The impact of feeding growing-finishing pigs with daily tailored diets using precision feeding techniques on animal performance, nutrient utilization, and body and carcass composition

The impact of moving from conventional to precision feeding systems in growing-finishing pig operations on animal performance, nutrient utilization, and body and carcass composition was studied. Fifteen animals per treatment for a total of 60 pigs of 41.2 (SE = 0.5) kg of BW were used in a performance trial (84 d) with 4 treatments: a 3-phase (3P) feeding program obtained by blending fixed proportions of feeds A (high nutrient density) and B (low nutrient density); a 3-phase commercial (COM) feeding program; and 2 daily-phase feeding programs in which the blended proportions of feeds A and B were adjusted daily to meet the estimated nutritional requirements of the group (multiphase-group feeding, MPG) or of each pig individually (multiphase-individual feeding, MPI). Daily feed intake was recorded each day and pigs were weighed weekly during the trial. Body composition was assessed at the beginning of the trial and every 28 d by dual-energy X-ray densitometry. Nitrogen and phosphorus excretion was estimated as the difference between retention and intake. Organ, carcass, and primal cut measurements were taken after slaughter. The COM feeding program reduced (P < 0.05) ADFI and improved G:F rate in relation to other treatments. The MPG and MPI programs showed values for ADFI, ADG, G:F, final BW, and nitrogen and phosphorus retention that were similar to those obtained for the 3P feeding program. However, compared with the 3P treatment, the MPI feeding program reduced the standardized ileal digestible lysine intake by 27%, the estimated nitrogen excretion by 22%, and the estimated phosphorus excretion by 27% (P < 0.05). Organs, carcass, and primal cut weights did not differ among treatments. Feeding growing-finishing pigs with daily tailored diets using precision feeding techniques is an effective approach to reduce nutrient excretion without compromising pig performance or carcass composition.

DNA fingerprinting of Mycobacterium leprae strains using variable number tandem repeat (VNTR) - fragment length analysis (FLA)

The study of the transmission of leprosy is particularly difficult since the causative agent, Mycobacterium leprae, cannot be cultured in the laboratory. The only sources of the bacteria are leprosy patients, and experimentally infected armadillos and nude mice. Thus, many of the methods used in modern epidemiology are not available for the study of leprosy. Despite an extensive global drug treatment program for leprosy implemented by the WHO¹, leprosy remains endemic in many countries with approximately 250,000 new cases each year.² The entire M. leprae genome has been mapped^3,4 and many loci have been identified that have repeated segments of 2 or more base pairs (called micro- and minisatellites).⁵ Clinical strains of M. leprae may vary in the number of tandem repeated segments (short tandem repeats, STR) at many of these loci.^5,6,7 Variable number tandem repeat (VNTR)⁵ analysis has been used to distinguish different strains of the leprosy bacilli. Some of the loci appear to be more stable than others, showing less variation in repeat numbers, while others seem to change more rapidly, sometimes in the same patient. While the variability of certain VNTRs has brought up questions regarding their suitability for strain typing^7,8,9, the emerging data suggest that analyzing multiple loci, which are diverse in their stability, can be used as a valuable epidemiological tool. Multiple locus VNTR analysis (MLVA)¹⁰ has been used to study leprosy evolution and transmission in several countries including China^11,12, Malawi⁸, the Philippines^10,13, and Brazil¹⁴. MLVA involves multiple steps. First, bacterial DNA is extracted along with host tissue DNA from clinical biopsies or slit skin smears (SSS).¹⁰ The desired loci are then amplified from the extracted DNA via polymerase chain reaction (PCR). Fluorescently-labeled primers for 4-5 different loci are used per reaction, with 18 loci being amplified in a total of four reactions.¹⁰ The PCR products may be subjected to agarose gel electrophoresis to verify the presence of the desired DNA segments, and then submitted for fluorescent fragment length analysis (FLA) using capillary electrophoresis. DNA from armadillo passaged bacteria with a known number of repeat copies for each locus is used as a positive control. The FLA chromatograms are then examined using Peak Scanner software and fragment length is converted to number of VNTR copies (allele). Finally, the VNTR haplotypes are analyzed for patterns, and when combined with patient clinical data can be used to track distribution of strain types.

Distribution of intramuscular fat content and marbling within the longissimus muscle of pigs

A better knowledge of intramuscular fat (IMF) content distribution would allow the identification of a predictive site on the longissimus muscle to assess the total IMF content. For this purpose, 50 commercial crossbred pigs of both genders were selected live with ultrasound equipment at the 3rd/4th last rib in order to provide backfat differences varying from 10 to 34.7 mm. Left longissimus muscles were deboned and sliced every 2 cm from the posterior (3rd last lumbar vertebra) to the anterior (5th thoracic rib) end. In all, 14 locations on the longissimus muscle were established and labeled as T5-T14 (thoracic region) and L1-L4 (lumbar region). The slices were used for subjective marbling evaluation and for intramuscular fat content (IMF) measurement. The results showed that total IMF content and marbling scores were correlated (r = 0.86) and followed a similar pattern, with highest values being obtained in the middle section of the thoracic region and in the middle-caudal section of the lumbar area. In addition, both IMF content and marbling scores were anatomical location dependant. Gender did not affect IMF content, but influenced marbling score, castrates being more marbled (score: 2.77 vs. 2.35) than females. The IMF content (R2: 0.94–0.95) and marbling score (R2: 0.7–-0.81) were the best predictors of mean IMF when measured at or near the grading site (3rd/4th last rib). Key words: Pork, intramuscular fat, marbling score, longissimus muscle, within muscle variation

Predicting loin-eye area from ultrasound and grading probe measurements of fat and muscle depths in pork carcasses

The mathematical relationships between loin-eye area (m. longissimus thoracis) and linear measurements of fat and muscle depth were studied on digitalized images from 250 hog loins cut between the 3rd- and 4th-last ribs. Depth measurements were collected using (1) an Ultrascan 50 ultrasound system on immobilized, live animals, (2) a Hennessy grading probe on hanging carcasses under normal slaughtering conditions and (3) image analysis on digitalized images of chops separated between the 3rd- and 4th-last ribs. Loin-eye area was accurately predicted by its depth when the measurement was performed on digitalized images (R2 > 0.86; RSD < 1.87 cm2). The accuracy of the relationship between loin-eye area and muscle depth was reduced using ultrasound (R2 = 0.58, RSD = 3.29 cm2) or the probe (R2 = 0.29, RSD = 4.28 cm2) due to measurement errors on muscle depth. Muscle flatness, the perimeter irregularity or its angle in relation to the midline did not improve prediction accuracy. Consequently, muscle depth as measured by the Ultrascan 50 ultrasound system should be used with caution to predict loin-eye area since the measurement is only moderately accurate. Measurements obtained with the Hennessy probe under normal slaughtering conditions are not recommended for predicting loin-eye area in pork carcasses. Key words: Pork, backfat, muscle depth, loin-area, ultrasound, prediction

A dynamic model of protein digestion in the small intestine of pigs

A dynamic mathematical model of the digestion of proteins in the small intestine of pigs was developed. The model integrates current knowledge on the transit of digesta along the small intestine, endogenous secretions, digestion of proteins, and absorption of amino acids into a mechanistic representation of digestion. The main characteristics of the model are the following: the small intestine is divided into several segments of variable length but with equal digesta retention time; the rate of transfer of digesta between segments is based on the progression of myoelectric migration complexes; pancreatic and biliary secretions are poured into the first segment, whereas intestinal secretions enter all intestinal segments; protein hydrolysis is described by first-order equations; and an intestinal absorption capacity is used to estimate absorption of hydrolyzed protein. Simulation results are consistent with observed data, although more information is needed to represent reality more closely. The sensitivity analysis shows that parameters for protein hydrolysis largely determine protein digestibility. The absorption capacity of the small intestine limits the absorption of amino acids at the beginning of a meal and modulates the appearance of amino nitrogen in the portal vein. It also shows that amino acid absorption can be limiting to protein digestibility when large amounts of protein are eaten in a single daily meal. The model is useful in evaluating the dynamics of protein digestion and absorption of feedstuffs. The model can be used in evaluating protein digestion of different feedstuffs and feeding strategies.

Differential diagnosis of parkinsonism

The diagnosis of Parkinson's disease is predominantly clinical, based on a combination of the cardinal features of tremor, bradykinesia and rigidity. The differential essentially lies between other conditions resulting in tremor, of which essential tremor is the commonest, and other akinetic-rigid syndromes. These include progressive supranuclear palsy, multiple system atrophy, toxins and other degenerative disorders, including diffuse Lewy body disease and corticobasal degeneration. The key clinical features of these disorders and a practical diagnostic approach are briefly reviewed in this article.

COMT inhibitors in Parkinson's disease

The COMT inhibitors, tolcapone and entacapone, are a new class of Parkinson's medications. By inhibiting the enzyme catechol-o-methyl-transferase (COMT), they prevent peripheral degradation of levodopa, allowing a higher concentration to cross the blood-brain barrier. Pharmacokinetic studies have shown that both tolcapone and entacapone significantly prolong the elimination half life, and increase the area under the curve of levodopa without increasing C max. Clinical studies with COMT inhibitors have shown benefit in both stable and fluctuating PD patients with improvement in motor function with lower levodopa doses. Fluctuating patients also had increased "on" time and reduced "wearing off". Side effects were most commonly related to increased dopaminergic stimulation. Specific side effects included diarrhea and elevated liver enzymes. The recent reports of three cases of fulminant hepatitis with the use of tolcapone has led many countries to remove this compound from their market. Concerns about a possible class effect should impose close monitoring of liver function tests with the use of any of the nitrocatechols.

Prediction of methane production from dairy cows using existing mechanistic models and regression equations

Ruminants may contribute to global warming through the release of methane gas by enteric fermentation. Until now, methane emissions from ruminants were estimated using simple regression equations. The objective of this study was to compare the capacity of dynamic and mechanistic models to that of regression equations to predict methane production from dairy cows. The updated version of the model of Baldwin et al. and a modified version of the model of Dijkstra et al. and the regression equations of Blaxter and Clapperton and Moe and Tyrrell were challenged with 32 experimental diets selected from 13 publications. The predictive capacity of mechanistic models and regression equations was evaluated by comparing predicted and observed methane production using regression analysis. Results of regression showed better prediction of methane production with mechanistic models than with regression equations. The modified model of Dijkstra et al. predicted methane production with the higher R2 (.71) and the smaller error of prediction (19.87% of the observed mean). The model of Baldwin et al. predicted methane production with a similar R2 (.70) but a higher error of prediction (36.93%). However, a large proportion of this error can be eliminated by a correction factor. Predictions using the equations of Moe and Tyrrell and Blaxter and Clapperton were poor (R2 = .42 and .57; error of prediction = 33.72% and 22.93%, respectively). This study demonstrated that from a large variation in diet composition, mechanistic models allow the prediction of methane production more accurately than simple regression equations.

Perceptual learning of orientation discrimination by more than one attribute

Using a perceptual learning paradigm, we evaluated whether information from the attributes: color, luminance and motion is combined to provide orientation coding. Four observers were trained to discriminate the orientation between color-defined bars, four between luminance-defined bars, and four between motion-defined bars. Before and after training, they were tested with each of the three attributes separately and all superimposed, at the same and at a different location as the one seen during training. A similar improvement was found whether the bars seen after training were defined by the same, or by a different attribute as the one seen during training, or by the three attributes superimposed. This improvement was significantly more substantial at the location where the bars were presented during training. Moreover, orientation discrimination was always better when the bars were defined by three attributes than by any one alone. Because the improvement was retinotopic and not restricted to the attribute seen during training, we suggest that training changed the sensitivity of orientation-selective cells responsive to color, luminance and motion. Moreover, the overall better performance with additional attributes supported an integration of information from color, luminance, and motion at a common site for orientation coding.

Botulinum toxin in the treatment of writer's cramp

Forty-four patients with disabling writer's cramp (WC) and one with a musician's cramp were treated with botulinum toxin (BT) injections for a mean period of 12 (range, 3-48) months. The forearm muscles causing the dystonic position were identified by inspection while writing; BT was then administered under electromyographic (EMG) guidance. The degree of improvement in writing and amelioration of pain were rated with self-assessment scales. Patients reported significant improvement in writing after 56% treatment sessions (TS) and in pain after 62% TS. Mild weakness occurred after 32% TS. Twenty-nine patients discontinued treatment, generally after the initial BT injection. In 16 patients who remained on treatment with a mean follow-up of 21 (range, 3-48) months, the improvement in writing and pain was present after 76 and 79% of the TS, respectively. We conclude that BT injections offered a worthwhile and sustained functional improvement to 36% of our patients with WC.

Localizing contours defined by more than one attribute

Two experiments were run in order to test how information from different attributes is combined to localize contours. In Expt 1 the apparent position of a contour defined by one attribute was measured while a contour defined by another attribute was presented beside it. Interactions were found between all pairings of luminance, color, motion and texture. These results suggested that the information associated with each contour is integrated at a common site. In Expt 2 the precision of localization was measured for contours defined by one, two or three attributes (combinations of luminance, color and texture). The improvement in precision with additional attributes again supported an integration of contour information at a common site prior to a decision of localization.

The contribution of color to depth perceived from motion parallax

Perceived depth was measured in a colored stimulus while stimulus movement yoked to head displacement simulated a depth of 1 cm. Velocity judgments were also made for similar stimuli moving at the same average speed but without head movement. Both measures decreased to a minimum of about 30-40% of the veridical values when the stimuli were equiluminous. Perceived depth and speed also decreased for a monochromatic stimulus as a function of luminance contrast but much more abruptly than for the chromatic stimuli. The results indicate that equiluminous color stimuli contribute to the perception of depth from motion parallax and that the contribution is not mediated by residual luminance.

Interhemispheric depth judgement

Interhemispheric depth comparisons were studied by requiring subjects to align in depth two textured plates, one presented to the left hemifield and the other to the right. Callosal agenesis subjects and neurologically-normal control subjects adjusted the plates so that they appeared to be at the same distance. Subjects viewed the plates monocularly or binocularly while keeping their head still, moving it side-to-side or moving it up and down. Subjects fixated a target located between the two plates while performing the task. For all subjects, the results showed that the deviations from veridical settings were significantly smaller for the binocular than for the monocular viewing conditions. Moreover, there were no significant differences among the three binocular viewing conditions (horizontal, vertical or no head movement), indicating that neither vertical nor horizontal motion parallax improves the precision of depth judgement when binocular disparity is available. These results further suggest that the precision of interhemispheric comparison for binocular depth is not affected by the absence of the corpus callosum. Looking at the plates monocularly, the control subjects judge the relative depth between the plates more precisely when they moved their head than when they kept it still. These results show that motion parallax is a useful depth cue when relative motion is extracted from different hemifields. Unlike the control subjects, the callosal agenesis subjects did not judge the relative depth between the plates more precisely when they moved their head than when they kept it still. These results show that interhemispheric comparison of depth using relative motion is not possible without the corpus callosum.

Botulinum toxin treatment of spasmodic torticollis

We reviewed the efficacy and adverse effects of repeated botulinum toxin injections into hyperactive neck muscles of 107 successive patients with spasmodic torticollis. They received 510 injection treatments over a median period of 15 months (range 3-42 months). One patient failed to benefit at all, but 101 (95%) patients reported considerable (moderate or excellent) benefit from at least one treatment. On a global subjective response rating, 93% of 429 treatments resulted in some improvement and 76% in moderate or excellent improvement. Pain reduction followed 89% of 190 treatments with moderate or excellent reduction after 66%. Median duration of benefit was 9 weeks. All torticollis types responded equally well and injections into two (or more) involved neck muscles were more effective than injection into a single muscle. The most frequent adverse effect was dysphagia, occurring after 44% of all treatments, but this was severe after only 2%. Antibodies to botulinum toxin were detected in the serum of three out of the five patients in whom loss of treatment efficacy occurred. We conclude that botulinum toxin treatment is the most effective available therapy for spasmodic torticollis and practical advice is provided for anyone wishing to set up the technique.

Botulinum Toxin Treatment of Spasmodic Torticollis

We reviewed the efficacy and adverse effects of repeated botulinum toxin injections into hyperactive neck muscles of 107 successive patients with spasmodic torticollis. They received 510 injection treatments over a median period of 15 months (range 3–42 months). One patient failed to benefit at all, but 101 (95%) patients reported considerable (moderate or excellent) benefit from at least one treatment. On a global subjective response rating, 93% of 429 treatments resulted in some improvement and 76% in moderate or excellent improvement. Pain reduction followed 89% of 190 treatments with moderate or excellent reduction after 66%. Median duration of benefit was 9 weeks. All torticollis types responded equally well and injections into two (or more) involved neck muscles were more effective than injection into a single muscle. The most frequent adverse effect was dysphagia, occurring after 44% of all treatments, but this was severe after only 2%. Antibodies to botulinum toxin were detected in the serum of three out of the five patients in whom loss of treatment efficacy occurred. We conclude that botulinum toxin treatment is the most effective available therapy for spasmodic torticollis and practical advice is provided for anyone wishing to set up the technique.

Treatment of cervical dystonia hand spasms and laryngeal dystonia with botulinum toxin

One hundred and twenty-six patients with different forms of focal dystonia (89 with cervical dystonia, 12 with hand cramps and 25 with laryngeal dystonia) were treated with localised injections of botulinum toxin. Mean doses per muscle were 200 mouse units (m.u.) for treating cervical dystonia, 40-120 m.u. for forearm muscles in writers' cramp and 3.7 m.u. for the thyroarytenoid muscle in laryngeal dystonia. Responder rates have been above 80% in all patient groups and beneficial effects could be reproduced over follow-up periods of up to 4 years. The commonest side-effects were dysphagia after treatment of spasmodic torticollis, weakness of neighbouring muscles after injections for hand cramps and breathiness and hypophonia following laryngeal injections. All these were transient and generally well tolerated. It is concluded that botulinum toxin injections are a safe and effective treatment in all three types of focal dystonia.

Pharmacological modulation by cetirizine and ebastine of the cutaneous reactivity to histamine

The peripheral H1-inhibiting effects of cetirizine 10 mg and ebastine 10 mg were compared at the skin level after single oral administration. The study was performed in 9 healthy subjects under double-blind randomized crossover conditions. Both drugs were significantly effective up to 24 h. The suppressive effect of cetirizine was significantly more rapid and more marked.

Writer's cramp: treatment with botulinum toxin injections

Twelve patients with writer's cramp were treated with injections of botulinum toxin. The overactive muscles were identified by clinical observation of the subjects while they were writing. Repeated injections were given at 2-week intervals until the optimal response was obtained. Eleven patients reported some benefit, which was considered by seven to be significant. Eight of the 10 patients who had pain reported moderate to significant relief. Five patients had local complications, consisting of disabling weakness of target or neighbouring muscles. These preliminary results suggest that this treatment can be successfully applied to many patients with writer's cramp without performing complex electromyographic recordings while the patients are writing.

Periodic lateralized epileptiform discharges with transitional rhythmic discharges: association with seizures

Low amplitude rhythmic discharges (RDs) closely associated in time and in spatial distribution to inter-ictal epileptiform discharges are not seen in scalp EEGs of patients with non-periodic focal epileptiform discharges (NPEDs) but they are unexpectedly common in patients with periodic lateralized epileptiform discharges (PLEDs). A classification of PLEDs into PLEDs Proper (PLEDs without RDs), and PLEDs Plus (PLEDs with RDs) is proposed. Such a classification is useful for an easier appreciation of PLEDs' pleomorphism. It underscores the changing periodicity of PLEDs and allows for a more inclusive definition of the phenomenon than the one reported by the literature. It also emphasizes the importance of recognizing RDs in scalp EEGs as transitional anomalies intercalated between inter-ictal PLEDs and ictal seizure discharges, analogous to those observed by Ralston in animal models. Indeed, the occurrence of recorded seizures is higher in patients with PLEDs Plus than in those with PLEDs Proper or NPEDs.

Dystonia in Parkinson's disease, multiple system atrophy, and progressive supranuclear palsy

Adult-onset dystonia-parkinsonism is a syndrome in search of a pathology. We therefore reviewed the literature on dystonic manifestations in autopsy-proven cases of multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and idiopathic Parkinson's disease (PD). Only 6 of 140 autopsy reports of MSA remarked on the presence of dystonia in life, but personal observations suggest prominent antecollis may develop at some stage in up to 1/2 of sufferers. Similarly, very few (15/118) clinicopathologic observations on PSP included convincing dystonic manifestations, in contrast to some clinical reports where blepharospasm and early limb dystonia were prominent. Virtually any form of focal and segmental dystonia may sometimes occur with clinically diagnosed PD, with occasional descriptions of hemidystonia-hemiparkinsonism. However, there is pathologic confirmation of this diagnosis in only 1 case. With many patients thought clinically to have PD proving pathologically to have another cause for their parkinsonism, the true frequency and the range of dystonic manifestations acceptable in PD remain unknown.

Trunk and head tremor as isolated manifestations of dystonia

Five patients presenting with isolated tremors of the trunk or neck are described. Their clinical features were similar to seven other patients who presented with head tremor, or arm and head tremor, but then eventually developed obvious torticollis, sometimes with arm dystonia. We conclude that isolated tremor of the trunk or head, especially of slow frequency (2-5 Hz), and in the case of the head in a "no-no" direction, may be the initial manifestation of focal dystonia.

The roles of convergence and apparent distance in depth constancy with motion parallax

The question of whether motion parallax is calibrated by convergence or by apparent distance for depth perception was addressed in three experiments. In Experiment 1, a random dot parallactic display was viewed monocularly at a distance of 80 cm, and the convergence angles were set for distances of 40, 60, and 80 cm. Averaged apparent depth was not different across conditions. In Experiment 2, a display consisting of one surface showing dollar bills and one surface showing random dots was viewed monocularly at a distance of 80 cm. It was presented at two different apparent distances, which were manipulated by varying the size of the dollar bills. In one condition, normally sized dollar bills were presented, and in another condition, the size was reduced by 30%. The averaged apparent depth associated with the small-bill display was larger than the depth associated with the normally sized bill display. In Experiment 3, a random dot display was viewed monocularly at 120 cm. In the primary condition, the random dot display was viewed with an induction screen at 80 cm, and it was moved from side to side such that it appeared stationary and close to the plane of the induction screen. In a comparison condition, the display was viewed without the induction screen and was moving from side to side at 120 cm. In another comparison condition, the display was again viewed without the induction screen but was stationary at 120 cm. Observers adjusted the extent of motion parallax so that apparent depth was 1 cm. The mean extent of parallax was larger in the primary conditio.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient anosognosia for episodic hemiparesis: a singular manifestation of TIAs and epileptic seizures

Anosognosia is a well-known manifestation of non-dominant parietal lobe lesions and typically lasts a few days. That anosognosia may last only a few minutes to a few hours, as observed in six patients, has not been reported. In five patients, transient anosognosia for equally brief left-sided hemiparesis was a manifestation of transient ischemic attacks (TIAs). In the sixth patient, anosognosia for both a left-sided motor seizure and a subsequent brief left hemiparesis could best be explained by an epileptic ictal and post-ictal transient dysfunction of the non-dominant parietotemporal cortex. Prompt recognition of transient anosognosia, whether ischemic or epileptic, is mandatory for proper diagnosis and for rapid initiation of specific therapy.

Depth perception as a function of motion parallax and absolute-distance information

The results of three experiments demonstrated that the visual system calibrates motion parallax according to absolute-distance information in processing depth. The parallax was created by yoking the relative movement of random dots displayed on a cathode-ray tube to the movements of the head. In Experiment 1, at viewing distances of 40 cm and 80 cm, observers reported the apparent depth produced by motion parallax equivalent to a binocular disparity of 0.47 degree. The mean apparent depth at 80 cm was 2.6 times larger than at 40 cm. In Experiment 2, again at viewing distances of 40 cm and 80 cm, observers adjusted the extent of parallax so that the apparent depth was 7.0 cm. The mean extent of parallax at 80 cm was 31% of that at 40 cm. In Experiment 3, distances ranged from 40 cm to 320 cm, and a wide range of parallax was used. As distance and parallax increased, the perception of a rigid three-dimensional surface was accompanied by rocking motion; perception of depth was replaced by perception of motion in some trials at 320 cm. Moreover, the mean apparent depths were proportional to the viewing distance at 40 cm and 80 cm but not at 160 cm and 320 cm.

Depth perception as a function of motion parallax and absolute-distance information

The results of three experiments demonstrated that the visual system calibrates motion parallax according to absolute-distance information in processing depth. The parallax was created by yoking the relative movement of random dots displayed on a cathode-ray tube to the movements of the head. In Experiment 1, at viewing distances of 40 cm and 80 cm, observers reported the apparent depth produced by motion parallax equivalent to a binocular disparity of 0.47 degree. The mean apparent depth at 80 cm was 2.6 times larger than at 40 cm. In Experiment 2, again at viewing distances of 40 cm and 80 cm, observers adjusted the extent of parallax so that the apparent depth was 7.0 cm. The mean extent of parallax at 80 cm was 31% of that at 40 cm. In Experiment 3, distances ranged from 40 cm to 320 cm, and a wide range of parallax was used. As distance and parallax increased, the perception of a rigid three-dimensional surface was accompanied by rocking motion; perception of depth was replaced by perception of motion in some trials at 320 cm. Moreover, the mean apparent depths were proportional to the viewing distance at 40 cm and 80 cm but not at 160 cm and 320 cm.

HLA system, body fat and fat distribution in children and adults

The association between the genotypes and the alleles at the A, B or C locus of the HLA system and body fat was studied in a total of 1578 individuals subdivided in four cohorts: adult males (n greater than or equal to 204), adult females (n greater than or equal to 184), boys and male adolescents (n greater than or equal to 282), and girls and female adolescents (n greater than or equal to 257). None of these subjects were grossly obese or had known metabolic disorders. Percent body fat from underwater weighing, subcutaneous fat from 6 skinfold measurements, trunk fat (3 skinfolds) and extremity fat (3 skinfolds) were considered in the analysis. Although a few significant associations were encountered, the lack of consistency across samples suggested that they were probably random and biologically not meaningful. The same negative findings were found for the ratio of trunk subcutaneous fat to extremity subcutaneous fat and the ratio of subcutaneous fat (6 skinfolds) to total fat mass. Earlier reports indicating a significant association between high body fat content and antigens B18, Bw35 or Cw4 were not supported by the results of this study. It was concluded that no consistent pattern of association emerged between genotypes or alleles of the HLA system and percent body fat, subcutaneous fat or fat distribution in children and adults of both sexes.