Effects of chelation on the bioconcentraton of cadmium and copper by carp (Cyprinus carpio L.).
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Animals↗
Biomedical subjects
J Mei
Publications and source records attributed to J Mei.
Inhibition of insulin release by intraduodenally infused enterostatin-VPDPR in rats.
Enterostatin, an amino-terminal pentapeptide produced in the intestinal lumen after cleavage of pancreatic procolipase, has been shown to suppress fat intake in rats after intraduodenal infusion. In this study, female Sprague-Dawley rats fitted with a duodenal catheter were intestinally infused with enterostatin (Val-Pro-Asp-Pro-Arg, 11.3 and 22.6 nmol/kg/min) plus 20% Intralipid for 30 min. Plasma insulin levels were significantly reduced, whereas plasma glucose concentrations were not altered by enterostatin-VPDPR. The tripeptide Asp-Pro-Arg was also found to decrease the levels of plasma insulin. However, the pentapeptide with the sequence Val-Pro-Gly-Pro-Arg, des-Arg-enterostatin Val-Pro-Asp-Pro and the tripeptide Pro-Asp-Pro failed to cause the reduction of plasma insulin levels in rats following intestinal infusion of these peptides. Radiolabeled enterostatin ([3H]VPDPR) was identified in plasma by HPLC following intraduodenal infusion of the peptide, indicating that the appearance of an intact enterostatin-VPDPR in blood. It is concluded that intestinally administered enterostatin-VPDPR and its metabolites reduce plasma levels of insulin stimulated by Intralipid.
Animals↗
Effects of cyclosporine A and methotrexate on induction of tumour necrosis factor-alpha in rat cardiac allografts.
Experimental and clinical studies have yet to determine the extent to which methotrexate (MTX) or cyclosporine A (CSA) treatment alone affects the expression in vivo of tumour necrosis factor-alpha (TNF alpha), a cytokine produced primarily by macrophages and believed to be directly involved in the pathogenesis of cardiac allograft rejection. In light of previously published findings from this laboratory examining the effects of combination CSA/MTX treatment, these studies were designed to examine the individual effects of CSA and MTX upon TNF alpha gene expression post-transplant (post-tx) using an accessory cervical heart transplant model in the rat. These studies have focused on a highly sensitive method with which to detect changes in gene expression, reverse transcriptase-polymerase chain reaction (RT-PCR) methodology and enzyme-linked immunosorbent assay (ELISA) assessment of transplant TNF alpha protein levels. Both techniques consistently demonstrated biphasic TNF alpha expression in cardiac transplant tissue obtained from untreated allograft recipients during the first week post-tx in contrast to isograft recipients. Previously demonstrated in combination to prolong cardiac allograft survival, low-dose MTX and low-dose CSA were each evaluated alone in the course of these studies to determine their impact on TNF alpha gene expression. While TNF alpha levels were up-regulated during untreated allograft rejection, both TNF alpha RNA and protein were significantly diminished with low-dose combination CSA/MTX treatment, with CSA alone, but not significantly with MTX treatment alone. In conclusion, TNF alpha gene expression in untreated allografts is consistent with the hypothesis that TNF alpha may play a role in events leading to allograft rejection. Results of these studies indicate that TNF alpha levels are significantly regulated in vivo by CSA but not by MTX treatment. These studies further implicate a role for low-dose MTX in mediating statistically significant immunosuppressive effects in conjunction with low-dose CSA.
Animals↗
Dissociation of affinity and efficacy in KOR-3 chimeras.
KOR-3 chimeras were constructed in which the first coding exon of KOR-3 was exchanged for the corresponding first coding exon of either MOR-1 (MOR-1/KOR-3) or DOR-1 (DOR-1/KOR-3). All three clones were expressed in CHO cells and characterized with regards to their binding profiles for orphanin FQ/nociceptin (OFQ/N) and a variety of opioids as well as their functional activities in cyclase studies. 125I[Tyr14]OFQ/N labels both KOR-3 (KD 37 pM) and the MOR-1/KOR-3 chimera (KD 39 pM) equally well. Although its affinity for the DOR-1/KOR-3 chimera is quite good (KD 135 pM), it is slightly lower than the other two. Competition studies confirm the high affinity of OFQ/N for all three clones. However, several competitors clearly distinguish the chimeras from KOR-3. OFQ/N(1-11) competes KOR-3 (Ki 55 nM) over 6-fold more potently than either of the chimeras. (Ki values > 350 nM). Conversely, the modest affinity of naloxone benzoylhydrazone for KOR-3 (310 nM) is greatly increased in both the MOR-1/KOR-3 (Ki 69 nM) and DOR-1/KOR-3 (Ki 74 nM) chimeras. The remainder of the opioids tested have no appreciable affinity against any of the clones. Functionally, OFQ/N inhibits forskolin-stimulated cAMP accumulation in both the KOR-3 and the MOR-1/KOR-3 chimera by almost 40%, with IC50 values in the low nanomolar range. Little activity is seen against the DOR-1/KOR-3 chimera. Naloxone benzoylhydrazone inhibits cAMP accumulation in the KOR-3 and the DOR-1/KOR-3 chimera. Although naloxone benzoylhydrazone has higher affinity for the MOR-1/KOR-3 chimera in binding studies than KOR-3 itself, it is inactive in cyclase studies using the MOR-1/KOR-3 chimera, implying that the replacement of the first coding exon increases affinity while decreasing intrinsic activity.
Animals↗
Procolipase is produced in the rat stomach--a novel source of enterostatin.
Procolipase was identified in the stomach by in situ hybridisation. A strong autoradiographic labelling of chief cells was seen in the fundus region, declining more distally and being almost absent in antrum. There was no labelling seen in the intestine. Colipase activity was estimated in rat gastric juice following pentagastrin stimulation and was found to average 2 microM. Furthermore, enterostatin, the N-terminal pentapeptide of procolipase, has been identified in the rat gut and pancreas. Extracts from gastric mucosa, intestinal mucosa and pancreas were purified by gel filtration (Sephadex G25), ion-exchange chromatography (CM-Sepharose) and HPLC (C18 reverse phase). Using an ELISA assay with antibodies directed against enterostatin, two forms of the peptide were identified both in the gut and in the pancreas, with the amino-acid sequences APGPR and VPGPR, respectively. APGPR was found to be the predominant form of enterostatin, whereas only a small amount had the structure VPGPR. Enterostatin in the form of APGPR, when injected intracerebroventricularly in female Sprague-Dawley rats, significantly reduced high-fat food intake in a two-choice situation of low-fat (14% fat by energy) and high-fat (38% fat) food. It is concluded that procolipase is produced in the stomach and secreted into the gastric juice. This is also a novel source of enterostatin.
Amino Acid Sequence↗
Plasma insulin in response to enterostatin and effect of adrenalectomy in rats.
Enterostatin has previously been reported to alter serum insulin and corticosterone levels after central administration of the peptide. The purpose of the present study was to investigate the effect of peripheral administration of enterostatin on insulin and corticosterone levels as well as the response of plasma insulin to enterostatin administration in adrenalectomized rats. Female Sprague-Dawley rats were given a bolus injection intravenously with enterostatin alone or together with glucose. Enterostatin increased basal plasma levels of insulin, but significantly inhibited the increase in plasma insulin stimulated by glucose. Plasma corticosterone levels were not altered after a single intravenous injection of enterostatin. In rats infused chronically with enterostatin, plasma insulin levels were significantly reduced and plasma corticosterone levels were increased. The daily food intake was lower in these rats, but there was no effect on body weight. After adrenalectomy, the responsiveness of plasma insulin to enterostatin infusion was completely abolished. Furthermore, adrenalectomy itself reduced basal plasma levels of insulin and increased plasma levels of endogenous enterostatin. These results suggest that peripheral enterostatin administration produces a similar effect as central infusion of the peptide, and that the glucocorticoid hormones are involved in the regulation of plasma insulin by enterostatin.
Adrenalectomy↗
Role of intraduodenally administered enterostatin in rats: inhibition of food.
Central and peripheral administration of enterostatin have been reported to reduce fat or high-fat food intake in rats. Enterostatin is formed in the intestinal lumen by tryptic cleavage of pancreatic procolipase during intraluminal fat digestion. The present experiments were designed to test if enterostatin following intraintestinal infusion would affect food intake in a similar way as intracerebraventricularly or intravenously administered enterostatin. Female Sprague-Dawley rats were fitted with a duodenal catheter and adapted to feeding schedule for 6 hours each day. After 10 days enterostatin (5.65 and 11.3 nmol/kg/min) or saline were infused into the duodenum and food intake measured. Enterostatin significantly reduced high-fat food intake during the 6 hours of feeding, but had no inhibitory effect on low-fat food intake. Addition of tetracaine to the enterostatin infusates blocked the satiating potency of intestinal enterostatin. These results support the hypothesis of a preabsorptive site of action for enterostatin.
Anesthetics, Local↗
Enterostatin in gut endocrine cells--immunocytochemical evidence.
The presence of enterostatin, a pentapeptide acting as a potential satiety signal in rats, was investigated in rat intestine by immunocytochemical methods. Using antibodies directed against the C-terminal part of enterostatin, the peptide was identified in endocrine cells in the antral part of the stomach and in the small intestine of rat. The immunoreactive cells were more frequent in the antrum and duodenum and became gradually fewer towards the distal small intestine. In some of the labeled endocrine cells, a coexistence of enterostatin with serotonin was revealed by immunocytochemical double staining, implying that the cells were enterochromaffin cells. In the pancreas, no enterostatin-immunoreactive cells were detected, indicating enterostatin to be included in its parent molecule, procolipase. In addition, the existence of procolipase in the gastrointestinal tract, including the pancreas, was investigated. Procolipase immunoreactivity was also identified, except in the pancreas, in chief cells in the fundus region of the stomach. The number of labeled cells declined distally in the stomach, finally being absent in the intestine. Immunoreactive enterostatin was measured with a specific ELISA method. Intestinal content and serum were found to average 540 +/- 70 and 50 +/- 4 nM, respectively. Pancreatic duct ligation strongly reduced the levels of enterostatin in intestinal content to 5.4 +/- 1.5 nM (p < 0.001), and also reduced the serum enterostatin level to 35 +/- 5 nM (p < 0.05). It is concluded that the peptide enterostatin in the rat is produced both in the exocrine pancreas, as part of pancreatic procolipase, and in gut endocrine cells, both sources of peptide being important for the circulating enterostatin.
Amino Acid Sequence↗
A porcine model of peritonitis and bacteremia simulates human septic shock.
Cardiovascular responses to systemic bacteremia were evaluated in a pre-instrumented, conscious pigs. Basal observations were obtained 5-7 days after instrumentation. On the next day, Escherichia coli 0111.B4 (1.1 to 33 x 10(9) CFU/kg)-laden fibrin clots were implanted intraperitoneally. Nonsurvivors (9/18) demonstrated rapid cardiovascular decompensation. Survivors (9/18) demonstrated significant cardiovascular injury, which was reversed by 5-7 days postimplant. Cardiac inotropicity was significantly reduced in this period, but recovered by day 7. Circulating myocardial depressant substance activity (assayed by serum-induced depression of beating neonatal rat myocytes) was present on days 1-4 of bacteremia and recovered to basal values on day 6. No clinical or cardiovascular changes were seen in pigs implanted with sterile clots (n = 4). These data demonstrate that implantation of bacteria-laden fibrin clots in pigs induces cardiovascular alterations that mimic responses seen in human sepsis.
Animals↗
Interactions of the origin of replication (oriV) and initiation proteins (TrfA) of plasmid RK2 with submembrane domains of Escherichia coli.
It has been possible to locate a submembrane domain representing less than 10% of the total membrane that appears to be responsible for sequestering some essential components required for plasmid RK2 DNA replication. This subfraction, whose cellular location in the membrane prior to extraction is still unknown, is derived from the inner membrane fraction, since it possesses enzyme marker activity (NADH oxidase) exclusively associated with the inner membrane. The subfraction was detected by a modification of the methods of Ishidate et al. (K. Ishidate, E. S. Kreeger, J. Zrike, S. Deb, B. Glauner, T. MacAlister, and L. I. Rothfield, J. Biol. Chem. 261:428-443, 1986) in which low pressure in a French pressure cell and lysozyme were used to preserve the supercoil plasmid DNA template during cell disruption. This was followed by successive cycles of sucrose gradient sedimentation and flotation density gradient centrifugation to reveal a number of subfractions, including the one of interest. The characteristics of plasmid interaction with the subfraction include the presence of supercoil DNA after extraction, the binding of the origin of plasmid replication (oriV) in vitro, and the association of the two plasmid-encoded initiation (TrfA) proteins (encoded by overlapping genes). However, another peak, the outer membrane fraction, also binds oriV in vitro, contains plasmid DNA in vivo, and associates with the TrfA initiation proteins. Nevertheless, it contains much less of the initiation proteins, and the specific activity of binding oriV is also much reduced compared with the other subfraction. There is a strong correlation between the association of the TrfA initiation proteins with a particular membrane fraction and the binding of oriV in vitro or plasmid DNA in vivo. Since the proteins are known to bind to repeated sequences in oriV (S. Perri, D. R. Helinski, and A. Toukdarian, J. Biol. Chem. 266:12536-1254, 1991; M. Pinkney, R. Diaz, E. Lanka, and C. M. Thomas, J. Mol. Biol. 203: 927-938, 1988), it appears that the initiation proteins themselves could be responsible, at least in part, for the association of plasmid DNA to the membrane.
Bacterial Proteins↗
[Effects of intracerebroventricular administration of norepinephrine on paraventricular neurosecretory cells].
Extracellular electrical activities of paraventricular nucleus (PVN) cells were recorded in anaesthetized adult rats by using glass microelectrodes. After antidromical identification of the magnocellular neurosecretory cells, the effects of intracerebroventricular (i.c.v.) injection of norepinephrine (NE) on such cells were observed. Of 49 neurons of antidromic stimulation, phasic, fast continuous and slowly irregularly. firing units constituted 42.9%, 36.7%, and 20.4% of the total population respectively. With i.c.v. injection, NE inhibited the activity of most phasically firing units, but enhanced that of most fast continuous and slowly irregular firing units. The inhibition effect of NE could be partially antagonized by i.c.v. injection of phentolamine (2 micrograms/microliters), showing that the effect is possibly mediated by alpha-receptor. The above findings indicate that NE plays different roles in different PVN magnocellular neurons having different patterns of firing activity.
Animals↗
[Aging changes of the electro-physiological characteristics of hypothalamic neurons in culture].
The aging changes of the electrophysiological characteristics of the hypothalamic neurons cultured for 0-140 days were studied in neonatal SD rats by the intracellular microelectrode recording technique. The growth velocity of the neurites was used as an index to divide the living process of the neurons into three periods, i.e. recovering period, growth period and aging period. It was found that the time constant and the membrane capacitance reached a top value in the growth period and then decreased significantly in the aging period (P < 0.05, P < 0.01). In the recovering period, the membrane resistance reached the highest; and then decreased significantly in growth period but did not change significantly in the aging period. The amplitude of the membrane resting potential was about -30 - -60 mv and increased with the days in vitro (P < 0.05). The neurons could produce single or burst discharges. It appears that certain electrophysiological characteristics of the hypothalamic neurons in culture could characterize certain aging changes.
Animals↗
[Experimental studies on the preventive effect of artemether against schistosomal infection].
In order to study the preventive effect of artemether (Art) against schistosomal infection, mice, rabbits and dogs infected with Schistosoma japonicum cercariae were treated intragastrically (ig) with Art on various days after infection. The preventive effect was assessed by total and female worm reduction rate, the number of the animals without female worm, measurement of some parameters relevant to the acute schistosomiasis, and histopathological observation on the liver. The results showed that in mice a promising effect was obtained when an initial dose of Art 300 mg/kg was given ig on d7 after infection with cercariae, followed by repeated dosing every wk for 4 times. In rabbits and dogs treated ig with Art according to above-mentioned appropriate regimen on d7 after infection at a dosage of 10 or 15 mg/kg given every 1 or 2 wk for 2-4 times, the total and female worm reduction rates were 96.8%-100%, and part of the animals were free from female worm. After preventive treatment of the rabbits with Art, the body temperature and eosinophil count were normal and no schistosome egg was found in the feces. When rabbits infected with 48-52 schistosome cercariae once every other day for 5 times were initially treated ig with Art 15 mg/kg on d7 after the first infection, and the same dosing was given repeatedly every 1 or 2 wk for 2-4 times, the total and female worm reduction rates were 97.6%-98.4%. Histopathological observation showed that the above-mentioned infected dogs and rabbits received preventive treatment with Art exhibited a promising protective effect on their livers. The protective effect of Art given every 1 wk on the liver was similar to that of the drug given every 2 wk. The results indicate that Art possesses an effect for prevention of schistosomiasis which could be helpful for reducing infection rate and intensity of infection, and controlling acute schistosomiasis.
Animals↗
TrfA-dependent, inner-membrane-associated plasmid RK2 DNA synthesis in Escherichia coli maxicells.
Previous results of experiments in which plasmid-encoded proteins were selectively labeled in ultraviolet sensitive "maxicell" mutants suggested that the essential initiation proteins of RK2 (33 and 43 kDa) were bound to the inner membrane of Escherichia coli (D. Kostyal et al., 1989, Plasmid 21, 226-237). However, in the present studies using a specific polyclonal antibody against the TrfA initiation proteins, significant levels of these proteins were also detected for the first time in the outer membrane fraction as well as the inner membrane fraction. Only in the cytosol fraction were the initiation proteins relatively absent. In order to determine whether initiation and replication were also associated with either or both of the membrane fractions, it was necessary to develop a replicating system more active than the one previously extracted from minicell membranes, which did not separate the membrane into its component parts (J. A. Kornacki and W. Firshein, 1986, J. Bacteriol. 167, 319-326). In addition, it was also necessary to devise an extraction procedure that did not degrade the supercoil DNA template during the separation of the inner from the outer membrane fraction. Both criteria were met, first by the use of maxicells containing a miniplasmid derivative of RK2 and second by disrupting cell envelopes in the French pressure cell using low pressure. Under these conditions, not only were the two major membrane fractions separated successfully from the cytosol fraction, but supercoil DNA template was also preserved in both fractions, detergents were avoided, and replication was significantly higher than that described in the earlier experiments. TrfA-dependent initiation of DNA replication was associated primarily with the inner membrane fraction.
Antibodies, Bacterial↗
Early treatment with artemether and praziquantel in rabbits repeatedly infected with Schistosoma japonicum cercariae.
When rabbits infected with 48-52 Schistosoma japonicum cercariae once every wk for 6 times or every other day for 5 times were treated ig with artemether (Art) 10 or 15 mg.kg-1 on d7 after the first infection, followed by the repeated administration of the same dose once every 1-2 wk, a promising effect was seen in the groups treated with Art at higher dose. In another group of rabbits with the same drug administration regimens of praziquantel (Pra) were also used in early treatment, but the initial dose was given on d21 after the first infection. The results showed that Pra given at 40 mg.kg-1 in each administration was more promising than the lower dose of 30 mg.kg-1 especially in group treated at 2 wk intervals. Further study indicated that the presence of adult schistosomes in rabbits increased the effect of Pra not only on 21-day-old schistosomule, but also on 14-day-old schistosomules. The results suggest that Art and Pra could be used in field trial for controlling acute schistosomiasis and decreasing the intensity of schistosomal infection.
Animals↗
[Effect of artemether on glycogen, protein, alkaline phosphatase and acid phosphatase of Schistosoma japonicum].
When mice infected with Schistosoma japonicum for 32-35 d were treated ig with artemether (Art) at a single dose of 300 mg.kg-1 for 24 h, the glycogen content of female and male schistosomes decreased significantly with reduction rates of about 50%. 72 h after medication, the glycogen reduction rates were 64.1-77.9%. Meantime, the protein content of female and male worms was also decreased, the reduction rates being 68.1% and 49.3%, respectively. In infected mice treated ig with Art at the same dosage for 24 h, the inhibition rates of alkaline phosphatase (AKP) activity in female and male worms were 30% and 25%, respectively. 72 h later, the AKP activity of female worm was further inhibited to 62.3% as compared with the control. Besides, the inhibitory effect of Art on acid phosphatase (ACP) activity of female worm was also more apparent than that of male worm. 72 h after medication, the respective inhibition rates of ACP activity in female and male worms were 75.7% and 47.6%. The results indicated that Art might exert its effect on both carbohydrate and protein metabolism of schistosomes.
Acid Phosphatase↗
[Treatment of MSOF after heart valve replacement: an analysis of 53 cases].
We treated 53 patients with multiple system organ failure (MSOF) following heart valve replacement. MVR was performed in 20 cases, AVR in 6 and DVR in 27. Before operation, NYHA functional class II was in 5, III in 17, and IV in 31. MSOF of all 53 patients occurred within 2-7 days after operation, and failing organs involved heart, lungs, kidneys, brain, gastrointestinal and blood coagulation system. The patients with the maximum organ failure had 6 failing organs, 36 of the 53 patients were living and 17 (32.1%) died. The mortality correlated positively with the number of failing organs. The results of MSOF which occurred sequentially were better compared with those occurred simultaneously. The death rate in patients with class IV was higher than that in those class II, III. The type of operation (MVR, AVR, DVR) did not effect the result of MSOF. The causes and management of MSOF after heart valve replacement were discussed.
Adult↗
[Study and improvement of Reed-Frost model].
The purpose of this paper is to modify the Reed-Frost theory of epidemics with the underlying assumptions of the model including the occurrence of inapparent infections, and their influence on the course of the epidemic. With this model two epidemics were computed: (1) the Aycock outbreak of measles in a New England boy-boarding school in 1934; (2) the outbreak of chickenpox in a Shanghai kindergarten in 1950. The calculated and observed results were well in agreement. A substantial improvement in fitness was shown as measured by chi-square tests. As presented, the model offers a reasonably good explanation on the occurrence of inapparent infections and its effect on the pattern of the disease.
Chickenpox↗