Measurement of muscle mass in humans: validity of the 24-hour urinary creatinine method

Measuring muscle mass is an important component of the nutritional assessment examination and a suggested index of this body space is the 24-h urinary excretion of creatinine. The method originated from studies in a variety of animal species in whom early workers found a parallelism between total body creatine and urinary excretion of creatinine. Assuming that nearly all creatine was within muscle tissue, that muscle creatine content remained constant and that creatinine was excreted at a uniform rate, an obvious "corollary" was that urinary creatinine was proportional to muscle mass. The so-called "creatinine equivalence" (kg muscle mass/g urinary creatinine) ranged experimentally from 17 to 22. One of the limiting factors in firmly establishing this constant and its associated variability was (and is) the lack of another totally acceptable noninvasive technique of measuring muscle mass to which the creatinine method could (or would) be compared. An improved understanding of creatine metabolism and a variety of clinical studies in recent years has tended to support the general validity of this approach. However, specific conditions have also been established in which the method becomes either inaccurate or invalid. While creatinine excretion may serve as a useful approximation of muscle mass in carefully selected subjects, there remains a need for accurate and practical indices of muscle mass for use in the individuals in whom the method cannot be reliably applied.

Anthropometric measurement of muscle mass: revised equations for calculating bone-free arm muscle area

Arm muscle area (AMA, cm2) is currently calculated from triceps skinfold thickness (TSF, cm), and midarm circumference (MAC, cm). In assessing the accuracy of the current equation by comparison to AMA measured by computerized axial tomography, error in each of the four approximations made was found to result in a 20 to 25% overestimate of AMA. Two correctible error sources were: a 10 to 15% overestimation caused by assuming a circular midarm muscle compartment and a 5 to 10% overestimation due to inclusion of midarm cross-sectional bone area. Corrected AMA equations for men and women were respectively: [(MAC - pi x TSF)2/4 pi] - 10, and [MAC - pi x TSF)2/4 pip] - 6.5. With two additional study groups, the overall improved accuracy of the new equations was confirmed, although the average error for a given patient was 7 to 8%; the relationship between corrected AMA and total body muscle mass was established [muscle mass (kg) = (ht, cm2) (0.0264 + 0.0029 x corrected AMA)]; and the minimal range of corrected AMA values compatible with survival (9 to 11 cm2) was defined. Bedside estimates of undernutrition severity and prognosis can therefore be calculated from two simple measurements, TSF and MAC.

MCP-1, MCP-2 and MCP-3 expression in multiple sclerosis lesions: an immunohistochemical and in situ hybridization study

Chemokines are low molecular weight chemotactic cytokines that have been shown to play a central role in the perivascular transmigration and accumulation of specific subsets of leukocytes at sites of tissue damage. Two major families have been defined depending on the positioning of four conserved cysteines. The CXC chemokines predominantly attract neutrophils, whereas the CC chemokines predominantly attract monocytes and other leukocyte cell types. Members of the monocyte chemotactic protein (MCP)-1 family form a major component of the CC family of chemokines and are considered the principal chemokines involved in the recruitment of monocytes/macrophages and activated lymphocytes. In this study we addressed the expression and distribution of MCP-1, -2 and -3 in multiple sclerosis (MS) lesions of differing ages and levels of inflammatory activity using immunohistochemistry and in situ hybridization. In acute and chronic-active MS lesions immunoreactivity for MCP-1, -2 and -3 was prominent throughout the lesion center with reactivity diminishing abruptly at the lesion edge. Hypertrophic astrocytes were strongly reactive and inflammatory cells showed variable reactivity. Outside of the lesion only hypertrophic astrocytes were reactive. The results obtained by in situ hybridization for MCP-1 were in agreement with those obtained by immunostaining. In more chronic lesions immunoreactivity for MCP-1, -2 and -3 was considerably diminished, and in chronic-silent lesions immunoreactivity was restricted to a few scattered reactive astrocytes. Normal control brains showed no immunoreactivity for MCP-1, -2 and -3. Although the cellular distribution of all three members of this family was similar, antibodies to MCP-3 gave prominent staining of the extracellular matrix that was not noted for MCP-1 and -2. These results support the conclusion that members of the MCP family of chemokines are involved in the development of MS lesions in the central nervous system.

A neurological basis for visual discomfort

Certain patterns of stripes are judged to be unpleasant to look at. They induce illusions of colour, shape and motion that are sometimes perceived predominantly to one side of fixation. People who suffer frequent headaches tend to report more illusions, and if the pain consistently occurs on the same side of the head the illusions tend to be lateralized. The parameters of the patterns that induce illusions (including their shape, spatial frequency, duty cycle, contrast and cortical representation) closely resemble those that elicit epileptiform electroencephalographic abnormalities in patients with photosensitive epilepsy. The viewing conditions under which such abnormalities are likely to appear are also those under which more illusions are seen.

HIV-1 gp120 and chemokines activate ion channels in primary macrophages through CCR5 and CXCR4 stimulation

HIV type 1 (HIV-1) uses the chemokine receptors CCR5 and CXCR4 as coreceptors for entry into target cells. Here we show that the HIV-1 envelope gp120 (Env) activates multiple ionic signaling responses in primary human macrophages, which are important targets for HIV-1 in vivo. Env from both CCR5-dependent JRFL (R5) and CXCR4-dependent IIIB (X4) HIV-1 opened calcium-activated potassium (K(Ca)), chloride, and calcium-permeant nonselective cation channels in macrophages. These signals were mediated by CCR5 and CXCR4 because macrophages lacking CCR5 failed to respond to JRFL and an inhibitor of CXCR4 blocked ion current activation by IIIB. MIP-1beta and SDF-1alpha, chemokine ligands for CCR5 and CXCR4, respectively, also activated K(Ca) and Cl(-) currents in macrophages, but nonselective cation channel activation was unique to gp120. Intracellular Ca(2+) levels were also elevated by gp120. The patterns of activation mediated by CCR5 and CXCR4 were qualitatively similar but quantitatively distinct, as R5 Env activated the K(Ca) current more frequently, elicited Cl(-) currents that were approximately 2-fold greater in amplitude, and elevated intracellular Ca(+2) to higher peak and steady-state levels. Env from R5 and X4 primary isolates evoked similar current responses as the corresponding prototype strains. Thus, the interaction of HIV-1 gp120 with CCR5 or CXCR4 evokes complex and distinct signaling responses in primary macrophages, and gp120-evoked signals differ from those activated by the coreceptors' chemokine ligands. Intracellular signaling responses of macrophages to HIV-1 may modulate postentry steps of infection and cell functions apart from infection.

Sensitivity to the displacement of facial features in negative and inverted images

Subjects have previously been reported to show difficulties in recognising faces which are either inverted or in photographic negative. Experiments are reported in which a two-alternative forced-choice technique was used to measure sensitivity for distinguishing faces which have been modified by having the eyes moved vertically or horizontally. Subjects were less sensitive to such changes for inverted faces or negative faces, and were even less sensitive for faces that were both inverted and negative. No such effects were found for a control stimulus consisting simply of three solid circles in the same positions as the eyes and mouth of a face. When the stimuli consisted of eyes, nose, and mouth, but without a surround, no evidence of inversion or negation effects was found, which suggests that a facial surround is necessary. When the stimulus consisted of a facial surround with the eyes, nose, and mouth replaced by solid circles, effects of negation were found, but no effects of inversion. This dissociation of the effects of negation and inversion may suggest that they are the result of different underlying mechanisms.

Stereotastic radiosurgery for glomus jugulare tumors

OBJECTIVES/HYPOTHESIS

Surgery is considered to be the mainstay of treatment for glomus jugulare tumors. A subset of patients are poor surgical candidates based on age, medical problems, tumor size, or prior treatment failure. The purpose of this study was to review our results with stereotactic radiosurgery (gamma knife treatment) in this group of patients, with particular attention to adverse reactions and symptom relief.

STUDY DESIGN

Retrospective review and phone survey.

METHODS

Charts were reviewed for size and location of tumor, history of previous treatment, symptoms before and after treatment, amount of radiation received, acute and late complications, and functional level before and after treatment. Pre-treatment and posttreatment magnetic resonance imaging scans were also reviewed. Identified patients were then contacted for a phone interview.

RESULTS

Eight patients were identified. Phone interviews were conducted with four patients. Four patients had failed previous treatment. Follow-up ranged from 7 to 104 months. One patient experienced an acute complication: intractable vertigo requiring hospitalization. No patient experienced delayed cranial neuropathies. No patient reported worsening of any of the following symptoms: pulsatile tinnitus, hearing loss, facial weakness, hoarseness, or difficulty swallowing. Three patients reported improvement in their pulsatile tinnitus. Two patients reported improvement in hearing loss, and one patient each reported improvement in vertigo and difficulty swallowing.

CONCLUSIONS

Preliminary results suggest that stereotactic radiosurgery is useful to control symptoms and may be delivered safely in patients with primary or recurrent glomus jugulare tumors who are poor surgical candidates.

Self-criticism in adulthood and recalled childhood experience

We investigated in a sample of 75 medical students the hypothesis that higher levels of self-criticism, a major vulnerability factor for depression, are related to retrospective reports of less satisfactory parenting, even when the potentially confounding factors of mood state and social desirability response set are controlled. At each of 2 measurement times, there were significant cross-sectional correlations between parental ratings and both depression and self-criticism, but the associations with self-criticism were no longer significant when depression was controlled. However, even after controlling for the effects of mood state and social desirability, persons with high levels of self-criticism at both measurement points (high trait self-criticism subjects) reported significantly worse relationships with their mothers than did the remaining subjects. They were also more likely to report below average relationships with both parents jointly.

Biochemical composition of muscle in normal and semistarved human subjects: relevance to anthropometric measurements

Anthropometric methods aimed at assessing muscle size in undernourished subjects assume a constant proportionality between the mass (i.e., size) and composition (specifically protein-energy content) of this tissue. This assumption was examined in three autopsy groups: controls (n = 11, sudden traumatic death), early semistarvation (n = 6), acute preterminal disease), and chronic semistarvation (n = 34, severe weight loss over time). Results of semistarved groups were expressed relative to respective control value. Early semistarvation produced no detectable change in muscle mass, protein, or total energy content (per gram wet weight), although RNA and glycogen were -50 to -70% of control value (p less than 0.05). Chronic semistarvation caused muscle atrophy (-54.2%), but not all measured constituents were reduced to the same degree. The results were H2O--52.9%, collagen--46%, noncollagen proteins--65.3%, total lipids--40%, DNA--54.1%, RNA--81.7%, glycogen--90.3%, and total energy--59.6%. Muscle per unit mass in chronic semistarvation thus reflects relatively more H2O and less protein and energy when compared to normal tissue. About 85 to 95% of muscle protein-energy loss can be detected by anthropometric measurements of muscle size; the remaining 5 to 15% depletion of protein and energy is masked by muscle compositional changes. Proper interpretation of anthropometric data requires an understanding of these unmeasured but important compositional differences in normal and semistarved muscle.

Fourth report of the cooperative, open-ended study of slowly growing mycobacteria by the International Working Group on Mycobacterial Taxonomy

The open-ended study of the International Working Group on Mycobacterial Taxonomy is an ongoing project to characterize slowly growing strains of mycobacteria that do not belong to well-established or thoroughly characterized species. In this fourth report we describe two numerical taxonomic clusters that represent subspecies or biovars of Mycobacterium simiae, one cluster that encompasses the erstwhile type strain of the presently invalid species "Mycobacterium paraffinicum," one cluster that is phenotypically very similar to Mycobacterium avium and Mycobacterium intracellulare but may be a separate genospecies, one cluster that appears to be phenotypically distinct from M. avium but reacts with a nucleic acid probe specific for M. avium, and three tentatively defined clusters in proximity to a cluster that encompasses the type strain of Mycobacterium malmoense. Of special practical interest is the fact that one of the latter three clusters is composed of clinically significant scotochromogenic bacteria that can be misidentified as the nonpathogenic organism Mycobacterium gordonae if insufficient biochemical tests are performed.

LetB Structure Reveals a Tunnel for Lipid Transport across the Bacterial Envelope

Gram-negative bacteria are surrounded by an outer membrane composed of phospholipids and lipopolysaccharide, which acts as a barrier and contributes to antibiotic resistance. The systems that mediate phospholipid trafficking across the periplasm, such as MCE (Mammalian Cell Entry) transporters, have not been well characterized. Our ~3.5 Å cryo-EM structure of the E. coli MCE protein LetB reveals an ~0.6 megadalton complex that consists of seven stacked rings, with a central hydrophobic tunnel sufficiently long to span the periplasm. Lipids bind inside the tunnel, suggesting that it functions as a pathway for lipid transport. Cryo-EM structures in the open and closed states reveal a dynamic tunnel lining, with implications for gating or substrate translocation. Our results support a model in which LetB establishes a physical link between the two membranes and creates a hydrophobic pathway for the translocation of lipids across the periplasm.

Clinical and microbial evaluation of a histatin-containing mouthrinse in humans with experimental gingivitis

OBJECTIVE

P-113, a 12 amino acid histatin-based peptide, was evaluated in a mouthrinse formulation for safety, prevention of the development of experimental gingivitis, and for its effects on periodontal flora.

METHOD

159 periodontally healthy subjects abstained from oral hygiene procedures and self-administered either 0.005%, 0.01%, 0.05% P-113 or placebo mouthrinse formulations twice daily over a four week treatment period. During this time, the safety, anti-plaque, and anti-gingivitis effects of P-113 were evaluated.

RESULTS

There was a significant reduction in plaque (p=0.046) and a reduction in gingivitis (p=0.086) for subjects using 0.01% P-113 mouthrinse. Significantly more subjects in the 0.01% and 0.05% treatment groups showed a small increase in plaque index of <0.25 as compared to the placebo group (p<0.05). Similar trends were noted for changes in the % of sites with bleeding on probing in the 0.01% P-113 group. There were no treatment-related adverse events, and there were no adverse shifts in supragingival microflora during the study.

CONCLUSION

These data suggest that P-113 mouthrinse is safe and reduces plaque, gingivitis and gingival bleeding in the human experimental gingivitis model.

Prospective longitudinal studies of salmonid alphavirus infections on two Atlantic salmon farms in Ireland; evidence for viral persistence

Prospective longitudinal studies of two outbreaks of pancreas disease in Atlantic salmon (AS), Salmo salar L., in Ireland were conducted. Both outbreaks occurred during the marine phase of production, with one caused by salmonid alphavirus subtype 1 (SAV1) and the other by SAV4. In addition to screening a range of tissues by real-time reverse transcriptase polymerase chain reaction (RRT-PCR), virological, serological and histopathological examinations were performed along with partial genome sequencing and results were related to environmental and production data and farm history. On Farm 1 (marine sampling only), infection was detected within 3 weeks of smolts being placed on the farm, while on Farm 2 (freshwater and marine sampling), infection was first detected 315 days after transfer to sea. In both outbreaks, RRT-PCR signals were detected in a range of tissues including gill, heart, kidney, pancreas/pyloric caeca, brain and serum. Persistence of signal was longest in gill and heart (> or =265 days on both farms) and shortest in serum. Mortalities on the two farms varied from 10.9% to 30%. In both cases, partial genome sequence of the causative viruses were identical to SAV strains detected in previous populations of AS on each of the study farms, including populations with which the study populations overlapped in time and space.

Handedness, anxiety and sex differences

Anxiety scores of 35 male and 35 female students (28 right-handers, 23 left-handers and 19 mixed-handers) were assessed in relation to the handedness classification of each individual. Females were found to show higher anxiety scores than were males; but in contradiction to previous findings, left-handers and mixed-handers were not found to be more anxious than right-handers. Extremes of handedness, however, were closely related to anxiety scores, with the strongly right-handed and the strongly left-handed both showing higher anxiety scores than those whose hand preferences were less extreme.

Psychological adjustment and family functioning in a group of British children with sickle cell disease: preliminary empirical findings and a meta-analysis

Sickle cell disease (SCD) is a family of inherited blood disorders of variable severity which have in common haemolytic anaemia, recurrent painful crises, end-organ failure and the risk of reduced life expectancy. In Britain, the condition predominantly occurs among families of African or Afro-Caribbean origin. This study examines the effects of the condition on the psychological adjustment and family functioning of 39 children with SCD and 24 control children. Participants were assessed on measures of behaviour, depression, self-esteem, IQ and reading skills, family relationships and maternal mental health. Assessment on the Family Environment Scale showed that SCD children came from families who reported more cohesion and less conflict than did the families of controls. Maternal mental health showed no significant differences between the SCD group and controls. Children with SCD showed an IQ deficit of five points, a difference that was not statistically significant. However, a meta-analysis of six studies in the literature, including this one, did show a highly significantly decreased intellectual ability. SCD children did not show significant differences from controls on measures of depression and self-esteem. However, differences in behavioural problems were found between the three groups, with the SC group showing more behavioural problems. Results of regression analyses suggest that maternal mental health is associated with children's behavioural problems.

Socio-economic deprivation and excess winter mortality and emergency hospital admissions in the South Yorkshire Coalfields Health Action Zone, UK

The aims of this study were to describe the pattern of excess winter mortality and emergency hospital admissions in the South Yorkshire Coalfields Health Action Zone, and to examine the relationship between excess winter mortality and emergency hospital admissions and socio-economic deprivation at the enumeration district level. We analysed monthly deaths from 1981 to 1999 and monthly emergency hospital admissions from 1990 to 1999 for cardiovascular disease, respiratory disease and all other causes of death for people aged 45 years and above. We used the enumeration district level Townsend socio-economic deprivation score to categorize enumeration districts by quintile. Excess winter mortality ratios (observed/expected) for females and males, respectively, were 1.70 and 1.58 for respiratory disease, 1.25 and 1.20 for cardiovascular disease, and 1.09 and 1.07 for all other causes of death. The excess winter hospital admission ratio for respiratory disease was 1.80 for females and 1.58 for males. No excess was evident for the other two groups of conditions. We found no significant increase in excess winter mortality ratios with increasing socio-economic deprivation. There was also no significant increase in the excess winter respiratory admission ratio with increasing deprivation. With regard to age, we found P<0.0001 and for all other diseases P>0.001 and also in the excess winter hospital admission ratio for respiratory disease P<0.0001 With regard to sex, the excess ratios were lower in men than in women for both respiratory mortality P<0.05 and respiratory hospital admissions P<0.0001 We also observed that excess winter mortality ratios decreased significantly over the 18-year period for cardiovascular disease P<0.05 and for all other diseases P<0.05. Our results suggest that measures to reduce excess winter mortality should be implemented on a population-wide basis and not limited to socio-economically deprived areas. There may also be a case for tailoring interventions to specifically meet the needs of older people.

Dynamics of genomic architecture during composite breed development in cattle

Some livestock breeds face the challenge of reduced genetic variation, increased inbreeding depression owing to genetic drift and selection. Hybridization can reverse these processes and increase levels of productivity and adaptation to various environmental stressors. Samples from American Brangus were used to evaluate the indicine/taurine composition through nine generations (~45 years) after the hybridization process was completed. The purpose was to determine how hybridization alters allelic combinations of a breed over time when genetic factors such as selection and drift are operating. Furthermore, we explored genomic regions with deviations from the expected composition from the progenitor breeds and related these regions to traits under selection. The Brangus composition deviated from the theoretical expectation, defined by the breed association, of 62.5% taurine, showing taurine composition to be 70.4 ± 0.6%. Taurine and indicine proportion were not consistent across chromosomes. Furthermore, these non‐uniform areas were found to be associated with traits that were probably under selection such as intermuscular fat and average daily gain. Interestingly, the sex chromosomes were predominantly taurine, which could be due to the composite being formed particularly in the final cross that resulted in progeny designated as purebred Brangus. This work demonstrated the process of new breed formation on a genomic level. It suggests that factors like genetic drift, selection and complementarity shift the genetic architecture into a uniquely different population. These findings are important to better understand how hybridization and crossbreeding systems shape the genetic architecture of composite populations.

Characterization of the live salmonid movement network in Ireland: Implications for disease prevention and control

Live fish movement is considered as having an important role in the transmission of infectious diseases. For that reason, interventions for cost-effective disease prevention and control rely on a sound understanding of the patterns of live fish movements in a region or country. Here, we characterize the network of live fish movements in the Irish salmonid farming industry during 2013, using social network analysis and spatial epidemiology methods, and identify interventions to limit the risk of disease introduction and spread. In the network there were 62 sites sending and/or receiving fish, with a total of 130 shipments (84 arcs) comprising approx. 17.2 million fish during the year. Atlantic salmon shipments covered longer distances than trout shipments, with some traversing the entire country. The average shipment of Atlantic salmon was 146,186 (SD 194,344) fish, compared to 77,928 (127,009) for trout, however, variability was high. There were 3 periods where shipments peaked (February-April, June-September, and November), which were related to specific stages of fish. The network was disconnected and had two major weak components, the first one with 39 nodes (mostly Atlantic salmon sites), and the second one with 10 nodes (exclusively trout sites). Correlation between in and out-degree at each site and assortativity coefficient were slightly low and non-significant: -0.08 (95% CI: -0.22, 0.06) and -0.13 (95% CI: -0.36, 0.08), respectively, indicating random mixing with regard to node degree. Although competing models also produced a good fit to degree distribution, it is likely that the network possesses both small-world and scale-free topology. This would facilitate the spread and persistence of infection in the salmon production system, but would also facilitate the design of risk-based surveillance strategies by targeting hubs, bridges or cut-points. Using Infomap community detection algorithms, 2 major communities were identified within the giant weak component, which were linked by only 4 nodes. Communities found had no correspondence with geographical zones within the country, which could potentially hinder the implementation of zoning strategies for disease control and eradication. Three significant spatial clusters of node centrality measures were detected, two in county Donegal (betweenness and outcloseness) and one in county Galway (incloseness), highlighting the importance of these locations as hot spots of highly central sites with a higher potential for both introduction and spread of infection. These results will assist in the design and implementation of measures to reduce the sanitary risks emerging from live fish trade within Ireland.

The factor structure of the BDI in facial pain and other chronic pain patients: a comparison of two models using confirmatory factor analysis

OBJECTIVES

1) To compare two measurement models of the BDI in chronic pain sufferers to see which provides the better fit; 2) to assess whether model fit differs for a facial pain sample compared to a sample of pain sufferers attending a multidisciplinary pain clinic; and 3) to establish which affective and somatic sub-scales of the BDI could be used in chronic pain research.

DESIGN

Two groups of chronic pain sufferers, a facial pain group, and a group attending a multidisciplinary pain clinic completed self-report questionnaires on pain (Multidimensional Pain Inventory), depression (BDI), and measures of anxiety and depression-related pain cognitions (the Spielberger State-Trait Anxiety Inventory and the Pain Cognitions Questionnaire). The measurement models of the BDI were tested using LISREL structural equation modelling and their construct validity examined using partial correlation analysis.

METHOD

A total of 173 people attending a multidisciplinary pain clinic and 157 patients attending a facial pain clinic completed self-report measures of pain and mood prior to their respective clinical consultations.

RESULTS

The model offered by Novy et al. (containing one affective factor 'Negative-attitude suicide' and two somatic factors 'Performance difficulty' and 'Physiological manifestations') fitted both pain groups better than the model offered by Williams and Richardson (containing one affective factor 'Self-reproach', one somatic factor 'Somatic disturbance' and one factor with a mixture of both affective and somatic items 'Sadness about health'). However, when the factors were allowed to correlate in the latter model, both models were broadly equivalent.

CONCLUSIONS

The two measurement models adequately fitted data in both pain samples when the factors were allowed to intercorrelate in the Williams and Richardson model. Both the affective scales offered by both models could be used in future research, although the somatic factor offered by the Williams and Richardson model offered much higher levels of internal reliability than either of those offered in the Novy et al. model. The findings are discussed in relation to the issue of depression in chronic pain.

Multivariate analyses for determining the association of field porcine fertility with sperm motion traits analysed by computer-assisted semen analysis and with sperm morphology

This study investigates the association of semen traits with boar fertility. The fertility outcome (farrowing rate - FR and total piglets born - TB) of 14 boars was obtained from a field trial conducted during 10 week of breeding period on a commercial farm using multiparous sows (n = 948) through single-sire mating with 2 × 10(9) motile sperm cells per artificial insemination (AI) dose. Sperm motion parameters, evaluated with computer-assisted semen analysis system in raw and stored semen at 17°C for 240 h, in addition to morphological sperm defects, measured on the collection day, were included in the analysis to determine which semen traits were important to discriminate the fertility potential of ejaculates from these boars. The data underwent multivariate cluster, canonical and discriminant analyses. Four clusters of boars were formed based on fertility outcome. One boar, with the lowest FR and TB values (89.7% and 11.98), and two boars, with the highest FR and TB values (97.8% and 14.16), were placed in different clusters. The other boars were separated in two distinct clusters (four and seven boars), including boars with intermediate TB (12.64 and 13.22) but divergent values for FR (95.9% vs 91.8%). Semen traits with higher discriminatory power included total motility, progressive motility, amplitude of lateral head displacement and cytoplasmatic droplets. Through multivariate discriminant analysis, more than 80% of the 140 ejaculates were correctly classified into their own group, showing that this analysis may be an efficient statistical tool to improve the discrimination of potential fertility of boars. Nevertheless, the validation of the relationship between fertility and semen traits using this statistical approach needs to be performed on a larger number of farms and with a greater number of boars.

Nutrient bioavailability from nasojejunally administered enteral formulas: comparison to solid food

The net absorption and retention of energy, fat, nitrogen, and six elements (potassium, phosphorus, calcium, magnesium, sodium, and chloride) from two intrajejunally infused enteral formulas were compared to solid food. Undernourished patients (group 1) underwent two consecutive 7-day balance studies on a predigested protein-low fat (elemental) formula and an intact protein-standard fat (polymeric) formula, the initial diet selected randomly. Periods were isocaloric and isonitrogenous, but differed in the amounts of remaining elements. The undernourished patients in group 2 ate a solid food standard hospital diet for the 7-day balance study in an amount equal in energy and protein to group 1. There were no major differences in the nutrient absorption between the three diets. Nitrogen balance was similar for the two formulas (mean +/- SD) (elemental 6.1 +/- 3.5 g/day; polymeric 4.8 +/- 3.2 g/day) and solid food (5.2 +/- 3.5 g/day), and the balance for the six remaining elements was approximately proportional to the amount supplied. Subjective tolerance of both formulas was good, with a tendency for superior tolerance of the polymeric formula. We conclude that for the nutrients investigated, 1) intrajejunally administered enteral formulas are capable of renourishing hospitalized patients with an efficacy similar to that of solid food, and 2) predigestion of the formula does not improve absorption.

Transitional choice behavior in concurrent-chain schedules

The choice responses of four pigeons were examined in 20 periods of transition in a concurrent-chain procedure with variable-interval schedules as initial links and fixed delays to reinforcement as terminal links. In some conditions, the delays to reinforcement were different for the two terminal links, and changes in preference were recorded after the delays for the two response keys were switched. In other conditions, the reinforcer delays were equal for the two keys, but which key delivered 80% of the reinforcers was periodically switched. Choice proportions changed more quickly after a switch in reinforcement percentages than after a switch in the delays, thereby contradicting the hypothesis that faster changes would occur when the switch in conditions was easier to discriminate. Analyses of response sequences showed that the effects of individual reinforcers were larger and lasted longer in conditions with changing reinforcement percentages than in conditions with changing terminal-link delays. Rates of change in choice behavior do not appear to be limited by the unpredictability of variable reinforcement schedules, because the changes in behavior were slow and gradual even when there was a large and sudden change in reinforcer delays.