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1.  Effects of dietary ratio of n-6 to n-3 polyunsaturated fatty acids on immunoglobulins, cytokines, fatty acid composition, and performance of lactating sows and suckling piglets 
This experiment was conducted to investigate the effects of dietary ratios of n-6:n-3 polyunsaturated fatty acids (PUFA) on the performance of lactating sows and their piglets. Thirty pregnant Landrace sows were assigned to one of three treatments from d 108 of gestation until weaning (26–29 d) and were fed diets containing different ratios of n-6:n-3 PUFA including 3:1, 9:1 and 13:1. The effects on sow and litter production traits were examined together with an assessment of sow body condition. No differences were detected among the treatments for the daily feed intake of sows or changes in sow weight and back-fat levels during lactation (P > 0.05). Litter size at d 14 and d 21 were tended to increase in 3:1 treatment compared with 9:1 and 13:1 treatments (P < 0.10). Litter weight gain (1.77 kg/d) from d 0 to d 14 was tended to increase in 9:1 groups compared with the other two treatments (P < 0.10). A significant difference was observed for the content of α -linolenic acid, total n-3 PUFA, and the ratio of n-6:n-3 PUFA in the colostrum, milk, and piglets plasma (P < 0.01). The effects of different ratios of n-6:n-3 PUFA in sow diets on colostrum, milk, and piglet plasma immunoglobulin concentrations are studied. No difference was observed among treatments in the concentrations of IgM, and IgA in colostrum (P > 0.05). A great significant difference for IgG concentration was observed among 3 group in colostrum. A great significant difference for IgA, and IgM (P < 0.01) concentrations in piglet plasma at d14 and a significant difference for IgG(P < 0.05) was observed at d14. Furthermore, at d 21 of lactation, piglet plasma IgG and IgA concentration were greater in 3:1 compared with 13:1 group (P < 0.01).
In summary, the current study demonstrated that altering the ratio of n-6:n-3 PUFA in lactating sow diet had an effect on the immune component including immunoglobulin and cytokines, and it tended to increase the litter average daily gain and improve the immune status of piglets when dietary ratio of n-6:n-3 PUFA was 9:1.
PMCID: PMC3598561  PMID: 23270637
n-6:n-3 polyunsaturated fatty acids; Performance; Fatty acid composition; Immunoglobulin; Cytokines
2.  Altered sodium channel-protein associations in critical illness myopathy 
Skeletal Muscle  2012;2:17.
During the acute phase of critical illness myopathy (CIM) there is inexcitability of skeletal muscle. In a rat model of CIM, muscle inexcitability is due to inactivation of sodium channels. A major contributor to this sodium channel inactivation is a hyperpolarized shift in the voltage dependence of sodium channel inactivation. The goal of the current study was to find a biochemical correlate of the hyperpolarized shift in sodium channel inactivation.
The rat model of CIM was generated by cutting the sciatic nerve and subsequent injections of dexamethasone for 7 days. Skeletal muscle membranes were prepared from gastrocnemius muscles, and purification and biochemical analyses carried out. Immunoprecipitations were performed with a pan-sodium channel antibody, and the resulting complexes probed in Western blots with various antibodies.
We carried out analyses of sodium channel glycosylation, phosphorylation, and association with other proteins. Although there was some loss of channel glycosylation in the disease, as assessed by size analysis of glycosylated and de-glycosylated protein in control and CIM samples, previous work by other investigators suggest that such loss would most likely shift channel inactivation gating in a depolarizing direction; thus such loss was viewed as compensatory rather than causative of the disease. A phosphorylation site at serine 487 was identified on the NaV 1.4 sodium channel α subunit, but there was no clear evidence of altered phosphorylation in the disease. Co-immunoprecipitation experiments carried out with a pan-sodium channel antibody confirmed that the sodium channel was associated with proteins of the dystrophin associated protein complex (DAPC). This complex differed between control and CIM samples. Syntrophin, dystrophin, and plectin associated strongly with sodium channels in both control and disease conditions, while β-dystroglycan and neuronal nitric oxide synthase (nNOS) associated strongly with the sodium channel only in CIM. Recording of action potentials revealed that denervated muscle in mice lacking nNOS was more excitable than control denervated muscle.
Taken together, these data suggest that the conformation/protein association of the sodium channel complex differs in control and critical illness myopathy muscle membranes; and suggest that nitric oxide signaling plays a role in development of muscle inexcitability.
PMCID: PMC3441911  PMID: 22935229
Skeletal muscle; NaV 1.4 sodium channel; NaV 1.5 sodium channel; Nitric oxide (NO); Neuronal nitric oxide synthase (nNOS); Glycosylation; Phosphorylation; Action potential; Excitability; Denervation
3.  Loss of synaptic vesicles from neuromuscular junctions in aged MRF4-null mice (78/80 characters) 
Neuroreport  2011;22(4):185-189.
MRF4 belongs to the basic helix-loop-helix class of transcription factors and it and other members of its family profoundly influence skeletal muscle development. Less is known about the role of these factors in aging. Since MRF4 is preferentially expressed in sub-synaptic nuclei, we postulated it might play a role in maintenance of the neuromuscular junction. To test this hypothesis, we examined the junctional regions of 19-20 month old mice and found decreased levels of SV2B, a marker of synaptic vesicles, in MRF4-null mice relative to controls. There was a corresponding decrease in grip strength in MRF4-null mice. Taken together, these data suggest that the intrinsic muscle factor MRF4 plays an important role in maintenance of neuromuscular junctions. (117/120 words)
PMCID: PMC3043462  PMID: 21278612
Endplate; synapse; neuromuscular junction; basic helix-loop-helix transcription factor; muscle regulatory factor; skeletal muscle; aging; denervation; MRF4
Rab3A is a small GTPase associated with synaptic vesicles that is required for some forms of activity-dependent plasticity. It is thought to regulate the number of vesicles that fuse through an effect on docking, vesicle maturation, or mobilization. We recently showed that at the neuromuscular junction, loss of Rab3A led to an increase in the occurrence of miniature endplate currents (mepcs) with abnormally long half widths (Wang et al., 2008). Here we show that such events are also increased after short-term activity blockade, and this process is not Rab3A-dependent. However, in the course of these experiments we discovered that the homeostatic increase in mepc amplitude after activity blockade is diminished in the Rab3A deletion mouse and abolished in the Rab3A Earlybird mouse which expresses a point mutant of Rab3A. We show that homeostatic plasticity at the neuromuscular junction does not depend on TNFα, is not accompanied by an increase in the levels of VAChT, the vesicular transporter for ACh, and confirm that there is no increase in ACh receptors at the junction, three characteristics distinct from that of central nervous system homeostatic plasticity. Activity blockade does not produce time course changes in mepcs that would be consistent with a fusion pore mechanism. We conclude that Rab3A is involved in a novel presynaptic mechanism to homeostatically regulate the amount of transmitter in a quantum.
PMCID: PMC3072228  PMID: 21389214
synaptic plasticity; synaptic vesicle release; presynaptic mechanisms; MEPP; knockout mice; TNFα
5.  Retinal Oscillations Carry Visual Information to Cortex 
Thalamic relay cells fire action potentials that transmit information from retina to cortex. The amount of information that spike trains encode is usually estimated from the precision of spike timing with respect to the stimulus. Sensory input, however, is only one factor that influences neural activity. For example, intrinsic dynamics, such as oscillations of networks of neurons, also modulate firing pattern. Here, we asked if retinal oscillations might help to convey information to neurons downstream. Specifically, we made whole-cell recordings from relay cells to reveal retinal inputs (EPSPs) and thalamic outputs (spikes) and then analyzed these events with information theory. Our results show that thalamic spike trains operate as two multiplexed channels. One channel, which occupies a low frequency band (<30 Hz), is encoded by average firing rate with respect to the stimulus and carries information about local changes in the visual field over time. The other operates in the gamma frequency band (40–80 Hz) and is encoded by spike timing relative to retinal oscillations. At times, the second channel conveyed even more information than the first. Because retinal oscillations involve extensive networks of ganglion cells, it is likely that the second channel transmits information about global features of the visual scene.
PMCID: PMC2674373  PMID: 19404487
LGN; retina; visual coding; natural stimuli; oscillations
6.  Feedforward Excitation and Inhibition Evoke Dual Modes of Firing in the Cat’s Visual Thalamus during Naturalistic Viewing 
Neuron  2007;55(3):465-478.
Thalamic relay cells transmit information from retina to cortex by firing either rapid bursts or tonic trains of spikes. Bursts occur when the membrane voltage is low, as during sleep, because they depend on channels that cannot respond to excitatory input unless they are primed by strong hyperpolarization. Cells fire tonically when depolarized, as during waking. Thus, mode of firing is usually associated with behavioral state. Growing evidence, however, suggests that sensory processing involves both burst and tonic spikes. To ask if visually evoked synaptic responses induce each type of firing, we recorded intracellular responses to natural movies from relay cells and developed methods to map the receptive fields of the excitation and inhibition that the images evoked. In addition to tonic spikes, the movies routinely elicited lasting inhibition from the center of the receptive field that permitted bursts to fire. Therefore, naturally evoked patterns of synaptic input engage dual modes of firing.
PMCID: PMC2587266  PMID: 17678858
7.  Receptive field structure varies with layer in the primary visual cortex 
Nature neuroscience  2005;8(3):372-379.
Here we ask whether visual response pattern varies with position in the cortical microcircuit by comparing the structure of receptive fields recorded from the different layers of the cat's primary visual cortex. We used whole-cell recording in vivo to show the spatial distribution of visually evoked excitatory and inhibitory inputs and to stain individual neurons. We quantified the distribution of ‘On’ and ‘Off’ responses and the presence of spatially opponent excitation and inhibition within the receptive field. The thalamorecipient layers (4 and upper 6) were dominated by simple cells, as defined by two criteria: they had separated On and Off subregions, and they had push-pull responses (in a given subregion, stimuli of the opposite contrast evoked responses of the opposite sign). Other types of response profile correlated with laminar location as well. Thus, connections unique to each visual cortical layer are likely to serve distinct functions.
PMCID: PMC1987328  PMID: 15711543
8.  Colocalization of dihydropyridine and ryanodine receptors in developing heart with a neural crest-associated defect 
Neural crest-associated congenital heart defects in humans are among the most lethal and costly to treat. In avian and mouse embryos with persistent truncus arteriosus (PTA), the most severe of the neural crest anomalies, there is poor cardiac function because of impaired excitation-contraction coupling. One possible explanation for poor excitation-contraction coupling is that peripheral junctions, composed of closely associated sarcoplasmic reticulum Ca2+ release channels (ryanodine receptors) and surface membrane L-type Ca2+ channels (dihydropyridine receptors), are not well colocalized.
To compare the degree of colocalization of these two Ca2+ channel proteins in isolated ventricular myocytes from normal hearts and hearts with PTA.
PTA was induced in the embryonic chick by laser ablation of the cardiac neural crest before migration from the neural tube. Immunofluorescent staining of dihydropyridine and ryanodine receptors along with computer-assisted image analysis was used to measure relative colocalization.
Dihydropyridine and ryanodine receptor colocalization was greater by 20% in embryos with PTA. Much of the increase appeared to result from a 14% increase in the area stained for ryanodine receptors. A third observation was that a high level of colocalization was maintained even after enzymatic dissociation in which the embryonic myocytes had typically lost their elongated appearance and assumed a spherical shape.
The increased colocalization of dihydropyridine and ryanodine receptors in hearts with PTA may be a compensatory response to a defect at the level of single Ca2+ channel proteins. These results indicate the high degree of stability of sarcoplasmic reticulum junctional complexes.
PMCID: PMC2858959  PMID: 20428438
Calcium release channel; Excitation-contraction coupling; Heart development; Heart defect; L-type calcium channel

Results 1-8 (8)