLinked to original sources
PubMed2001

Effort has a greater effect on test scores than severe brain injury in compensation claimants.

Nine-hundred and four consecutive patients, including 80 neurological patients and 470 with head injuries, were given neuropsychological tests. All 43 test scores were converted to normative Z-scores and averaged, giving an Overall Test Battery Mean (OTBM). A variable measuring effort correlated 0.73 with the OTBM. The OTBM mean score was 1.20 SD lower in those who failed the Word Memory Test (WMT) than in those who passed the WMT. Sub-optimal effort suppressed the OTBM 4.5 times more than did moderate-severe brain injury. When only those making a good effort were included, patients with severe brain injuries and neurological diseases scored significantly lower than groups presumed to have no neurological impairment, but these group differences were not seen when all cases were analysed together. These data illustrate the importance of measuring and controlling for sub-optimal effort in individual neuropsychological evaluations, as well as in empirical research with similar groups of patients.

Adult↗
PubMed2001

Effort testing in patients with fibromyalgia and disability incentives.

OBJECTIVE: To examine whether symptom exaggeration is a factor in complaints of cognitive dysfunction using 2 new validated instruments in patients with fibromyalgia (FM). METHODS: Ninety-six patients with FM and 16 patients with rheumatoid arthritis (RA) were administered 2 effort or symptom validity tests designed to detect exaggerated memory complaints as part of a battery of psychological tests and self-report questionnaires. RESULTS: A large percentage of patients with FM who were on or seeking disability benefits failed the effort tests. Only 2 patients with FM who were working and/or not claiming disability benefits and no patient with RA scored below the cutoffs for exaggeration of memory difficulties. CONCLUSION: This study illustrates the importance of assessing for exaggeration of cognitive symptoms and biased responding in patients with FM presenting for disability related evaluations.

Adult↗
PubMed2000

Prenatal ultrasound evaluation of fetal diastematomyelia: two cases of type I split cord malformation.

Isolated diastematomyelia is a rare form of spinal dysraphism characterized by a sagittal cleft in the spinal cord, conus medullaris and/or filum terminale with splaying of the posterior vertebral elements. This condition is the result of the presence of an osseous or fibrocartilaginous septum producing a complete or incomplete sagittal division of the spinal cord into two hemicords. It may be isolated or associated with other segmental anomalies of the vertebral bodies. Prenatal diagnosis of this anomaly is possible in the early midtrimester by sonography, thus allowing for early surgical intervention and a favorable prognosis. Two cases of fetal diastematomyelia diagnosed by prenatal sonography are presented, each demonstrating the typical sonographic features diagnostic of this condition. The first case, detected at 28 weeks' gestation, presented with disorganization of the bony processes of the vertebral column with a midline echogenic focus. The second fetus, diagnosed at 17 weeks' gestation, had a similar appearance with widening of the posterior elements and the presence of a midline echogenic bony spur. Postnatally, both infants underwent magnetic resonance imaging for a definitive diagnosis. Surgical repair of the defect was performed in the neonatal period in both cases.

Adult↗
PubMed1998

Gender differences in factor structure of the Self-Administered Alcoholism Screening Test.

Recent studies have revealed differences between men and women alcoholics in symptoms, consequences, and help-seeking behavior related to alcohol usage. Based on these findings, it was hypothesized that gender differences also would appear on alcohol screening instruments. The Self-Administered Alcoholism Screening Test (Colligan, Davis, & Morse, 1988: SAAST: Swenson & Morse, 1975) of 1,920 men and 1,775 women was subjected to a within-gender, principle-components, factor analysis with a varimax rotation. Gender differences at the component level were revealed. Men endorsed the "help-seeking for alcohol-related problems" component while women endorsed the "help-seeking for emotional problems" component. In addition, men expressed concern about receiving a psychiatric label while women expressed concern about receiving a drinker label. The results suggest that different items need to be used in screening women for alcohol-related problems.

Adult↗
PubMed1994

Trends in the prevalence of congenital heart disease: comprehensive observations over a 24-year period in a defined region of Canada.

OBJECTIVE: To determine the prevalence of congenital heart disease (CHD) in the three Maritime provinces, and to study prevalence differences among provinces and defined regions within these provinces. DESIGN: Each province was divided by counties into regions. All cases of CHD who were born alive in the study area between 1966 and 1989 were entered in a registry. Prevalences were analyzed for each province and for selected regions per year, per 1000 live births, and by diagnosis made by one year of age and by the 16th birthday. Comparison was then made with prevalences of a group who had severe lesions. INTERVENTIONS: Excepting a small number of CHD cases who were diagnosed by autopsy only, diagnosis was made by pediatric cardiologists using appropriate procedures, including cardiac ultrasound and cardiac catheterization. SETTING: The only tertiary care centre for children's heart disease in the provinces of Nova Scotia, New Brunswick and Prince Edward Island, areas of relative geographic isolation (combined population of 1.75 million people). MAIN RESULTS: A statistically significant positive linear trend occurred in these provinces during the study. The recorded prevalence of CHD in New Brunswick was significantly lower. Pooled prevalences by the first and 16th birthdays (8.0 and 12.5 per 1000 live births, respectively) of two regions of highest prevalence for 1980-86 were significantly higher (P < 0.05) than the pooled prevalence rate of all the remaining regions. Prevalence rates of a group with severe lesions were stable for 1976-86 in all regions. CONCLUSIONS: Differences in prevalence of CHD among provinces and regions were related to ascertainment levels. Prevalence of CHD with diagnosis by the first and 16th birthdays were approximately 8.0 and 12.5 per 1000 live births, respectively. The prevalence rate of a severe lesion group was a stable measure.

Adolescent↗
PubMed1989

Flow cytometric enumeration of colonies for in vitro chemotherapeutic drug evaluation.

The percentage of 50-100 micron colonies formed by LX-T cells in medium containing agarose was determined microscopically, and this value was compared with the percentage determined by a flow cytometric method based on the forward and 90 degree light scatter of the colonies. As assessed by both in vitro methods, LX-T cells exposed to chemotherapeutic agents formed fewer colonies as the drug concentration increased. However, flow cytometric analysis indicated that a change in the number of colonies formed was a consequence of changing chemotherapeutic drug concentration, whereas microscopic colony counting did not always detect the corresponding change in colony number. These experiments demonstrate that measurement of a drug's chemotherapeutic potential by flow cytometric counting of colonies is an alternative to the enumeration of colonies microscopically.

Animals↗
PubMed1984

Slow infusion of vinca alkaloids in the treatment of idiopathic thrombocytopenic purpura.

Vinca alkaloids are useful in the treatment of idiopathic thrombocytopenic purpura, a disorder in which macrophages remove platelets sensitized with antibody. Because vinca alkaloids avidly bind to platelets, drugs can be delivered selectively to macrophages. However, drugs given by bolus injection are cleared too rapidly to bind optimally to autologous platelets, and the use of allogeneic platelets loaded with drug in vitro is cumbersome, expensive, and dangerous. Therefore, slow infusions were devised to prolong the duration of enhanced plasma drug concentrations, thereby providing better conditions for in-vivo drug loading into autologous platelets. Twenty-four patients with refractory idiopathic thrombocytopenic purpura were given slow infusions; 17 had good to excellent responses. Eleven of eighteen patients who had been treated with bolus injections had better results when treated with slow infusions. Patients with improved responses had slower plasma clearance rates than did patients with poor responses. Slow infusion therapy had fewer side effects than bolus injection therapy. Slow infusions are the best method for long-term management.

Adolescent↗
PubMed1984

A double-blind study of prazosin in the treatment of Raynaud's phenomenon in scleroderma.

Nineteen patients with Raynaud's phenomenon in conjunction with progressive systemic sclerosis were given either prazosin hydrochloride (1 mg orally three times a day) or a placebo for eight weeks, after which the treatment procedure was reversed for four weeks. Prazosin was shown to be effective in reducing both the frequency and the severity of vasospasm reported by the patients.

Adult↗
PubMed1983

Neuroendocrine response to cold in Raynaud's syndrome.

Eleven patients with Raynaud's syndrome accompanied by monospecific IgG ANA, nine patients with Raynaud's syndrome in the absence of ANA, and nine normal volunteers were exposed to an ambient cold challenge during which time venous blood was continuously sampled. ANA negative patients were shown to have significantly higher levels of cortisol during a cold challenge than either ANA positive patients or normal controls, and exhibited significantly lower levels of plasma norepinephrine compared with normal controls. ANA positive patients did not differ significantly from normals in their neuroendocrine response to cold. It is suggested that the high plasma cortisol found in Raynaud's syndrome in the absence of ANA may be responsible for the vasospasticity in this group of patients.

Antibodies, Antinuclear↗
PubMed1983

Intra-arterial reserpine for Raynaud's syndrome. Systemic reactions without therapeutic benefit.

Twenty-four patients classified as having Raynaud's disease or Raynaud's phenomenon were given bilateral brachial artery injections of reserpine or saline in a double-blind fashion. In the six weeks following injection, there was no indication that reserpine produced clinical improvement or changed vasomotor reactivity in the treated patients. However, intra-arterial reserpine did produce systemic cardiovascular effects lasting up to six weeks. It is concluded that intra-arterial reserpine as used in this study is an ineffective treatment for Raynaud's disease or Raynaud's phenomenon and may have significant adverse effects.

Adult↗
PubMed1982

Combination chemotherapy of the epipodophyllotoxin derivatives, teniposide and etoposide. A pharmacodynamic rationale?

Previous studies in vitro on the influence of extracellular protein binding of Teniposide (VM26) and Etoposide (VP16-213) on subsequent cellular uptake by experimental murine tumor cells [Cancer Res 38:2549 (1978); Drug Metab Rev 8:119 (1978)] suggested that a timed-sequential combination of VM26 and VP16-213 may increase the bioavailability of VP16-213. This was studied clinically in six cancer patients with ascites (five ovarian, one rectal) whereby VM26 (20 mg/m2) was given i.p. 2 h prior to VP16-213 (100 mg/m2; i.p.) In some patients, this regimen was administered i.v. The i.v. regimen was found to be more toxic (myelosuppression, nausea, vomiting) than i.p. regimen at same doses of drugs. Several patients remained stable to disease during 1-2 courses of therapy (3 weeks per course), one patient had partial remission, and has been stable in her disease for more than 4 months. In two patients, plasma and ascites fluid was analyzed for VP16-213 and VM26 by a new reverse-phase high performance liquid chromatography method. Both VM26 and VP16-213 could be eluted isocratically (28% v/v acetonitrile in water) from a c18 column with retention times of 6.6 and 13.3 min, respectively. Subsequent pharmacokinetic analysis of one patient suggests that protein binding displacement of VP16-213 in plasma and perhaps ascites fluid increased the pharmacokinetic volume of distribution (28 l) and reduced the elimination half-life (12 h). The data suggests that VP16-213 is distributed more widely in the body and is represented by a single compartment pharmacokinetic model. Analysis of VM26 in ascites and plasma suggests that the so-called "deep pharmacokinetic compartment" represents ascites equivalent space and that the plasma concentration represents VM26 as free and protein-bound drug in kinetic distinguishable compartments. Determinants of drug action are potentially composed of a multiplicity of physiological, biochemical, and other factors. The potential for manipulating the pharmacodynamic properties of drugs to achieve greater therapeutic potential needs further study.

Adult↗
PubMed1981

High performance liquid chromatographic determination of cyanuric acid in human urine and pool water.

A reverse phase high performance liquid chromatographic (HPLC) assay for the quantitative determination of cyanuric acid (CA) in urine and water is described. For purification, samples are passed through a pre-activated reverse phase C18 column. The effluent is dried by lyophilization, and the residue is reconstituted in hexane-washed water and then passed through a prewashed Dowex-1 column. The effluent is again dried by lyophilization, and the dry residue is extracted with hot dioxane. The solution is cooled to ambient temperature and centrifuged. The supernatant liquid is removed, dried under a nitrogen steam, and dissolved in water for final extraction by reverse phase chromatography. This effluent is dried, dissolved in the sodium phosphate monohydrate in methanol (pH 7.0) mobile phase, and injected into a pre-equilibrated chromatographic system. An external standard is used for quantification by peak height comparison. A sample of HPLC column effluent is collected, dried, dissolved in methanol, and used for mass spectrometric confirmation by a solid probe insert procedure. Average combined recovery determined at 1.0, 5.0 and 10.0 micrograms CA/mL is 103 +/- 3% with an average coefficient of variation of 8.6%. Standard deviations for the 3 concentration levels are 0.04, 0.58, and 0.76, respectively, with average precisions of 4.28, 10.92, and 7.61%. The limits of detection are approximately 0.05 micrograms/mL for urine and 0.1 micrograms/mL for swimming pool water. Recorder response to CA is linear over the concentration range 1-10 microgram/mL.

Chromatography, High Pressure Liquid↗
PubMed1981

Inhibition of cell cycle progression of human pancreatic carcinoma cells in vitro by L-(alpha S, 5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid, Acivicin (NSC 163501).

The inhibition of cell cycle progression of a human pancreatic carcinoma line, MiaPaCa-2, by L-(alpha S, 5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid (Acividin), an antimetabolite and glutamine antagonist, was investigated by means of flow cytometry, cell cycle kinetics, and cell enumeration. Flow cytometric criteria for logarithmically growing MiaPaCa-2 cells were established. Logarithmically growing cells exposed to 50 microM Acivicin appeared to markedly reduce their rate of cell cycle progression after they passed a point in later G1 phase or in early S phase. MiaPaCa-2 cells grew in the presence of 50 microM Acivicin with a population-doubling time of approximately 74 hr compared to a 20-hr doubling time for controls. The inhibition of cell cycle progression was at least partially reversed by removal of the drug. Based on previous reports of the biochemical mechanisms of Acivicin actions, several additives to the tissue culture medium were tested for their ability to protect MiaPaCa-2 cells from inhibition of cell cycle progression. Those cultures which contained cytidine partially protected the cells from Acivicin. The mechanism of inhibited growth induced by exposure to Acivicin is likely a complex reaction to the inhibition of several enzyme systems.

Cell Count↗