ALBERT

Notes: This investigation was undertaken to examine the observations of Becker ('72) pertaining to the electrical facilitation of partial limb regenerative responses by means of Ag-Pt wire couples applied to the limb stumps of young, forelimb-amputated white rats. Additionally, in order to examine the possible role of mechanical effects of such device implantations, we have employed uncoupled devices delivering no current or potential difference. In the present experiments, in response to coupled device implantation, cartilage and bone were actively formed in the vicinity of the Pt electrode tip. These tissues contributed to the lengthwise extension of the limb and to the partial restoration of the distal humeral extremity. In limbs bearing the uncoupled electrical devices, qualitatively similar responses were noted, but osteogenesis was diminished in extent compared to that seen in limbs bearing the active or coupled devices. It is therefore necessary to consider the role of mechanical factors in the elicitation of the observed regenerative responses. Myogenesis was enhanced in electrically stimulated limbs, but not in those rats bearing uncoupled devices.

Notes: Early passage mouse embryo fibroblasts, mouse 3T3 cell lines, and early passage diploid human fibroblasts grew to higher cell densities in tissue culture medium supplemented with serum than in medium supplemented with defibrinogenated platelet-poor plasma (PPP). Unlike the mouse cells, the human fibroblasts displayed this differential growth response only in the presence of hypophysiologic concentrations of calcium. The addition of heat-treated extracts of human platelets to PPP-supplemented medium stimulated the replication of both the normal mouse cells and early passage human embryo fibroblasts.Human or mouse fibroblasts transformed by either retroviruses or by SV40, including SV40 infected “serum revertants” and “flat transformants,” grew to equal cell densities in medium supplemented with either serum or PPP. Infection of Balb/c-3T3 cells with SV40 rapidly induced them to grow in PPP-supplemented medium demonstrating that the ability of SV40-transformed cell lines to proliferate in PPP-supplemented medium does not arise from the cell culture selection procedures usually employed to obtain stable virus-transformed cell lines. 3T3 cells infected but not transformed by retroviruses do not replicate in PPP-supplemented medium demonstrating that reduction of the growth requirement for the platelet growth factor(s) by retroviruses is a transformation-specific response. Cell cultures that did not proliferate well in PPP-supplemented medium did not form tumors when inoculated into athymic nude mice. Many, although not all, of the lines which grew well in PPP medium were tumorigenic in nude mice. Together, these findings indicate that: (1) normal fibroblast-like cells display a growth requirement for factor(s) present in serum but not found in PPP; (2) this serum specific growth factor is derived from platelets; (3) a primary response to viral transforming genes is a reduction in the growth requirement for these platelet-derived factors; and (4) cells that have a reduced requirement for the platelet-derived growth factor are often tumorigenic.

Notes: Much controversy regarding the relationship between nutrients and serum in regulation of cell growth can be reconciled by recognizing that serum contains multiple factors which regulate different events in the cell cycle. Serum was fractioned into a platelet-derived growth factor (PDGF), which induces cells to become competent to synthesize DNA, and plasma which allows competent cells to traverse G0/G1 and enter the S phase. Nutrients are not required for the cellular response to PDGF; however amino acids are required for plasma to promote the entry of PDGF-treated, competent cells into S phase. The nutrient independent, PDGF-modulated, growth regulatory event (competence) is located 12 hours prior to the G1/S phase boundary in quiescent, density-arrested Balb/c-3T3 cells. The nutrient dependent, plasma-modulated event is located six hours prior to the G1/S phase boundary and corresponds in time to a plasma dependent growth arrest point. Moreover, plasma controls the concentration of amino acids required for DNA synthesis. Infection of density-arrested Balb/c-3T3 cells with SV40 overrides both the nutrient independent and the nutrient dependent growth regulatory events.

Notes: Stimulation of Balb/c-3T3 cell growth by TPA requires factors found in serum. We examined the interaction between TPA and serum growth factors in the stimulation of cell growth. The number of cells synthesizing DNA (incorporating 3H-thymidine) within 24 to 30 hours after the addition of TPA and the growth factors to density-inhibited Balb/c-3T3 cultures in serum-free medium was determined by autoradiography. With no additions or with TPA (30-300 ng/ml) alone, only 3-7% of cells synthesized DNA. However, TPA synergistically promoted DNA synthesis in combination with each of the defined serum growth fractions, platelet derived growth factor and platelet poor plasma. TPA also synergistically promoted DNA synthesis in combination with purified growth factors including fibroblast growth factor, insulin (10-6-10-5 M), and epidermal growth factor. In all conditions, TPA enhancement of DNA synthesis also resulted in an increase in cell number. Because TPA synergistically enhanced the activity of each growth factor tested, it did not act identically to any of the growth factors.

Notes: The reactions of hydroxyl radicals with eight substituted aromatic hydrocarbons and four olefins were studied utilizing the flash photolysis-resonance fluorescence technique. The rate constants were measured at 298°K using either Ar or He as the diluent gas. The values of the rate constants (k × 1012) in the units of cm3/molec. sec are (a) OH + o-xylene → products: (12.9±3.8), 20 torr He; (13.0±0.3), 20 torr Ar; (12.4±0.1), 200 torr He;(b) OH + m-xylene → products: (15.6±1.4), 3 torr Ar; (19.4±0.8), 20 torr Ar; (21.4±0.2), 20 torr He; (20.3±1.9), 200 torr Ar; (20.6±1.3), 200 Torr He;(c) OH + p-xylene → products: (8.8±1.2), 3 torr Ar; (10.1±1.0), 20 torr He; (10.5±0.6), 200 torr He;(d) OH + ethyl benzene → products: (7.50±0.38), 3 torr He; (7.06±0.26), 20 torr He; (7.95±0.28), 200 torr He;(e) OH + n-propylbenzene → products: (6.40±0.36), 20 torr He; (5.86±0.16), 200 torr He;(f) OH + isopropylbenzene → products: (7.79±0.40), 200 torr He;(g) OH + hexafluorobenzene → products: (0.221±0.020), 20 torr He; (0.219±0.016) 200 torr He;(h) OH + n-propyl pentafluorobenzene → products: (2.52±0.54), 3 torr He; (3.01±0.76), 20 torr He; (3.06±0.24), 200 torr He;(i) OH + propylene → products: (25.6±1.2), 20 torr He; (26.3±1.2), 200 torr He;(j) OH + 1-butene → products: (29.6±1.9), 3 torr He; (29.4±1.4), 20 torr He;(k) OH + cis-2-butene → products: (43.2±4.1), 3 torr He; (42.6±2.5), 20 torr He;(l) OH + tetramethylethylene → products: (56.9±1.3), 20 torr He.

Notes: 1-Methylallyl, 1,1-dimethylallyl, 1,2-dimethylallyl, 1,3-dimethylallyl, 1,1,2-trimethylallyl, and 1-ethylallyl radicals have been generated in the gas phase at 20 ± 1°C by addition of H atoms, formed by Hg(63P1) photosensitization of H2, to appropriate dienes. Their combination reactions with ethyl radicals have been studied and the relative reactivities of the reaction centers in each allylic radical determined. Similar measurements have been made for some combination reactions of n-propyl, i-propyl, and t-butyl with 1-methylallyl and 1,1,2-trimethylallyl radicals. The more substituted reaction centers are found to be the less reactive. In addition the self-combination and disproportionation of 1-methylallyl radicals has been investigated, as has cross disproportionation of each allylic radical with ethyl. The results establish a general pattern of reactivity for these radicals, which is interpreted primarily in terms of the effects of steric interaction during reaction.

Notes: The flash photolysis resonance fluorescence technique has been utilized to determine the rate constants for three reactions involving the hydroxyl radical [OH(2≅)] and three halogenated C2 alkanes. The nominal temperature range covered was 250-375 K. The compounds studied and the resulting Arrhenius expressions in units of cm3/molec·sec are The error limits in these expressions are such that they include any possible systematic errors due to the presence of impurities in the halocarbon samples. Tropospheric lifetimes have been calculated for the above species by combining the above rate constant data with global seasonally and diurnally averaged hydroxyl radical concentrations.

Notes: The kinetics of the thermal decomposition of trans-1,2-dicyanocyclobutane, which yields only vinyl cyanide, have been studied in the temperature range of 570°-660°K using a stirred-flow reactor. The reaction was found to be first order and homogeneous with rate constants represented by the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}k{\rm (sec}^{- 1} {\rm) =}{{{\rm (16}{\rm .0} \pm {\rm 0}{\rm .3)} - {\rm (52}{\rm .9} \pm {\rm 0}{\rm .8)}} \mathord{\left/ {\vphantom {{{\rm (16}{\rm .0} \pm {\rm 0}{\rm .3)} - {\rm (52}{\rm .9} \pm {\rm 0}{\rm .8)}} \theta}} \right. \kern-\nulldelimiterspace} \theta} $$\end{document} where θ = 2.303 RT kcal/mol. The Arrhenius parameters are considerably higher than previously reported. On the assumption of a biradical mechanism the results are consistent with a cyano stabilization energy of ∼5 kcal/mol, in good agreement with the results of recent studies of related systems.

Notes: The fine structure of the mid-gut musculature of the desert locust, Schistocerca gregaria is described and compared with that of the visceral muscles of other species. The gross morphology and fine structure of the nervous system which supplies the mid-gut muscle fibres is described.

Notes: The dorsal ventricular ridge (DVR) is a subcortical, telencephalic structure in reptiles and birds that protrudes into the lateral ventricle. The structure of DVR has been studied in the red-eared turtle (Pseudemys scripta elegans) in Nissl and Golgi preparations. The DVR in Pseudemys is divided into the anterior dorsal ventricular ridge (ADVR) and the basal dorsal ventricular ridge (BDVR) by the dorsal branch of the middle ventricular sulcus. The structure of ADVR has been examined in detail.The ADVR is divided into four regions with distinct boundaries termed dorsal area, medial area, ventral area and central area. Dorsal area, medial area and ventral area border on the lateral ventricle; central area lies deep to the other areas. Three classes of neurons are found in Golgi preparations of ADVR. Juxtaependymal cells have somata near the perikarya of ependymal cells; their dendrites are found primarily in a periventricular fiber zone. Aspiny neurons were observed only in the dorsal half of ADVR and appear to be restricted to deep regions of the ridge. These multipolar neurons are rarely encountered in Golgi preparations, and the observed distribution may not represent their actual distribution in ADVR. The majority of the cells observed in ADVR are spiny neurons with dendritic fields that range from stellate to double-pyramidal. Cells in this class may be subdivided on the basis of axonal morphology into at least two groups, but further studies are needed to determine the range of axonal morphology exhibited by these neurons.An analysis of the distribution of these cell types in Golgi material shows that dorsal area, medial area and ventral area are organized in four zones concentric with the ventricular surface. Central area apparently lacks a concentric pattern of organization. Zone 1 is a periventricular fiber band that contains juxtaependymal neurons and ascending dendrites of zone 2 spiny neurons, and it may serve as a structural substrate for segregated input onto these cell populations. Zone 2 contains clusters of spiny neurons with apposed somata, which vary in size and distribution between areas. Dendrites of zone 4 neurons are also found in the deep half of zone 2. Zone 3 is a cell-poor region which lies at the center of a region of overlapping dendritic fields of zone 2 and zone 4 neurons. Zone 4 contains predominantly spiny neurons (aspiny neurons are found only in the dorsal half of ADVR) which are either isolated or in small clusters with apposed somata. Dendrites of zone 2 cells extend superficially into zone 4, so that the deep portions of zone 4 may be a substrate for segregated input to zone 4 neurons. These zones are differentially elaborated in each area. Central area, by contrast, consists of scattered spiny and aspiny neurons among fibers connecting ADVR and the lateral forebrain bundle.A comparison of these findings with the ADVR of snakes (Ulinski, '78a,b) shows both similarities and differences in DVR organization in the two taxa. Although snakes lack areal divisions, ADVR is organized in four concentric zones (zones A-D). Zones A and B resemble zones 1 and 2 in turtles, consisting of a superficial fiber zone and a subjacent cell cluster zone. The clusters are smaller in snakes than in turtles. However, snakes lack a cell-poor band deep to zone B, and dendrites of cells in zone C enter zone A. Thus, there are differences in both areal and zonal dimensions of ADVR organization in turtles and snakes.