Muscarinic cholinergic receptor binding in rat brain following traumatic brain injury

Recent evidence suggests that excessive activation of muscarinic cholinergic receptors (mAChRs) contributes significantly to the pathophysiological consequences of traumatic brain injury (TBI). To examine possible alterations in mAChRs after TBI, the affinity (Kd) and maximum number of binding sites (Bmax) of mAChRs in hippocampus, neocortex, brain stem and cerebellum were determined by [3H]QNB binding. Three groups of rats were examined: 1 h post-TBI (n = 21), 24 h post-TBI (n = 21) and sham-injured rats (n = 21). Kd values were significantly higher in hippocampus and brain stem at 1 but not 24 h post-TBI compared with sham-injured controls (P < 0.05). Kd values did not significantly differ in neocortex and cerebellum at 1 or 24 h post-TBI compared with sham-injured controls. Bmax values did not significantly differ in any brain areas at 1 or 24 h post-TBI compared with sham-injured controls. These results show that TBI significantly decreases the affinity of mAChRs in hippocampus and brain stem at an early stage post-TBI, which may contribute to desensitization of mAChRs after TBI. The findings of no change in Bmax values are consistent with a transient elevation in ACh concentrations after TBI.     

Plasma concentrations of prolactin, glucose, insulin, urea nitrogen, and total amino acids in stallions after ingestion of feed or gastric administration of feed components

Concentrations of prolactin, glucose, insulin, urea N, and total amino acids in plasma of stallions after ingestion of pelleted feed were compared to those after direct gastric administration of water, NaCl, egg albumin, or corn starch (Exp. 1) or water, egg albumin, hydrolyzed casein (Amicase), or a mixture of indispensable amino acids (Exp. 2). Stallions were fed once daily (75% pellet and 25% hay) at 1500 for 30 d. On d 22, 24, 26, 28, and 30, blood samples were collected every 30 min from 1 h before through 4 h after treatment, which occurred at 1100. In Exp. 1, there was a positive secretory response for prolactin (P = .013) only after the meal. Positive glucose and insulin responses were observed after the meal (P < .055) and after gastric administration of corn starch (P < .001). Total amino acids increased (P = .008) only after the meal. In Exp. 2, a positive prolactin response (P < .001) occurred after the meal and a negative response (P = .023) after administration of water; administration of Amicase increased (P = .061) prolactin concentrations after a 2.5-h delay. Positive responses were observed for glucose, insulin, and total amino acids after the meal (P < .001) and after administration of Amicase or the amino acid mixture (P < .026). Positive urea N responses were observed after administration of Amicase and the amino acid mixture (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)     

A controlled trial of intravenous immune globulin to reduce nosocomial infections in very-low-birth-weight infants. National Institute of Child Health and Human Development Neonatal Research Network

BACKGROUND: Nosocomial infections are a major cause of morbidity and mortality in premature infants. As a rule, their low serum gamma globulin levels at birth subsequently decline to hypogammaglobulinemic values; hence, prophylactic administration of intravenous immune globulin may reduce the rate of hospital-acquired infections. METHODS: In this prospective, multicenter, two-phase controlled trial, 2416 infants were stratified according to birth weight (501 to 1000 g and 1001 to 1500 g) and randomly assigned to an intravenous immune globulin group (n = 1204) or a control group (n = 1212). Control infants were given placebo infusions during phase 1 of the study (n = 623) but were not given any infusions during phase 2 (n = 589). Infants weighing 501 to 1000 g at birth were given 900 mg of immune globulin per kilogram of body weight, and infants weighing 1001 to 1500 g at birth were given a dose of 700 mg per kilogram. The immune globulin infusions were repeated every 14 days until the infants weighed 1800 g, were transferred to another center, died, or were sent home from the hospital. RESULTS: Nosocomial infections of the blood, meninges, or urinary tract occurred in 439 of the 2416 infants (18.2 percent): 208 (17.3 percent) in the immune globulin group and 231 (19.1 percent) in the control group (relative risk, 0.91; 95 percent confidence interval, 0.77 to 1.08). Septicemia occurred in 15.5 percent of the immune globulin recipients and 17.2 percent of the controls. During phase 1 the rate of nosocomial infections was 13.4 percent in the immune globulin group and 17.8 percent in the control group; the respective rates during phase 2 were 21.0 percent and 20.4 percent. The predominant organisms included gram-positive cocci (53.0 percent), gram-negative bacilli (22.4 percent), and candida species (16.0 percent). Adverse reactions were rarely observed during the infusions. Immune globulin therapy had no effect on respiratory distress syndrome, bronchopulmonary dysplasia, intracranial hemorrhage, the duration of hospitalization, or mortality. The incidence of necrotizing enterocolitis was 12.0 percent in the immune globulin group and 9.5 percent in the control group. CONCLUSIONS: Prophylactic use of intravenous immune globulin failed to reduce the incidence of hospital-acquired infections in very-low-birth-weight infants.     

Effects of a prolonged administration of valepotriates in rats on the mothers and their offspring

Valeriana officinalis L. (Valerianaceae) is widely known to be associated with sedative properties. The effects of a valepotriates mixtures on mothers and progeny were evaluated in rats. A 30-day administration of valepotriates did not change the average length of estral cycle, nor the number of estrous phases during this period. Also, there were no changes on the fertility index. Fetotoxicity and external examination studies did not show differences, although internal examination revealed an increase in number of retarded ossification after the highest doses employed--12 and 24 mg/kg. No changes were detected in the development of the offspring after treatment during pregnancy. As for temperature, valepotriates caused a hypothermizant effect after administration by the intraperitoneal route but not after oral administration. Generally, the valepotriates employed induced some alterations after administration by the intraperitoneal route, but doses given orally were innocuous to pregnant rats and their offspring.     

Stimulus control of copulatory behavior in male Japanese quail

The copulatory behavior of sexually experienced male Japanese quail was tested using taxidermic models with varying proportions of natural and artificial features. Completely artificial models exerted little control over copulatory behavior, and whole natural body models reliably elicited copulatory behavior. In single model presentation tests, a model containing a natural head and neck with an artificial body was as effective in eliciting copulatory behavior as a whole body model, but a model containing a natural body with an artificial head and neck was largely ineffective. In choice tests, however, males clearly preferred a whole model over a natural head and neck model, and a natural body model over a completely artificial model. These data indicate male Japanese quail do attend to features of body plumage. Furthermore, test procedures can influence conclusions about effective controlling stimuli.     

Inhibition of transforming growth factor alpha stimulation of human squamous cell carcinoma of the head and neck with anti-TGF-alpha antibodies and tyrphostin

BACKGROUND: Transforming growth factor alpha (TGF-alpha) and its receptor (EGF-R) may regulate normal and malignant epithelial cell growth by an autocrine mechanism. We investigated the role of TGF-alpha in regulating head and neck SCC tumor growth. METHODS: TGF-alpha and EGF-R levels were measured in 7 SCC cell lines and 14 SCC biopsies by RIA, Scatchard, and Western analysis. TGF-alpha autocrine stimulation of DNA synthesis in SCC cell lines was assessed by incubation with TGF-alpha neutralizing antibodies and tyrphostin AG 1478, a selective and potent inhibitor of EGF-R kinase. RESULTS: All SCC cell lines synthesized TGF-alpha and expressed elevated EGF-R levels compared to normal keratinocytes. Twelve of the 14 SCC biopsies contained TGF-alpha protein and 8 had specific EGF-R. Exogenous TGF-alpha or EGF significantly increased DNA synthesis in 4 of 5 SCC cell lines. TGF-alpha neutralizing antibodies or tyrphostin AG 1478 reduced DNA synthesis in the two SCC cell lines (FaDu and SCC9) tested. CONCLUSIONS: These results indicate that SCC cell lines and tumors usually synthesize TGF-alpha, have elevated levels of EGF-R, and are mitogenically stimulated by a TGF-alpha autocrine system. Selective inhibition of the TGF-alpha system by EGF-R kinase inhibitors or TGF-alpha neutralizing antibodies may be useful strategies for treating SCC that overexpress TGF-alpha and its receptor.     

Regulation of the functional activity of the human dopamine transporter by protein kinase C

The role of protein kinase C (PKC) was examined in the regulation of dopamine transport in C6 glioma cells stably expressing the human dopamine transporter. The PKC activating phorbol esters phorbol 12-myristate 13-acetate (PMA) and 4 beta-12,13-dibutyrate phorbol-ester (PDBu) inhibited [3H]dopamine uptake concentration dependently. These effects were attenuated by the PKC inhibitor staurosporine but were unaltered by another inhibitor, chelerythrine, or the phosphatase inhibitor okadaic acid. The potency of PMA in inhibiting [3H]dopamine uptake was similar to that in inhibiting the binding of 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane ([3H]WIN 35,428), and again staurosporine, but not chelerythrine, weakened the effect of PMA. The reduction in dopamine transporter activity by PMA was caused by a decrease in the Vmax value of [3H]dopamine uptake, opposed by a smaller reduction in the Km value, whereas the effect of PMA on [3H]WIN 35,428 binding was caused by a reduction in the Bmax value without a change in the Kd value. The lower Km value in the presence of PMA was accompanied by a higher IC50 of dopamine in inhibiting [3H]WIN 35,428 binding; the latter effect was attenuated by the co-presence of staurosporine. The results are discussed in the context of transporter loss from the cell surface, or a model with phosphorylation affecting the shared dopamine and WIN 35,428 binding domain on the transporter as well as affecting a part of the dopamine binding domain lying outside that for WIN 35,428.     

Dephosphorylation of the cadherin-associated p100/p120 proteins in response to activation of protein kinase C in epithelial cells

Protein kinase C signaling pathways have been implicated in the disruption of intercellular junctions, but mechanisms are not clear. p100 and p120 are members of the Armadillo family of proteins and are localized to cellular adherens junctions. In strain I Madin-Darby canine kidney cells, protein kinase C activation leads to disruption of tight junctions and an increase in permeability of cell monolayers. We show that this permeability increase is accompanied by dephosphorylation of p100/p120 on serine and threonine residues. The dephosphorylation of these proteins can also be induced by the kinase inhibitors staurosporine, KT5926, and G? 6976. Treatment of cells with phosphatase inhibitors induced hyperphosphorylation of p100 and p120. Thus, p100 and p120 participate in a regulatable cycle of serine/threonine phosphorylation and dephosphorylation. Protein kinase C must act, directly or indirectly, by perturbing this phosphorylation cycle, by inhibition of a p100/p120 kinase and/or activation of a phosphatase. These data clearly show that p100 and p120 are targets of a novel protein kinase C signaling pathway. Dephosphorylation of these proteins precedes the permeability increase across epithelial cell monolayers seen in response to phorbol esters, raising the possibility that this pathway may play a role in the modulation of intercellular junctions.     

Models of calcium activation account for differences between skeletal and cardiac force redevelopment kinetics

To explain observed differences in the activation dependence of force redevelopment kinetics between cardiac and skeletal muscle, two numerical models of contractile regulation by Ca2+ were investigated. Ca2+ binding and force production were each modelled as two-state processes with forward and reverse rate constants taken from the literature. The first model incorporates four possible thin-filament states. In the second model Ca2+ is assumed not to dissociate from a thin-filament unit in the force-generating state, resulting in three states. The four-state model can account for the activation dependence of the rate constant of tension redevelopment (ktr) seen in skeletal muscle, without requiring that Ca2+ directly modulates the kinetics of any step in the cross-bridge cycle. Using identical kinetic parameters, the three-state model shows no activation dependence of ktr, consistent with our results in cardiac muscle. Following a step increase in [Ca2+], the rate of rise in tension (as described by the rate constant kCa) varies with the final [Ca2+] for both models, consistent with experimental results from skeletal and cardiac muscle. These numerical models demonstrate that experimental measurements thought to reveal changes in kinetic parameters may simply reflect coupling between the two kinetic processes of Ca2+ binding and force generation. Furthermore, the models present possible differences in the Ca2+ activation scheme between cardiac and skeletal muscle which can account for the contrasting activation dependencies of force redevelopment kinetics.