Feeding reduced-fat dried distillers grains with solubles to lactating Holstein dairy cows does not alter milk composition or cause late blowing in cheese.

Feeding dried distillers grains with solubles (DDGS) to lactating dairy cows has been implicated as a cause of late blowing defects in the production of Swiss-style cheeses. Our objectives were (1) to test the effect of feeding reduced-fat DDGS (RF-DDGS; ∼6% fat) to lactating dairy cows on the composition of milk and on the suitability of the milk for production of baby Swiss cheese and (2) to evaluate the effect of diet on cow lactation performance. Lactating Holstein dairy cows were fed both dietary treatments in a 2 × 2 crossover design. Cows were housed in a 48-cow freestall pen equipped with individual feeding gates to record feed intake. The control diet was a corn, corn silage, and alfalfa hay diet supplemented with mechanically expelled soybean meal. The experimental diet was the same base ration, but 20% (dry matter basis) RF-DDGS were included in place of the expelled soybean meal. The RF-DDGS diet was additionally supplemented with rumen-protected lysine; diets were formulated to be isoenergetic and isonitrogenous. Cows were allowed ad libitum access to feed and water, fed twice daily, and milked 3 times daily. For cheese production, milk was collected and pooled 6 times for each dietary treatment. There was no treatment effect on milk yield (35.66 and 35.39 kg/d), milk fat production (1.27 and 1.25 kg/d), milk fat percentage (3.65 and 3.61%), milk protein production (1.05 and 1.08 kg/d), lactose percentage (4.62 and 4.64%), milk total solids (12.19 and 12.28%), and somatic cell count (232.57 and 287.22 × 103 cells/mL) for control and RF-DDGS, respectively. However, dry matter intake was increased by treatment, which implied a reduction in feed efficiency. Milk protein percentage also increased (3.01 and 3.11%), whereas milk urea nitrogen decreased (14.18 and 12.99 mg/dL), indicating that protein utilization may be more efficient when cows are fed RF-DDGS. No differences in cheese were observed by a trained panel except cheese appearance; control cheese eyes were significantly, but not practically, larger than the RF-DDGS cheese. These results indicate that RF-DDGS can be effectively used in the rations of lactating Holstein cows with no deleterious effects on milk production and composition and metrics of the physiology of the cow (i.e., blood glucose and nonesterified fatty acids); however, feeding RF-DDGS increased dry matter intake, which decreased feed efficiency. Finally, feeding RF-DDGS did not negatively influence quality and suitability of milk for production of baby Swiss cheese.

Cholecystokinin octapeptide potentiates the inhibitory response mediated by D2 dopamine receptors in slices of the ventral tegmental area of the brain in the rat.

The ability of cholecystokinin octapeptide (CCK8) to modulate dopamine (DA)-induced inhibition of the firing of neurons in the ventral tegmental area of the rat was examined. Extracellular recordings were obtained from putative DA-containing neurons, identified on the basis of their electrophysiological characteristics and response to DA, in an in vitro slice preparation from the ventral tegmental area of the brain. Application of DA produced a concentration-dependent reduction in firing rate. This DA-induced inhibition was mimicked by the D2 selective agonist, LY 171555 (trans-(-)-4,4a,5,6,7,8,8a,9-octahydro-5-propyl-2H- pyrazolo[3,4-g]quinoline), but not by the D1 selective agonist, SKF 38393 (R-(+)-2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine). The DA-induced inhibition was antagonized selectively by the D2 antagonist, l-sulpiride, but not by the D1 antagonist, SCH 23390 (R-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7- ol). However, CCK8 elicited a transient increase in firing rate in some neurons and, in addition, potentiated the inhibitory response evoked by DA or LY 171555. Again SKF 38393 was without effect following the administration of CCK8. Taken together, these results suggest that DA-induced inhibition of DA-containing neurons in the ventral tegmental area of the brain of the rat is mediated by activation of D2-receptors and that CCK8 potentiates this D2-mediated inhibition.

A highly potent and selective N-methyl-D-aspartate receptor antagonist from the venom of the Agelenopsis aperta spider.

Agatoxin-489, extracted from the venom of the Agelenopsis aperta spider, was studied on acutely isolated perfused hippocampal neurons of rat using the concentration clamp technique. Agatoxin-489 proved to be a selective N-methyl-D-aspartate antagonist; responses to applications of N-methyl-D-aspartate or L-aspartate were blocked by concentrations of agatoxin-489 ranging between 0.1 nM and 1 microM, while responses to kainate were not affected by agatoxin-489 at concentrations up to 10 microM. The actions of agatoxin-489 against responses to N-methyl-D-aspartate or L-aspartate were use- and voltage-dependent, being less pronounced with an increase in the holding potential from -100 to -30 mV. The action of agatoxin-489 could be completely or partially reversed only after washout in the presence of an N-methyl-D-aspartate agonist. The washout was more effective at positive membrane potentials ranging from 0 to +20 mV. These results imply that the spider toxin agatoxin-489, like dizocilpine, is a potent and selective N-methyl-D-aspartate antagonist which preferentially interacts with activated N-methyl-D-aspartate receptors and/or open N-methyl-D-aspartate-activated ionic channels.

NPS 1506, a novel NMDA receptor antagonist and neuroprotectant. Review of preclinical and clinical studies.

NPS 1506 is a moderate affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. NPS 1506 is neuroprotective in rodent models of ischemic stroke, hemorrhagic stroke, and head trauma, with a 2-hr window of opportunity. Neuroprotectant doses of NPS 1506 ranged from approximately 0.1-1.0 mg/kg, with peak plasma concentrations ranging from 8-80 ng/mL. Even at doses producing behavioral toxicity, NPS 1506 did not elicit MK-801-like behaviors, did not generalize to phencyclidine (PCP), and did not elicit neuronal vacuolization. In a Phase I study, intravenous (i.v.) doses of NPS 1506 from 5-100 mg were well tolerated and provided plasma concentrations in excess of those required for neuroprotection in rodents. Adverse events at the 100-mg dose included mild dizziness and lightheadedness, and mild to moderate ataxia. Neither PCP-like psychotomimetic effects nor cardiovascular effects were noted. The long plasma half-life of NPS 1506 (approximately 60 hr) suggests that a single i.v. dose will provide prolonged neuroprotection in humans.

Intracellular recording from putative dopamine-containing neurons in the ventral tegmental area of Tsai in a brain slice preparation.

Coronal slices of rat mesencephalon containing the ventral tegmental area of Tsai (VTA) and the substantia nigra were prepared. Stable intracellular recordings were obtained from presumed dopamine (DA)-containing neurons in the VTA. Both silent and spontaneously active cells were encountered; spontaneously active neurons fired in an extremely regular pacemaker-like fashion. These neurons had resting membrane potentials ranging from -45 to -75 mV and input resistances ranging from 80-400 M omega. DA-containing neurons in the VTA demonstrated marked anomalous rectification in response to hyperpolarizing current pulses. Application of DA or the GABAB agonist, baclofen, to the bathing medium produced suppression of spontaneous firing, sometimes accompanied by membrane hyperpolarization. Neuronal input resistance was not changed consistently by DA and was generally reduced by baclofen.

Noradrenergic responses in rat hippocampus: evidence for medication by alpha and beta receptors in the in vitro slice.

The effect of perfused norepinephrine (NE) on evoked potentials in CA1 of the in vitro rat hippocampus was examined. Weak and variable effects on population spike amplitude were observed, with lower doses of NE generally producing excitations and higher doses more often producing inhibitions. Clonidine, an alpha-receptor agonist, produced a dose-dependent inhibition of population spike amplitude; this inhibition was effectively antagonized by the alpha-antagonist, phentolamine. Isoproterenol (ISO), a beta-agonist, produced marked increases in population spike amplitude which could be antagonized by timolol, a beta-receptor antagonist. Phentolamine did not antagonize the excitations produced by ISO, and timolol had no effect on the inhibitions seen with clonidine. After pretreatment with either phentolamine or timolol, NE perfusion elicited robust and consistent elevations or reductions in the population spike, respectively. A potent cyclic AMP derivative, 8-p-chlorophenylthio cyclic AMP, produced large increases in population spike amplitude which appeared similar to the responses seen with beta-agonists. No changes in field EPSP amplitudes were observed with any of the drugs tested. Taken together, these results suggest that NE may interact with alpha-adrenergic receptors to decrease pyramidal cell excitability, and the beta-adrenergic receptors to increase pyramidal cell excitability; the beta-effect may involve cAMP.

Electrophysiological and biochemical sequelae of the destruction of hippocampal noradrenergic afferents by DSP4.

The effects of DSP4 lesions were examined 20-53 days postlesion in the rat hippocampus. A single treatment with DSP4 produced decreases of 42-94% in the norepinephrine (NE) content of this brain region. There was, however, no effect of DSP4 treatment on either the number or affinity of beta-adrenergic receptor sites as determined by radioligand binding studies with (-)-[125I]pindolol; furthermore, there was no relationship between the concentrations of NE and the number of receptor sites in individual hippocampi. The DSP4-induced depletion of functionally releasable NE was confirmed by the loss of electrophysiological responsiveness to amphetamine in the in vitro hippocampus following such lesions. In contrast, electrophysiological responses to direct acting beta-adrenergic or alpha-adrenergic agonists were unchanged following DSP4 treatment. This finding again suggests the lack of any change in postsynaptic sensitivity. The results of this study demonstrate that while the potent noradrenergic neurotoxin DSP4 is able to reduce NE concentrations significantly in noradrenergic target regions in brain, these lesions are not necessarily associated with postsynaptic changes in adrenergic systems.

Effects of adenosine on neurally mediated norepinephrine release from the cat spleen.

The effects of adenosine on the release of 3H-norepinephrine (3H-NE) from the isolated, perfused cat spleen consequent to nerve stimulation were evaluated. Electrical stimulation of the splenic nerve (5 Hz/100 impulses total) caused a release of 3H-NE and a rise in perfusion pressure. Adenosine added to the perfusion fluid (final concentrations 1 X 10(-6), 1 X 10(-5), and 1 X 10(-4) M) significantly reduced the pressure response elicited by nerve stimulation. In addition, adenosine (1 X 10(-4) M) slightly increased the release of total 3H consequent to nerve stimulation. Theophylline (1 X 10(-4) M) produced both a slight increase in the release of total 3H and a diminished pressure response. The effects of adenosine were effectively antagonized by this concentration of theophylline. Neither substance had any effect on the spontaneous release of total 3H. Adenosine (1 X 10(-4) M) also antagonized the pressure response elicited by perfusion of NE.

Actions of GABA in developing rabbit hippocampus: an in vitro study.

The development of neuronal responses to gamma-aminobutyric acid (GABA) was examined using intracellular recording techniques in area CA1 of rabbit hippocampal slices maintained in vitro. Microapplication of GABA (via pressure ejection) in stratum pyramidale in slices from mature rabbits (age 1 month) evoked a hyperpolarization of CA1 pyramidal neurons. The reversal potential (Erev) for this response was approximately -70 mV. In contrast, local application of GABA into stratum pyramidale in slices from immature rabbits (age 7-10 days) produced a depolarizing response with an Erev of approximately -54 mV. The relationship between these findings and the development of inhibitory synaptic activity in rabbit hippocampus is discussed.

Hippocampal noradrenergic responses in vivo and in vitro. Characterization of alpha and beta components.

Pressure ejection of l-norepinephrine (NE) in the in vivo rat hippocampus generally produced depression of pyramidal cell spontaneous activity. In addition, both excitation and biphasic responses were observed. NE-induced inhibition of firing rate was effectively antagonized by concurrent administration of the alpha antagonist phentolamine, but was largely unaltered by the beta antagonist timolol. On the other hand, NE-induced elevation in spontaneous firing rate was effectively blocked by timolol, and largely unaffected by phentolamine. Another beta antagonist, sotalol, did not selectively antagonize either NE-induced inhibition or NE-induced excitation. The beta agonist 2-fluoro-NE produced increases in pyramidal cell firing rates in most cells studied, while the alpha agonist 6-fluoro-NE inhibited the majority of cells examined. The effects of sotalol were also examined on alpha and beta receptor-mediated field responses in the in vitro hippocampal slice. Sotalol was shown to be a selective beta antagonist in this system, blocking excitation evoked by the beta agonist isoproterenol while having no effect on inhibition elicited by the alpha agonist clonidine; however, the potency of sotalol (Ki = 3.5 microM) was considerably less than that of timolol (Ki = 50 nM). Taken together, these results suggest that NE-induced depression and elevation in hippocampal pyramidal cell spontaneous discharge in vivo are mediated via alpha and beta adrenoceptors, respectively.

Neuroprotective effects of NPS 846, a novel N-methyl-D-aspartate receptor antagonist, after closed head trauma in rats.

OBJECT: The authors sought to determine whether 3,3-bis (3-fluorophenyl) propylamine (NPS 846), a novel noncompetitive N-methyl-D-aspartate receptor antagonist, alters outcome after closed head trauma in rats. METHODS: The experimental variables were: presence or absence of closed head trauma, treatment with NPS 846 or no treatment, and time at which the rats were killed (24 or 48 hours). The NPS 846 (1 mg/kg) was administered intraperitoneally at 1 and 3 hours after closed head trauma or sham operation. Outcome measures were the neurological severity score (NSS), ischemic tissue volume, hemorrhagic necrosis volume, and specific gravity, water content, and concentrations of calcium, sodium, potassium, and magnesium in brain tissue. The following closed head trauma-induced changes in the injured hemisphere (expressed as the mean +/- the standard deviation) were reversed by NPS 846: decreased specific gravity of 1.035 +/- 0.006 at 24 hours was increased to 1.042 +/- 0.004; the decreased potassium level of 0.583 +/- 0.231 mg/L at 48 hours and at 24 hours was increased to 2.442 +/- 0.860 mg/L; the increased water content of 84.7 +/- 2.6% at 24 hours was decreased to 79.8 +/- 2%; the increased calcium level of 0.592 +/- 0.210 mg/L at 24 hours was decreased to 0.048 +/- 0.029 mg/L; and the increased sodium level of 2.035 +/- 0.649 mg/L was decreased to 0.631 +/- 0.102 mg/L. Administration of NPS 846 also lowered the NSS (improved neurological status) at 48 hours (7 +/- 3) and caused no significant changes in ischemic tissue or hemorrhagic necrosis volumes in the injured hemisphere at 24 or 48 hours. CONCLUSIONS: In this model of closed head trauma, NPS 846 improved neurological outcome, delayed the onset of brain edema, and improved brain tissue ion homeostasis.

A second example of anti-Esa, an antibody to a high-incidence Cromer antigen.

A blood sample contained an antibody to a high-incidence antigen that reacted with all red blood cells (RBCs) tested by the indirect antiglobulin test (IAT). The antibody reacted with papain-, ficin-, and trypsin-treated RBCs, but not with a-chymotrypsin-treated RBCs. This pattern of reactivity suggested the possibility that the antibody was recognizing an antigen in the Cromer blood group system. Tests against RBCs deficient in decay-accelerating factor (which carries the Cromer antigens) were weakly positive. Tests with antibodies to high-incidence Cromer antigens and with RBCs lacking high-incidence Cromer antigens led to identification of the second example of anti-Esa in an Es(a-) person. The antibody was IgG1 and reacted by the IAT to a titer of 64. The monocyte monolayer assay indicated potential clinical significance of this antibody in relation to transfusion.

Long-term size-increasing adaptation of saccades in macaques.

Motor learning adjusts movement size and direction to keep movements accurate. A useful model of motor learning, saccade adaptation, uses intra-saccade target movement to make saccades seem inaccurate and elicit adaptive changes in saccades. In the most studied saccade adaptation procedure, which we call short-term saccade adaptation (STSA), monkeys decrease or increase the size of their saccades by tracking 1000-2000 adapting target movements in a single saccade session. STSA elicits rapid changes of limited size and duration. Larger, more persistent reduction in saccade size results from adapting saccades daily for 19 days, a procedure that we call long-term saccade adaptation (LTSA). LTSA mimics the demands of rehabilitation more closely than does STSA and, unlike STSA, produces changes that could maintain long-term accuracy. Previous work describes LTSA that reduces saccade size in monkeys. Though convenient to study, size-decreasing LTSA is not a good model for rehabilitation because few injuries necessitate making movements smaller. Here we characterize size-increasing LTSA and compare it, in the same monkeys, to size-reducing LTSA. We found that size-increasing LTSA can double saccade gain in ∼21 days, and is slower than size-decreasing LTSA. In contrast to a single size-decreasing STSA, a single size-increasing STSA does not prevent additional saccade size increase at the normal rate when a monkey continues to track adapting target movements. We conclude that size-increasing LTSA is slower than size-decreasing LTSA but can make larger changes in saccade size. Size-increasing and size-decreasing LTSA use distinct mechanisms with different performance characteristics.

Anticonvulsant and proconvulsant actions of alpha- and beta-noradrenergic agonists on epileptiform activity in rat hippocampus in vitro.

The ability of l-norepinephrine to influence epileptiform activity was examined in an in vitro rat hippocampal slice preparation. Exogenously applied norepinephrine (NE) had anticonvulsant properties in that it slowed or stopped spontaneous interictal discharges which had been initiated by superfusion of slices with medium containing penicillin and elevated levels of potassium. This anticonvulsant property of NE was shared by the alpha receptor agonists 6-fluoro-norepinephrine, l-alpha-methyl-norepinephrine, and clonidine, but not by d-alpha-methyl-norepinephrine or l-phenylephrine. The beta receptor agonists 2-fluoro-norepinephrine and l-isoproterenol, on the other hand, were proconvulsant in that they increased interictal discharge rate. The alpha receptor antagonist phentolamine selectively blocked anticonvulsant responses, whereas the beta receptor antagonist timolol selectively blocked proconvulsant activity. These results suggest that activation of alpha or beta receptors has opposing inhibitory or excitatory effects respectively on epileptiform discharges in the rat hippocampus.

Fetal hemoglobin (HbF) synthesis in baboons, Papio cynocephalus. Analysis of fetal and adult hemoglobin synthesis during fetal development.

Fetal hemoglobin (HbF) and adult hemoglobin (HbA) synthesis was studied in fetal baboons, Papio cynocephalus, to determine the normal pattern of hemoglobin production during fetal development. Fetuses ranging from 53 to 180 days gestation (term gestation 184 days) were used. Erythroid cells were incubated with 3H-L-leucine, and the rates of globin chain synthesis and the distribution of radioactivity into hemoglobin intermediates and completed hemoglobin molecules were determined. Gamma chain synthesis accounted for approximately 97% of the total nonalpha chain synthesis up to 140 days gestation; beta chain synthesis accounted for the remainder. After 140 days gestation, approximately equal quantities of gamma and beta chain were synthesized in the bone marrow. Prior to 140 days gestation, total alpha chain synthesis was 30% greater than total non-alpha chain synthesis, while there was balanced chain synthesis after 140 days gestation. During the period of excess alpha chain synthesis, fetal erythrocytes contained a large pool of alpha-hemoglobin (alpha chain with heme attached) molecules uncombined with beta or gamma chains. In view of the possibility that alpha chains may have a lower affinity for gamma chains than beta chains, excess alpha chain synthesis may be required to maintain low levels of free gamma chains.

Electrophysiological actions of somatostatin (SRIF) in hippocampus: an in vitro study.

The electrophysiological actions of somatostatin (somatotropin release inhibiting factor; SRIF) were investigated in the in vitro hippocampal slice preparation. Intracellular recordings were obtained from pyramidal neurons in area CA1 in slices of hippocampus from guinea pigs and rabbits. Somatostatin, applied via micropressure ejection to CA1 pyramidal-cell somata, was primarily excitatory. The effects, however, were quite variable, with nearly all cells displaying pronounced tachyphylaxis. A majority of cells was depolarized by SRIF, but hyperpolarizations or biphasic depolarization/hyperpolarization responses were also recorded. Only minimal conductance changes were associated with the SRIF-induced voltage changes. Depletion of SRIF, by injection of the intact animal with cysteamine several hours before preparing slices, resulted in no obvious abnormalities in hippocampal slice electrophysiology. Our results obtained with application of exogenous SRIF are consistent with the concept that SRIF acts as an excitatory neurotransmitter/neuromodulator in hippocampus. However, our attempts to demonstrate endogenous SRIF action have thus far been unsuccessful.

Development of hyperpolarizing inhibitory postsynaptic potentials and hyperpolarizing response to gamma-aminobutyric acid in rabbit hippocampus studied in vitro.

The postnatal development of IPSPs and response to locally applied GABA were examined using intracellular recording techniques in region CA1 of rabbit hippocampal slices maintained in vitro. Pyramidal neurons in slices from mature rabbits demonstrated an EPSP-IPSP sequence following stimulation of stratum radiatum. In these same slices, pressure application of GABA into stratum pyramidale and stratum radiatum produced membrane hyperpolarization and depolarization, respectively. Pyramidal neurons in slices from immature rabbits (age 6 to 10 days) responded differently. Stimulation of stratum radiatum produced a prolonged depolarizing postsynaptic potential; few IPSPs were observed. Ejection of GABA into either stratum pyramidale or stratum radiatum evoked a depolarizing response. The GABA agonist, 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridine-3-ol (THIP), which has been reported to activate "hyperpolarizing" GABA receptors selectively, primarily produced membrane hyperpolarization when applied to the somata of mature neurons, but it evoked a depolarization when applied to immature neurons. Bicuculline, a GABA antagonist which may have a preferential selectivity for "depolarizing" GABA receptors, was somewhat more efficacious (at 50 microM concentration) at antagonizing GABA-evoked depolarization in immature cells than GABA-evoked hyperpolarization in mature cells. This same concentration of bicuculline partially antagonized IPSPs in mature cells, and it markedly potentiated depolarizing PSPs in immature cells. Taken together, these results suggest that the late development of synaptic inhibition in rabbit hippocampus is due, at least in part, to an immaturity in the GABAergic system.