Neural phenotype expression of cultured human cord blood cells in vitro.

Neural stem cells have been proposed as useful vectors for treating diseases in the CNS, but their utility is severely limited by lack of accessibility. Brain development is ongoing extensively in early postnatal life. However, it is unclear whether stem cells that differentiate into neurons exist in the blood during early postnatal life. We showed in this experiment that neural markers (NeuN, neurofilament, MAP2, GFAP) are expressed and long cytoplasmic processes are elaborated in the cultured human cord blood monocytes prepared from newborn umbilical blood. These results suggest that stem cells in human cord blood may be potential sources of neurons in early postnatal life. We suggest that the neonatal blood system functions as a circulating pool of different types of stem cell.

Differential antinociceptive effect of transcutaneous electrical stimulation on pain behavior sensitive or insensitive to phentolamine in neuropathic rats.

The effects of transcutaneous electrical stimulation and systemic injection of phentolamine, a non-specific alpha-adrenergic antagonist, on the behavioral signs of mechanical allodynia and cold hyperalgesia in rats with nerve injury were investigated. Mechanical allodynia and cold hyperalgesia were evaluated by measuring the paw withdrawal frequency (PWF) resulting from repetitive application of a von Frey hair and the paw lift duration (PLD) at a cold temperature, respectively. After a unilateral nerve injury, both PWF and PLD increased in the injured hind paw. Application of low-frequency, high-intensity transcutaneous electrical stimulation (LFHI-TES) to the injured hind paw depressed the injury-induced increased PWF, whereas it had no effect on the injury-induced increased PLD. Naloxone reversed the LFHI-TES produced depression of PWF. Intraperitoneal administration of phentolamine depressed the injury-induced increased PLD without affecting the injury-induced increased PWF. Our results suggest that LFHI-TES, which activates the endogenous opioid systems, produces an antinociceptive effect that appears to be related to whether or not the pain is mediated by sympathetic activity.

Adrenergic sensitivity of uninjured C-fiber nociceptors in neuropathic rats.

We investigated the adrenergic sensitivity of afferent fibers in the L4 dorsal roots of rats with a unilateral ligation of the L5-L6 spinal nerves. About 12% of nociceptive fibers on the affected side were excited by sympathetic stimulation or by intra-arterial injection of norepinephrine which did not affect A beta-fiber activity. Sympathetic excitation of nociceptive fibers was suppressed by alpha 1-antagonist prazosin, while it was unaffected by alpha 2-antagonist yohimbine. Most of these fibers were excited by intra-arterial injection of alpha 1-agonist phenylephrine, without being affected by an injection of alpha 2-agonist clonidine. Sympathetic excitation was blocked by lidocaine applied near the receptive fields of recorded fibers. The results suggested that some nociceptors remaining intact after partial nerve injury become sensitive to sympathetic activity by the mediation of alpha 1-adrenoceptors in the peripheral endings.

The effects of laminin on the characteristics and differentiation of neuronal cells from epidermal growth factor-responsive neuroepithelial cells.

Many extracellular matrix molecules are expressed in the embryonic nervous system and there is some evidence that they are important regulators of neural development. Of these molecules, laminin appears to be the most potent, affecting virtually all neurons of the peripheral and central nervous system. This study was undertaken to investigate the effects of laminin on the proliferation and differentiation of cultured neuroepithelial cells taken from fetal rat forebrains (embryonic day 17-19). The results are summarized as follows. 1) Neuroepithelial cells cultivated in epidermal growth factors containing serum-free medium subsequently differentiated into neurons, astrocytes, and oligodendrocytes. 2) Neuronal cells derived from neuroepithelial cells were immunoreactive for gamma-aminobutyric acid (GABA) or substance P, but were not for serotonin and tyrosine hydroxylase. 3) In western blot analysis, the phosphorylated neurofilament content in neuronal cells was higher in culture on laminin than in culture on poly-L-lysine (PLL). 4) The proliferation rate of GABAergic neurons was higher in culture on laminin than in culture on PLL. These results suggest that GABAergic and substance P-ergic neurons can be differentiated from neuroepithelial cells and that laminin promotes the differentiation of neuronal cells from neuroepithelial cells and the increased proliferation rate of GABAergic cells.

Differentiation and maturation of astrocytes derived from neuroepithelial progenitor cells in culture.

Neuroepithelial progenitor cells from striata of adult mice develop into either astrocytes or neurons when cultured in the presence of epidermal growth factor (B. A. Reynolds, and S. Weiss, Science 255: 1707-1710, 1992). We instituted primary cultures of such progenitor cells from forebrains of newborn rat pups in an epidermal growth factor-containing medium free of serum in order to study the development of astrocytes in culture. At 4-6 days, primary cultures consisted of floating clusters of proliferating cells which expressed nestin, a marker for neuroepithelial progenitor cells, the ganglioside GD3, and vimentin. When clusters were transferred to polylysine-coated dishes, cells attached to the substrate and began to express antigens characteristic of particular differentiated neurons, astrocytes, or oligodendrocytes within 2 weeks. In 4- to 6-week-old secondary cultures, levels of vimentin expression appeared to decrease within maturing astrocytes which had increased levels of glial fibrillary acidic protein. These results suggest that multipotential epidermal growth factor-progenitor cells can give rise to both neurons and macroglia of the adult central nervous system, and that maturation of the astrocytes in vitro may be occurring in a pattern similar to that seen in vivo. Furthermore, no glial fibrillary acidic protein-positive cells expressed the A2B5 antigen in the same cell indicating an absence of type-2 astrocytes.

Effects of ketamine on contractile responses in vascular smooth muscle.

This study was designed to determine the effects of ketamine on contractions induced by norepinephrine (NE), K+ or histamine (Hist) and on agonist-induced calcium mobilization, in rabbit thoracic aorta with or without endothelium. Contractile responses to NE, K+ or Hist were markedly attenuated by prior exposure to ketamine. Subsequent addition of ketamine to the rabbit aorta undergoing an isometric contraction induced by NE, K+ or Hist also decreased the contractile responses in a calcium ion concentration-dependent manner. Preincubation with ketamine produced a concentration-dependent inhibition of contractile responses elicited by the addition of calcium ion (1.6 mM) to a Ca(++)-free depolarizing solution. However, the phasic contraction produced by NE with 2mM lanthanum pretreatment, which is release of intracellular calcium, was also inhibited by ketamine. Moreover, the tonic contraction produced by NE after depletion of the agonist-releasable pool of intracellular calcium, which is thought to be due to calcium influx, was depressed by ketamine. These data suggest that ketamine relaxes NE-contracted rings of rabbit thoracic aorta by decreasing calcium entry and by producing an extracellular calcium-independent relaxant effect.

Effect of wearing gloves on the thermal balance of Korean women wet-suit divers in cold water.

Effect of wearing neoprene gloves on the thermal exchanges of wet-suited divers was studied in 8 Korean diving women. Subjects, clad with 5-6-mm-thick neoprene wet suits (jacket, pants, and boots) either with or without wearing 3-mm-thick neoprene gloves, were immersed for 3 h in water of critical temperature (17.3 degrees +/- 0.8 degree C) while the rectal and skin (chest, leg, arm, and hand) temperatures and oxygen consumption were measured. Overall thermal insulation of the subject plus suit was calculated from the rectal-to-water temperature difference divided by the estimated rate of skin heat loss. The skin heat loss was assumed to equal metabolic heat production minus respiratory heat loss, corrected for changes in heat storage when mean body temperature changed. All measurements were carried out in a resting condition. During the 3rd h of immersion, the rectal temperature was lower with gloves (delta Tre = 0.30 degree +/- 0.04 degree C; P less than 0.05) whereas metabolic heat production was not significantly different. Consequently, the total thermal insulation was nearly 16% lower with gloves than without gloves. In both the hands and forearms, the regional heat flux determined directly using a heat flux transducer was higher and the thermal insulation index was lower with gloves than without gloves. These results indicate that in wet-suited subjects resting in cold (17 degrees C) water gloves do not provide additional protection against heat loss, but rather decrease the efficiency of thermoregulatory mechanisms. We suggest that sensory input from cold receptors in the distal extremities is particularly important in thermoregulation during immersion in cold water.

Changes in thermal insulation during underwater exercise in Korean female wet-suit divers.

The present work was undertaken to examine the effect of wet suits on the pattern of heat exchange during immersion in cold water. Four Korean women divers wearing wet suits were immersed to the neck in water of critical temperature (Tcw) while resting for 3 h or exercising (2-3 met on a bicycle ergometer) for 2 h. During immersion both rectal (Tre) and skin temperatures and O2 consumption (VO2) were measured, from which heat production (M = 4.83 VO2), skin heat loss (Hsk = 0.92 M +/- heat store change based on delta Tre), and thermal insulation were calculated. The average Tcw of the subjects with wet suits was 16.5 +/- 1.2 degrees C (SE), which was 12.3 degrees C lower than that of the same subjects with swim suits (28.8 +/- 0.4 degrees C). During the 3rd h of immersion, Tre and mean skin temperatures (Tsk) averaged 37.3 +/- 0.1 and 28.0 +/- 0.5 degrees C, and skin heat loss per unit surface area 42.3 +/- 2.66 kcal X m-2 X h. The calculated body insulation [Ibody = Tre - Tsk/Hsk] and the total shell insulation [Itotal = (Tre - TW)/Hsk] were 0.23 +/- 0.02 and 0.5 +/- 0.04 degrees C X kcal-1 X m2 X h, respectively. During immersion exercise, both Itotal and Ibody declined exponentially as the exercise intensity increased. Surprisingly, the insulation due to wet suit (Isuit = Itotal - Ibody) also decreased with exercise intensity, from 0.28 degrees C X kcal-1 X m2 X h at rest to 0.12 degrees C X kcal-1 X m2 X h at exercise levels of 2-3 met.(ABSTRACT TRUNCATED AT 250 WORDS)

Energetics of wet-suit diving in Korean women breath-hold divers.

Contemporary Korean women divers wear wet suits during diving work to avoid the cold water stress. The present study was undertaken to evaluate the effect of wearing wet suits on the daily thermal balance of divers and on the duration of diving work. Rectal (TR) and skin temperatures and O2 consumption (VO2) were measured in four divers before and during diving work in summer (22.5 degrees C water) and winter (10 degrees C water). Subjects wore either wet suits (protected) or cotton suits (unprotected) for comparison. TR decreased 0.4 degrees C in summer and 0.6 degrees C in winter after 2 h of diving work in protected divers, while it decreased to 35 degrees C in 60 min in summer and in 30 min in winter in unprotected divers. Mean skin temperature of protected divers decreased to 31 degrees C in summer and 28 degrees C in winter, while that of unprotected divers decreased to 24 degrees C in summer and 13 degrees C in winter. VO2 toward the end of the diving work period increased by 80 (summer) and 140% (winter) in protected divers and by 160 (summer) and 250% (winter) in unprotected divers. From these values total thermal cost of diving work was estimated to be 260 and 370 kcal . day-1 in summer and winter, respectively.