Learning disabilities, low achievement, and mild mental retardation: more alike than different?

Children identified with learning disabilities (LD), low achievement (LA), or mild mental retardation (MMR) were contrasted on 41 measures of ability, academic achievement, social skills, problem behavior, academic engaged time, perceptual-motor skills, and school history. Both multivariate, univariate, and meta-analytic comparisons among the three groups showed relatively large differences on measures of aptitude and achievement, with the LD group scoring higher on measures of cognitive ability than the LA and MMR groups and the LA group showing higher tested academic achievement than the LD and MMR groups. Teacher ratings of academic competence showed similar levels of functioning for the LD and LA groups. No differences among the groups were found on measures of social skills, problem behaviors, or academic engaged time, or on most indices reflecting school history. Results were interpreted in light of studies contrasting LD and LA groups. Comparisons with earlier studies were difficult in light of demographic differences in samples and the lower cognitive and academic functioning of children in the present study. The current study showed that 61% of the LD group could be differentiated from the LA group, with LD-MMR and LA-MMR differentiation levels being 68.5% and 67.5%, respectively.     

Use of lectins to characterize plasma membrane preparations from boar spermatozoa: a novel technique for monitoring membrane purity and quantity

The object of this study was to develop a method to quantify the amount of outer acrosomal membrane material in isolated plasma membranes from boar sperm cells. The cells were fractionated by nitrogen cavitation, and plasma membranes were isolated by subsequent differential centrifugation steps. Marker enzyme measurement showed that the plasma membrane isolates were enriched in plasma membrane markers and did not contain nuclei, inner acrosomal membranes, or mitochondria. Since there is no marker enzyme known for the outer acrosomal membrane, lectins were used for the detection of this membrane. The membrane specificity of a number of lectin conjugates was tested with fluorescence microscopy and transmission electron microscopy. Membrane binding of these lectin conjugates was quantified with flow-cytometry and an enzyme-linked lectin binding assay. Wheat germ agglutinin was specific for the plasma membrane while peanut agglutinin was specific for the outer acrosomal membrane. The use of these lectins made it possible for the first time to discriminate between these two membranes. The isolated plasma membrane fraction was enriched more than 10-fold (17-fold after further purification by a sucrose gradient) in plasma membrane material compared to outer acrosomal membrane material. Highly purified sperm plasma membranes should prove to be useful for research on primary sperm-zona interactions.     

Functional dissociation between local and systemic immune response during anti-melanoma peptide vaccination

Peptide vaccination against tumor Ags can induce powerful systemic CTL responses. However, in the majority of patients, no tumor regression is noted. To study this discrepancy, we analyzed CTL reactivity in a melanoma patient (F001) vaccinated with g209-2M peptide, a single residue variant of gp100(209-217). G209/g209-2M-reactive CTL were identified in post- but not prevaccination PBL. Limiting dilution analysis identified one predominant CTL clone (C1-35), with TCR Vbeta6s2, recognizing g209/HLA-A*0201-expressing targets. Additionally, two autologous melanoma lines (F001TU-3 and -4) and 20 separate tumor-infiltrating lymphocyte cultures were generated from a fine needle aspirate of a metastatic lesion progressing after initial response to vaccination. Both F001TU did not express gp100 and were not recognized by C1-35. Loss of gp100 by F001TU correlated with a marked reduction of gp100 expression in the same metastatic lesion compared with prevaccination. Thus, ineffectiveness of C1-35 and tumor progression could be best explained by loss of target Ag expression. Interestingly, 12 of 20 tumor-infiltrating lymphocyte cultures recognized F001TU, but none demonstrated g209/g209-2M reactivity, suggesting a functional dissociation between systemic and local immune response. This study suggests that vaccination effects must be analyzed in the target tissue, rather than in the systemic circulation alone.     

Mapping of the ligand-selective domain of the Xenopus laevis corticotropin-releasing factor receptor 1: implications for the ligand-binding site

The nonselective human corticotropin-releasing factor receptor 1 (hCRF-R1) and the ligand-selective Xenopus CRF-R1 (xCRF-R1) were compared. To understand the interactions of sauvagine and ovine CRF, both high-affinity ligands for hCRF-R1 but surprisingly weak ligands for xCRF-R1, chimeric receptors of hCRF-R1 and xCRF-R1 followed by double or multiple point mutations were constructed. Binding studies and cAMP assays demonstrated that the N-terminal domain exhibited the complete ligand selectivity of xCRF-R1. The important region was mapped between amino acids 70 and 89; replacement of amino acids Arg76, Asn81, Gly83, Leu88, and Ala89 in hCRF-R1 with the corresponding amino acids of xCRF-R1 (Gln76, Gly81, Val83, His88, and Leu89) resulted in a receptor that had approximately 30-fold higher affinity for human/rat CRF than for sauvagine. Mutagenesis of these amino acids in xCRF-R1 to the human sequence completely abolished the ligand selectivity of xCRF-R1. Mutagenesis of amino acids 88 and 89 in hCRF-R1 or xCRF-R1 had only a minor (approximately 2.5-fold) effect on the ligand selectivity of the mutant receptor. Substitution of Arg76, Asn81, and Gly83 in hCRF-R1 with the corresponding sequence of xCRF-R1 (Gln76, Gly81, and Val83) resulted in a receptor with approximately 11-fold higher affinity for human/rat CRF compared with ovine CRF or sauvagine. When only two of these three amino acids were mutated, no effect on the ligand selectivity was observed. On the basis of these data, it is suggested that amino acids 70-89 of CRF-R1 are important for the ligand binding site.     

The value of palpation as basis for decision on lymph node excision

The purpose of the study was to evaluate palpation of the regional lymph nodes in control examinations of patients with malignant disease. A retrospective review of the medical records of 188 cases in which the patients had had an extirpation of the regional lymph nodes was performed. We have compared the preoperative findings through palpation with the histological diagnosis. The patients were grouped according to the region in which the lymph node removal had been done. The specificity of palpation when the histological diagnosis was malignant was (with 95% confidence limits), in the axilla 0.65 (0.54-0.75), in the inguinal region 0.86 (0.75-0.94) on the neck 0.83 (0.52-0.98) and in the suprahyoid region 0.58 (0.28-0.85). In conclusion, palpation of regional lymph nodes is not a sufficient control examination in the estimation of the course of malignant disease. Supplementary examination methods are recommended.     

Chromosome 15-linked limb-girdle muscular dystrophy: clinical phenotypes in Reunion Island and French metropolitan communities

Erb's type limb-girdle muscular dystrophy (LGMD) was identified and clinically studied in detail in a small community living in the Reunion Island (RI). It was linked to chromosome 15q and related to mutations in the muscle specific calpain 3 gene. A series of cases were afterwards clinically and genetically identified in the French metropolitan community. The phenotype was identical to the RI type in the great majority of cases, although clinical differences were noticed in a few cases. Six different mutations were identified in the RI families, whereas a series of 39 mutations were detected in the French metropolitan families, all different from those present in the RI patients. Phenotype-genotype correlations were attempted in both communities.     

Comparison of brown midrib-6 and -18 forage sorghum with conventional sorghum and corn silage in diets of lactating dairy cows

Total mixed rations containing conventional forage sorghum, brown midrib (bmr)-6 forage sorghum, bmr-18 forage sorghum, or corn silage were fed to Holstein dairy cows to determine the effect on lactation, ruminal fermentation, and total tract nutrient digestion. Sixteen multiparous cows (4 ruminally fistulated; 124 d in milk) were assigned to 1 of 4 diets in a replicated Latin square design with 4-wk periods (21-d adaptation and 7 d of collection). Diets consisted of 40% test silage, 10% alfalfa silage, and 50% concentrate mix (dry basis). Acid detergent lignin concentration was reduced by 21 and 13%, respectively, for the bmr-6 and bmr-18 sorghum silages when compared with the conventional sorghum. Dry matter intake was not affected by diet. Production of 4% fat-corrected milk was greatest for cows fed bmr-6 (33.7 kg/d) and corn silage (33.3 kg/d), was least for cows fed the conventional sorghum (29.1 kg/d), and was intermediate for cows fed the bmr-18 sorghum (31.2 kg/d), which did not differ from any other diet. Total tract neutral detergent fiber (NDF) digestibility was greatest for the bmr-6 sorghum (54.4%) and corn silage (54.1%) diets and was lower for the conventional (40.8%) and bmr-18 sorghum (47.9%) diets. In situ extent of NDF digestion was greatest for the bmr-6 sorghum (76.4%) and corn silage (79.0%) diets, least for the conventional sorghum diet (70.4%), and intermediate for the bmr-18 sorghum silage diet (73.1%), which was not different from the other diets. Results of this study indicate that the bmr-6 sorghum hybrid outperformed the conventional sorghum hybrid; the bmr-18 sorghum was intermediate between conventional and bmr-6 in most cases. Additionally, the bmr-6 hybrid resulted in lactational performance equivalent to the corn hybrid used in this study. There are important compositional differences among bmr forage sorghum hybrids that need to be characterized to predict animal response accurately.     

Undesired phenotypic and genetic trend for stillbirth in Danish Holsteins

The primary aim of this study was to evaluate the phenotypic and genetic trends for stillbirth in Danish Holsteins. Trends of calving difficulty and calf size were also evaluated. The second aim was to compare predicted transmitting abilities (PTA) of sires for stillbirth using a linear and a threshold model. Direct and maternal genetic effects were modeled by fitting correlated additive genetic effects of the sire and the maternal grandsire (MGS). For both the calf and the dam, covariates of breed proportions of Holstein-Friesian (HF) and the heterozygosity between HF and the original Danish Black and White (ODBW) were included. Records from 1.8 million first-calving Danish Holstein cows calving from 1985 to 2002 were used. In this period, the overall frequency of stillbirth increased from 0.071 to 0.090. An unfavorable genetic trend of stillbirth was found for both the direct and maternal effect. The background for the genetic trends was an intense use of HF sires as sires of sons, which increased the proportion of HF genes to 94% in the Danish Holstein calves born in 2002. The effect of the imported HF genes was higher direct effects of calf size, calving difficulty, and stillbirth compared with the ODBW genes. The maternal effect of stillbirth was poorer for HF than for ODBW even though HF had a better maternal calving performance than ODBW. The threshold and the linear models showed almost similar predictions of transmitting abilities of sires.     

Design of near-field holographic optical elements by grating matching

A new method for designing holographic optical elements is presented. The method is based on matching the grating-spacing profile of the recording light interference pattern to the desired grating-spacing profile. We show that for designing near-field holograms, in which the optical images involved are close to the hologram aperture, the grating-matching technique is superior to the well-established aberration-balancing method introduced by Latta [Appl. Opt. 10, 609 (1971)].