Significance of administration of fat emulsion: hepatic changes in infant rats receiving total parenteral nutrition with and without fat.

Total parenteral nutrition (TPN) is associated with cholestasis and hepatic steatosis, which can be lethal in infants who cannot be fed orally. The present animal study focused on the metabolic complications in the liver that may occur due to the excessive administration of fat-free TPN. Thirty infant (3-week-old) male SD rats weighing 60-70 g were randomly allocated to five groups (n = 6): the OD group received an oral diet, the FT group received an oral diet and was fasted overnight on the last day of experiment before sacrifice, the 0% fat group received TPN without fat, the 20% fat group received TPN with 20% of calories from fat emulsion, and the 40% fat group received TPN with 40% of calories from fat emulsion. All TPN regimens were isocaloric, isonitrogenic, and administered for 4 days. In the 0% fat group, plasma levels of liver enzymes were significantly higher than in the other groups. Pathological examination showed hepatomegaly and severe fatty changes without cholestasis in the 0% fat group. The results of this study in infant rats indicate the importance of including fat in the TPN regimen in order to prevent the abnormal hepatic changes associated with the excessive administration of fat-free TPN.

Evaluation of the effect of arginine-enriched amino acid solution on tumor growth.

To investigate the effect of arginine-enriched solution on tumor growth and metastasis, rats were infused with solutions containing 5.5 and 0.66% arginine for 8 days. Infusions were started at the same time of subcutaneous transplant of Yoshida sarcoma. Arginine-rich solution suppressed tumor growth at an early stage and prevented metastases to the liver and kidney. In addition, arginine supplements enhanced the phagocytic activity of alveolar macrophages. It also resulted in maintenance of a positive nitrogen balance and prevented the increases in the levels of several amino acids observed in the control group. The suppressive effect of arginine-enriched solution on tumor growth may be due to its activation of the immunologic system, in which the phagocytic activity of macrophages probably participates.

[Effects of lidocaine and its metabolite, monoethylglycine xylidide (MEGX), on transmembrane action potentials in guinea-pig papillary muscles].

Effects of lidocaine 5, 10, 20 micrograms.ml-1 and its metabolite, MEGX 5, 10, 20 micrograms.ml-1, on transmembrane action potentials were studied in isolated guinea-pig papillary muscles, perfused with modified Tyrode's solution. The basic driving rate was 1 Hz and the rate was changed from 1 Hz to 0.25, 0.5, 2, 3 and 4 Hz in a stepwise manner. Both lidocaine and MEGX produced dose- and rate-dependent depression of maximum rate of rise of action potential (Vmax) without significant changes in resting membrane potentials. The recovery kinetics of Vmax was studied by either applying premature stimuli at basic driving rate of 0.25 Hz or by stopping the basic driving of 1 Hz for 1s to 60s. A slow component (time constant: 176-206 ms for lidocaine, 300-340 ms for MEGX) was observed in premature response. And a slower component (time constant: 3-4s for MEGX) was observed in the first response after stopping stimulation. Both drugs shortened the action potential duration. These results suggest that MEGX has a lidocaine-like class I antiarrhythmic actions and that it might modify the actions of lidocaine especially in patients with elevated plasma MEGX concentration.

[Voltage-dependent effects of lidocaine and its metabolite, monoethylglycine xylidide (MEGX), on maximum rate of rise (Vmax) of action potential upstroke in guinea-pig papillary muscles].

We studied the effects of lidocaine and MEGX on the sodium current, using Vmax as an indicator, at an extracellular potassium concentration ([K]o) of 10 mmol.l-1, and compared the present results with those obtained at 5.4 mmol.l-1 [K]o in our previous study. At 10 mmol.l-1 [K]o, both lidocaine (10 micrograms.ml-1) and MEGX (10 micrograms.ml-1) significantly decreased the Vmax at the steady-state of 1 Hz, caused a significant rate-dependent decrease in Vmax, and slowed the recovery kinetics of Vmax. These effects of both agents were more prominent than those obtained at 5.4 mmol.l-1 [K]o, suggesting that MEGX as well as lidocaine produce voltage-or [K]o-dependent blocking effects on Vmax.

[Effects of volatile anesthetics on force interval relationships in guinea-pig atrial preparations].

Depressant effects of halothane, enflurane and isoflurane on isolated guinea-pig left atrial muscles bathed in Tyrode's solution at 30 degrees C were examined. Contractions were elicited by stimulation through external field electrodes while tension was recorded continuously. Frequency-force relationships at stimulation rates of 0.1, 0.2, 0.5 and 1 Hz were studied. The pD2 values of these volatile anesthetics at each stimulation rates were not different significantly, suggesting the frequency-independent depressions of these anesthetics. Interval-strength relationships at time intervals of 0.3-20 sec during 1 Hz-stimulation were also studied. Mechanical restitution curves after converting to logistic function reached a peak at 8-20 sec and were fitted well to double exponential functions with time constants of 200-600 msec (k1) and 2-6 sec (k2). All volatile anesthetics depressed the magnitude constants for fast response in a dose dependent manner. Accordingly, at high concentrations, mechanical resuscitation curves tended to fit single exponential function. Halothane and enflurane did not alter time constant k1, k2 significantly, while isoflurane increased k2 significantly. These results suggest that the mechanisms of myocardial depressant effects are different between these anesthetics.

[Application of the concept of fuzzy logistic controller for treatment of hypertension during anesthesia].

The concept of Zadeh's fuzzy logistic controller was applied to control hypertension during anesthesia, and its clinical usefulness was examined in patients undergoing elective surgery. Arterial blood pressure was determined by use of an automatic blood pressure device. Nicardipine was used as hypotensive drug. Based on the fuzzy control rules, we developed state-action diagram so as to maintain systolic blood pressure at around 130 mmHg. Nicardipine was infused by using a digitally controlled infusion pump, and its infusion rate was changed according to this diagram. Although acute hypertension associated with endotracheal intubation was not significantly attenuated, hypertension associated with either skin incision or endotracheal extubation, where blood pressure increased slowly, was successfully controlled with our system. These results suggest that the application of the concept of fuzzy logistic controller is useful for treatment of hypertension during anesthesia, especially when blood pressure increases slowly.

[Physiological and anatomical characteristics of the vestibular ganglion of the bull frog].

Spatial distributions of the vestibular nerve fibers from end organs to the vestibular ganglion (VG) were studied using physiological and anatomical methods. Physiologically, ampullary nerve compound action potentials (AP) were recorded from VG. Anatomically, HRP (horseradish peroxidase) was injected into the cut end of the ampullary nerve, and the stained neural elements were counted on serial sections. Nerve fibers from the anterior semicircular canal (SC) were distributed in the anterior half of the VG. The horizontal SC nerves were also distributed in the anterior half of the VG, but tended to be posterior. The posterior SC nerves were found predominantly in the posterior half and the antero-dorsal portions of the VG. These distribution patterns corresponded well to those confirmed by recording of AP. Furthermore, neural connections were found between the superior and the inferior vestibular nerves, suggesting receptor-receptor fibers. The majority of these fibers were small in diameter.

Halothane increases epinephrine threshold for the development of slow responses in isolated canine trabeculae.

We studied halothane/epinephrine interaction in isolated canine trabeculae using the doses of epinephrine necessary to produce slow responses (epinephrine threshold for the development of slow responses, ETSR) as an indicator. The preparations were depolarized in Tyrode's solution containing 26 mmol/L of KCl, then epinephrine concentrations in the solution were increased in a stepwise manner. Halothane (1%) had no significant effect, whereas 2% and 4% halothane significantly increased the ETSR. alpha 1-Blockade with either 4, 8, or 16 ng/mL of prazosin or 20, 40, or 80 ng/mL of droperidol did not alter the ETSR, whereas beta 1-adrenergic blockade with 8, 17, or 34 ng/mL of metoprolol significantly increased the ETSR. The same trend was observed when either 8 ng/mL of prazosin or 17 ng/mL of metoprolol was given in combination with 2% halothane. Verapamil (5, 10, or 20 ng/mL) increased the ETSR in a dose-dependent manner. These results indicate that halothane decreases rather than increases the sensitivity of slow calcium channels to epinephrine and that any increase above the baseline ETSR after halothane administration cannot be ascribed to halothane/adrenoceptor interaction but rather to calcium entry-blocking effects of halothane. As slow responses are induced by the activation of slow calcium channels, our findings are consistent with known data that halothane can interfere with slow calcium channel conductance.

Loci on murine chromosomes 7 and 13 that modify the phenotype of the NOA mouse, an animal model of atopic dermatitis.

The NOA (Naruto Research Institute Otsuka Atrichia) mouse is an animal model of allergic or atopic dermatitis, a condition characterized by ulcerative skin lesions with accumulation of mast cells and increased serum IgE. We reported earlier that a major gene responsible for dermatitis in the NOA mouse lay in the middle of chromosome 14, and that the incidence of disease clearly differed according to parental strain; the mode of inheritance was autosomal recessive with incomplete penetrance. In the study reported here, we searched for genes that might modify the NOA phenotype, and we identified two candidate loci that appeared to contain genes capable of modifying atopic or allergic dermatitis, one in the middle of chromosome 7 (chi2 = 14.66; P = 0.00013 for D7Mit62) and the other in the telomeric region of chromosome 13 (chi2 = 15.352; P = 0.000089 for D13Mit147). These loci correspond to regions of synteny in human chromosomes where linkages to asthma, atopy, or related phenotypes, such as serum IgE levels, have been documented.

Determination of reduced, protein-unbound, and total concentrations of N-acetyl-L-cysteine and L-cysteine in rat plasma by postcolumn ligand substitution high-performance liquid chromatography.

A high-performance liquid chromatographic assay was developed for the quantitative determination of the sulfur-containing amino acids N-acetyl-L-cysteine (NAC) and L-cysteine (Cys) in rat plasma. The thiols were separated by reverse-phase ion-pair chromatography, and the column eluent was continuously mixed with an iodoplatinate-containing solution. The substitution of sulfur of the thiol compound with iodide was quantitatively determined by measuring changes in the absorption at 500 nm. The low-molecular-weight disulfides and mixed disulfide conjugates of thiols with proteins were entirely reduced to the original reduced compounds by dithiothreitol. By reducing these two types of disulfides separately during sample pretreatment, the reduced, protein-unbound, and total thiol concentrations could also be determined. Validation testing was performed, and no problems were encountered. The limit of detection was approximately 20 pmol of thiol on the column. The present method was used to measure the plasma concentrations of NAC and Cys in the rat after a bolus intravenous administration of NAC, focusing on disulfide formation. The binding of NAC to protein through mixed disulfide formation proceeds in a time-dependent and reversible manner. Moreover, this "stable" covalent binding might limit total drug elimination, while the unbound NAC is rapidly eliminated. Consequently, the analytical method described in this study is very useful for the determination of plasma NAC and Cys, including disulfide conjugates derived from them.

Anatomical and physiological characteristics of the vestibular ganglion of the bull frog.

The spatial distribution of nerve fibers from individual vestibular end organs in the vestibular ganglia (VG) was studied using horseradish peroxidase (HRP). HRP was injected into the cut end of the bull frog ampullary nerve. Stained neural elements were counted on the serial sections. Spatial distribution was also studied by recording ampullary nerve compound action potentials (AP) from VG. The anterior semicircular canal (SC) nerves were distributed in the anterior half of VG. The horizontal SC nerves were also distributed in the anterior half of VG, but tended to be posterior. The posterior SC nerves were found predominantly in the posterior half and antero-dorsal portions. These distribution patterns corresponded well with those confirmed by AP recording. There were a few neural connections between anterior and posterior SC, or horizontal and posterior SC, indicating receptor-receptor fibers.

Role of intestinal bacteria in ileal ulcer formation in rats treated with a nonsteroidal antiinflammatory drug.

The role of intestinal bacteria in induction and repression of ulcer formation in the ileum of rats treated with one of the nonsteroidal antiinflammatory drugs (NSAIDs), 5-bromo-2-(4-fluorophenyl)-3-(4-methylsulfonylphenyl) thiophene (BFMeT), was examined in this study. BFMeT was administered by intragastric gavage once at doses of 500-1,500 mg/kg of body weight to Wistar rats treated with and without antibiotics (bacitracin, neomycin, streptomycin), germ-free rats and gnotobiotic rats, and 72 hr later their gastrointestinal tracts were examined for ulcer formation. A single oral administration of BFMeT induced ileal ulcers in specific pathogen-free rats. However, the rats given antibiotics to reduce the intestinal bacteria had no ulcers. BFMeT-treated germ-free rats and gnotobiotic rats mono-associated with Bifidobacterium adolescentis or Lactobacillus acidophilus also had no intestinal ulcers. However, the drug induced ileal ulcers in gnotobiotic rats mono-associated with Eubacterium limosum or Escherichia coli. An overnight culture of B. adolescentis or L. acidophilus or yogurt containing Bifidobacterium breve and Streptococcus thermophilus, when given as drinking water, inhibited ulcer formation in the ileum of rats treated with BFMeT. Gram staining of the ileal contents of normal rats revealed that 97.4% of the stained microorganisms were Gram-positive rods and only 1.2% were Gram-negative rods. In the group of rats with ulcers induced by BFMeT, the Gram-positive rods decreased by 56.4% and the Gram-negative rods including Escherichia coli, Klebsiella, Proteus and Bacteroides increased by 37.3%. However, in the group of rats administered the Bifidobacterium culture, the Lactobacillus culture or yogurt, the percentages of the Gram-negative rods were decreased. Although Lactobacillus was a major bacterium in the ileum of normal rats, the Gram-negative facultatively anaerobic rods E.coli, Klebsiella and Proteus were increased in the ulcerated ileum of rats treated with BFMeT, suggesting that these bacteria are associated with ulcer formation in rats treated with NSAIDs, and that Lactobacillus and Bifidobacterium inhibit it by repressing the growth of ulcer-inducing bacteria.

Culture supernatants of Lactobacillus acidophilus and Bifidobacterium adolescentis repress ileal ulcer formation in rats treated with a nonsteroidal antiinflammatory drug by suppressing unbalanced growth of aerobic bacteria and lipid peroxidation.

A nonsteroidal antiinflammatory drug, 5-bromo-2-(4-fluorophenyl)-3-(4-methylsulfonylphenyl) thiophene (BFMeT), induced ileal ulcers in rats after oral administration, while no ulcers were observed after subcutaneous injection. The ileal ulcer formation in BFMeT-treated rats was examined to correlate the administration of cultures of Lactobacillus acidophilus or Bifidobacterium adolescentis with intestinal bacteria in the ileal contents and lipid peroxidation of the small intestinal mucosa. Ileal ulcers were observed in more than 85% of the rats treated with BFMeT at a dose of 1,000 mg/kg when they were given tap water as drinking water. The incidence of ulcer formation was repressed by giving culture supernatants of L. acidophilus or B. adolescentis as drinking water, but not by giving the cell suspension as drinking water. Gram staining of the ileal contents of normal rats revealed that 97% of the stained bacteria were gram-positive rods and only 1.5% were gram-negative rods. The percentage of gram-negative rods 72 hr after BFMeT administration was 49.8% and increased over 30-fold in BFMeT-treated rats. However, the percentage of gram-negative rods was 9.7 % or 16%, respectively, in rats taking culture supernatants of L acidophilus or B. adolescentis. In addition, thiobarbituric acid-reactive substances in the ileal mucosa increased significantly in the rats given tap water for 72 hr after BFMeT treatment, but not in rats given the culture supernatants of L. acidophilus or B. adolescentis. Since BFMeT induced an unbalanced intestinal microflora, the effect of antibiotic treatment on ulcer formation in rats was examined. The magnitude of the ulcer formation in the antibiotic-treated rats was, in decreasing order, metronidazole >none > kanamycin > a mixture (bacitracin, neomycin and streptomycin). These results suggest that the intestinal microflora plays an important role in ulcer formation and that a metabolite(s) of L. acidophilus and B. adolescentis inhibits ileal ulcer formation by repressing changes in the intestinal microflora and lipid peroxidation in BFMeT-treated rats.