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"Chondroid chordoma" is a controversial and confusing entity that was originally described by Heffelfinger and colleagues as a biphasic malignant neoplasm possessing elements of both chordoma and cartilaginous tissue. Because the premise for this distinction was based strictly on histomorphologic criteria, the light microscopic, immunohistochemical, and electron microscopic features of the chondroid and chordoid areas of five chondroid chordomas of the skull base were evaluated separately, and compared to five typical chordomas and six low grade chondrosarcomas. Using light microscopy, chondroid chordoma revealed areas that resembled typical chordoma (chordoid areas) and areas that resembled low grade chondrosarcoma (chondroid areas). However, both the chordoid and chondroid areas had an epithelial phenotype and stained strongly for cytokeratin and EMA as well as S-100. 5'-nucleotidase, an enzyme that has been described in chordoma but not in chondrosarcoma, was found in both the chordoid and chondroid areas of one chondroid chordoma. Electron microscopic studies of both the chordoid and chondroid areas in four of the tumors demonstrated both tonofibrils and desmosomes. Chordoma demonstrated immunohistochemical and electron microscopic features that were nearly identical to chondroid chordoma. Chordoma was cytokeratin, EMA, S-100, and 5'-nucleotidase positive. Ultrastructurally, chordoma exhibited variably-sized vacuoles, abundant rough endoplasmic reticulum (RER), and desmosomes with tonofilaments. In contrast to chondroid chordoma, chondrosarcoma consistently stained for only S-100 protein and was cytokeratin, EMA and 5'-nucleotidase negative. Ultrastructurally, chondrosarcoma demonstrated a flocculogranular matrix, glycogen, abundant RER, and scalloped cellular outlines, but lacked desmosomes with tonofilaments. These findings indicate that "chondroid chordoma" is a variant of chordoma with histologic features that may mimic chondrosarcoma. Despite the resemblance of these hyalinized areas to cartilaginous tissue, these tumors retain their epithelial phenotype. Biphasic differentiation is not present. These findings undermine the original premise for distinguishing "chondroid chordoma" from typical chordoma. The authors propose that these tumors be classified as "hyalinized chordomas," rather than "chondroid chordoma," to clarify their histogenesis and avoid confusion with chondrosarcomas of the base of the skull.

Several insecticides were applied to cattle at various rates, mixtures, application methods and numbers of treatments and evaluated for control of cattle lice. The insecticides included permethrin at various rates as a pour-on with and without the synergist piperonyl butoxide (PBO), and also at various rates as a spray with and without PBO. Pirimiphos-methyl was evaluated as a pour-on at various rates and with one or two applications. Lambda cyhalothrin in microencapsulated formulation was compared to a non-microencapsulated formulation. Rabon(R) was applied as a pour-on at two rates and at one or two treatments for each rate. Dimilin(R) was applied as a pour-on at two rates and mixed with permethrin and applied at two rates. Five endectocides, Eprinex(R), Ivomec(R), Dectomax(R), Cydectin(R) and Phoenectin(R) were all applied at the same rate. The cattle utilized in this research were all infested with a mixture of lice species. The species included: Bovicola (Damalinia) bovis (L.), Haematopinus eurysternus (Nitzsch), Linognthus vituli (L.) and Solenoptes capillatus (Enderlein). Most of the cattle were infested with at least two species and some had three or all four species present. All of the treatments except permethrin 1.0%+5% PBO, at a rate of 3ml/45.4kgwt. provided acceptable lice control with one application. Data indicated that applying the insecticides in early January should provide enough control to render the need for a second treatment unnecessary.

This study examined the superovulatory responses of Bos taurus beef cows maintained in a commercial embryo transfer facility. Donors were superovulated 1 to 3 times each with either a traditional 8 injection FSH protocol (controls, n = 126) or 6 injections of FSH with the seventh or eighth FSH treatments replaced by 2 injections of eCG (treatment, n = 134). During the 5-month study, 132 donors were alternatively assigned to a control or treatment group for a single superovulation and an additional 62 animals were superovulated 2 (n = 58) or 3 times (n = 4) in a crossover design. Although 14 beef breeds were represented in the study, 87% of the cows were Angus, Red Angus, Polled Hereford, or Charolais. All donors were synchronized on Day 0 with a CIDR, 5 mg of oestradiol-17β and 100 mg of progesterone. Starting on Day 4 (p.m.), controls were injected twice daily for 4 days with descending doses of porcine FSH (Folltropin-V®, Bioniche Animal Health, Belleville, Ontario, Canada). Cows received 750 μg of cloprostenol (Estrumate®, Intervet Schering-Plough, Summit, NJ, USA) at the seventh FSH injection and the CIDR was removed at the eighth FSH injection. Based on previous experience with specific, individual animals, total FSH dose per donor ranged from 240 to 400 mg. However, 74% of treatments involved 380 mg for controls and 310 mg for treated donors that received eCG. In addition, donors that were superovulated more than once received the same FSH dose in the crossover, treatment-control design. In the treatment group, 200 IU of eCG (Pregnecol™ 6000, Bioniche Animal Health) was substituted for the seventh and eighth FSH injections. Inseminations were conducted on a timed AI basis, with one unit of semen 32 h and a second 48 h following CIDR removal. Results were analysed by ANOVA as shown in Table 1. Although more ova/embryos and unfertilized ova (UFO) were recovered in the control group, the control and treatment groups did not differ in the number of grade 1, 2, or 3 embryos or in the number of degenerate embryos. Previous superovulation studies in South America using eCG to replace the last 2 injections of FSH resulted in more total ova/embryos in Nelore cows but not heifers and in more embryos in Brangus and Sindhi cows. The mean embryo production for the control cows in this study was high and the addition of eCG in the protocol did not improve embryo production. Failure of eCG to increase the number of embryos for Bos taurus cows in this study compared with previous studies may be due to differences with Bos taurus versus Bos indicus breeds or differences in management factors between Canada and South America. The high response rate in the controls may also have contributed to the failure of any advantage of adding eCG to the treatment protocol. Table 1.Mean numbers (± SEM) of ova and embryos recovered from Bos taurus females superovulated with 2 different protocols

CELL growth and differentiation are usually mutually exclusive1. Transformation of myoblasts by retroviruses containing the myc oncogene inhibits differentiation, preventing cells from withdrawing from the cell cycle4,5. If cell-cycle withdrawal is a prerequisite for myoblast differentiation, it is probably an early event in terminal cell differentiation, but this has not yet been established6. MyoD1 regulates myogenesis7. It is expressed only in skeletal muscle8, but can convert other cells to muscle cells9,10. The MyoD1 protein, a nuclear phosphoprotein in part similar to the myc family of proteins, is a DNA-binding protein binding to the enhancer sequences of the muscle-specific creatine phosphokinase gene11. Thus, introduction of MyoD1 into cells provides a simple approach to study the effect of induction of differentiation on cell growth. In cultured NIH 3T3 cells, inhibition of cell proliferation occurs within 18 hours, and expression of myosin starts after 72 hours. Furthermore, injection of MyoD1 into quiescent NIH3T3 cells inhibits the serum-induced G0–S phase transition of the cell cycle. In CV1 cells, which are not induced to differentiate by MyoD1, DNA synthesis is also inhibited. Expression of MyoD1 can thus inhibit cell proliferation independently of induction of differentiation. Deletion of the myc-like domain in the MyoD1 gene12 eliminates the inhibition of DNA synthesis, but substitution of the basic domain with the analogous domain from the E12 transcription factor13 inhibits growth yet fails to induce differentiation. Inhibition of DNA synthesis, therefore, seems to be controlled separately from myogenic differentiation.

Populations of cotton rats (Sigmodon hispidus) frequently exhibit extreme fluctuations in abundance, which have been attributed to changes in food quality and its possible effect on survival of juveniles. Weanling cotton rats fed low-protein diets experience altered immune-system function. We evaluated the effects of moderate restriction of dietary protein on splenocyte subpopulations of weanling cotton rats and determined the influences of onset of protein restriction at an earlier age compared with previous studies. Weanling cotton rats (14 days old) were fed three isocaloric diets containing 4, 8, or 16% protein for 24 days. Splenocyte subpopulations were assigned to one of eight categories by dual-staining with a panel of surface markers for T-cells (peanut agglutinin, PNA ; soybean agglutinin, SBA, and Helix pomatia agglutinin, HP) and B-cells (rabbit-anti-rat immunoglobulin-G, BS). Total numbers of all splenocyte subpopulations were lower in rats subjected to moderate (8%) or severe (4%) protein restriction ; B-cells were more sensitive to protein restriction than were T-cells. Prevalence (percent of total splenocytes) of PNA - /BS + splenocytes was reduced, whereas prevalence of PNA + /BS - and SBA - /HP + splenocytes was elevated with decreased protein intake. Multivariate statistical analysis of immune parameters revealed peripheral blood lymphocytes and splenocyte subpopulations as well as hemolytic complement activity and mean corpuscular volume most accurately described the degree of protein restriction and suggested a change in immunocompetence as a result of either moderate or severe protein restriction.

Antisera specific for six regions of the v- abl protein were used to serologically characterize the Abelson murine leukemia virus tyrosine kinase. Chemically synthesized peptides corresponding to the predicted v- abl protein sequence and larger regions of the v- abl protein expressed as fusion proteins in bacteria were used as immunogens. The specificity of each antiserum was confirmed by immunoprecipitation analysis with defined deletion mutants of Abelson murine leukemia virus. Several of these v- abl -specific antisera display much higher titers and avidities than serum harvested from mice bearing Abelson murine leukemia virus-induced tumors, previously the only source of anti- abl -specific serum. Two antisera were found to block the in vitro autophosphorylation of the v- abl protein as well as its ability to phosphorylate a peptide substrate. Examination of the sites against which the kinase-blocking antisera were prepared revealed that both are in close proximity to the in vivo sites of tyrosine phosphorylation, which fall within the region of high homology with v-src and other tyrosine kinases. Antisera directed against other regions of v- abl did not inhibit kinase activity.

Raising and lowering the oxygen content in the fluid bathing the skin of the leech modified the frequency of the heartbeat. In raised concentrations of oxygen, the period between bursts of impulses in the heart excitor motoneurones (HE cells) was reduced. Conversely, with lowered oxygen concentrations bathing the skin, the heart rate was slowed, with longer periods between bursts of firing in the HE motoneurones. Changes in oxygen concentration did not affect HE motoneurone firing patterns in preparations in which the CNS was dissected from the skin and surrounding body tissues. Various other stimuli were tried, including stroking, pinching, stretching the skin, blood vessels and gut, as well as changing the temperature. None of these stimuli mimicked the specific effects of oxygen on rhythmicity. It is concluded that peripheral receptors sensitive to changes in oxygen tension are able to influence the central neuronal circuits responsible for generating the rhythm of the heartbeat.

The v-abl protein of Abelson murine leukemia virus is a tyrosine-specific kinase. Its normal cellular homolog, murine c-abl, does not possess detectable tyrosine kinase activity in vitro. Previously, we have detected tyrosine kinase activity in vitro for an altered c-abl gene product (c-abl P210) in the K562 human chronic myelogenous leukemia cell line. The expression of this variant c-abl gene product correlates with chromosomal translocation and amplification of the c-abl gene in K562 cells. Like v-abl, c-abl P210 is a fusion protein containing non-abl sequences near the amino terminus of c-abl. We compared the in vitro tyrosine kinase activity of c-abl P210 with that of wild-type murine v-abl. The remarkable similarities of these two proteins with respect to cis-acting autophosphorylation, trans-acting phosphorylation of exogenous substrates, and kinase inhibition, using site-directed abl-specific antisera, suggested that c-abl P210 could function similarly to v-abl in vivo. In addition, c-abl P210 possessed an associated serine kinase activity in immunoprecipitates. The serine kinase activity was not inhibited by site-directed, abl-specific antisera that inhibit the tyrosine kinase activity, suggesting that the serine kinase activity is not an intrinsic property of c-abl P210. Thus, the activation of the c-abl gene in a human leukemia cell line may have functional consequences analogous to activation of the c-abl gene in Abelson murine leukemia virus.

SynopsisThe data indicated partial dominance of gene action conditioning cold susceptibility in Canadian Variegated, Du Puits, and African alfalfas, and, using a model for tetrasomic inheritance, 17% of the variation associated with fall growth was attributed to additive gene action.

Crosses of early fall dormant ✕ early fall dormant,early dormant ✕ late dormant, and late dormant ✕ late dormant clones of Medicago sativa L. were planted in greenhouse flats and subsequently transplanted into the field. Seedling height, greenhouse regrowth, fall height (regrowth), spring height (regrowth), and percent winterkill were recorded. Correlation coefficients indicated that 25 to 36% of the variation in greenhouse regrowth could be associated with seedling height. Less than 5% of the variation in fall height and spring height could be associated with seedling height. A similar relationship was noted between fall height and spring height. This relationship, along with the range of types found in any seedling class, suggested that plants with good seedling vigor and good spring recovery could be selected from the early dormant ✕ early dormant group even though the tallest plants for fall height were only about half as tall as those in the early ✕ early or late ✕ late group. The segregation in the early ✕ late and late ✕ late group suggested that winterhardy plants with good seedling vigor, good regrowth, having tall fall and spring height could be selected.

SINCE Stokstad and Jukes (1950a) reported growth stimulation of chicks by including aureomycin in the diet, there has been a renewed interest in the practicability of increasing growth by the inclusion of antibiotics in the diet of the chick and poult. Various antibiotics have been shown to promote growth of chicks. Moore et al. (1946) reported that the feeding of streptomycin in purified diets accelerated the growth of chicks. Whitehall et al. (1950) have reported growth stimulation with crystalline aureomycin hydrochloride, penicillin, or streptomycin when given orally to chicks but not when injected. Peppler and Oberg (1950), using small lots of birds, reported stimulated growth with charcoal-adsorbed crude polymyxin D when fed orally. Physiological studies revealed marked reduction of coliform bacteria and practically no absorption of antibiotic into the blood stream. A stimulatory effect of streptomycin and aureomycin in chicks was also reported by Groschke and Evans (1950). Scott and . . .

Electrophoretic and immunological properties of the soluble root protein complement of 6 Medicago sativa L. genotypes in the cold hardened and non-hardened physiological condition were compared. These 6 genotypes were chosen to represent a range of abilities to survive exposure to subfreezing temperatures when in the cold hardened condition. A zone of highly charged and/or low molecular weight protein components were found to be more prevalent in the protein complements of the cold-hardened material than the non-hardened material. Immunodiffusion plate tests were not so definitive as the electrophoretic patterns for identifying the genotypes or physiological conditions, but did corroborate the electrophoretic interpretations.

Data pooled from three individual trials, with average stable fly populations of 2.58, 5.21, and 7.07 per leg, indicated a significant reduction in weight gains and a decrease in feed efficiency among feedlot cattle. Graphs of pooled data and previously reported data, converted to percentage loss on a per fly basis, indicated the economic threshold for stable flies (cost of treatment versus number of flies)is less than two stable flies per leg on feeder heifers.

The nervous system is involved in the acquired immunodeficiency syndrome (AIDS) by infections and infestations, by neoplasms, and by several diseases of uncertain pathogenesis. The most common pathological abnormalities are the changes associated with the HIV agent itself, the 'HIV subacute encephalitis'; the most specific change is demyelination with multinucleate giant cells. Cytomegalovirus (CMV) is the most common secondary virus, but progressive multifocal leucoencephalopathy (PML) is more frequently seen at biopsy. Toxoplasmosis is the most common cause of abscess formation, but fungal infections, especially by cryptococcus, are more often the cause of meningitis. Mycobacterial infections and other opportunistic organisms are relatively rarely seen in the CNS. A vacuolar myelopathy of unknown pathogenesis is seen in AIDS; it involves the dorsal and lateral columns and the thoracic spinal cord most prominently. Endarteritis of unknown cause with resultant infarction is seen in children. Primary CNS lymphoma accounts for a major percentage of the lymphomas seen in AIDS; they are high grade tumours, are most often multiple, and are of B-cell origin. Metastatic Kaposi's sarcoma is very rare. Several peripheral neuropathies occur in AIDS, and recently a myopathy with small rod bodies has been reported.

1. The voltage-dependent properties of rectifying and non-rectifying electrical synapses formed between identified leech neurones were quantified during their regeneration in vitro. 2. Junctional conductance increased with time in culture. This was evaluated by making comparisons between cell pairs maintained in vitro for differing amounts of time, as well as by taking repeated measurements from a single cell pair at different time intervals. 3. Non-rectifying electrical synapses were formed between certain identified neurones of the same type. Thus, Leydig cells cultured with Leydig cells established non-rectifying electrical connections, as did Retzius cells, longitudinal motoneurones (L cells) and anterior pagoda (AP) cells, each paired with its own cell type. 4. Rectifying synapses developed when sensory neurones (P cells or N cells) were paired with the other neurones mentioned above that form non-rectifying connections between themselves. The cell combinations examined were L cell-P cell. Leydig cell-N cell, and AP cell-P cell. The direction of current flow across these rectifying synapses was consistently from the sensory neurone to the other cell in the pair. 5. Non-rectifying connections early in the process of synapse regeneration (1-3 days) showed non-linearities greater than those observed in established non-rectifying synapses. There was a subtle, but clear, voltage dependence even at the later stages of synapse formation (4-18 days). 6. In contrast to non-rectifying connections, rectifying synapses formed between cells at early times in culture showed less voltage dependence than those observed at later times. 7. The marked non-linearities of the non-rectifying connections at early stages in synapse formation along with the reduced voltage dependence of the rectifying connections within the same time period revealed unexpected similarities between the two. At the early stages of synapse formation, the two types of electrical synapse were essentially indistinguishable for one direction of junctional current.

In an earlier report by Davis et al. (1951) the data showed that if “chick size” cracked corn replaced part of the ground corn in a corn-soybean oilmeal chick starting ration, poorer growth, increased variation in chick size, and poorer feed utilization resulted. This was attributed to the selection of the corn particles in preference to the rest of the diet. The purpose of this report is to extend this work and show the effect on the chicks of various particle sizes of ground corn as produced by the use of different size hammermill screens. EXPERIMENTAL Day-old White Leghorn female chicks from the Poultry Division flock were used in groups of 10. They were reared in electrically heated metal batteries with raised wire screen floors. Feed was supplied ad libitum and the water changed daily. Six different moduli of cornmeal were prepared from the same sample of #2 yellow dent . . .

There has been a considerable number of reports published dealing with the vitamin B12 requirement of the chick employing high protein diets, depleted chicks or other “stress factors.” A great deal of disagreement exists in these reports concerning the minimum level of vitamin B12 required for optimum growth. The purpose of this report is to show the level of vitamin B12 required for growth of normal, undepleted chicks fed a practical chick ration. EXPERIMENTAL White Leghorn chicks of both sexes were used in groups of 10. The chicks were from hens maintained on built-up litter and fed a standard breeder ration containing animal protein. They were reared on wire in electrically heated batteries. Feed and water were supplied ad libitum and feed consumption records were kept. Mortality was negligible; consequently the figures are not included. The practical corn-soybean ration used (E5, 20 percent protein), was the same as the one . . .