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Biomedical subjects

J Anderson

Publications and source records attributed to J Anderson.

At least 487 records · Page 27Linked to original sources
PubMed1991

Measurement of maximum variability within event related potentials in schizophrenia.

One limitation of averaging individual late component event related potential (ERP) responses is that a single average ERP cannot reflect the variability of responses from epoch to epoch. In this article, we describe a method to quantify this variability and determine if any part of the overall ERP reflects a maximum variance through the use of response variance curves. We then apply this method to one disorder, schizophrenia, in which variability of information processing is hypothesized to underlie aspects of the symptomatology. Response variance curves in a group of unmedicated schizophrenic patients reveal systematic differences, maximal between 190 and 250 ms, compared with those in a group of medicated schizophrenic patients and normal control subjects.

Adult↗
PubMed1991

Development of radiolabelled albumin microspheres: a comparison of gamma-emitting radioisotopes of iodine (131I) and indium (111In/113mIn).

Biodegradable albumin microspheres have been prepared incorporating either 131I or 111In/111In. Using cDTPAA/albumin molar ratios of 1, 3 and 10, approx. 0.7, 2.1 and 7 molecules of DTPA could be coupled to an albumin molecule, labelling efficiency being constant over this range. Because 131I microspheres were more stable in plasma than the system labelled with radionuclides of indium it was selected for clinical evaluation: potential uses of this radiopharmaceutical are illustrated.

Biodegradation, Environmental↗
PubMed1991

Effects of acetate dialysate on transforming growth factor beta 1, interleukin, and beta 2-microglobulin plasma levels.

To evaluate potential adverse effects of acetate use in hemodialysis (HD), we measured plasma interleukin (IL-1 alpha, IL-1 beta, IL-6), TNF alpha, TGF beta 1, and beta 2-microglobulin levels with ELISA assays in normal (N = 9), CRF (N = 6), CAPD (N = 7) and HD (N = 8) subjects and compared the effects of acetate (Ac) and acetate-free (Ac-free) dialysate. TGF beta 1 was the only cytokine consistently detected. Compared to normals (median 57, range 53 to 68 pg/ml, one undetected; N = 8), TGF beta 1 was higher in the CRF (75, 70 to 97 pg/ml, one undetected) and CAPD (75.5, 66 to 116 pg/ml, N = 6) groups (P less than 0.05), and was somewhat higher in the HD (68, 52 to 88 pg/ml) group (P less than 0.10). Acutely, TGF beta 1 pre-HD (70, 63 to 88 pg/ml) increased above normals post AcHD [79.5, 65 to 140 pg/ml uncorrected for ultrafiltration (UF)] and was higher after AcHD versus Ac-free HD both uncorrected (79.5, 65 to 140 pg/ml vs. 70, 52 to 86 pg/ml) and corrected for UF (68, 51 to 115 pg/ml vs. 57, 43 to 69 pg/ml; P less than 0.05). beta 2-microglobulin was not different after AcHD (81.2 +/- 8.0 mg/ml) versus Ac-free HD (72.5 +/- 6.9 mg/ml). Significantly lower serum inorganic phosphorus was also found four hours post-AcHD compared to four hours post-Ac-free HD (0.87 mmol +/- 0.10 SEM vs. 1.05 mmol +/- 0.07 SEM; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1991

Measurement and prediction of digestible energy values in feedstuffs for the herbivorous fish tilapia (Oreochromis niloticus Linn.).

Digestible energy (DE) values were measured in a selection of feedstuffs for the tilapia (Oreochromis niloticus Linn.) and used to develop equations for predicting DE values of a wider range of feedstuffs from chemical analyses. Preliminary work examined the influences of substitution level in a reference diet and adaptation over time on DE values for soya-bean meal. Length of adaptation period significantly affected DE values (P less than 0.01), but substitution level, over the range 200-600 g soya-bean meal/kg reference diet, did not. The DE values of sixteen feedstuffs, thirteen derived from plant sources and three animal by-products, were subsequently determined. DE values for plant-derived feedstuffs were found to be higher than those quoted in the literature for trout (Oncorhynchus mykiss) and catfish (Ictalurus punctatus), whereas DE values for animal-derived feedstuffs were lower than those for trout and pigs. It was concluded that energy values quoted in tables of feed composition for other species are inaccurate when used as proxy values for tilapia. Regression equations were therefore computed using data from the present study to provide a rapid means of predicting DE values of feedstuffs for tilapia. Equations using neutral-detergent fibre as an independent variable were found to predict DE values of plant-derived feedstuffs reliably. Where fibre values were not used as independent variables, available carbohydrate and crude protein (nitrogen x 6.25) were found to be useful predictors of DE values. These equations offer the possibility of reducing the need for time-consuming digestibility trials with tilapia when formulating least-cost production diets for this species.

Animal Feed↗
PubMed1991

The prevalence of dementia in a total population: a comparison of two screening instruments.

Two short screening tests for dementia, the Information/Orientation (IO) sub-test of the Clifton Assessment Scale (CAPE) and the Mini-Mental State Examination (MMSE) were included in a survey of 1579 elderly people of a large general practice. All those scoring 21 and under on the MMSE, a one in two sample of those scoring 22, 23 and a one in ten sample of the remainder were investigated further using the Cambridge Examination for Mental Disorders of the elderly (CAMDEX). The prevalences of moderate to severe dementia and mild to severe dementia determined from the CAMDEX interview were 4.8% and 14.2%, respectively. For detection of moderate to severe dementia, a cut-point of 21/22 on the MMSE gave a sensitivity of 100%, specificity of 85% and an overall prevalence of 19.7%; mild to severe dementia was best detected by a cut-point of 23/24 giving a sensitivity of 89%, specificity of 81% and prevalence of 28.5%. A cut-point of 7/8 on the IO sub-test gave a sensitivity and specificity for detecting moderate to severe dementia of 87% and 97%, respectively, with a prevalence of 7.3%; for mild to severe dementia a cut-point of 10/11 gave a sensitivity of 67%, specificity of 94% and prevalence of 14.7%.

Aged↗
PubMed1991

Delayed facial nerve palsy after temporal lobectomy for epilepsy: report of four cases and discussion of possible mechanisms.

Four cases of idiopathic peripheral facial nerve palsy were documented after 110 consecutive resections of the temporal lobe for intractable epilepsy. In 3 of the 4 cases, the palsy was ipsilateral to the side of the temporal lobectomy. The onset of facial weakness was delayed 7 to 13 days after surgery (mean, 9.7 days). One patient underwent facial electroneurography, which documented 17% of normal facial motor function at the height of his weakness and the absence of the acoustic stapedius reflex. All patients were treated with prednisone (60-80 mg per day by mouth for 10-14 days, tapering off throughout the subsequent week). Facial function recovered fully in all patients within 6 to 8 weeks. Possible mechanisms are discussed, including heat and/or mechanical trauma to the facial nerve near the geniculate ganglion during resection of mesial temporal lobe structures.

Adult↗
PubMed1991

Altered expression of HLA antigens and CD16 Fc receptors on leukocytes of alcoholic subjects and uremic patients.

The possible influences of ethanol and its metabolic product acetate on the surface expression of HLA class I and class II antigens and CD16 Fc receptors were examined. Fluorescent-labeled monoclonal antibodies and flow cytometry were used to measure these antigens on leukocytes from reference controls, subjects admitted for alcohol detoxification, uremic patients undergoing hemodialysis using Cu-prophan dialyzers and fluids containing 4 to 37 mM acetate, and uremic patients that were not hemodialyzed. In comparison to the controls, the mean intensity of staining for class I antigens was not changed significantly on lymphocytes or monocytes from alcoholics but was depressed on cells from eight of 12 uremic patients. Interferon-gamma above 5 units/ml was detected in less than 15% of plasma samples from controls, uremic patients or alcoholics on admission but was detected in four of eight samples from alcoholics at discharge (2-4 days after admission). The intensity of staining for class II antigens was depressed by more than 50% on lymphocytes from alcoholics and uremic patients. The expression of HLA class I and class II antigens was depressed whether uremic patients were hemodialyzed or not. The percentage of lymphocytes expressing CD16 was depressed in three of seven alcoholics and five of seven hemodialyzed patients. In contrast, the percentage of monocytes expressing CD16 was increased in six of seven hemodialyzed patients and three of five uremic patients not undergoing hemodialysis suggesting activation of monocytes in these patients. Plasma levels of beta 2-microglobulin were elevated by 61% in alcoholics, 50-fold in hemodialyzed patients, and 26-fold in nonhemodialyzed uremic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Moclobemide in depression: a randomized, multicentre trial against isocarboxazide and clomipramine emphasizing atypical depression.

Moclobemide was compared with isocarboxazide and clomipramine in patients with depression. A total of 167 outpatients were allocated to daily treatment with 300 mg moclobemide, 30 mg isocarboxazide or 150 mg clomipramine for 6 weeks. Moclobemide was slightly inferior to clomipramine, whereas isocarboxazide had an intermediate position. There was no interaction between treatment and atypical or nonatypical depression. Anticholinergic symptoms and orthostatic hypotension were most pronounced in the clomipramine group.

Adult↗
PubMed1991

Pulmonary vascular pressure profile in adult ferrets: measurements in vivo and in isolated lungs.

We have determined the vascular pressure profile in lungs of adult ferrets utilizing an anaesthetized open chested preparation and have compared the pressure profile in vivo with that in isolated, perfused lungs. Ten adult ferrets, mean body weight 980 +/- 108 g, were studied. For in vivo measurements, five ferrets were anaesthetized, mechanically ventilated and the left chest wall resected. Pressures were measured in the pulmonary artery, left atrium and by micropuncture, in 20-50 microns diameter subpleural arterioles and venules. During micropuncture, ventilation was stopped for 1-2 min and the lungs kept distended at an airway pressure of 6 cmH2O. Left atrial pressure was raised to approximately 8 cmH2O with saline infusion so that lungs were in Zone 3. Cardiac output was measured by thermodilution. Lungs of five other ferrets were isolated and perfused with a steady flow roller pump. In these lungs blood flow was adjusted so that pulmonary artery pressure was similar to that in anaesthetized ferrets, with airway and left atrial pressures at 6 and 8 cmH2O respectively (Zone 3). Blood haematocrit (35 +/- 7%) was similar in the two groups. In lungs of anaesthetized ferrets total arteriovenous pressure drop was 12.1 +/- 1.9 cmH2O, with cardiac output being 210 +/- 80 ml kg body weight-1 min-1. Fractional resistance in arteries was 37%, 37% in microvessels and 26% in veins. In isolated ferret lungs, though blood flow was only 48 +/- 10 ml kg body wt-1 min-1 for the same total arteriovenous pressure drop as in vivo, the longitudinal distribution of vascular resistance was similar to that in live ferrets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Preschool vision screening.

Although a good case for preschool screening for vision defects can be made there is very little evidence that existing programmes are effective in practice. A comparative trial of three different methods of preschool vision screening is described. Some 7000 children initially aged 5 months (younger cohorts) and 30 months (older cohorts) in three matched areas entered the trial during 1987. During 18 months of follow up new visual and ocular defects among these children were ascertained through ophthalmology outpatients and from optician records. Screening at 35 months by an orthoptist based in the community is superior to conventional health visitor surveillance at 30 months and to an agreed programme of primary care screening for squint at 30-36 months as judged by screening sensitivity (100% v 50% v 50%) and the incidence of treated target conditions (17 v 3 v 5 per 1000 person years). A notable feature in the area served by the orthoptist is that 13 children received treatment for straight eyed visual acuity loss from among 1000 children whereas there were no such cases among 2500 in the comparison areas. In the younger cohorts (that is, screening at age 5-9 months) all three programmes showed equally poor results, only one of the eight treated target conditions arising from all 3500 younger children being screen detected.

Amblyopia↗
PubMed1991

Tissue doses in the upper gastrointestinal fluoroscopy examination.

A method was developed to estimate tissue doses from the upper gastrointestinal fluoroscopy examination. It involved measuring the technical parameters of the clinical examination, partitioning the dynamic examination into a set of discrete x-ray fields, and generating corresponding tissue does tables with an existing computer program. Knowledge of the radiation exposures associated with each of the fields enabled the calculation of tissue doses for the entire dynamic examination. In this limited sample (eight patients), fluoroscopy times ranged from 108 to 183 seconds. Radiation exposures ranged from 2.3 to 7.2 mC/kg (9.1-28 R), thyroid doses from 0.15 to 3.5 mGy (15-350 mrad), uterine doses from 0.16 to 1.0 mGy (16-100 mrad), lung doses from 0.90 to 4.2 mGy (90-420 mrad), and active bone marrow doses from 0.81 to 5.4 mGy (81-540 mrad).

Digestive System↗
PubMed1991

Endothelin effects in isolated, perfused lamb lungs: role of cyclooxygenase inhibition and vasomotor tone.

We have determined the sites of action of endothelin-1 (ET) in the lamb pulmonary circulation. The influence of cyclooxygenase inhibition and baseline vasomotor tone on ET effects was also studied. Lungs of 14 lambs (6-9 wk of age, 12.1 +/- 0.6 kg body wt) were isolated and perfused with blood. Group I lungs (n = 5) were untreated, group II lungs (n = 5) were treated with indomethacin to inhibit cyclooxygenase, and group III lungs (n = 4) were treated with indomethacin and a thromboxane A2 analogue, U-46619, to elevate vasomotor tone. All lungs were perfused with constant flow in zone 3, with left atrial and airway pressures being 8 and 6 cmH2O, respectively. We measured pulmonary arterial pressure and, by the micropuncture servo-null method, pressures in 20- to 50-microns diameter subpleural venules, both before and after each dose of ET was infused (50, 100, 250, and 500 ng/kg). Group I lungs, with high baseline vasomotor tone, exhibited a biphasic response to ET; 50-100 ng/kg of ET dilated both arteries and veins, whereas 500 ng/kg of ET constricted both arteries and veins. In group II lungs with low vasomotor tone, all doses of ET caused constriction of arteries only. In group III lungs (indomethacin treated with elevated vasomotor tone), 50-100 ng/kg of ET caused dilation of arteries and veins, whereas 500 ng/kg of ET induced constriction, this time only in arteries. We conclude that ET has both dilator and constrictor effects in arteries and veins of isolated, perfused lamb lungs. ET-induced arterial and venous dilation is dependent on initial vasomotor tone but not on cyclooxygenase metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Segmental vascular resistance during pulsatile and steady perfusion in 3- to 5-wk-old rabbit lungs.

To determine the mechanisms by which pulsatile perfusion reduces vascular resistance in isolated lungs, we compared the effects of pulsatile versus steady perfusion on total and segmental vascular resistance in isolated lungs of 3- to 5-wk-old rabbits. Lungs were perfused alternately with steady and pulsatile flow for 45-min periods at a constant total arteriovenous pressure drop. Blood flow was adjusted to keep mean pulmonary arterial pressure at 20 cmH2O, when left atrial and airway pressures were 8 and 6 cmH2O, respectively. We partitioned the pulmonary circulation into three longitudinal vascular segments, i.e., arteries, microvessels, and veins, by measuring pressures in 20- to 50-microns-diameter subpleural arterioles and venules by the micropipette servo-nulling method. We found that in the isolated, perfused 3- to 5-wk-old rabbit lung, in which arteries and veins are the main sites of resistance, pulsatile flow results in a 20-36% reduction in total vascular resistance, mainly due to a reduction in arterial and venous resistances. The decrease in total vascular resistance was similar in lungs that were untreated or treated with papaverine, indicating that the effect of pulsatile flow was not due to active vasomotion. The reduction in arterial resistance was greater than that in veins (31-55 vs. 19-22%), especially when pulse amplitude was high (5-10 vs. 20-30 cmH2O). Total vascular resistance was also lower after 45 min of pulsatile perfusion with a pulse rate of 200 pulses/min than 80 pulses/min (0.126 +/- 0.04 vs. 0.154 +/- 0.059 cmH2O.min.ml-1.kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of pentoxifylline in rabbit pulmonary circulation: influence of age and vasomotor tone.

We determined the influence of vasomotor tone and age on pentoxifylline (PTX) effects in rabbit lungs. Lungs of adult, juvenile, and neonatal rabbits were isolated and perfused with blood at constant flow in zone 3. In adult lungs only, pressures were measured in 20- to 50-microns-diameter subpleural arterioles and venules (by micropuncture) to partition the circulation into arteries, microvessels, and veins during baseline, after PTX infusion (20 mg/kg), and terminally, after treatment with papaverine. In some adult and juvenile lungs, vasomotor tone was elevated with KCl, and some adult lungs were pretreated with indomethacin to inhibit cyclooxygenase. We found that PTX's vasodilator effect was influenced by age; it was approximately 52, approximately 65, and approximately 82% as effective as papaverine in untreated neonatal, juvenile, and adult lungs, respectively, and approximately 49 and approximately 93% as effective as papaverine in KCl-constricted adult and juvenile lungs, respectively. The site(s) of PTX action depended on basal vasomotor tone; in lungs with moderate tone, PTX dilated arteries only, and in lungs with high tone, PTX dilated both arteries and veins. Cyclooxygenase inhibition did not attenuate PTX effects. We conclude that, in rabbit lungs, PTX dilates arteries and veins and that the magnitude of PTX effect is dependent on age and basal vasomotor tone.

Aging↗
PubMed1991

Erythrocyte deformability and lung segmental vascular resistance: effect of hematocrit.

We have investigated the role of erythrocyte (RBC) deformability and perfusate viscosity on lung segmental vascular resistance in 12 isolated perfused lungs of 3- to 5-wk-old rabbits. Each lung was perfused alternately with control and formaldehyde-fixed rabbit RBCs at a flow rate of 80 ml.kg-1.min-1, left atrial and airway pressures being 8 and 6 cmH2O, respectively (zone 3). Perfusate RBC concentration was kept constant at 3.2 x 10(6)/mm3 for group I lungs (n = 6) and 7.2 x 10(6)/mm3 for group II lungs (n = 6). In all lungs, we measured pressures in the pulmonary artery and in 20- to 50-microns-diam arterioles and venules with the micropipette servo-null method during both perfusion periods. Compared with control, fixed cells had a 60% decrease in deformability index (i.e., the volume of a dilute solution of RBCs filtered through a 5-microns Nuclepore filter in 1 min). In groups I and II, perfusate viscosity of fixed cells was 15 and 55% greater, respectively, than that of control cells. We found that perfusion with fixed cells in group I lungs did not alter total or segmental vascular pressure drops. However, in group II lungs, perfusion with fixed cells at twice the cell concentration resulted in an increase in total vascular pressure drop, mainly due to an increase in pressure drop in veins (50% of total) and arteries (33%). The relatively small (17%) increase in pressure drop in microvessels was probably due to distension and/or recruitment of capillaries resulting from increased venular pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Segmental vascular resistance in isolated perfused rat lungs. Influence of vasomotor tone and cyclooxygenase and lipoxygenase inhibition.

We have determined the profile of pressures in isolated perfused lungs of adult rats and investigated the influence of vasomotor tone and cyclooxygenase and lipoxygenase inhibition on total and segmental vascular resistance. We isolated and blood-perfused lungs of 30 rats (480 +/- 21 g). Group 1 (n = 7) was untreated, group 2 (n = 8) was paralyzed with papaverine, group 3 (n = 11) was treated with indomethacin, and group 4 (n = 4) was treated with indomethacin and U60257, a putative lipoxygenase inhibitor. Blood flow was adjusted initially to raise pulmonary artery pressure to approximately 15 cm H2O and then held constant. Airway and left atrial pressures were held constant at 7 and 8 cm H2O, respectively (zone 3 conditions). In all lungs, we measured pressures in subpleural 20-50-microns-diameter arterioles and venules using the micropuncture servonull technique. Thus, the pulmonary circulation was partitioned into three segments: arteries, microvessels, and veins. In group 1 lungs, arteries presented the largest fractional resistance to flow at 46% of total resistance, with microvessels and veins contributing 34% and 20%, respectively. In group 2 lungs that had no vasomotor tone, total vascular resistance was approximately 27% lower than in group 1 lungs, mainly due to a lower resistance in veins. In indomethacin-treated lungs (group 3) and indomethacin and U60257-treated lungs (group 4), total and segmental vascular resistance was not significantly different from untreated lungs (group 1). We conclude that in isolated perfused rat lungs, arteries are the predominant site of resistance to blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗