Erythrocyte membrane skeletal protein bands 4.1 a and b are sequence-related phosphoproteins

Bands 4.1 a and b are proteins of 80,000 and 78,000 molecular weight, which are both present at approximately 100,000 copies per erythrocyte ghost. Both proteins are components of the erythrocyte membrane skeleton. Bands 4.1 a and b are labeled when intact erythrocytes are incubated with [32P]orthophosphoric acid, and, therefore, are phosphoproteins. One-dimensional partial proteolytic mapping analysis of 32P-labeled bands 4.1 a and 4.1 b and two-dimensional peptide mapping analysis of 125I-labeled bands 4.1 a and 4.1 b clearly demonstrated that the two proteins are sequence-related phosphoproteins. Band 4.1 purified by standard techniques (Tyler, J. M., Hargreaves, W. R., and Branton, D. (1979) Proc. Natl. Acad. Sci. U. S. A. 76, 5192-5196) contains bands 4.1 a and 4.1 b. Bands 4.1 a and 4.1 b bind to spectrin heterodimers in solution. We conclude that the erythrocyte skeletal proteins bands 4.1 a and 4.1 b are sequence-related phosphoproteins, both capable of binding spectrin.

The methylphenidate-induced stereotypy in the awake rat: local cerebral metabolism

The local cerebral metabolic rate for glucose (1=CMRg) was computed in rats with methylphenidate-induced stereotypy using the quantitative 14C-2-deoxyglucose (2-DG) technique. Four rats received methylphenidate 15 mg per kilogram IP. Compared to five control animals, treated rats showed statistically significant (p less than or equal to 0.05) increases in 1-CMRg in globus pallidus, ventral lateral nucleus of the thalamus, subthalamic nucleus, red nucleus, substantia nigra, entopeduncular nucleus, inferior olivary nucleus, and the lateral cerebellar cortex. Significantly, 1-CMRg decreased in area 4 of the motor cortex. The auditory system showed no change in 1-CMRg, demonstrating the specific action of methylphenidate in the rat brain. This technique allows evaluation of the functional anatomy of the entire central nervous system and may be helpful in understanding the mechanisms of methylphenidate-induced stereotypy.

Effect of dexamethasone on hexamethylene bisacetamide-induced Friend cell erythrodifferentiation

Friend erythroleukemic cells can be induced to differentiate by chemicals such as dimethyl sulfoxide and hexamethylene bisacetamide (HMBA) in a dose-dependent manner. Others have shown that dexamethasone and other steroid hormones can inhibit the differentiation induced by dimethyl sulfoxide. We show here that dexamethasone has a dual mode of action on the HMBA-induced differentiation of a Friend cell line, DS19. At concentrations above 10(-10) M, dexamethasone inhibits the HMBA-induced differentiation in DS19 cells. We further found that as the concentration of HMBA is reduced, the amount of dexamethasone required to inhibit differentiation increases. Such inhibition seems to act primarily by decreasing the probability that a cell will become committed to differentiate. Besides, dexamethasone does not inhibit hemoglobin synthesis of cells which are committed in its absence. In addition, we show that sensitivity to the inhibition by dexamethasone is inversely related to the inducibility of cell populations. The second action of dexamethasone, observed at concentrations between 10(-10) and 10(-13) M, is to increase the proportion of hemoglobin-containing cells relative to that for cells cultured in its absence. The degree of this synergistic effect for induced differentiation is inversely related to the level of induction in the absence of dexamethasone and thus is best observed in the cells cultured at low levels of HMBA. We present evidence that this synergistic effect may be due to an increased viability of the induced cells and possibly an increase in the proliferative capacity of these cells.

Rehabilitation following brain damage: some neurophysiological mechanisms. Animal models of recovery with training after central nervous system lesions

Animal studies revealed that training with techniques of instrumental conditioning produces another phase of functional recovery beyond spontaneous recovery after CNS lesions. Such conditioned behaviour is difficult to transfer to an unconditioned or another conditioned response. Conditioned and unconditioned behaviours are mediated through different pathways and mechanisms. Conditioned behaviour requires less specific pathways and can probably be achieved as long as the basic spinal mechanisms are activated. Other studies showed that reflex recovery can be maximized through non-specific training, probably by protecting the neuromuscular system from deterioration. However, such a programme does not appear to improve the reflexes beyond the level attributable to spontaneous recovery, nor to facilitate the rate of recovery. If the training is specifically directed towards augmentation of a particular reflex, the reflex can be improved beyond that seen with spontaneous recovery but may be exaggerated to a functional disadvantage. These findings have significant clinical implications.

Quantitative measurement of local cerebral metabolic rate for glucose utilizing tritiated 2-deoxyglucose

The [14C]2-deoxyglucose (2-DG) technique has been widely utilized for quantitative measurement of local cerebral metabolic for glucose (1CMRG) in animals. The technique as presently used is limited by the energy of 14C beta-particles, which can travel relatively great distances in tissue. This results in limited audioradiographic resolution and in computed 14C concentrations which are a function of tissue section thickness. [3H]2-DG has less energetic beta-particles; hence, autoradiographs have better resolution and optical densities are independent of tissue thickness for sections greater than 5 micrometer. We have developed a method for quantitation of 1CMRG in rats using [3H]2-DG and a newly developed ultrasensitive X-ray film. Autoradiographic tissue standards were prepared by injecting rats with [3H]2-DG and assaying micro-samples of brain for 3H concentration. Ten rats were used in this study. Five rats received [3H]2-DG (300 muCi/100 g) and 5 rats received [14C]2-DG (7.5 muCi/100 g). The mean 1CMRG values for selected areas of the central nervous system demonstrated no significant difference (P greater than 0.05) between the [14C]2-DG and the [3H]2-DG groups. Values for 1CMRG from the [3H]2-DG group showed no variation attributable to inadequate microtome precision. The improved resolution obtained by utilizing [3H]2-DG is especially evident where gray matter (high 1CMRG) is immediately adjacent to white matter (low 1CMRG).

Effects of vestibulospinal lesions upon locomotor function in cats

We used cats to study the consequences of bilateral ablation of the vestibular complex. The animals were very severely ataxic and incapable of head support for nearly two weeks. They gradually regained the ability to stand and to walk on a treadmill, at first with a marked reduction of the extensor components of stepping. After stabilization of recovery we could not obtain decompensation by dorsal hemisection. We conclude that the key consequence of these lesions is a temporary reduction in facilitatory drive to joint extensor muscle groups. Neither the corticospinal nor the rubrospinal tracts mediate the functional recovery observed.

Prevalence of the tarsal tunnel syndrome in rheumatoid arthritis

Forty-eight patients with definite of classical rheumatoid arthritis (RA) were studied for the presence of tarsal tunnel syndrome (TTS). Nerve conduction velocities and distal latencies were determined in a constant temperature room and the findings compared with a group of 35 normal, age-matched subjects. After excluding four patients with peripheral neuropathy, a definite delay in the distal motor latency of the tibial nerve was documented in 11 subjects (25%). Two of the 11 had foot symptoms suggestive of TTS. These 11 patients with prolonged distal motor latencies did not otherwise differ from RA patients without TTS in terms of disease duration or severity, treatment, or the presence of foot deformity. Thus, compressive neuropathy of the branches of the posterior tibial nerve is a relatively frequent finding in patients with definite or classical RA.

Effects of corticospinal lesions upon treadmill locomotion by cats

We studied the pattern of stepping in cats, before and after the placement of lesions in the corticospinal system. We found a deficit after the lesions, which was characterized by increased extension of the involved hindlimbs during the stance (E2--E3) phase of the step cycle. This deficit lasted two weeks or less. It may reflect loss of inhibitory influences upon extensor motoneuron pools.

Serum proteins of mice with splenomegaly

Our earlier serum electrophoretic study in 'lethargic' mutant mice showed that the quantity of protein in 1 band is inversely related to the size of the spleen. In this study, we demonstrate that this protein band almost entirely disappears in mice with splenomegaly following spontaneous skin infection. The results suggest that this serum protein may play a role in regulating growth of lymphoid tissue.

Syndeins: the spectrin-binding protein(s) of the human erythrocyte membrane

Two-dimensional tryptic and chymotryptic analyses of all the major bands in a sodium dodecyl sulfate/polyacrylamide gel of the human erythrocyte membrane show that each band has a characteristic map. However, band 2.1 (nomenclature of T. L. Steck) and several polypeptides below this band exhibit similar tryptic and chymotryptic peptide maps and thus appear to be a family of closely related proteins or degradation products. Furthermore, they all contain a subset of peptides that are accounted for by the peptides from two known spectrin-binding fragments. We show that both fragments derive from 2.1-related proteins and conclude that band 2.1 and its related proteins, which we name "syndeins", bind spectrin and connect it to the erythrocyte membrane.

Reconstitution of intramembrane particles in recombinants of erythrocyte protein band 3 and lipid: effects of spectrin-actin association

The integral membrane protein Band 3 of the human erythrocyte, either purified or in a crude Triton X-100 extract of ghosts, was combined with egg lecithin in a cholate solution. During dialysis to remove cholate, lipid bilayer vesicles formed in which Band 3 existed as a dimer and in which intramembrane particles indistinguishable from those in the native membrane were exposed by freeze-fracturing. The recombinant vesicles were stable in both high and low salt concentrations, sedimented at a density that increased in prportion to their protein content, and bound spectrin-actin extracted from erythrocyte ghosts. When spectrin-actin was associated with the vesicles, the behavior of the recombinant intramembrane particles simulated that of the erythrocyte ghost intramembrane particles: they were dispersed at pH 7.6 and aggregrated at pH 5-5.5. Thus, some of the characteristics of the native membrane have been reconstituted in the recombinant.

Interosseous muscles in claw finger

The third and fourth fingers of the normal hands of 75 adult subjects were tested for active finger extension with the wrists in neutral position. Seventy-two of the subjects could not actively extend the interphalangeal (IP) joints when the metacarpophalangeal (MCP) joints were passively and maximally extended. However, the IP joints could be passively extended without pain in 67 subjects and with pain in 5 subjects. This indicated that the inability to actively extend the IP joints when the MCP joints were maximally extended is seldom due to tightness of the flexor tendons. Electromyographic recordings of the interossei muscles in one subject showed voluntary activity of these muscles with the MCP joints maximally extended while the IP joints remained flexed. A macrospoic study was made of the dissected third and fourth fingers of five embalmed cadaver hands and, in two of these specimens polygraphic recordings were made with the use of the strain gauge. In each of these specimens, when traction was applied in the appropriate interosseous muscle, movement of the lateral band of the extensor aponeurosis was noted when the MCP joint was at neutral or slight flexion, while no motion could be detected when the MCP joint was in maximal extension. Thus, maximal extension of the MCP joint blocks not only the action of the extensor digitorum communis tendon, as shown by Mulder and Landsmeer, but also blocks the action of the interossei in extension of the fingers. This explains the mechanism of development of claw finger in those cases without intrinsic hand muscle paralysis.

Radiolysis of ferric hexafluoroacetylacetonate–toluene solutions

In the 120 krad/h, 60Co-γ radiolysis of air-free, anhydrous solutions of ferric hexafluoroacetylacetonate (Fe(HFA)3) in toluene at 27 °C, G(—Fe(HFA)3) = G(Fe(HFA)2) = 1.05 ± 0.03 molecules/100 eV and G(HHFA) = 0 where Fe(HFA)2 is radiolytically inert ferrous hexafluoroacetylacetonate and HHFA is hexafluoroacetylacetone. G(H2) = 0.13 ± 0.03 is not affected by Fe(HFA)3 while G(CH4)is reduced from 0.0088 &([a-z]+); 0.0020 to 0.0052 ± 0.0020 and [Formula: see text] is increased from 0.102 ± 0.019 to 0.307 ± 0.026 by Fe(HFA)3. Activation energies for the radiolytic formation of Fe(HFA)2, H2, CH4, and [Formula: see text] in the temperature range −95 to 27 °C, are 670 ± 130, 0, 1200 ± 900, and 1280 ± 25 cal mol−1, respectively.G(—Fe(HFA)3) = 1.05 represents the total yield of radicals scavenged since at the concentrations of solute used in the radiolyses the quantum yield for the disappearance of Fe(HFA)3 by reaction with solvent S1 and/or T1 states, generated by flash photolysis, is negligible [Formula: see text] Radicals trapped by Fe(HFA)3 are••CH3 (G ≈ 0.004) and unknown radicals (G ≈ 0.4) which are capable of combining with [Formula: see text] does not scavenge [Formula: see text] radicals (G ≈ 0.6). The formation of H2 in scavenger inaccessible spurs and CH4 and [Formula: see text] outside spurs has been confirmed.

Heterogeneity in the conformation of different protein fractions from the human erythrocyte membrane

We have isolated 5 families of proteins from human red blood cell membranes and characterized their secondary structure by ultraviolet circular dichroism measurements. The protein families were prepared by selective solubilization from ghosts under nondenaturing conditions. We find that the intact ghost has a mean alpha-helix fraction of 0.37, whereas a low-ionic-strength extract (bands 1, 2, 5, "spectrin") has a substantially higher helix fraction, 0.55. Further extraction of the ghosts with para-chloromercuribenzoate yields bands 2.1, 4.1, 4.2, and 6; their helix content is only 0.17. Finally, the major intrinsic protein, band 3, was solubilized by a non-ionic detergent. Its helix fraction is 0.38.

Functional recovery with and without training following brain damage in experimental animals: a review

Review of observations on experimental animals following brain damage shows that some functions may recover spontaneously and functional accomplishment can be increased by training even with unchanged reflex status. Training consists of a combination of two basic techniques: forced use of the impaired body part, and instrumental conditional relfexes. The possible mechanisms of recovery include restoration by an alternative pathway, compensation through complicated interactions among brain structures and, with training, activation of a parallel system essential to conditioned responses. Factors, such as motivation and emotion, may complicate the course of recovery. Results of recovery with training in experimental animals strongly indicate that such training can play an active and specific role in functional improvement following brain damage in man. Future development of rehabilitation medicine in this direction is suggested.

Isolation and characterization of band 3, the predominant polypeptide of the human erythrocyte membrane

Band 3 is the predominant approximately 90,000-dalton polypeptide component of the human erythrocyte membrane. It was solubilized selectively, along with the other major glycoproteins, by extracting membrane ghosts with Triton X-100 under nondenaturing conditions. Two major polypeptides remained associated with Band 3 under these conditions; however one (Band 6) could be dissociated at an ionic strength of 0.15 and the other (Band 4.2) by treatment with p-chloromercuribenzoate. Band 3 was then purified (greater than or equal to 97%) by aminoethyl cellulose ion exchange chromatography. The isolated protein was free of phospholipid and was moderately enriched in apolar amino acid residues; it contained galactose and glucosamine but very little sialic acid and galactosamine. When Band 3 was labeled by treatment of ghosts with galactose oxidase plus KB3H4 and then purified, the electrophoretic mobility of its radioactivity lagged slightly behing that of its Coomassie blue staining profile. Variation in glycosylation could therefore cause the diffuse trailing zone characteristically observed for Band 3 on polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The ultraviolet circular dichroism of Band 3 was stable in nonionic detergent and suggested an alpha helix content of 43%, a value close to that estimated for this polypeptide in the membrane.