Evidence for the involvement of protein kinase C isoforms in alpha-1 adrenergic activation of phospholipase A2 in FRTL-5 thyroid cells

BACKGROUND

FRTL-5 thyroid cells are a cell line extensively used for the investigation of thyroid functions. Activation of alpha-1 adrenergic receptors stimulates both arachidonic acid (AA) release and cytosolic Ca2+ increase in this cell line. Cytosolic Ca2+ and arachidonic acid are known to be important second messengers regulating a variety of thyroid functions. The generation of these messengers is regulated primarily by two different types of phospholipases, phospholipase C (PLC) and phospholipase A2 (PLA2).

METHODS

Norepinephrine (NE, 10 mumol/L) was used as an alpha-1 adrenergic activator, and cytosolic-free Ca2+ concentration ([Ca2+]i) was determined using the fluorescent dye indo-1. Arachidonic acid release was measured as an indicator of PLA2 activation, and protein kinase C (PKC) activity determination and isoforms identification were performed using commercial kits.

RESULTS

Norepinephrine increased [Ca2+]i and AA release. Prevention of NE-induced cytosolic Ca2+ influx, either by removal of extracellular Ca2+ or by use of Ca2+ channel blockers, NiCl2 or CoCl2, inhibited AA generation entirely. Inhibition of NE-induced increase in [Ca2+]i by the Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), also significantly suppressed NE-induced AA release. Inhibition of PKC activity by PKC inhibitors (H-7 or staurosporine) or downregulation induced by prolonged treatment with phorbol 12-myristate 13-acetate (PMA) or thyleametoxin (TX) significantly blocked the NE-induced AA release, which indicates PKC is involved in mediating NE-induced AA release. Protein kinase C activity measurement indicated that NE induced an activation of PKC in 5 minutes. To further characterize the role of PKC or Ca2+ in regulation of AA release, we identified PKC isoforms by immunoblotting with specific antibodies against 8 different Protein kinase C isoforms. PKC-alpha, -beta I, -beta II, -gamma, delta, -epsilon, -zeta, and -eta isoforms were identified. Norepinephrine induced translocation of PKC-alpha, -beta I, -beta II, -gamma, -delta, and -epsilon isoforms but not -zeta and -eta from cytosol to membrane. Chelation of intracellular Ca2+, prevention of Ca2+ influx, or prolonged treatment with thymeleatoxin (TX) completely blocked the NE-induced translocation of PKC-alpha.

CONCLUSIONS

These results, taken together with data obtained from AA experiments, suggest that PKC plays a critical role in alpha-1 adrenergic receptor mediated PLA2 activation and subsequent AA release. Extracellular Ca2+ influx is a prerequisite for both PKC-alpha translocation and AA release. Whether Ca2+ acts directly upon the PLA2, or via PKC-alpha, to regulate AA generation is an intriguing question that remains to be clarified.

Alterations in intestinal function in acute pancreatitis in an experimental model

Gastrointestinal tract failure may be involved in the development of systemic septic complications in acute pancreatitis. Systemic and intestinal circulation, intestinal permeability and absorptive function were evaluated in the early course of acute pancreatitis induced in rats by retrograde intraductal injection of 0.2 ml of 5 per cent sodium taurodeoxycholate and 0.4 nmol trypsin. A decrease in systemic arterial pressure and intestinal blood flow and an increase in intestinal permeability as measured by the leakage of 125I-labelled human serum albumin from blood to lumen were noted in the distal ileum and colon, reaching statistically significant differences 6 h after induction of pancreatitis. The transport of small molecular markers (sodium fluorescein and 51Cr-labelled ethylenediamine tetra-acetic acid) through the distal ileum and colon in vitro from the mucosal to the serosal site in Ussing chambers significantly increased in the early periodic (20-60 min) of incubation, while the passage of a macromolecular marker (ovalbumin) demonstrated a definite increase at 60-120 min of incubation. D-Xylose absorption from the gut lumen to the portal vein was significantly less in acute pancreatitis than after sham operation. Intravenous administration of the hydroxyl radical scavenger dimethylsulphoxide prevented the compromised intestinal permeability and gut absorptive capacity induced by acute pancreatitis, but did not affect the reduced arterial pressure and intestinal microcirculation. Cytotoxic oxygen-derived free radicals may contribute to the development of alterations in intestinal permeability and absorptive function found in the early stage of acute pancreatitis in the rat.

Beta-oxidation in rabbit liver in vitro and in the perfused ferret liver contributes to retinoic acid biosynthesis from beta-apocarotenoic acids

The biosynthesis of retinoic acid from beta-apocarotenoic acids was examined for a beta-oxidation-like process using both rabbit liver mitochondrial fractions with various beta-apocarotenoic acids (beta-apo-14'-, beta-apo-12'-, and beta-apo-8'-carotenoic acid) and perfusion in ferret liver through the portal vein with beta-apo-8'-carotenoic acid. The in vitro incubation of beta-apo-8', beta-apo-12'-, and beta-apo-14'-carotenoic acids gave rise to shorter chain beta-apocarotenoic acids as well as retinoic acid. The rate of retinoic acid synthesis from 10 microM beta-apo-8', beta-apo-12'-, and beta-apo-14'-carotenoic acids was 11 +/- 2, 18 +/- 3, and 30 +/- 7 pmol/h/mg of protein, respectively. The stepwise oxidation of beta-apocarotenoic acid in mitochondria was dose-related to both protein concentration and substrate concentration. beta-Apocarotenoic acid oxidation was inhibited in a dose-dependent manner when it was co-incubated with oleoyl-CoA. The in vivo perfusion of ferret liver with beta-apo-8'-carotenoic acid resulted in a linear increase in the retinoic acid concentration of bile, which was completely abolished by co-perfusion of 3-mercaptopropionic acid, an inhibitor of long chain acyl-CoA dehydrogenase, and partially inhibited by 2-tetradecylglycidic acid, an inhibitor of carnitine-palmitoyl-CoA transferase I. However, the formation of retinoic acid from the beta-apocarotenoic acids was not inhibited, either in vitro or in vivo, by citral, an inhibitor of retinal oxidase. Thus, the formation of retinoic acid was not occurring by the central cleavage pathway. These data suggest that the oxidation of intermediate compounds between beta-carotene and retinoic acid may undergo a type of beta-oxidative process to form retinoic acid, which is reminiscent of mitochondrial fatty acid beta-oxidation. This pathway may play an important role in the biosynthesis of retinoic acid from beta-carotene.

Heat shock inhibits the hypoxia-induced effects on iodide uptake and signal transduction and enhances cell survival in rat thyroid FRTL-5 cells

Chronic hypoxia inhibits rat thyroid function in vivo. To determine possible mechanisms, we studied the effect of hypoxia on iodide uptake, the involvement of second messengers, and cell membrane permeability in rat thyroid FRTL-5 cells. Since sublethal heat stress protects tissues from ischemia, we also determined effects of heat stress. The initial rate of iodide uptake in untreated cells was between 12.98 and 15.28 pmol/micrograms DNA/min. Hypoxia (5% O2) increased the rate of uptake in a time-dependent manner. Heating cells at 45 degrees C for 15 min (heat shock) prior to exposure to hypoxia for 3 days inhibited the increase in the initial rate of I-uptake. Using fura-2, we found that the resting [Ca2+]i in suspended FRTL-5 cells was 65 +/- 7 nM (n = 16). [Ca2+]i was not increased in cells exposed to hypoxia for 1 day, while a 3-day exposure increased [Ca2+]i by 43 +/- 4% (p < 0.05); no additional increase occurred after 7 days of exposure. When cells were heated prior to hypoxia exposure for 3 days, the hypoxia-induced increase in [Ca2+]i did not occur. Similar observations were found with inositol trisphosphates (InsP3). Exposure of cells to hypoxia for 3 days increased InsP3 from 0.08 +/- 0.02 (n = 5) to 0.32 +/- 0.04% total cpm (n = 5, p < 0.05), but sublethal heating of cells prior to hypoxia exposure prevented the increase. Three-day hypoxia increased PKC activity in the membrane fraction (from 67 +/- 7 to 86 +/- 4% of total activity, p < 0.05), and heat shock inhibited these changes also. Immunoblots showed that hypoxia treatment alone and heat shock plus hypoxia resulted in the translocation of PKC-alpha, -delta, -epsilon, and -zeta isoforms, whereas heat shock alone translocated only PKC-beta I, -beta II, and -zeta. Cell membrane integrity was assayed by trypan blue exclusion. Hypoxia alone for 3 days did not affect membrane permeability, but only 49 +/- 3% of cells excluded trypan blue when a 3-day hypoxia exposure was followed by a 6 h reoxygenation. Heat shock prior to hypoxia and reoxygenation protected cell membrane function. Heat shock also induced heat shock protein 70 kDa (HSP-70) synthesis at the transcriptional level. Results suggest that heat shock protects FRTL-5 cells from hypoxic injury, perhaps by inhibiting the initial rate of iodide uptake and second messengers. It is likely that HSP-70 plays an essential role in the process of protection.

Reverse cholesterol transport in the rat following a short-term intravenous infusion of fat emulsion

The effect on cholesterol transport of an intravenous infusion of a fat emulsion (10%) Intralipid or 10% Lipovenös) in vivo was investigated in the rat. Intralipid (1.85 ml/hr/kg body weight in rts for 3 hr) caused a reduction (P < 0.05) in free cholesterol in the aorta (by 25%), in plasma high-density lipoproteins (64%) and in erythrocytes (11%) with a concomitant enrichment of liver free cholesterol (16%), suggesting an enhanced reverse cholesterol transport in this species. Lipovenös under the same conditions gave similar results. Our data support our previous in vivo study in man indicating that infusion of a fat emulsion is able even to remove cholesterol from the arterial wall and thereby possibly be considered as an antiatherosclerotic agent.

Influence of colostomy on in vivo and in vitro permeability of the rat colon

PURPOSE

Barrier properties of an isolated colon loop and the remnant colon in continuity with the gastrointestinal tract after colostomy were studied in the rat.

METHODS

The in vivo absorption after colonic loop administration of the marker fluorescein sodium was measured as the urinary recovery. The in vitro permeability was measured in Ussing diffusion chambers as the transmucosal passage of [14C]mannitol and of human serum albumin in the isolated and the nonexcluded colonic segments and was compared with the corresponding colonic regions from sham-operated rats at 1 to 14 days after operation.

RESULTS

Body weight gain of the rats decreased and diarrhea appeared from day 2 after colostomy. Histologic examination showed mucosal atrophy with decreased villus height in the isolated colonic loop and an increased villus height in the nonexcluded colon segment. Absorption of fluorescein sodium in the isolated loop was increased at 8 and 14 days. Moreover, permeability in the isolated loop was increased for both mannitol and human serum albumin from four days after colostomy compared with the corresponding colonic segments after the sham operation, whereas a decrease in the passage of mannitol was noted in the nonexcluded colon.

CONCLUSIONS

Experimentally performed colostomy diversion in the rat induced alterations of the barrier function in both the isolated colonic loop and the nonexcluded colon in continuity with the fecal stream.

Ultrasound-guided internal radiotherapy using yttrium-90-glass microspheres for liver malignancies

Treatment of liver malignancies, in particular hepatocellular carcinoma, remains a serious problem because of the difficulty of delivering adequate therapeutic agents to the lesions while sparing the surrounding normal tissue. In an attempt to overcome this obstacle, intratumoral injection of 90Y, a beta-emitter, was performed.

METHODS

Twenty-seven hepatocellular carcinomas and six liver metastases were studied, most of which had failed other therapeutic modalities. Guided by ultrasound, 90Y-glass microspheres (GMS) were carefully injected into predetermined tumor sites. The procedure was repeated at 3--4-wk intervals where indicated. Echographic, clinical and laboratory follow-up was conducted at regular intervals.

RESULTS

Twelve to 32 mo after treatment, 27 patients were still alive, with dramatic improvement of their clinical condition: 90.6% of the tumor foci became smaller, with echogenic or blood flow changes on liver sonograms. Serum titers of alpha-FP in 10 of 13 patients returned to normal levels. Repeat biopsy in nine patients showed complete tumor destruction in eight. Six patients died of either end-stage disease or wide dispersion of the tumor.

CONCLUSION

The intratumoral administration of 90Y-GMS under ultrasound guidance yielded a higher cure rate for liver malignancy with no severe side effects. The higher radiation dosage delivered by injected 90Y to the periphery of the lesions (up to 28,215-75,720 cGy) was thought to account for the successful outcome. These results show that intratumoral radionuclide injection is feasible for treatment of malignant lesions inside the body.

In vivo biosynthesis of retinoic acid from beta-carotene involves and excentric cleavage pathway in ferret intestine

This study was done to determine whether retinoic acid can be produced by excentric cleavage of beta-carotene in vivo. By using an inhibitor of retinaldehyde oxidation, citral, either retinaldehyde or beta-carotene was incorporated in a micellar solution and perfused through the upper portion of small intestine of ferrets. After 2 h perfusion of 1 microM retinaldehyde, retinoic acid rose in portal blood (+3.5 +/- 1.3 nmol/L) and was detected in the intestinal mucosa (30 +/- 2 pmol/g). When citral was added at 2 mM along with retinaldehyde, retinoic acid decreased in the portal blood and retinoic acid was not detected in the intestinal mucosa. With or without the presence of citral (2 mM), the perfusion of beta-carotene (10 microM) during 2 h caused a significant rise of retinoic acid in portal blood (+2.6 +/- 0.6 nmol/L and + 4.1 +/- 0.6 nmol/L, respectively) and in liver; moreover, significant amounts of retinoic acid were detected in the intestinal mucosa (19 +/- 3 pmol/g and 36 +/- pmol/g, respectively. This study demonstrates that after intestinal perfusion of beta-carotene in the ferret in vivo, a substantial amount of retinoic acid is formed via an excentric cleavage pathway.

Bacterial translocation in acute liver injury induced by D-galactosamine

Acute liver injury is associated with a high rate of infectious and septic complications. Most of these infections are produced by gram negative enteric bacteria. We evaluated bacterial translocation, intestinal permeability, blood flow, portal pressure, and intestinal microflora after induction of liver injury and 70% liver resection in the rat. The rate of translocation to both portal and arterial blood was 100% at 24 hours and 50% at 48 hours after liver resection compared with 83% to portal vein and 50% to aortic blood at both time points after acute liver injury. Translocation to intraabdominal organs (liver, spleen, and mesenteric lymph nodes) was 100% in both groups at both 24 and 48 hours. The rate of translocation increased after liver injury at 48 hours with progression of the liver injury but was decreased in the 70% liver resection group with improvement of liver function. "Total aerobic" and "total anaerobic" bacterial counts in small intestine and cecum were not affected. Pulmonary, distal small intestine, and cecal blood flow were decreased in both groups, whereas blood flow in the proximal small intestine was unaffected. Portal pressure and flow were increased after 70% liver resection, but they were decreased in acute liver injury. After acute liver injury, permeability of both distal small intestine and cecum increased, but after liver resection only cecal permeability increased. The results of this experiment show that bacterial translocation occurs in experimental acute liver injury and that its dynamic, pattern and fate are different from that observed after liver resection, which is a reversible surgical model of liver insufficiency.

Cisapride prevents enteric bacterial overgrowth and translocation by improvement of intestinal motility in rats with acute liver failure

Enteric bacterial overgrowth resulting from compromised gastrointestinal motility has been suggested to be important for the development of enteric bacterial translocation. In the present study, the effect of cisapride, a 5-hydroxytryptamine-4-receptor agonist and stimulant of intestinal motility, was evaluated concerning intestinal motility, as measured by intestinal transit time, enteric bacterial overgrowth, and bacterial translocation from the gut in rats with acute liver failure induced by 90% hepatectomy. The results demonstrated that (1) the incidence of bacterial translocation to the systemic and portal circulation as well as to the liver, spleen, kidneys, and lungs was nil, and 17-33% to MLN in hepatectomized animals treated with cisapride, i.e. significantly lower than in hepatectomized rats administered saline; (2) overgrowth of E. coli in the intestine was noted in hepatectomized animals given saline, but not following cisapride treatment; (3) cisapride improved the otherwise delayed intestinal transit time following hepatectomy as shown by an increase in the leading edge of isotopic propulsion and the linear slope of the cumulative percent of radioactivity through each intestinal segment. Thus, we conclude that intravenous administration of cisapride prevents enteric bacterial overgrowth and bacterial translocation by improving intestinal motility in rats with acute liver failure induced by subtotal hepatectomy.

The Effects of Doping on the Selectivity and Response Time of Fluoride Ion-Selective Electrodes

We report the effect of doping on the response time and hydroxide ion interference of fluoride ion-selective electrodes made by using membranes consisting of single crystals of CeF3, LaF3 and NdF3, both undoped and doped with divalent cations , and of mixed crystals of neodymium and samarium fluorides (Nd0.95Sm0.05F3 and Nd0.86Sm0.14F3). Doping not only increases the bulk conductivity of the membrane, but also reduces both the response time and the hydroxide ion interference of the electrode. This behaviour is due to an increase in the number of Frenkel defects in the crystal membrane, an effect which increases the mobility of the fluoride ion. It has also been established that doped single crystals of either LaF3 or NdF3 offer the best performance in terms of selectivity.

[Study on relationship of lipid peroxide in coronary heart disease with and without diabetes]

Activity of erythrocyte superoxide dismutase (RBC-SOD), levels of serum malondialdehyde (MDA), plasma 6-keto-prostaglandin F 1 alpha (6-keto-PGF 1 alpha) and thromboxane B2(TXB2) were measured in 30 healthy subjects and 57 coronary heart desease (CHD) patients inoluding 21 cases complicated with diabetes and 36 without. Their characteristics of Syndrome Differentiation and typing were observed. The results showed that the activity of RBC-SOD, 6-keto-PGF 1 alpha in CHD patients were significantly lower than those in the healthy subjects, but the levels of TXB2, MDA were significantly higher. The levels of TXB2 in CHD patients with diabetes were significantly higher than tose without, but the activity of RBC-SOD were significantly lower. There were remarkably positive correlations between the levels of serum MDA and that of blood sugar, TXB2, TG and BMI in CHD patients with diabetes. There were remarkably negative correlations between the levels of serum MDA and plasma 6-keto-PGF 1 alpha. The results suggested that the metabolic abnormality of lipoperoxides was more serious in CHD patients with diabetes than without. The main Syndrome of CHD with diabetes was Qi-Yin Deficiency with Blood Stasis, while that of without diabetes was Qi Deficiency with Blood Stasis.

Antioxidant and calcium channel blockers counteract endothelial barrier injury induced by acute pancreatitis in rats

BACKGROUND

Multiple organ failure is the major mortality-related complication in severe acute pancreatitis. Endothelial barrier injury may be involved in its pathophysiology.

METHODS

The present study evaluated alterations in endothelial barrier integrity in different organs/tissues 12 h after induction of acute pancreatitis by intraductal infusions of bile. Potential effects of oxygen free radicals and calcium influx were evaluated by pretreatment with an antioxidant, N-acetyl-L-cysteine, and calcium channel antagonists, verapamil and diltiazem.

RESULTS

Tissue edema, reflected by an increase in tissue water content, was noted in the stomach, proximal small intestine, cecum, spleen, pancreas, kidneys, liver, lungs, heart, and brain in rats with pancreatitis. Also, an increased endothelial barrier permeability, as evidenced by the leakage of radiolabeled human serum albumin from blood to tissues, occurred in the stomach, proximal small intestine, colon, peritoneum, spleen, pancreas, kidneys, liver, lungs, and heart, accompanied by altered liver functions, increased levels of pancreatic enzymes, compromised renal function, and delayed intestinal motility. N-acetyl-L-cysteine prevented tissue edema and endothelial permeability changes in most organs/tissues, whereas the effects of verapamil and diltiazem were less marked. The preventive effects occurred in an organ-dependent manner.

CONCLUSIONS

Endothelial barrier injury is found in all investigated organs/tissues in acute experimental pancreatitis. Oxygen free radicals and calcium influx may play a role in the development of these changes.

Intestinal absorption and metabolism of 9-cis-beta-carotene in vivo: biosynthesis of 9-cis-retinoic acid

This study was done to examine the intestinal absorption and cleavage of 9-cis-beta-carotene in vivo. A micellar solution, containing either no addition or 10 mumol of 9-cis- or all-trans-beta-carotene, was perfused for 2 h through the upper portion of the small intestine of ferrets. The effluent of a mesenteric lymph duct cannulation was collected, as well as intestinal mucosa scrapings, a portal blood sample, and a liver biopsy, both before and after perfusion. Carotenoids and retinoids were measured by reverse-phase, high performance liquid chromatography. 9-Cis- and all-trans-beta-carotene were transported equally well into mesenteric lymph, although the intestinal concentration of the corresponding isomer was tenfold higher after perfusion of the 9-cis- isomer than after perfusion of all-trans-beta-carotene. Regardless of which isomer was used, perfusion of beta-carotene resulted in the biosynthesis of similar amounts of retinoic acid in portal blood, liver, and intestine. However, after the perfusion of all-trans-beta-carotene, all the retinoic acid formed was in the all-trans- form, whereas the perfusion of 9-cis-beta-carotene resulted in the biosynthesis of about 50% of the total retinoic acid as the 9-cis-isomer. We conclude that in the in vivo ferret model, 9-cis-beta-carotene has a good bioavailability and is a precursor of 9-cis-retinoic acid.

Identification of protein kinase C and its multiple isoforms in FRTL-5 thyroid cells

Protein kinase C (PKC) has been implicated as an important regulator of signal transduction in the FRTL-5 thyroid cell line, but little is known about its isoforms in this cell line. In the present investigation, we characterized the activation of PKC by measuring the enzyme activity and identifying its isoforms in both cytosol and membrane fractions. Phorbol 12-myristate 13-acetate (PMA) was used as a PKC activator in this study. PKC activity assay revealed that PMA (300 nM) induced a rapid translocation from cytosol to membrane within 1 min and led to an almost complete translocation within 15 min. Multiple PKC isoforms were examined by Western blot analysis with specific antibodies against alpha, beta, gamma, delta, epsilon, and zeta isoforms. PKC alpha, delta, epsilon, and zeta were identified in this cell line, but PKC beta and gamma were not. Exposure of the cells to PMA (300 nM) for 5 to 30 min led to the translocation of PKC alpha, delta, and epsilon from the cytosol to the membrane fraction, while PKC zeta was not affected. Treatment with PMA (300 nM) for 24 h resulted in the down-regulation of PKC alpha, delta, and epsilon, but not PKC zeta. This study demonstrates for the first time direct evidence for the activation of PKC, and expression and distribution of its isoforms in FRTL-5 thyroid cells.

Vitamin E enhances the lymphatic transport of beta-carotene and its conversion to vitamin A in the ferret

BACKGROUND/AIMS

beta-Carotene and alpha-tocopherol may have either antagonistic or synergistic effects on each other's absorption and metabolism. The effects of both physiological and pharmacological concentrations of alpha-tocopherol on the absorption and metabolism of beta-carotene in ferret intestine were determined.

METHODS

A high concentration of beta-carotene was perfused through the upper portion of the small intestine of ferrets in vivo with varying levels of alpha-tocopherol. The effluent of a mesenteric lymph duct cannulation, the intestinal mucosal scraping, and portal vein blood were sampled and analyzed by high-performance liquid chromatography.

RESULTS

The lymphatic transport of beta-carotene was enhanced 4-fold by alpha-tocopherol at a physiological dose and 12-21-fold at a pharmacological dose. The lymphatic transport of alpha-tocopherol was linearly (r = 0.8; P < 0.05) related to the luminal alpha-tocopherol concentration even in the presence of a high concentration of beta-carotene. Furthermore, alpha-tocopherol increased the conversion of beta-carotene into retinol in the intestine in a dose-dependent manner.

CONCLUSIONS

alpha-Tocopherol has a positive effect on the intestinal absorption of intact beta-carotene and may modulate the metabolic conversion of beta-carotene into retinoids.

The role of oral administration of oatmeal fermented by Lactobacillus reuteri R2LC on bacterial translocation after acute liver failure induced by subtotal liver resection in the rat

BACKGROUND

Previous experimental studies showed that a disturbed ecology of the enteric bacterial population might contribute to the occurrence of bacterial translocation from the gut in acute liver failure (ALF).

METHODS

In the present study the effects of oral administration of exogenous Lactobacillus reuteri R2LC and oat fiber on bacterial overgrowth and translocation and on enterocyte protein contents were investigated in rats with ALF induced by subtotal liver resection. The oatmeal soup base was anaerobically inoculated with L. reuteri R2LC and fermented for 15 h. The animals were then fed with fermented or unfermented oatmeal or saline daily for 6 days before the experimental procedure.

RESULTS

The incidence of bacterial translocation to the systemic circulation was nil and 17% in rats subjected to sham operation with saline or 90% hepatectomy with fermented oatmeal, respectively, and 80-90% and 34-50% in rats subjected to hepatectomy with saline or unfermented oatmeal. One rat treated with fermented oatmeal had positive bacterial growth in mesenteric lymph nodes (MLN), which was significantly lower than in hepatectomized rats with saline or unfermented oatmeal (80-100% and 50-67%). No significant differences was demonstrable between hepatectomized animals with oral administration of fermented or unfermented oatmeal as compared with sham-operated rats. The number of anaerobic bacteria, Gram-negative anaerobes, and Lactobacillus decreased significantly, and the number of Escherichia coli increased in the distal small intestine and colon in hepatectomized animals with saline or unfermented oatmeal, as compared with animals subjected to sham operation or hepatectomy with fermented oatmeal.

CONCLUSIONS

The occurrence of bacterial translocation from the gut in 90% hepatectomy-induced ALF could be prevented by fermented oatmeal, which implies possibilities for biologically balancing the enteric bacterial ecology.

Phospholipids prevent enteric bacterial translocation in the early stage of experimental acute liver failure in the rat

BACKGROUND

Bacterial infections and bacteremia in acute liver failure may at least partly be attributed to translocation of enteric bacteria. Attempts to prevent or treat such infections by the use of antibiotics may instead result in overgrowth of surviving microbes.

METHODS

In the present study, normal saline (1.5 ml/100 g body weight), phosphatidylcholine (1.5 ml/100 g body weight), and phosphatidylinositol (1.5 ml/100 g body weight) were orally administered by means of a gastric tube both 12 h and 30 min before operation. Effects of enteric administration of phospholipids on the prevention of enteric bacterial translocation, intestinal and mucosal mass, and enterocyte protein contents in acute liver failure induced by subtotal liver resection in the rat were evaluated.

RESULTS

The incidence of bacterial translocation increased significantly 2 and 4 h after 90% hepatectomy as compared with sham-operated animals. Enteric administration of phospholipids, however, significantly reduced the incidence of bacterial translocation after 90% hepatectomy. Phospholipid treatment prevented the postoperative decrease in intestinal mucosal mass and enterocyte protein content.

CONCLUSIONS

Enteral administration of phospholipids thus seems to protect against translocation of enteric bacteria and prevent against a decrease in intestinal mucosal mass and enterocyte protein content after subtotal hepatectomy in the rat.

Biosynthesis of 9-cis-retinoic acid from 9-cis-beta-carotene in human intestinal mucosa in vitro

The role of 9-cis-beta-carotene (9-cis-beta-C) as a potential precursor of 9-cis-retinoic acid (9-cis-RA) has been examined in human intestinal mucosa in vitro. By using HPLC, uv spectra, and chemical derivatization analysis, both 9-cis-RA and all-trans-retinoic acid (all-trans-RA) have been identified in the postnuclear fraction of human intestinal mucosa after incubation with 9-cis-beta-C at 37 degrees C. The biosynthesis of both 9-cis-RA and all-trans-RA from 9-cis-beta-C was linear with increasing concentrations of 9-cis-beta-C (2-30 microM) and was linear with respect to tissue protein concentration up to 0.75 mg/ml. Retinoic acid was not detected when a boiled incubation mixture was incubated in the presence of 9-cis-beta-C. The rate of synthesis of 9-cis- and all-trans-RA from 4 microM 9-cis-beta-C were 16 +/- 1 and 18 +/- 2 pmol/hr/mg of protein, respectively. However, when 2 microM all-trans-beta-C was added to the 4 microM 9-cis-beta-C, the rate of all-trans-RA synthesis was increased to 38 +/- 6 pmol/hr/mg of protein, whereas the rate of 9-cis-RA synthesis remained the same. These results suggest that 9-cis-RA is produced directly from 9-cis-beta-C. Furthermore, incubations of either 0.1 microM 9-cis- or all-trans-retinal under the same incubation conditions showed that 9-cis-RA could also arise through oxidative conversion of 9-cis-retinal. Although only 9-cis-RA was detected when 9-cis-RA was used as the substrate, the isomerization of the all-trans-RA to 9-cis-RA cannot be ruled out, since both all-trans-RA and trace amounts of 9-cis-RA were detected when all-trans-retinal was incubated as the substrate. These data indicate that 9-cis-beta-C can be a source of 9-cis-RA in the human. This conversion may have a significance in the anticarcinogenic action of beta-C.

A phospholipase C inhibitor, U-73122, blocks TSH-induced inositol trisphosphate production, Ca2+ increase and arachidonic acid release in FRTL-5 thyroid cells

To characterize the role of phospholipase C (PLC)-mediated intrathyroid signal transduction by thyrotropin, we studied the effect of U-73122, an aminosteroid inhibitor of PLC-dependent activity, on TSH-activated PLC-Ca2+ and arachidonic acid (AA) signalling systems in cultured FRTL-5 rat thyroid cells. In the presence of extracellular Ca2+, TSH (0.1 microM) increased intracellular free calcium concentration ([Ca2+]i) by 63 +/- 6% with a sustained plateau phase, and AA release by 160 +/- 16%. By deletion of extracellular Ca2+, TSH induced a similar maximal [Ca2+]i increase, but the plateau phase and AA release were entirely suppressed. U-73122 (5 microM) inhibited TSH stimulation of 3H-labelled inositol trisphosphates (IP3) production by 73 +/- 3% (P < 0.01) in one study, and completely in another. U-73122 concentration-dependently blocked the TSH-induced Ca2+ increase in either the presence or absence of external Ca2+. U-73122 also showed a similar concentration-response inhibition of TSH-induced AA release. These results provide direct evidence of PLC mediation of TSH-stimulated signal transduction in FRTL-5 thyroid cells. TSH-induced external Ca2+ entry, as well as intracellular Ca2+ mobilization, is probably a PLC-mediated process. From an IP3-sensitive intracellular pool, TSH induces intracellular Ca2+ mobilization. External Ca2+ entry seems to be a prerequisite for TSH-induced AA release. U-73122 inhibition of both cytosolic Ca2+ increase and AA release further confirms [Ca2+]i dependence for TSH stimulation of AA release.

Review: absorption and metabolism of beta-carotene

To better understand the potential function of beta-carotene (beta-C) in the prevention of cancer, greater knowledge of beta-C metabolism and a suitable animal model to mimic human beta-C metabolism are necessary. The small intestinal mucosa contains beta-C cleavage enzyme(s), thereby playing an important role in both the provitamin A activity and anti-cancer properties of beta-C. The ability of the ferret (Mustela putorius furo) to absorb intact beta-C makes it an appropriate model for studying human beta-C absorption. This article reviews the absorption and cleavage mechanisms of beta-C in both the human and the ferret. The biosynthesis of retinoic acid (RA) from beta-C via central and eccentric cleavage pathways is reviewed. The possible significance of the conversion of beta-C to RA as an anticancer mechanism is discussed.

Bacterial translocation, intestinal ultrastructure and cell membrane permeability early after major liver resection in the rat

The process and route of bacterial translocation from the gut after major liver resection remain unclear. In the present study enteric bacterial translocation, enterocyte ultrastructure in the ileum and colon, the process and route of bacterial invasion and the permeability of the cell membrane system and blood-tissue barrier were evaluated in rats receiving sham operation, and 70 or 90 per cent hepatectomy. The incidence of bacterial translocation to mesenteric lymph nodes was 80-100 per cent in rats 6 h after 70 per cent and 2-4 h after 90 per cent hepatectomy, and 80-100 per cent to the systemic circulation 2-4 h after 90 per cent hepatectomy but only 20 per cent to the portal vein. An increase in bacterial adherence to the intestinal surface, damage to the permeability of the cell membrane system and blood-tissue barrier, and pathological alterations in the ileum and colon developed, correlating with the extent of liver removed and the time that had passed after hepatectomy. Most translocating bacteria appeared in morphologically intact enterocytes with increased membrane permeability, in antigen-presenting cells and in submucosal lymphatics, but some bacteria were also seen within damaged enterocytes 4h after 90 per cent hepatectomy. These results indicate that altered permeability of the cell membrane system may be one of the earliest characteristics of challenged enterocytes, and that enteric bacteria translocate through both morphologically normal and abnormal enterocytes. Translocation occurred mainly into the lymphatics, bacteria either being 'carried' by antigen-presenting cells or entering by active invasion.

The association between enteric bacterial overgrowth and gastrointestinal motility after subtotal liver resection or portal vein obstruction in rats

OBJECTIVE

To test the hypothesis that intestinal motility is delayed after hepatectomy, which alters the ecology of the enteric microflora and contributes to the development of bacterial translocation from the gut.

DESIGN

Open experimental study.

SETTING

University department of surgery.

MATERIAL

Adult male Sprague-Dawley rats (n = 6 in each group at each time point).

INTERVENTIONS

Sham operation, 90% hepatectomy, and portal venous obstruction.

MAIN OUTCOME MEASURES

Intestinal morphology, immunocytochemistry of the enteric nervous system, enteric bacterial growth in the small intestine and colon, and intestinal transit time.

RESULTS

Intestinal transit was already delayed one hour after 90% hepatectomy, and histopathological alterations and overgrowth by Escherichia Coli had developed after two hours. There were significant differences in intestinal transit time between sham operated rats and those subjected to portal venous obstruction on the one hand, and those that underwent 90% hepatectomy on the other. There was no difference in intestinal transit time between rats with portal venous obstruction and the sham operated animals.

CONCLUSION

Delayed intestinal transit after 90% hepatectomy may contribute to enteric bacterial overgrowth and thereby contribute to the development of bacterial translocation from the gut.

[Effect of sodium prasterone on termination of mid-trimester pregnancy]

Sodium prasterone sulfate was used before termination of mid-trimester pregnancy in 50 cases, and another 50 cases taking no drug as the control group. Both groups were given intraamniotic rivanol. In the treatment group, the results indicated that the Bishop score was elevated by 1 to 8. There were an effective rate of 86% and satisfactory rate of 98%. In comparison, the control group showed 40% (P < 0.001) and 76% (P < 0.01) respectively, and there was significant difference between the 2 groups. The average induction-abortion time interval was 13.2 hours shorter in treatment group (P < 0.01). Adverse effects such as nausea or fatigue was only seen occasionally.

Retinoic acid regulates retinol metabolism via feedback inhibition of retinol oxidation and stimulation of retinol esterification in ferret liver

When the plasma concentration of retinoic acid is increased, there is an accompanying reduction of circulating levels of retinol, suggesting that retinoic acid may have a regulatory effect on retinol metabolism in vivo. To determine which specific step(s) of retinol metabolism might be regulated by retinoic acid, retinol was incubated with ferret liver microsomes or cytosol with retinoic acid in vitro. Incubating the microsomal fraction with retinoic acid resulted in a dose-dependent (up to 0.5 mumol/L) decrease in the formation of retinal. On the contrary, no retinoic acid inhibitory effect was observed on retinal synthesis in the cytosol incubation, or in the cytosol plus microsome incubation. However, when retinoic acid was added to the cytosolic incubation mixture in the presence of the retinal oxidative inhibitor, citral, a dose-dependent inhibition of retinal synthesis was observed. Furthermore, the effect of retinoic acid on retinyl ester metabolism in ferret liver was studied by using endogenous retinyl esters of ferret liver as the substrate. When retinoic acid was added to the incubation mixture of microsomes plus cytosol, small, nonsignificant increases in retinol and retinyl esters were observed. When retinoic acid was added in the presence of citral, both the inhibition of retinol oxidation and the stimulation of retinol esterification were dose dependent up to approximately 0.3 mumol/L and then remained the same up to 1.0 mumol/L. These data strongly suggest that retinoic acid has a regulatory effect on retinol metabolism in ferret liver, which may occur via feedback inhibition of retinol oxidation and stimulation of retinol esterification.

Reverse cholesterol transport in the rat: influence of short-term D-myo-inositol-1,2,6 trisphosphate (PP56) infusion

D-myo-inositol-1,2,6 trisphosphate (PP56) was infused in rats for 3 hr at a rate of 30.28 microM/hr/kg body weight. The cholesterol content in plasma, erythrocytes, the aorta, and the liver was monitored before and at the end of the infusion and at 1 and 21 hr after the infusion. We found that the aortic total and free cholesterol content was reduced after the infusion and continuously until the end of the experiment (by 27% each after 21 hr P < 0.05, P < 0.01, respectively). Erythrocyte cholesterol was increased by 6.6% (P < 0.05) at the end of the infusion and 9.5% (P < 0.01) at the end of the experiment, while plasma and high-density lipoprotein cholesterol did not change significantly. Free cholesterol in the liver after infusion was decreased by 27% (P < 0.001) and cholesterol ester increased by 97% (P < 0.05) and did not return to the preinfusion level. Short-term PP56 infusion in the rat apparently influences cholesterol transport in a way which would suggest a promoted reverse cholesterol transport. Since the lipid values did not return to the preinfusion level, a long-term study is needed to elucidate in more detail the influence of PP56 on cholesterol metabolism in vivo.

Enteric bacterial translocation after intraperitoneal implantation of rubber drain pieces

To study the kinetics and mechanisms of bacterial translocation from the gut after intraperitoneal (IP) implantation of prosthetic materials, different sizes of rubber drain pieces were intraperitoneally implanted in the rat, followed by evaluation of ileal mucosal permeability after 2 days and of the occurrence of bacterial translocation and gut oxygen extraction at various time points. Enteric bacteria translocated to mesenteric lymph nodes and disseminated to systemic organs (liver, spleen, lungs, and kidneys), the portal vein, and inferior vena cava 2, 4, and 6 h after IP implantation of rubber drain pieces with 10-, 7-, and 3-cm2 areas, respectively, and subsequently to the IP rubber drain piece and the peritoneal cavity on the 2nd postoperative day. The incidence of translocation correlated with the size of the implanted material and time after implantation. The gut oxygen extraction increased significantly after IP implantation of 7- and 10-cm2 rubber drain pieces. The ileal mucosal permeability was enhanced in the groups implanted with 7- and 10-cm2 drain pieces. Thus, bacterial translocation occurs already in the early period after IP implantation of rubber drain and increased with time. The increased gut oxygen extraction implies that the gut is susceptible to IP inflammatory stimulation, and the enhanced ileal permeability suggests that the integrity of the gastrointestinal tract is compromised, which might facilitate bacterial translocation.

Intestinal perfusion of beta-carotene in the ferret raises retinoic acid level in portal blood

To determine whether beta-carotene (beta-C) can serve as a source of intestinally-derived retinoic acid (RA), either 15,15'-[14C]beta-C or unlabeled beta-C was perfused through 30 cm jejunal segments of ferrets in vivo. Portal vein blood was sampled periodically via an indwelling catheter. RA was identified in portal blood by comparing retention times in HPLC, by UV absorption, and by derivatization (methylation) and subsequent GC-MS analysis. The RA concentration in the portal blood increased 3-fold with perfusion of beta-C (P < 0.05), and remained at 18 nmol/L during the perfusion of beta-C. The single peak of RA in HPLC was shown to consist of four separate peaks by GC-MS, which may be cis-trans isomers of RA. The concentration of RA in portal blood returned to the initial level (5 nmol/L) after a 2 h period of intestinal perfusion with 5% dextrose. Retinyl ester concentration in portal blood did not change before or after the perfusion, whereas retinol decreased significantly during the perfusion of beta-C. This study clearly indicates that a considerable quantity and number of polar metabolites, including RA, are formed from beta-C in the ferret intestine which are transported via the portal vein to the liver.

[Intragenic variable number tandom repeats in coagulation factor VIII gene of Chinese origin]

Using polymerase chain reaction, we analysed the variable number tandom repeats (VNTR) in intron 13 of coagulation factor VIII gene in the Chinese. Study of 115 X chromosomes from 77 normal Chinese revealed that the VNTR is composed of at least 4 different alleles in the Chinese, i.e. 19, 20, 21, and 23 repeats 53% of the females analysed were heterozygous of this VNTR. The discovery and application of this new molecular genetic marker is of significance in genetic consultation and prenatal diagnosis of hemophilia A.

Identification of a nonsense mutation at amino acid 584-arginine of platelet glycoprotein IIb in patients with type I Glanzmann thrombasthenia

Using Southern blot, the restriction digests of genomic DNAs in 11 patients with Glanzmann thrombasthenia from 10 unrelated kindreds were probed with a full-length GPIIb cDNA. An additional 2.3 kb Taq I fragment and two 1.65 kb and 0.65 kb fragments with reduced band intensity were found in the genes of two affected siblings from a family originating from the city of Huang Yan in the Zhejiang province. The Taq I digest of the abnormal gene was further probed with three portions of GPIIb cDNA, revealing that the heterozygous mutation was present in the region around exons 15-17 of the GPIIb gene. Two primers for polymerase chain reaction (PCR) were then designed, and a 394 bp PCR product was generated and sequenced, indicating that a stop codon (TGA) was substituted for an Arg codon (CGA) at amino acid position 584 of GPIIb, and resulted in a premature termination of translation and production of a shortened protein. The Western blot analysis showed that GPIIIa at the platelet surface was apparently deficient, it may be ascribed to the rapid turn-over of GPIIIa uncomplexed with the truncated GPIIb. The abnormal 2.3 kb Taq I fragment was used as a specific genetic marker to detect the carrier status of the patient family. The abnormal allele was proved to be derived from the mother, the two affected siblings are double heterozygotes, and one clinically unaffected daughter has also inherited this defective allele, while the father carries another recessive abnormal allele unidentified.

Bacterial translocation in acute liver failure induced by 90 per cent hepatectomy in the rat

Bacterial infection and bacteraemia have been observed in patients with acute liver failure. The exact source of bacteria and nature of pathophysiological mechanisms explaining the development of infection remain unclear. In the present study, acute liver failure was induced by 90 per cent hepatectomy in the rat. The mesenteric lymph nodes and organs were harvested aseptically for bacteriological culture after sham operation or 90 per cent hepatectomy. Function of the liver and reticuloendothelial system (RES) was assayed; gut oxygen extraction was also measured. Translocation of enteric bacteria occurred 2 h after operation and increased with time following hepatectomy. Overgrowth of Escherichia coli in the distal small intestine started 2 h after operation. RES function decreased immediately after 90 per cent hepatectomy; uptake rates per gram tissue in other organs increased significantly. These results indicate that bacterial translocation occurred early after 90 per cent hepatectomy, associated with a decrease in RES function and gut oxygen extraction, and overgrowth of intestinal bacteria.

The influence of surgically induced acute liver failure on the intestine in the rat

The influence of acute liver failure induced by 90% hepatectomy on the intestine was evaluated in the rat. Small-intestinal mucosal mass decreased 2 h after hepatectomy. Microvillous height decreased significantly from 1 h and on, and villous height and area in the distal small intestine from 2 h after operation. Ninety per cent hepatectomy resulted in a decrease in systemic arterial blood pressure and an increase in portal venous pressure. Subserosal microcirculation and small-arterial circulation in the proximal and distal small intestine and colon decreased significantly after 90% hepatectomy. Overgrowth and colonization of Escherichia coli occurred in the distal small intestine from 1 h and on after hepatectomy. Protein content in enterocytes and bile secretion from the liver remnant were markedly reduced in hepatectomized rats. Thus, the present study shows evidence of alterations in intestinal morphology and function that can contribute to explain the enteric bacterial translocation after surgically induced acute liver failure.

Intestinal uptake and lymphatic absorption of beta-carotene in ferrets: a model for human beta-carotene metabolism

To determine the appropriateness of the ferret as a model for human beta-carotene (beta-C) metabolism, we have perfused both 15,15'-beta-[14C]C and unlabeled beta-C through the upper 30-cm portion of the small intestine of ferrets in vivo. The effluents of a mesenteric lymph duct cannulation and a common bile duct cannulation, as well as portal vein blood periodically sampled via an indwelling catheter, were collected. Ten percent (9.5 +/- 0.06%) of the total administered beta-C was taken up by the intestine after a 4-h perfusion. Of the radioactivity taken up, 68.6 +/- 6.5% remained in the intestinal mucosa, 3.2 +/- 0.2% was recovered in the lymph, and 28.2 +/- 6.5% (calculated) was absorbed via the portal system. The total uptake/absorption of beta-C was 12.9 +/- 6.8 nmol.h-1.30 cm intestine-1. Large amounts of unchanged beta-C and relatively small amounts of both beta-apo-12'-carotenal and beta-apo-10'-carotenal were isolated in the intestinal mucosa after a 4-h perfusion with beta-C. Considerable amounts of metabolites more polar than retinol were formed and comprised 35% of the total radioactivity recovered in the intestinal mucosa. Polar metabolites were absorbed mostly into the portal venous system, whereas retinol and retinyl esters were absorbed mainly into the mesenteric lymph. Of the total absorbed radioactivity in lymph, 10 +/- 1.0% appeared as unchanged beta-C, with peak absorption occurring at 3 h after beginning the perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

National epidemiological survey of blindness and low vision in China

According to the National Sample Survey of Blindness and Low Vision, the prevalence of blindness in China was 0.43%, resulting chiefly from cataract (41.06%), corneal diseases (15.38%), trachoma (10.87%), and glaucoma (8.80%); and the prevalence of low vision in China was 0.58%, of which the main causes were cataract (49.83%), ametropia/amblyopia (14.98%), trachoma (9.55%), corneal diseases (8.48%), chorioretinal diseases (6.27%), etc. Among children under 14 years of age, the leading cause of blindness and low vision was heredity (48.46%). Among elderly of 60 years and over, the leading cause of blindness and low vision was cataract (73.13%).

Mirror writing of Chinese characters in children and neurologic patients

Mirror writing was done in 72 preschool children, 40 school children, 60 mentally retarded school children, 40 normal adults, 37 patients suffering from cerebrovascular diseases with or without aphasia and 13 patients with Parkinson's disease. The results showed that total mirror writing was demonstrated in only 2 cases and partial mirror writing with the left hand in 72 cases and with the right hand in 16 cases. The incidence of mirror writing in writing with left hand was higher (45.8%) in preschool children. It gradually decreased to 43.3% in mentally retarded school children, 24.3% in cerebrovascular disease (CVD) patients, 10.0% in school children, 7.7% in Parkinson's disease (PD) patients and 2.5% in normal adults. The relationships between mirror writing and left/right disorientation, between mirror writing and development of Chinese writing language and between mirror writing and higher cerebral function were observed.

Retinoic acid can be produced from excentric cleavage of beta-carotene in human intestinal mucosa

The hypothesis that retinoic acid (RA) is produced from the excentric cleavage of beta-carotene was tested in human intestinal homogenates in vitro. Significant amounts of RA were identified by HPLC and derivatization after incubation of intestinal mucosal homogenates with retinal, beta-carotene, or beta-apocarotenals at 37 degrees C for 60 min. RA formation was inhibited, in a dose-dependent fashion, when retinal was incubated in the presence of 0.1-3.0 mM citral (3,7-dimethyl-2,6-octadienal) under identical experimental conditions. The formation of RA from both beta-carotene and beta-apocarotenals was dose and time dependent and RA was the major metabolite of both beta-apo-8'-carotenal and beta-apo-12'-carotenal after the incubation. However, citral (0.1 to 4 mM) did not inhibit the formation of beta-apocarotenals and RA from 2 microM beta-carotene (P greater than 0.05), which proves the existence of an excentric cleavage mechanism for beta-carotene conversion into retinoids. Furthermore, RA formation from both beta-apo-8'-carotenal and beta-apo-12'-carotenal in human intestinal homogenate occurred in the presence of citral, which demonstrates that RA can be produced from excentric cleavage of beta-carotene via a series of beta-apocarotenals as intermediates.

Molecular evolution of the urate oxidase-encoding gene in hominoid primates: nonsense mutations

Nucleotide sequences of portions of second and fifth exons of urate oxidase encoding gene (UOX) of chimpanzee, gorilla, orangutan, rhesus monkey and squirrel monkey obtained following amplification by polymerase chain reaction have been compared with corresponding sequences of human, baboon and rat UOX. Two or more nonsense mutations are found in the coding regions of this UOX gene thus far analyzed in human, chimpanzee, gorilla and orangutan, but not in the baboon, rhesus monkey and squirrel monkey. Of these nonsense mutations, the stop codon at amino acid position 33 is constant in the human and the three great apes suggesting that this may be the original mutation responsible for the inactivation of the UOX gene during hominoid evolution.

A factor that positively regulates cell division by activating transcription of the major cluster of essential cell division genes of Escherichia coli

Cell division in Escherichia coli requires the products of the ftsQ, ftsA and ftsZ genes. It is not known how the cell regulates the cellular concentrations of these essential elements of the division system. We describe here a factor that activates cell division by specifically increasing transcription from one of the two promoters that lie immediately upstream of the ftsQAZ gene cluster. The trans-acting factor is the product of the sdiA gene, which was isolated on the basis of its ability to suppress the division inhibitory effect of the MinC/MinD division inhibitor. In addition, the sdiA gene product suppressed the action of other chromosomally encoded division inhibitors, induced minicell formation in wild type cells, and restored division activity to an ftsZ temperature-sensitive mutant grown under nonpermissive conditions. All of these properties were explained by the ability of the sdiA gene product specifically to increase transcription of the ftsQAZ gene cluster, resulting in an increase in cellular concentration of the FtsZ protein. The sdiA gene product is the first factor thus far identified that specifically regulates expression of this key group of cell division genes.

Characterization of beta-apo-13-carotenone and beta-apo-14'-carotenal as enzymatic products of the excentric cleavage of beta-carotene

Two new products from the incubation of beta-carotene with intestinal mucosa homogenates of human, monkey, ferret, and rat were isolated using high-performance liquid chromatography (HPLC). Identification by comparing retention times in HPLC, by monitoring ultraviolet/visible spectra, by reduction to corresponding alcohol, by oxime formation, and by mass spectrometry demonstrated that they are beta-apo-13-carotenone and beta-apo-14'-carotenal. These compounds were not found in incubations done without intestinal homogenates or with disulfiram as an inhibitor. Under standard incubation conditions, these products increased linearly for 60 min and up to a protein concentration of 1.5 mg/mL and increased along with increasing concentrations of beta-carotene. Therefore, they are enzymatic cleavage products from beta-carotene. The formation of the beta-apo-13-carotenone and beta-apo-14'-carotenal provides direct evidence for an enzymatic excentric cleavage mechanism.

Improvement of the effects of intrasplenic transplantation of hepatocytes after 90% hepatectomy in the rat by cotransplantation with pancreatic islets

Acute liver failure is associated with high mortality. Whether support with transplanted hepatocytes improves the outcome is not established. We studied the potential beneficial effects of intrasplenic transplantation of hepatocytes in conjunction with islets of Langerhans on 90% hepatectomy-induced acute liver failure in rats. We found that all control rats died within 48 hr following 90% hepatectomy. In contrast, the mortality decreased significantly in rats transplanted with 10(7) hepatocytes into the spleen parenchyma at 1-3 days prior to 90% subtotal hepatectomy, whereas no significant reduction in mortality was seen in rats transplanted with hepatocytes immediately after the operation. However, cotransplantation of hepatocytes and 400 isolated pancreatic islets into the spleen reduced mortality when performed immediately after the 90% hepatectomy. Therefore, hepatocyte transplantation reduces mortality after 90% hepatectomy only if performed prior to the hepatectomy. However, transplantation of hepatocytes in conjunction with pancreatic islets reduces mortality when performed at the same time as 90% hepatectomy. Hence, the combined transplantation of hepatocytes and islets might offer support after liver failure.

Application of pyridostigmine in evaluation of growth hormone reserves in children and adolescents

There is evidence that the cholinergic system positively modulates growth hormone (GH) secretion. In the present study, we observed the effects of cholinergic enhancement by pyridostigmine (PD), a cholinesterases inhibitor, on GH release in both normal (n = 13) and GH deficient children and adolescents (n = 10). Responses of GH to insulin hypoglycemia (Ins) were also observed. In the normal subjects, PD-induced serum GH peak level was significantly higher than that induced by Ins (P less than 0.01), while the GH level in the patients with pituitary dwarfism showed no increase in both tests. This study indicates that PD test may be considered a sensitive dynamic test in evaluating pituitary function of GH secretion in children and adolescents.