Peabody Individual Achievement Test: concurrent validity with juvenile delinquents

The present study examined the concurrent validity of the Peabody Individual Achievement Test with the Wide Range Achievement Test and Wechsler Intelligence Scale for Children in a juvenile delinquent population. The three tests were administered to 18 male delinquents between the ages of 12–4 and 15–11. Intercorrelations between subtests of the first two tests were significant, as was the Peabody Achievement Total Test with the Wechsler Intelligence Scale for Children Full Scale IQ. However, the two achievement measures agreed in terms of gross intellectual classification less than 56% of the time on all subtests. As the Peabody Achievement subtest, Mathematics, vs Wide Range subtest, Arithmetic, yielded significantly different achievement levels the two were not measuring comparable achievement levels. Substitution of one for the other is questionable. Suggestions were made for research concerning concurrent validity employing the present methodology.

Hereditary myokymia and periodic ataxia

A kindred in which at least 11 individuals in 3 consecutive generations have continuous muscle movement, i.e., myokymia, and periodic ataxia, has been studied. Three patients, a 24-year-old woman, her 4-year-old son and her 27-year-old sister, have been studied in detail. The disorder is inherited as an autosomal-dominant trait and presents in early childhood with attacks of ataxia of 1-2 min in duration, with associated jerking movements of the head, arms and legs. Attacks are provoked by abrupt postural change, emotional stimulus, and caloric-vestibular stimulation. At the age of 12 years approximately, facial and extremity myokymia appears. Physical findings include large calves, normal muscle strength and widespread myokymia of face, hands, arms and legs with a hand posture resembling carpopedal spasm. EMG studies at rest showed continuous spontaneous activity of otherwise normal motor units. Nerve conduction velocities were normal. Gastrocnemius biopsy in 2 patients showed fiber type grouping and small angular fibers, and was consistent with denervation. Histographic analysis of the biopsies demonstrated enlargement of both fiber types, particularly of Type I fibers. These findings are consistent with chronic denervation and an abnormality of motor neuron population or firing. The myokymia described here is of interest not only because of its genetic association with a movement disorder, but also because the muscle findings support a peripheral basis for the muscle movements.

Siroheme: a new prosthetic group participating in six-electron reduction reactions catalyzed by both sulfite and nitrite reductases

Ferredoxin-nitrite reductase (EC 1.7.7.1) of spinach, an enzyme that catalyzes the six-electron reduction of nitrite to ammonia, contains siroheme, the new type of prosthetic group recently found in several sulfite reductases (both assimilatory and dissimilatory) that can catalyze the reduction of sulfite to sulfide, also a six-electron reduction. The prosthetic group of sulfite reductase had previously been shown to be an iron-tetrahydroporphyrin of the isobacteriochlorin type (adjacent pyrrole rings reduced) with eight carboxylate side chains. This finding suggests that both types of "multi-electron" reduction processes may share common mechanistic features.

Ultrastructural analysis of antibody synthesis in cells from lymph and lymph nodes

A variety of cells containing antibody were found in lymph from sheep responding to secondary challenges with horseradish peroxidase. Antibody was present in blast cells in lymph within the perinuclear space, the endoplasmic reticulum, the Golgi apparatus and on polyribosomes. Some lymphocytes in lymph also contained antibody but in these cells it was located principally in the perinuclear space. No cells were found containing antibody distributed throughout their cytoplasm nor were any lymphocytes found with a Golgi apparatus positive for antibody. After the immune response in the lymph had died away, a population of cells containing antibody was still present in the regional lymph node. These were all plasma cells in which the antibody was present for the most part in a highly organized endoplasmic reticulum. Cells of this type were never found in the lymph. The cells containing the smallest amounts of antibody had a few discrete focal points in the perinuclear space and a few positive groups of ribosomes in their cytoplasm. The endoplasmic reticulum in some cells was filled completely with antibody, while in others positive segments were found adjacent to negative ones. The antibody in the cytoplasmic endoplasmic reticulum was in continuity with the antibody in the perinuclear space. The Golgi apparatus contained antibody in only a small proportion of the cells but when it was positive it was strongly so, suggesting that antibody was concentrated in this organelle. In some cells a positive reaction to horseradish peroxidase antibody appeared in the nucleus over the nucleoli. The significance of this finding is not known.

Quantitative studies on the proliferation and differentiation of antibody-forming cells in lymph

The transforming cells that appear in the efferent lymph from a lymph node responding to an antigenic challenge are part of a heterogeneous population which changes as the response progresses. Some cells containing small amounts of antibody appear early in the response and these cells have the cytologic characteristics of small and medium lymphocytes. They are, however, actively synthesizing DNA. As the immune response progresses, the antibody content of the cells in lymph increases. When incubated in vitro, cells in lymph appearing late in the response released 20 times more antibody per cell than those appearing early in the response. Large blast cells are the predominant antibody-forming cell in lymph. At the peak of a secondary challenge with horseradish peroxidase, up to 40% of the cells in lymph may be blast cells and, of these, two-thirds may contain specific antibody. It seems probable that most if not all of the blast cells responding to the antigen are involved directly in antibody and DNA synthesis. Cells in all stages of ultrastructural differentiation, and even mature plasma cells, were found to incorporate (3)H-thymidine into their nuclear DNA.

Identifying Characteristics of the Haematopoietic Precursor Cell

Studies are reported utilizing the known ability of homologous marrow cells to prevent death in otherwise lethally X-irradiated mice by ‘colonizing’ their spleens. The proportion of marrow cells functioning as progenitor cells attains a peak value during post-hypoxic polycythaemia. On the third day post-hypoxia, bone marrows of mice were harvested and prepared for density-gradient centrifugation. The relatively pure fractions of marrow cells were concentrated on the basis of their density and directly injected into the surgically exteriorized spleens of mice which had received an otherwise lethal dose of X-irradiation 48 h previously. Animals were sequentially killed from 15 min to 8 days later and spleens were prepared for examination by light and electron microscopy.

Eighty to 95 % of the light-density fraction (ρ = 1.0200-1.0440) was composed of large mononuclear cells characterized by a leptochromatic nucleus with pachychromasia at the nuclear envelope, one or more prominent nucleoli, sparse endoplasmic reticulum, a moderate number of mitochondria, a conspicuous Golgi zone and a centrosome in the region of a nuclear indentation. Cells of this light fraction, devoid of erythroid elements, were competent in colonizing spleens (erythrocyte, granulocyte and megakaryocyte series) in contrast to the cells present in fractions of greater density.

The name ‘haematopoietic precursor cell’ (HPC) is tentatively used in describing this cell which is discussed in the light of some of the proposed models of haematopoiesis.