Clinician judgment vs formal scales for predicting intracerebral hemorrhage outcomes

OBJECTIVE

To compare the performance of formal prognostic instruments vs subjective clinical judgment with regards to predicting functional outcome in patients with spontaneous intracerebral hemorrhage (ICH).

METHODS

This prospective observational study enrolled 121 ICH patients hospitalized at 5 US tertiary care centers. Within 24 hours of each patient's admission to the hospital, one physician and one nurse on each patient's clinical team were each asked to predict the patient's modified Rankin Scale (mRS) score at 3 months and to indicate whether he or she would recommend comfort measures. The admission ICH score and FUNC score, 2 prognostic scales selected for their common use in neurologic practice, were calculated for each patient. Spearman rank correlation coefficients (r) with respect to patients' actual 3-month mRS for the physician and nursing predictions were compared against the same correlation coefficients for the ICH score and FUNC score.

RESULTS

The absolute value of the correlation coefficient for physician predictions with respect to actual outcome (0.75) was higher than that of either the ICH score (0.62, p = 0.057) or the FUNC score (0.56, p = 0.01). The nursing predictions of outcome (r = 0.72) also trended towards an accuracy advantage over the ICH score (p = 0.09) and FUNC score (p = 0.03). In an analysis that excluded patients for whom comfort care was recommended, the 65 available attending physician predictions retained greater accuracy (r = 0.73) than either the ICH score (r = 0.50, p = 0.02) or the FUNC score (r = 0.42, p = 0.004).

CONCLUSIONS

Early subjective clinical judgment of physicians correlates more closely with 3-month outcome after ICH than prognostic scales.

Abstract 211: Subjective Judgments of Physicians and Nurses Are More Accurate Than Formal Clinical Scales in Predicting Functional Outcome After Intracerebral Hemorrhage

Introduction: Providing an accurate prognosis is a fundamental responsibility of care providers for patients with intracerebral hemorrhage (ICH). The ICH and FUNC Scores are common clinical scales designed to predict functional outcome and mortality for ICH patients.

Hypothesis: The ICH Score and FUNC Score have superior accuracy, compared to the early clinical judgment of physicians and nurses, with regards to the prediction of the Modified Rankin Scale (mRS) achieved by ICH patients at 3 months.

Methods: We conducted a prospective study at 5 centers. For each consecutive adult patient admitted with primary ICH, one physician and one nurse on the treatment team were asked for prediction of mRS at 3 months. All predictions were collected within 24 hours of admission. ICH and FUNC Scores on admission and blinded outcome at 3 months were obtained for each patient, in part using data collected for the ongoing Ethnic/Racial Variations with ICH (ERICH) project. Predictive ability was measured by Spearman’s rank correlation (r).

Results: For a total of 100 patients, 100 physicians (75 attendings, 25 trainees) and 100 nurses gave predictions. In order of strength of association with actual 3-month mRS, correlations were attending physicians r = 0.81, nurses r = 0.72, and trainees r = 0.66. Although suggestive, none of these groups were statistically superior (p > 0.10). However, nurses (p = 0.015) and attending physicians (p = 0.002), but not trainees (p = 0.57), were superior in their predictive ability over ICH Score (r = 0.55). Similarly, nurses (p = 0.0003) and attending physicians (p < 0.0001), but not trainees (p = 0.27), were superior over FUNC Score (r = -0.46). This accuracy advantage remained when examining predictions for (1) only those patients alive at 3 months (n = 65), and (2) only those patients for whom providers indicated that they would not recommend comfort care within the first 24 hours (n = 82).

Conclusions: The ICH Score and FUNC Score did not have superior accuracy, compared to subjective clinical judgment, with regards to prediction of 3-month ICH outcome.

Electrophysiological correlates of categorization: P300 amplitude as index of target similarity

Two experiments examined event-related potentials (ERPs) and behavioral correlates of categorizing stimuli varying in perceptual similarity to targets. Participants performed a target-detection task in which non-target stimuli varied in target similarity but occurred with equivalent probability. The stimuli were variations of a schematic human face comprised of eight distinct features: two eyes, two eyebrows, one nose, one mouth, and two ears. Non-target stimuli that were perceptually similar to targets produced larger P300-like neurophysiological responses than did other non-target stimuli. These effects emerged whether participants' target was relatively complex (eight features) or quite simple (zero features). Accordingly, the presence of many constituent elements of a test stimulus does not appear necessary to trigger increases in categorical processing of non-targets that are similar to a target. The data further suggest that the P300 amplitude may be used as a good index of perceptual similarity between target and non-target stimuli.

fMRI activation in a visual-perception task: network of areas detected using the general linear model and independent components analysis

The Motor-Free Visual Perception Test, revised (MVPT-R), provides a measure of visual perceptual processing. It involves different cognitive elements including visual discrimination, spatial relationships, and mental rotation. We adapted the MVPT-R to an event-related functional MRI (fMRI) environment to investigate the brain regions involved in the interrelation of these cognitive elements. Two complementary analysis methods were employed to characterize the fMRI data: (a) a general linear model SPM approach based upon a model of the time course and a hemodynamic response estimate and (b) independent component analysis (ICA), which does not constrain the specific shape of the time course per se, although we did require it to be at least transiently task-related. Additionally, we implemented ICA in a novel way to create a group average that was compared with the SPM group results. Both methods yielded similar, but not identical, results and detected a network of robustly activated visual, inferior parietal, and frontal eye-field areas as well as thalamus and cerebellum. SPM appeared to be the more sensitive method and has a well-developed theoretical approach to thresholding. The ICA method segregated functional elements into separate maps and identified additional regions with extended activation in response to presented events. The results demonstrate the utility of complementary analyses for fMRI data and suggest that the cerebellum may play a significant role in visual perceptual processing. Additionally, results illustrate functional connectivity between frontal eye fields and prefrontal and parietal regions.

Effects of feeding regimens on bodyweight, composition and condition score in cats following ovariohysterectomy

The effects of ovariohysterectomy on bodyweight, composition and condition score were evaluated in 49 cats that were fed ad libitum and 11 cats that had their food allowances controlled with the aim of maintaining a stable bodyweight. In cats fed ad libitum, bodyweight increased by an average of 31 per cent in the 12 months following ovariohysterectomy compared with 3.1 per cent over the 12 months before surgery, and this was largely due to increased body fat content. There was no difference in weight gain between cats fed dry or canned foods, but weight gain was inversely related to age and bodyweight at the time of neutering. Mean bodyweight increased by 7.5 per cent in the controlled feeding group, compared with 3.6 per cent over the 12 months before surgery, and individual bodyweights were maintained to within 10 per cent of pre-neutering values in nine cats. The other two cats experienced substantial weight gain (+20 per cent and +36 per cent), despite being fed only 40 kcal/kg/day. There were no significant changes in body composition of cats with controlled dietary allowances and their condition scores were significantly lower than those of cats fed ad libitum. The results confirm a link between ovariohysterectomy and the development of obesity in cats with free access to food, and indicate that substantial reductions in energy intake are required to prevent weight gain in such cats.

Age differences in dynamic measures of EEG

Eighteen older adults and 18 younger adults were compared on two quantitative measures describing changes over time in the spatial distribution of running EEG. EEG was collected from 128 electrodes under resting eyes-open and eyes-closed conditions and during performance of a 13 minute sustained attention task. One EEG measure, the recrudescence rate, represented the number of changes in the location of the highest squared voltage per second. A second EEG measure consisted of the algorithmic complexity of changes in the location of the highest squared voltage over time. Regardless of the task condition, older adults had significantly higher scores than younger adults on both the recrudescence rate and the measure of algorithmic complexity. The implications of the results for neurologically-based theories of performance declines in older adults are discussed.

Influence of age and sex on plasma lipid and lipoprotein concentrations and associated enzyme activities in cats

OBJECTIVE

To determine effects of age and sex on plasma lipid and lipoprotein metabolism in cats.

ANIMALS

33 kittens and 16 adolescent, 23 adult, and 10 senior cats.

PROCEDURE

Plasma concentrations of cholesterol, triglyceride, and lipoprotein-cholesterol and activities of lipoprotein lipase, hepatic lipase, and lecithin:cholesterol acyl transferase (LCAT) were measured and compared within and among groups.

RESULTS

Plasma cholesterol and triglyceride concentrations were significantly higher in 5- and 7-week-old kittens, compared with the same kittens after weaning and cats in the other age groups. Cholesterol concentration was significantly less in 20-week-old kittens, compared with adolescent and adult cats. Lipid and lipoprotein-cholesterol concentrations were not significantly different among the adolescent, adult, and senior groups, nor did sex influence lipid and lipoprotein-cholesterol concentrations in these groups. Activities of lipoprotein and hepatic lipases were significantly less in senior cats, compared with the other groups. Activity of LCAT was highest in 20-week-old kittens and was greater in sexually intact adult and adolescent females, compared with their male counterparts. After castration, activities of hepatic lipase and LCAT significantly decreased in adolescent male cats.

CONCLUSIONS AND CLINICAL RELEVANCE

The upper limits of reference ranges for plasma cholesterol and triglyceride concentrations should be increased for kittens < 8 weeks of age. Low cholesterol concentrations in adolescent cats likely reflect high tissue demands for growth and steroidogenesis. Decrease in lipoprotein and hepatic lipase activity in senior cats could predispose this age group to hypertriglyceridemia, particularly in insulin-resistant cats or those fed a high fat diet.

The clinical and metabolic effects of rapid weight loss in obese pet cats and the influence of supplemental oral L-carnitine

The efficacy, safety, and metabolic consequences of rapid weight loss in privately owned obese cats by means of a canned weight-reduction diet and the influence of orally administered L-carnitine on rate of weight loss, routine clinical evaluations, hepatic ultrasonography, plasma amino acid profiles, and carnitine analytes were evaluated. A double-blinded placebo-controlled design was used with cats randomly divided into 2 groups: Group 1 (n = 14) received L-carnitine (250 mg PO q24h) in aqueous solution and group 2 (n = 10) received an identical-appearing water placebo. Median obesity (body condition scores and percentage ideal body weight) in each group was 25%. Caloric intake was restricted to 60% of maintenance energy requirements (60 kcal/kg) for targeted ideal weight. The reducing formula was readily accepted by all cats. Significant weight loss was achieved by week 18 in each group without adverse effects (group 1 = 23.7%, group 2 = 19.6%). Cats receiving carnitine lost weight at a significantly faster rate (P < .05). Significant increases in carnitine values developed in each group (P < .02). However, significantly higher concentrations of all carnitine moieties and a greater percentage of acetylcarnitine developed in cats of group 1 (P < .01). The dietary formula and described reducing strategy can safely achieve a 20% weight reduction within 18 weeks in obese cats. An aqueous solution of L-carnitine (250 mg PO q12h) was at least partially absorbed, was nontoxic, and significantly increased plasma carnitine analyte concentrations as well as rate of weight loss.

Diet and skin disease in dogs and cats

Dietary factors have a major role in the maintenance of healthy coat and skin, and are significant in the etiology and therapy of certain skin diseases. Nutritional deficiencies are now uncommon as a result of the widespread feeding of complete and balanced pet foods. Deficiencies of (n-6) polyunsaturated fatty acids, zinc and vitamins, however, do arise in certain animal- or product-related instances. Supraphysiologic doses of vitamin A have been used in the management of vitamin A-responsive dermatosis in Cocker spaniels; other keratinization defects and seborrheic conditions may respond to retinoid therapy. Much interest has been paid to the therapeutic value of polyunsaturated fatty acid supplements in the management of dermatologic conditions associated with hypersensitivity reactions or keratinization defects. These studies have generally yielded disappointing results, which may reflect shortcomings in the design of some trials. Nevertheless, a placebo-controlled, double-blind, cross-over study has demonstrated a clear benefit of high dose (n-3) fatty acids in the management of pruritic skin disease. There is also preliminary experimental evidence that specific dietary (n-6):(n-3) fatty ratios are useful in the dietary management of inflammatory diseases. Although results of controlled clinical trials are awaited, the argument exists that it is the absolute amount of (n-3) fatty acid intake rather than ratio that is responsible for potential health benefits.

The effect of smoking on post-heparin lipoprotein and hepatic lipase, cholesteryl ester transfer protein and lecithin:cholesterol acyl transferase activities in human plasma

INTRODUCTION

Smoking is associated with dyslipidaemia, particularly raised plasma triglycerides and reduced high-density lipoprotein (HDL)-cholesterol and a delayed clearance of triglyceride in fat tolerance tests. The aim of this study was to investigate whether these phenomena could be explained by a reduced lipoprotein lipase activity in smokers.

METHODS

A group of 40 healthy individuals [plasma cholesterol 5.07 (SD 0.90) mmol L-1, plasma triglyceride 1.02 (SD 0.39) mmol L-1)] was studied to examine the effects of smoking on plasma enzyme activities, particularly post-heparin lipase activities. The group comprised 20 smokers and 20 non-smokers, who were matched for age, gender and body mass index (BMI).

RESULTS

Post-heparin lipoprotein lipase (LPL) activity [3.89 (SD 1.58) vs. 5.85 (SD 2.30) mumol free fatty acids (FFA) mL-1 h-1, P < 0.005], but not post-heparin hepatic lipase (HL) activity, was reduced in smokers. Plasma cholesteryl ester transfer protein (CETP) activity and lecithin: cholesterol acyl transferase (LCAT) activity were measured in a subgroup of 18 individuals, comprising nine smokers with nine matched non-smokers. There was no difference in CETP activities between two groups, but smokers had a significantly reduced plasma LCAT activity [112 (SD 23) vs. 152 (SD 24) nmol cholesterol mL-1 h-1, P < 0.005]. In both smokers (r=-0.53, P < 0.05) and non-smokers (r=-0.54, P < 0.05), HDL2 concentration was negatively associated with HL activity. In non-smokers, HDL3 concentration was negatively associated with CETP activity (r= -0.77, P < 0.05), whereas in smokers HDL3 concentration was negatively associated with LCAT activity (r= -0.78, P < 0.050).

CONCLUSION

It was shown by direct measurement that the activity of plasma post-heparin LPL is reduced in smokers, independently of age, gender and BMI. It is concluded that this enzyme perturbation associated with smoking may contribute to the development of the atherogenic lipoprotein phenotype seen in smokers.

Metabolic basis of hypotriglyceridemic effects of insulin in normal men

The mechanism by which acute insulin administration alters VLDL apolipoprotein (apo) B subclass metabolism and thus plasma triglyceride concentration was evaluated in 7 normolipidemic healthy men on two occasions, during a saline infusion and during an 8.5-hour euglycemic hyperinsulinemic clamp (serum insulin, 490 +/- 30 pmol/L). During the insulin infusion, plasma triglycerides decreased by 22% (P < .05), and serum free fatty acid decreased by 85% (P < .05). The plasma concentration of VLDL1 apo B fell 32% during the insulin infusion, while that of VLDL2 apo B remained constant. A bolus injection of [3-(2)H]leucine was given on both occasions to trace apo B kinetics in the VLDL1 and VLDL2 subclasses (Svedberg flotation rate, 60-400 and 20-60, respectively), and the kinetic basis for the change in VLDL levels caused by insulin was examined using a non-steady-state multicompartmental model. The mean rate of VLDL1 apo B synthesis decreased significantly by 35% (P < .05) after 0.5 hour of the insulin infusion (523 +/- 87 mg/d) compared with the saline infusion (808 +/- 91 mg/d). This parameter was allowed to vary with time to explain the fall in VLDL1 concentration. After 8.5 hours of hyperinsulinemia, the rate of VLDL1 apo B synthesis was 51% lower (321 +/- 105 mg/d) than during the saline infusion (651 +/- 81 mg/d, P < .05). VLDL2 apo B production was similar during the saline (269 +/- 35 mg/d) and insulin (265 +/- 37 mg/d) infusions. No significant changes were observed in the fractional catabolic rates of either VLDL1 or VLDL2 apo B. We conclude that acute hyperinsulinemia lowers plasma triglyceride and VLDL levels principally by suppressing VLDL1 apo B production but has no effect on VLDL2 apo B production. These findings indicate that the rates of VLDL1 and VLDL2 apo B production in the liver are independently regulated.

Transient hyperlipidaemia and anaemia in kittens

Severe fasting hypertriglyceridaemia (5 to 126 mmol/litre) and anaemia (packed cell volume < 11 per cent) was observed in 12 litters of kittens around the time of weaning; the entire litter was usually affected, with significant mortality. Lipid analysis revealed marked increases in chylomicrons and moderate increases in very low density lipoproteins. Supportive measures for the treatment of anaemia and weaning on to a low fat diet resulted in rapid resolution of the clinical signs, anaemia and hypertriglyceridaemia. On recovery, plasma was collected from kittens from five of the affected litters, plus a number of closely related cats and unrelated cats living in the same environment. The lipoprotein lipase (LPL) activity was mildly but significantly lower in the previously affected kittens, their parents and unaffected siblings, than in the unrelated cats. The cats had normal apolipoprotein C-II function, normal heparin binding activity and no evidence of a circulating inhibitor to LPL. They did not have the LPL gene mutation reported previously in LPL-deficient cats from New Zealand.

Relations between plasma lipids and postheparin plasma lipases and VLDL and LDL subfraction patterns in normolipemic men and women

VLDL1, VLDL2, IDL, and LDL and its subfractions (LDL-I, LDL-II, and LDL-III) were quantified in 304 normolipemic subjects together with postheparin plasma lipase activities, waist/hip ratio, fasting insulin, and glucose. Concentrations of VLDL1 and VLDL2 rose as plasma triglycerides (TGs) increased across the normal range, but the association of plasma TGs with VLDL1 showed a steeper slope than that of VLDL2 (P < .001). Plasma TG level was the most important determination of LDL subfraction distribution. The least dense species, LDL-I, decreased as the level of this plasma lipid rose in the population. LDL-II in both men and women exhibited a positive association with plasma TG level in the range 0.5 to 1.3 mmol/L, increasing from about 100 to 200 mg/dL. In contrast, within this TG range the LDL-III concentration was low (approximately equal to 30 mg/dL) and changed little. As plasma TGs rose from 1.3 to 3.0 mmol/L there was a significant fall in LDL-II concentration in men (r = .45, P < .001) but not in women (r = .1, NS). Conversely, above the TG threshold of 1.3 mmol/L there was a steeper rise in LDL-III concentrations in men than in women (P < .001); 42% of the men had and LDL-III in the range associated with high risk of heart disease ( > 100 mg lipoprotein/dL plasma) compared with only 17% of the women. Other influences on the LDL subfraction profile were the activities of lipases and parameters indicative of the presence of insulin resistance. Men on average had twice the hepatic lipase activity of women. This enzyme was not strongly associated with variation in the LDL subfraction profile in men, but in women it was correlated with LDL-III (r = 39, P = .001) and remained a significant predictor in multivariate analysis. Increased waist/hip ratio, fasting insulin, and glucose were correlated negatively with LDL-I and positively with LDL-III, primarily, at least in the case of LDL-III, through raising plasma TGs. On the basis of these cross-sectional observations we postulate the following model for the generation of LDL-III. Subjects develop elevated levels of large TG-rich VLDL1 for a number of reasons, including failure of insulin action. The increase in the concentration of VLDL1 expands the plasma TG pool, and this, via the action of cholesteryl ester transfer protein (which facilitates neutral lipid exchange between lipoprotein particles), promotes the net transfer of TGs into LDL-II, the major LDL species.(ABSTRACT TRUNCATED AT 400 WORDS)

Pharmacokinetics of heparin and its pharmacodynamic effect on plasma lipoprotein lipase activity and coagulation in healthy horses

We evaluated the pharmacokinetics of IV administered sodium heparin and the pharmacodynamic effect of heparin on lipoprotein lipase (LPL) activity. Horses were allotted to 3 groups. Plasma samples were obtained from each horse before and at various times for 6 hours after heparin administration for determination of heparin concentration, LPL activity, and activated partial thromboplastin time (APTT). The disposition of heparin was dose dependent. The area under the plasma heparin concentration vs time curve (AUC) increased more than proportionally with dose, indicating that heparin elimination was nonlinear. Total clearance of heparin was similar after the 40 and 80 IU/kg of body weight dosages, averaging 0.45 and 0.36 IU/kg/min, respectively. However, after administration of the 120 IU/kg dose, clearance was significantly less than that after the 40 IU/kg dose. The half-life of heparin averaged 53, 70, and 136 minutes after 40, 80, and 120 IU/kg, respectively, with significant differences observed between the low and high doses. In contrast to heparin, the area under the plasma concentration vs time curve for LPL activity increased less than proportionally with dose. Maximal LPL activity observed was independent of dose, averaging 4.8 mumol of free fatty acids/ml/h. The APTT was significantly prolonged for 120 minutes after administration of the 40 IU/kg dose. Correlation coefficients for LPL activity vs either plasma heparin concentration or APTT were less than 0.7, indicating that neither laboratory measure can be used to accurately predict plasma LPL activity.

New in-vivo techniques for measuring lipoprotein metabolism

Stable, nonradioactive tracer techniques have provided a safe means of studying in-vivo lipoprotein metabolism, and endogenous labelling with amino acids has allowed apolipoprotein synthesis to be analysed directly. Recent studies have dealt with experimental design, mass spectrometry techniques and the validity of simple formulae used to derive primary kinetic data. Concerns that stable isotopes give different results to the traditional radiolabelling studies have been allayed, in the case of apolipoprotein A-I, by published work. Studies conducted during the review period have also examined the mechanisms responsible for the low plasma concentrations of apolipoprotein A-I and apolipoprotein A-II in lecithin:cholesterol acyltransferase deficiency and the increased concentrations of HDL-apolipoprotein A-I caused by transdermal oestrogen hormone replacement therapy. The first analysis of lipoprotein-lipid rather than lipoprotein-apolipoprotein metabolism using stable isotopes has also been reported.

Use of oral and intravenous fat tolerance tests to assess plasma chylomicron clearance in dogs

The reduced clearance of chylomicrons from plasma results in an exaggerated post prandial lipaemia and fasting hypertriglyceridaemia. This study evaluated whether oral and intravenous fat tolerance tests are appropriate for the in vivo analysis of chylomicron clearance in dogs. Plasma and chylomicron triglyceride concentrations were measured in eight beagles after the administration of a cream-based meal of 2.35 g fat kg-1 bodyweight. The changes in each parameter were determined chiefly by the activity of lipoprotein lipase, which was measured in plasma collected after the intravenous injection of heparin and did not appear to be influenced by intestinal fat absorption. The inclusion of retinyl palmitate in the meal provided additional information on the metabolic fate of chylomicron remnants. After the intravenous injection of 0.1 g Intralipid kg-1 bodyweight, there was an initial linear decay in plasma triglyceride concentrations that represented the maximal elimination rate K1. This was followed by a second exponential component so that the plasma triglyceride concentration returned to baseline by 60 minutes. Lipoprotein lipase was the major determinant of K1 and the area under the curve of plasma triglycerides.

Measurement and physiological significance of lipoprotein and hepatic lipase activities in preheparin plasma

A radiochemical method for selective measurement of postheparin lipase activities was adapted to analyze lipoprotein lipase and hepatic lipase in preheparin plasma. The assay sensitivity was increased about four-fold by doubling both the volume of plasma used and the volume of lipolytic products taken for liquid scintillation counting, and was further improved by increasing the incubation period by 50% to 90 min. Rabbit antiserum to human hepatic lipase was unsuitable for the selective measurement of lipoprotein lipase because of apparent endogenous lipolytic activity. Preheparin hepatic lipase, however, was sensitive to inactivation by sodium dodecyl sulfate (SDS), the inhibition being greatest (> 90%) for plasma incubated with an equal volume of 40 mmol/L SDS. Intra- and interassay CVs for the two enzymes were 12.5-14.6% and 17.4-19.7%, respectively. In a cross-sectional study of 84 healthy subjects, pre- and postheparin hepatic lipase activities were higher in men than women, were correlated with indices of obesity, and were significantly correlated with one another, which explained the association of the former with plasma concentrations of high-density lipoprotein (HDL), HDL2, and small, dense low-density lipoproteins. There was no significant relationship between pre- and postheparin lipoprotein lipase activities, but the former were correlated with plasma concentrations of free fatty acids (FFA) and very-low-density lipoprotein. Apparently, preheparin activities of hepatic lipase, but not of lipoprotein lipase, may be a useful measure of the physiological function of "whole body" enzyme activity in cross-sectional and metabolic studies, where heparinization is not possible. Preheparin lipoprotein lipase activities, however, may reflect displacement of the enzyme by FFA and subsequent binding to remnants of triglyceride-rich lipoproteins.

Measurement and physiological significance of lipoprotein and hepatic lipase activities in preheparin plasma

A radiochemical method for selective measurement of postheparin lipase activities was adapted to analyze lipoprotein lipase and hepatic lipase in preheparin plasma. The assay sensitivity was increased about four-fold by doubling both the volume of plasma used and the volume of lipolytic products taken for liquid scintillation counting, and was further improved by increasing the incubation period by 50% to 90 min. Rabbit antiserum to human hepatic lipase was unsuitable for the selective measurement of lipoprotein lipase because of apparent endogenous lipolytic activity. Preheparin hepatic lipase, however, was sensitive to inactivation by sodium dodecyl sulfate (SDS), the inhibition being greatest (&gt; 90%) for plasma incubated with an equal volume of 40 mmol/L SDS. Intra- and interassay CVs for the two enzymes were 12.5-14.6% and 17.4-19.7%, respectively. In a cross-sectional study of 84 healthy subjects, pre- and postheparin hepatic lipase activities were higher in men than women, were correlated with indices of obesity, and were significantly correlated with one another, which explained the association of the former with plasma concentrations of high-density lipoprotein (HDL), HDL2, and small, dense low-density lipoproteins. There was no significant relationship between pre- and postheparin lipoprotein lipase activities, but the former were correlated with plasma concentrations of free fatty acids (FFA) and very-low-density lipoprotein. Apparently, preheparin activities of hepatic lipase, but not of lipoprotein lipase, may be a useful measure of the physiological function of "whole body" enzyme activity in cross-sectional and metabolic studies, where heparinization is not possible. Preheparin lipoprotein lipase activities, however, may reflect displacement of the enzyme by FFA and subsequent binding to remnants of triglyceride-rich lipoproteins.

Development of methods for analyzing plasma lipoprotein concentrations and associated enzyme activities and their use to measure the effects of pregnancy and lactation in cats

Methods available for measurement of plasma lipoprotein-cholesterol concentrations and activities of lipoprotein lipase, hepatic lipase, lecithin:cholesterol acyl transferase (LCAT), and cholesteryl ester transfer protein were adapted for use in cats. A combined ultracentrifugation/precipitation procedure was used to isolate very low-density lipoproteins (VLDL), then to separate low-density lipoproteins (LDL) from high-density lipoproteins (HDL). The reagent used, 92 mM heparin-manganese chloride, provided complete precipitation of LDL with only trace and insignificant contamination by HDL. Efforts to selectively measure lipoprotein lipase activity in plasma, collected after IV injection of heparin, by inhibiting hepatic lipase with sodium dodecyl sulfate were unsuccessful, and the activity of this enzyme was calculated as the difference between total and hepatic lipase activities. The latter was measured in the presence of high salt concentration to inhibit lipoprotein lipase. Cholesterol esterifying activity was identified in feline plasma and was typical of LCAT, in that it was dependent on apolipoprotein A-I as a cofactor. The intra-assay and interassay coefficients of variation for measurement of lipoprotein lipase, hepatic lipase, and LCAT activities were 18.4, 4.6, and 7.2%, and 20.4, 10.7, and 5.3%, respectively. Appreciable cholesteryl ester transfer protein activity was not detected in either undiluted or diluted plasma. These methods were subsequently used to investigate the effects of pregnancy and lactation on lipoprotein metabolism in a group of 10 queens. Plasma concentrations of cholesterol and triglycerides were unaltered during pregnancy, but the concentrations of VLDL-cholesterol increased and those of HDL-cholesterol decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of LDL subfraction distribution and concentrations in young normolipidemic subjects

Human low-density lipoproteins (LDLs) comprise a spectrum of particles that vary in size, density, chemical composition, metabolic behavior, and atherogenicity. To identify determinants of this heterogeneity, we measured the percent distribution and plasma concentration of the three major LDL subfractions in 34 young healthy subjects. These parameters were correlated in univariate and multivariate analyses with various body and lifestyle factors; plasma lipids and lipoprotein; and the activities of cholesteryl ester transfer protein, lipoprotein lipase, and hepatic lipase (HL). Women (n = 15) had significantly more large, buoyant LDL (LDL-I; density, 1.025 to 1.034 g/mL) and high-density lipoprotein2 (HDL2) than men (n = 19). Both the percentage and concentration of LDL-I were correlated negatively with very-low-density lipoprotein triglycerides (VLDL-TG) and HL; they were correlated positively with HDL-cholesterol (HDL-C) and HDL2. In addition, percent LDL-I was negatively correlated with plasma triglycerides, VLDL-C, LDL-C, and apo-lipoprotein (apo) B concentrations. The concentrations of intermediate and small, dense LDL (LDL-II and LDL-III; density, 1.034 to 1.044 and 1.044 to 1.060 g/L, respectively) were positively correlated with LDL-C. LDL-III concentrations were also related to plasma cholesterol and apoB concentrations and HL activity. On multivariate analyses, approximately one third of the variability in LDL-I was explained by HL and plasma triglycerides. More than 80% of the variation in LDL-II was accounted for by a model that combined LDL-C and plasma apoB with body mass index and VLDL-TG.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma lipid transport in the horse (Equus caballus)

1. Equine plasma contains lipoproteins corresponding to very low density (VLDL), low density (LDL) and high density lipoproteins (HDL). 2. HDL accounts for approximately 60% of plasma lipoprotein mass and consists of a single population of particles. 3. LDL is heterogeneous comprising three discrete subfractions. 4. Two proteins are found in the region of apolipoprotein (apo) B-100 in VLDL and LDL and a third similar to apoB-48 is in VLDL. 5. Lecithin:cholesterol acyl transferase is active in plasma and hepatic lipase and lipoprotein lipase are evident in post-heparin plasma. 6. There is no significant cholesteryl ester transfer protein activity.

Effects of pregnancy and lactation on plasma lipid and lipoprotein concentrations, lipoprotein composition and post-heparin lipase activities in Shetland pony mares

The incidence of hyperlipaemia in ponies is highest in mares in late gestation and then early in lactation. Plasma lipid and lipoprotein concentrations were measured to establish the metabolic basis for this and the lipoprotein composition of six healthy Shetland ponies was analysed before pregnancy, in the last six weeks of gestation and one month after foaling. In the pregnant ponies, the concentrations of cholesterol and triglyceride were significantly increased (both P < 0.05) because of increased concentrations of high density lipoproteins (HDL) and very low density lipoproteins (VLDL), respectively (both P < 0.05). The VLDL were significantly enriched in triglyceride and depleted of protein (P < 0.05 in each case), with the majority of cholesterol in the free rather than esterified form. These changes appeared to reflect increased hepatic triglyceride synthesis and VLDL secretion because the activities of lipoprotein lipase and hepatic lipase, the enzymes responsible for the catabolism of VLDL and their remnants, were unaltered. After foaling, the concentrations of triglyceride and VLDL decreased significantly (both P < 0.05) because of increased lipoprotein lipase activity consistent with the induction of the enzyme in mammary tissue to provide for milk fat synthesis. Plasma cholesterol and HDL concentrations remained high and non-esterified fatty acid concentrations were significantly increased (P < 0.05). The VLDL remained enriched in triglyceride but had normal cholesterol and protein compositions, although the mass of phospholipids was reduced. The changes in plasma VLDL concentration and composition found in the pregnant ponies mimicked those previously reported in ponies with hyperlipaemia and suggested a metabolic basis for the incidence of the disease in late gestation.

High density lipoprotein metabolism in the horse (Equus caballus)

1. Apolipoprotein A-I dependent lecithin:cholesterol acyl transferase (LCAT) activity was identified in equine lipoprotein deficient plasma (LPDP). 2. LCAT activity showed no breed or sex variation, and was unaltered postprandially. 3. There was no significant cholesteryl ester transfer activity in equine LPDP. 4. Hydrophobic interaction chromatography on phenyl sepharose failed to unmask transfer activity or identify an inhibitor of cholesteryl ester transfer. 5. In 12 Shetland ponies, plasma high density lipoprotein (HDL) concentrations were positively correlated with those of triglyceride, but not with the activities of LCAT, lipoprotein lipase or hepatic lipase.

Post-prandial lipoprotein metabolism in nephrotic syndrome

Post-prandial lipaemia was investigated in a group of nine subjects with nephrotic syndrome by following the concentrations of triglyceride and retinyl palmitate in the d < 1.006 g ml-1 fraction of plasma after a standard oral fat load containing vitamin A. Lipoprotein lipase and hepatic triglyceride lipase activities were measured in post-heparin plasma. Subjects with other renal disease but insignificant proteinuria acted as controls. The time course of the lipaemic response was similar in both groups although individual patients demonstrated a prolonged lipaemia. Overall, there were no significant differences in the rise in triglyceride at 6 h (nephrotic--median 2.53 mmol l-1; range 0.87-4.76 vs. control 1.88; 0.38-4.12, P = 0.34), the peak concentration of retinyl palmitate (nephrotic 0.87 mg dl-1; 0.27-2.16 vs. control 0.65; 0.24-1.89, P = 0.97) or the areas under the curve from 0-24 h for triglyceride (nephrotic 10.5 mmol. h l-1; 2.9-43.6 vs. control 9.7; 4.3-27.0, P = 1.0) or retinyl palmitate (5.5 mg.h dl-1; 1.0-23.4 vs. 4.3; 1.5-12.4, P = 0.7). At baseline, the particles in the d < 1.006 g ml-1 fraction of plasma from nephrotic subjects had a higher free cholesterol:phospholipid ratio but this difference was no longer apparent 6 h after the test meal. There were no differences in total heparin-releasable lipase, lipoprotein lipase or hepatic triglyceride lipase activities between the two groups. These data suggest that impaired clearance of chylomicrons is not a major contributor to nephrotic hyperlipidaemia in man.

Plasma lipids, lipoproteins and post-heparin lipases in ponies with hyperlipaemia

The metabolic origins of equine hyperlipaemia were investigated by analysing the concentration and composition of plasma lipoproteins in 18 ponies with the condition. The mean concentrations of cholesterol, triglyceride and very low density lipoproteins (VLDL) were increased by 4-, 52- and 19-fold, respectively, compared with a control group of 18 healthy ponies. These increases were due to the appearance of a buoyant VLDL fraction (VLDL1) not present in healthy ponies. The mean diameter of VLDL1 particles was 44% greater than control VLDL, and the particles were enriched in triglyceride and free cholesterol and depleted of cholesteryl esters, phospholipid and protein. The apolipoprotein (apo) B-100 content of VLDL1 was reduced and the ratio of apoB-100 to apoB-48 particles was 1:1, compared with 2:1 in control VLDL. The VLDL1 was also enriched in apoE, but had normal complements of apoC-II and apoC-III. The conventional VLDL (called VLDL2), LDL and HDL fractions were moderately enriched with triglyceride, and HDL contained increased amounts of apoE, apoC-II and apoC-III. The activities of lipoprotein lipase and hepatic lipase, the enzymes responsible for the catabolism of VLDL and their remnants, were increased by 2- and 3-fold, respectively, in response to the increased concentrations of their substrates. The composition of VLDL1 suggested that the liver was maximising the secretion of triglyceride by producing larger number of VLDL particles that accommodated a greater mass of triglyceride by having apoB-48 rather than apoB-100 as their structural protein. Plasma free fatty acid (FFA) concentrations were elevated in 17 of the 18 ponies, suggesting that increased FFA flux might be the stimulus for hepatic triglyceride synthesis and VLDL secretion. We conclude that overproduction, rather than defective catabolism, of VLDL was the cause of the hyperlipidaemia and that lipid lowering agents which reduce VLDL synthesis, by decreasing adipose lipolysis and FFA flux, are candidates for the management of hyperlipaemia.

Equine hyperlipaemia in the United Kingdom: clinical features and blood biochemistry of 18 cases

The background, clinical signs, blood biochemistry and management of 18 cases of equine hyperlipaemia are described. Eleven of the animals were Shetland ponies, four were Welsh mountain ponies or their crosses, one was a fell pony and two were riding ponies of mixed breeding. Their average age was nine years. Fourteen of the cases were mares, of which nine were in foal and two were lactating; the remainder were geldings. Underlying or concurrent diseases were identified in only six animals, but in one other animal the hyperlipaemia appeared to have been precipitated by stress, and in another by undernutrition to prevent laminitis. Twelve of the animals were considered obese. There was no age, seasonal, or geographic bias to the distribution of cases. Plasma triglyceride concentrations were increased by between five- and 80-fold, and ranged from 4.7 to 78.8 mmol/litre. There was biochemical evidence of hepatic damage in 17 cases, of renal insufficiency in 15, and pancreatic pathology in three cases. Four animals were euthanased without therapy. The others were treated with oral glucose solutions, which were supplemented with injections of insulin and heparin in four cases, and insulin alone in two cases. Eight of the treated animals died, to give an overall mortality of 67 per cent. The outcome of the treatment was unrelated to the degree of hypertriglyceridaemia, to the presence and severity of hepatic, renal or pancreatic pathology or to the therapeutic regimen.

Selective measurement of lipoprotein lipase and hepatic triglyceride lipase in heparinized plasma from horses

Affinity chromatography on heparin sepharose was used to identify 2 lipolytic enzymes in heparinized plasma from horses. One enzyme was typical of hepatic triglyceride lipase (HTGL), because it was resistant to inactivation by high concentrations of NaCl, and it did not require the addition of serum for activity. The other enzyme was identified as lipoprotein lipase (LPL), because of its inactivation at NaCl concentrations in excess of 0.2M, and its dependency on addition of serum as a source of apolipoprotein C-II activator. The enzymes were purified by 347-(HTGL) and 442- (LPL) fold, with yields of 54 and 58%, respectively. The partially purified enzymes were used to design incubation conditions that gave optimal activities for each enzyme in vitro. A selective assay was then developed for direct measurement of LPL and HTGL activities in heparinized plasma from horses. Analysis of HTGL took advantage of the almost complete inactivation of LPL when serum cofactor was excluded from the assay at the NaCl concentration that gave optimal HTGL activity. Prior incubation of heparinized plasma with sodium dodecyl sulfate to inhibit HTGL was necessary for measurement of LPL, because HTGL retained 67% of its activity at the NaCl concentration required for optimal LPL activity. Activity of each enzyme was measured in heparinized plasma from 12 Shetland ponies. The mean activity +/- SD for LPL was 3.22 +/- 1.04 mumol of fatty acids/ml of heparinized plasma/h (mumol of FA/ml/h. The mean activity for HTGL was 4.9 +/- 1.56 mumol of FA/ml/h. The performance of the assay was assessed by replicate analysis of pools of each enzyme with high and low activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic valvular dysplasia in a calf

Aortic valvular dysplasia, a congenital abnormality not previously reported in cattle, was diagnosed in a calf with a pulsating mass at the base of its neck, an enlarged area of cardiac dullness and a loud (grade IV/V) systolic cardiac murmur. Electrocardiography and thoracic radiography demonstrated that the left atrium and ventricle were enlarged. Dysplasia of two aortic valve cusps and post stenotic dilatation of the ascending aorta were identified by echocardiography and confirmed post mortem.

The isolation, characterisation and quantification of the equine plasma lipoproteins

Plasma lipoproteins were isolated from eight Thoroughbred horses and eight Shetland ponies on the basis of particle size by gel filtration chromatography and according to density using rate-zonal ultracentrifugation. Three major classes corresponding to very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high density lipoproteins (HDL) were identified and characterised by their lipid and apolipoprotein compositions. The particle size distributions of each class were determined by electron microscopy and non-denaturing polyacrylamide gradient gel electrophoresis. HDL was found to dominate the equine lipoprotein spectrum, accounting for 61 per cent of the total plasma lipoprotein mass (VLDL 24 per cent, LDL 15 per cent). The VLDL class was isolated as a single population of particles that were triglyceride rich and cholesterol, phospholipid and protein poor. Equine LDL was characteristically cholesterol rich and was found to be polydisperse comprising three subfractions that were discrete with respect to particle size and lipid composition. The HDL class was composed of homogeneous particles that were typically protein rich. Apolipoprotein (apo) B was the major protein of VLDL and LDL, and presented two components on polyacrylamide gel electrophoresis with molecular weights in the region of human apoB-100 and a third in VLDL similar to that of apoB-48. ApoA-I was the predominant protein in equine HDL. Although there were no breed differences in the physical or chemical properties of each lipoprotein class, the Shetland ponies had higher plasma triglyceride and VLDL concentrations than their Thoroughbred counterparts.

Effects of detomidine on equine oesophageal function as studied by contrast radiography

The effects of sedation with detomidine on oesophageal function were assessed by contrast radiography in 10 healthy adult thoroughbred horses. Barium swallows were monitored by means of image intensification, first without sedation and then after the intravenous administration of detomidine at doses of 10 and 20 micrograms/kg bodyweight. The transit time of contrast agent to the oesophageal hiatus was recorded and each swallow was scored for markers of oesophageal dysfunction. Analysis of the data indicated that there were highly significant dose dependent increases in the transit time, the retention of barium within the longitudinal mucosal folds, and retrograde peristalsis and pooling of contrast agent within the oesophagus at both the thoracic inlet and caudal to the base of the heart. The degree of gastrooesophageal reflux was not affected at either dosage. These changes in oesophageal function were similar to those recorded from cases of grass sickness and indicate that care should be taken in the interpretation of studies of swallowing in animals that have been given detomidine before a radiographic examination.

An investigation of the relationships between body condition and plasma lipid and lipoprotein concentrations in 24 donkeys

Obese donkeys are susceptible to a hyperlipaemic crisis characterised by high plasma triglyceride concentrations. In this study, the relationships between the body condition of 24 donkeys and their basal lipid metabolism were investigated. Plasma cholesterol, triglyceride and lipoprotein cholesterol concentrations were measured in healthy donkeys classified according to their body condition as thin, ideal or obese. There were significant differences between the groups in the concentrations of triglyceride and very low density lipoprotein (VLDL), which increased in concentration with body condition (P less than 0.05). Cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) concentrations were similar in all the groups. Triglyceride and VLDL concentrations were positively correlated with body weight (r = 0.82) and plasma free fatty acid concentration (r = 0.48). There were no significant differences in basal plasma concentrations of insulin or cortisol. These results suggest that obesity in donkeys is associated with changes in lipid and lipoprotein metabolism that might predispose the animals to hyperlipaemia.

Juvenile bovine angiomatosis: a syndrome of young cattle

This report describes the clinical and pathological features associated with angiomatous lesions in two calves. In the first case, a single mass located in the atrioventricular ring of the heart was responsible for congestive cardiac failure. The mass was composed of numerous vascular cavities filled with blood and lined by a single layer of well differentiated endothelial cells. The second case had multiple blood-filled cutaneous masses which were confirmed as benign vascular tumours by histological examination of a biopsy specimen. The calf was later euthanased after profuse and uncontrollable haemorrhage from one of the lesions. At necropsy, additional tumours were found in the liver, spleen, kidneys, spinal canal and attached to the pleura, omentum and mesentery. It is proposed that these two cases are representatives of solitary and multiple forms of a syndrome which should be called juvenile bovine angiomatosis.

Objective benefit of nifedipine in the treatment of Raynaud's phenomenon. Double-blind controlled study

To compare the effects of the calcium channel antagonist, nifedipine, with that of placebo, a randomized double-blind crossover study was performed in 11 patients with moderate to severe Raynaud's phenomenon. Digital skin temperature recovery time was measured after immersing the patient's hand in ice water for 20 seconds. Patients were randomly assigned to receiving either nifedipine or placebo for one week, followed by the crossover phase. Skin temperature recovery time was also measured in 21 normal volunteers. The mean time to recovery for patients taking nifedipine was 28.5 +/- 20.8 minutes versus 44.9 +/- 18.9 minutes for patients receiving placebo (p less than 0.05 by analysis of variance with repeated measures). The mean time to recovery for the normal volunteers was 11.3 +/- 7.2 minutes versus 40.2 +/- 19.9 minutes for the patients (p less than 0.01 by the Student t test). Nine of the 11 patients noted improvement of symptoms during treatment with nifedipine. It is concluded that nifedipine is an effective, well-tolerated treatment for Raynaud's phenomenon.

Echocardiographic evaluation of the St. Jude medical prosthetic valve

M-mode and two-dimensional echocardiographic studies were performed on 19 patients with 25 normally functioning St. Jude Medical prosthetic cardiac valves, in an attempt to define the normal echocardiographic appearance of this new cardiac prosthesis. Satisfactory M-mode echocardiograms were obtained in 17 of the 19 patients, and satisfactory two-dimensional studies were obtained in all. M-mode measurements included the diameter of the orifice ring, leaflet separation, and the opening and closing slopes of the leaflets. The values obtained compared favorably with direct measurements from the prosthesis and were reasonably reproducible. Two-dimensional imaging revealed characteristic systolic and diastolic patterns and provided direct visualization of valvular motion. Echocardiographic evaluation of the prosthesis can be facilitated if it is positioned at implantation so that the open leaflets are perpendicular to the echocardiographic plane of the long axis of the ventricle.

A new single-position supine approach to sciatic-femoral nerve block

To overcome the disadvantages of other methods, the authors have devised a procedure for below-the-knee operations, involving a new technic of sciatic-femoral nerve block. The technic has so far been successful without use of adjuvant agents in 90 percent of over 100 patients so handled.