[The value of serum myelin basic protein in assessment of severity of acute closed head trauma]

Serum levels of myelin basic protein (MBP) were measured in 112 patients after acute head injury by enzyme linked immuno-absorbent assay (ELISA). Patients with cerebral concussion showed no significant change in serum MBP. Patients with cerebral contusion, extradural hematoma or intracerebral hematoma had a mean serum MBP concentration much higher than that of patients with cerebral concussion. And patients with extradural hematoma had a mean serum MBP concentration much lower than that of patients with cerebral contusion and intracerebral hematoma; the differences were significant (P < 0.05). But there was no significant difference between patients with cerebral contusion and intracerebral hematoma (P > 0.05). The amount of serum MBP was significantly correlated with the volume of extradural hematoma, intracerebral hematoma and with the extent of the cerebral contusion (P < 0.05). This study suggested that the serum MBP may reflect the type and severity of closed head injury patients.

Functional reconstitution of the purified mannose phosphotransferase system of Escherichia coli into phospholipid vesicles

The mannose transporter complex acts by a mechanism which couples translocation with phosphorylation of the substrate. It consists of a hydrophilic subunit (IIABMan) and two transmembrane subunits (IICMan, IIDMan). The purified complex was reconstituted into phospholipid vesicles by octyl glucoside dilution. Glucose export was measured with proteoliposomes which were loaded with radiolabeled glucose and to which purified IIABMan, cytoplasmic phosphorylcarrier proteins, and P-enolpyruvate were added from the outside. Vectorial transport was accompanied by stoichiometric phosphorylation of the transported sugar. Glucose added to the outside of the proteoliposomes was also phosphorylated rapidly but did not compete with vectorial export and phosphorylation of internal glucose. Glucose uptake was measured with proteoliposomes which were loaded with the cytoplasmic phosphoryl carrier proteins and P-enolpyruvate and to which glucose was added from the outside. Vectorial import and phosphorylation occurred with a higher specificity (Km 30 +/- 6 microM, kcat 401 +/- 32 pmol of Glc/micrograms of IICDMan/min) than nonvectorial phosphorylation (Km 201 +/- 43 microM, kcat 975 +/- 88 pmol of Glc/micrograms of IICDMan/min). A new plasmid pTSHIC9 for the controlled overexpression of the cytoplasmic phosphoryl carrier proteins, enzyme I, HPr, and IIAGlc, and a simplified procedure for the purification of these proteins are also described.

The effects of 10 triterpenoid compounds on experimental liver injury in mice

The purpose of this study was to compare the hepatoprotective effects of 10 oleanane-type triterpenoid compounds on three known hepatotoxicants in mice. These compounds include oleanolic acid, ursolic acid, uvaol, alpha-hederin (alpha-H), hederagenin, glycyrrhizin, 18 alpha-glycyrrhetinic acid (alpha-GA), 18 beta-glycyrrhetinic acid (beta-GA), 19 alpha-hydroxyl asiatic acid 28-O-beta-D-glucoside (HAG), and 19 alpha-hydroxyl asiatic acid (HA). They were administrated sc for 3 days at 200 mumol/kg, except for alpha-H, which was given at 100 mumol/kg for 2 days. Acute liver injury was produced in male CF-1 mice by CCl4 (15 microliters/kg, ip), acetaminophen (500 mg/kg, ip), and cadmium chloride (3.7 mg/kg, iv). Liver damage was assessed by serum activities of alanine aminotransferase and sorbitol dehydrogenase, as well as by histopathological examination. alpha-Hederin, ursolic acid, and oleanolic acid markedly decreased the toxicity produced by all three hepatotoxicants. Uvaol significantly decreased CCl4- and Cd-induced hepatotoxicity, but had no effect on acetaminophen toxicity. Glycyrrhizin, alpha-GA, and beta-GA decreased acetaminophen-induced liver injury, whereas hederagenin, HAG, and HA did not protect against any of the hepatotoxicants. In addition, alpha-hederin, ursolic acid, oleanolic acid, and uvaol increased hepatic metallothionein levels by 87-, 48-, 28-, and 10-fold, respectively, as determined by the Cd/hemoglobin assay. In conclusion, among the 10 triterpenoid compounds examined, alpha-hederin, ursolic acid, and oleanolic acid appear to be the most effective in protecting against CCl4-, acetaminophen-, and Cd-induced liver injury.

Kinetic behaviour of alpha-chymotrypsin in reverse micelles. A stopped-flow study

At the aim of investigating whether the early rapid phase of enzyme turnover is different in reverse micelles compared with bulk water, the kinetic properties of alpha-chymotrypsin have been studied in reverse micelles formed by sodium bis(2-ethylhexyl)sulfosuccinate in isooctane. Pre-steady state and steady-state kinetic constants, in water and in reverse micelles, have been determined by stopped-flow spectrophotometry for the hydrolysis of two substrates, namely acetyl-L-tryptophan-p-nitrophenyl ester and p-nitrophenyl acetate. It has been shown that, for both substrates, the acylation rate constant (k2) is very much lower in reverse micelles than in water. However, the deacylation rate constant (k3) and the turnover number (kcat) are not significantly changed in reverse micelles with respect to bulk water. Therefore, despite considerable rate changes in the acylation step, deacylation is rate limiting both in water as well as in reverse micelles, under the experimental conditions used.

Protective effects of fulvotomentosides on cadmium-induced hepatotoxicity

Fulvotomentosides (Ful) is the total saponins of Lonicera fulvotomentosa. In the present study, we examined the effects of Ful on cadmium (CdCl2)-induced acute liver injury in mice. Ful pretreatment (150 mg.kg-1, sc x 3 d) remarkably decreased CdCl2 (3.7 mg Cd.kg-1, iv)-induced liver damage as indicated by serum activities of alanine aminotransferase and sorbitol dehydrogenase. Distribution of Cd to 12 organs and hepatic subcellular fractions was determined 2 h after Cd challenge. Ful pretreatment did not produce a marked shift in the distribution of Cd to various organs, but markedly altered the hepatic subcellular distribution of Cd, with more Cd bound to metallothionein (MT) in the cytosol, less in the nuclear, mitochondrial, and microsomal fractions. Ful pretreatment produced a dose-dependent increase in hepatic MT as determined by the Cd.hemoglobin assay. In conclusion, Ful protected against Cd hepatotoxicity by inducing MT, which binds Cd in the cytosol and lowers the amount of Cd available to other critical organelles and proteins.

Protective effects of fulvotomentosides on acetaminophen-induced hepatotoxicity

Fulvotomentosides (Ful) is the total saponins of Lonicera fulvotomentosa. In the present study, we examined the effect of Ful on acetaminophen (AA)-induced hepatotoxicity in mice. Ful pretreatment (75-225 mg.kg-1, sc x 3 d) significantly decreased AA (500 mg.kg-1, ip)-induced liver damage as indicated by serum activities of alanine aminotransferase and sorbitol dehydrogenase. Ful pretreatment (225 mg.kg-1, sc x 3 d) decreased hepatic cytochrome P-450, cytochrome b5, and NADPH-cytochrome c reductase by approximately 15-20%. Microsomes from Ful-pretreated mice, incubated in vitro with AA, produced less AA-glutathione. A 28% increase in urinary excretion of AA-glucuronide was observed in Ful (150 mg.kg-1, sc x 3 d) pretreated mice. Ful pretreatment had no influence on liver UDP-glucuronic acid concentration, but increased hepatic glucuronyltransferase activity towards AA. In summary, Ful pretreatment protects against AA-induced hepatotoxicity. One of the mechanisms for this protection appears to be the decreased AA toxic activation via P-450, as well as increased detoxication via glucuronidation of AA.

Substrate effects on the enzymatic activity of alpha-chymotrypsin in reverse micelles

Six different substrates have been used for measuring the activity of alpha-chymotrypsin in reverse micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in isooctane. The substrates were glutaryl-Phe p-nitroanilide, succinyl-Phe p-nitroanilide, acetyl-Phe p-nitroanilide, succinyl-Ala-Ala-Phe p-nitroanilide, succinyl-Ala-Ala-Pro-Phe p-nitroanilide and acetyl-Trp methyl ester. It has been shown that the dependence of the kinetic constants (kcat and Km) on the water content of the system, on wo (= [H2O]/[AOT]), is different for the different substrates. This indicates that activity-wo profiles for alpha-chymotrypsin in reverse micelles not only reflect an intrinsic feature of the enzyme alone. For the p-nitroanilides it was found that the lower kcat (and the higher Km) in aqueous solution, the higher kcat as well as Km in reverse micelles. "Superactivity" of alpha-chymotrypsin could only be found with the ester substrate and with relatively "poor" p-nitroanilides. The presence of a negative charge in the substrate molecule is not a prerequisite for alpha-chymotrypsin to show "superactivity".