Microinjection of TRH analogs into the raphe pallidus stimulates gastric acid secretion in the rat

The effects of microinjection of the stable thyrotropin-releasing hormone (TRH) analog, RX 77368, [pGlu-His-(3,3'-dimethyl)-Pro-NH2] into the raphe pallidus on gastric acid secretion were studied in urethane-anesthetized rats with gastric fistula. RX 77368 microinjected into the raphe pallidus at doses of 0.07, 0.7 and 7.7 pmol induced a dose-dependent net stimulation of gastric acid secretion (7 +/- 4, 50 +/- 7 and 61 +/- 12 mumol/h respectively). The peak acid response was reached within 30 min and returned to basal level 90 min post-injection. The stimulatory effect was abolished by bilateral cervical vagotomy and pirenzepine pretreatment (1 mg/kg, i.v.). RX 77368 (7.7 pmol) microinjected into the inferior olive or pyramidal tract induced smaller or no gastric acid secretory response. These results demonstrate that chemical stimulation of the raphe pallidus increases gastric acid secretion through vagal pathways and peripheral muscarinic receptors. These data suggest that the nucleus raphe pallidus may be involved in vagal modulation of gastric acid secretion in the rat.

Hemostatic changes in women using a monthly injectable contraceptive for one year

The effect of consecutively injecting a one-a-month contraceptive (norethisterone enantate 50 mg with estradiol valerate 5 mg) for one year on haematological parameters was evaluated in 42 Chinese women. The healthy volunteers were randomly allocated to either the treatment group (22) or a control group (20). Blood samples were collected in the follicular and luteal phases of a pretreatment cycle, on days 28 +/- 3 after the 1st, 3rd, 6th, 12th injections and in the luteal phase of the post-treatment cycle. The results showed that in both groups, prothrombin time and fibrinogen fluctuated significantly, and leucocyte count was not significantly changed during the whole course. Factor VIII-related antigen and antithrombin III (AT-III) antigen showed minor changes, although in the 3rd treatment cycle, the differences between the two groups in both parameters reached statistical significance. A progressive and significant decrease in Factor X and AT-III functional activity occurred with the monthly injectable treatment, decreasing by about 14% and 20%, respectively, after 12 months of treatment. Haemoglobin levels were increased in the treatment group after the 3rd injection and remained at the higher level during the study period. It is doubtful whether these changes are likely to be of clinical relevance.

Somatostatin monoclonal antibody immunoneutralization increases gastrin and gastric acid secretion in urethane-anesthetized rats

The role of endogenous somatostatin in mediating urethane anesthesia-induced inhibition of gastric acid secretion was investigated using measurement of somatostatin messenger RNA concentrations in the antrum and the influence of somatostatin monoclonal antibody CURE.S6 on acid secretion in rats anesthetized with urethane and acutely implanted with gastric fistulas. Fifteen minutes after injection of urethane, somatostatin messenger RNA concentrations were increased by 128% compared with those in nontreated rats. The significant elevation of somatostatin messenger RNA was maintained for 2 hours after injection. Somatostatin monoclonal antibody injected intravenously (2 mg) completely reversed the inhibitory effect of somatostatin (20 micrograms/kg.h) on pentagastrin (24 micrograms/kg.h)-stimulated gastric acid secretion. The somatostatin monoclonal antibody dose dependently increased basal gastric acid secretion in urethane-anesthetized rats. Peak acid response to the somatostatin monoclonal antibody (2 mg) was observed 20 minutes after antibody injection (preinjection, 1.4 +/- 1.2 mumol/10 min; postinjection, 10.6 +/- 0.6 mumol/10 min); meanwhile, levels of plasma gastrin increased from 27 +/- 6 pg/mL to 75 +/- 8 pg/mL and were maintained elevated for the 2-hour experimental period. When gastrin monoclonal antibody 28.2 was injected together with somatostatin monoclonal antibody, the stimulatory effect of the somatostatin antibody was inhibited by 82%. A control monoclonal antibody 109-21 directed against the biologically inactive glycine-extended fragment 66-72 of progastrin did not alter basal gastric acid secretion or the inhibitory effect of somatostatin. These results indicate that one mechanism by which urethane induced low basal gastric acid secretion involved increased synthesis and release of endogenous somatostatin and associated inhibition of gastrin secretion.

Frame content independent stripping

Token rings have the property that a station that transmits a frame on the ring is responsible for removing the frame after it has been delivered to the destination stations. The algorithm to perform the frame removal is called 'Frame Stripping'. Most existing algorithms strip frames based on their content. This is not always adequate. The need for a new algorithm arises from the fact that frames transmitted by a station need not have the station's own address as the source address for a variety of reasons - such as when a bridge transmits a frame or when another address is used as the source address by a station instead of its original station address. This paper discusses a new frame content independent stripping (FCIS) algorithm for token rings.

The FCIS algorithm counts the number of frames transmitted by the station after capturing the token. In addition, the station places a special delimiter frame at the end of the transmission of frames, before releasing the token. The station then strips all received frames until either the number of frames stripped equals the number of frames transmitted or when either the delimiter frame or a token is received. We demonstrate that the FCIS algorithm has a minimal impact on the performance of the ring. We study the robustness of the algorithm to errors and demonstrate that its reliability is as good as the inherent mechanisms of the token ring.

The algorithm studied here is very simple to implement and interoperates with other stations not implementing this algorithm. The algorithm places no topological restrictions on the network and has the attractive feature of removing large fragments and no-owner frames.

Capsaicin-sensitive vagal afferents contribute to gastric acid and vascular responses to intracisternal TRH analog

Central injection of TRH or its stable analog, RX77368, produces a vagal cholinergic stimulation of gastric acid secretion, mucosal blood flow and motor function. In the present study, we have investigated the contribution of capsaicin-sensitive vagal afferent fibers to the gastric responses to intracisternal injection of RX77368. Gastric acid secretion, measured in acute gastric fistula rats anesthetized with urethane, in response to intracisternal injection of RX77368 (3-30 ng) was reduced by 21-65% by perineural pretreatment of the vagus nerves with capsaicin 10-20 days before experiments. The increase in gastric mucosal blood flow measured by hydrogen gas clearance induced by intracisternal injection of RX77368 (30 ng) was also reduced by 65% in capsaicin-pretreated rats. In contrast, increases in gastric motor function measured manometrically or release of gastric luminal serotonin in response to intracisternal injection of RX77368 (3-30 ng) were unaltered by capsaicin pretreatment. The mechanism by which vagal afferent fibers contribute to the secretory and blood flow responses to the stable TRH analog is unclear at present, but it is possible that the decrease in gastric mucosal blood flow by lesion of capsaicin-sensitive vagal afferents limits the secretory response.

A monoclonal antibody to somatostatin with potent in vivo immunoneutralizing activity

The spleen from a Robertsonian mouse with high titer and affinity antiserum after being immunized with somatostatin-14 conjugated to keyhole limpet hemocyanin was fused with FOX-NY cells. Hybridomas were cloned by limiting dilution, subcloned, and ascites was produced from the highest affinity close in pristine-primed Balb/c mice. Ascites fluid contained approximately 20 mg/ml IgG and bound 50% of 1 fmol 125I-[Tyr1]-somatostatin at a final dilution of 1:10,000,000. Binding of this IgG1 antibody, CURE.S6, was inhibited by 50% at 40 pM concentrations of either somatostatin-14 or somatostatin-28, but was not inhibited by [D-Trp8 -somatostatin at 1000-fold higher concentrations. The antibody produced very intense specific immunohistochemical staining of somatostatin endocrine cells in the stomach and pancreas and of intestinal somatostatin neurons with extremely low background staining. Intravenous injection of 2 mg purified antibody in urethane-anesthetized rats resulted in 300-fold increase in plasma GH within 15 min. CURE.S6 is a high affinity monoclonal antibody directed at the biologically active somatostatin ring structure. This antibody is useful for in vivo immunoneutralization of exogenous and endogenous somatostatin in the rat and also is an excellent reagent for immunohistochemical localization of somatostatin.

The effects of in vitro hyperthermia on natural killer activity from lung, blood and spleen

The in vitro effects of hyperthermia on natural killer (NK) activity from rat lung, peripheral blood and spleen were assessed. NK activity of all three compartments was very sensitive to heat shock. Exposure at 42.5 degrees C for 30 min resulted in more than 95% inhibition of NK activity. Conjugate-formation assays revealed that the mechanisms of hyperthermic NK inactivation are associated with post-binding lytic events. However, hyperthermia treated NK cells could partially recover their cytotoxic activity. Unheated lung lymphocytes (LL) were more sensitive to hyperthermic inhibition than spleen (SL) and blood (PBL) lymphocytes but they were also able to recover to a greater extent from such inactivation. Moreover, the responsiveness of NK cells from lung, blood and spleen to interleukin-2 (IL-2) and interferon (IFN-alpha/beta) was altered differently by heat shock. Hyperthermia treatment increased the ability of NK cells from blood to respond to IL-2 or IFN-alpha/beta. Similarly hyperthermia treated NK cells from spleen were more responsive to IFN-alpha/beta. By contrast such treatment did not change significantly the responsiveness of lung NK cells to these agents. Taken together, our findings indicate that NK cells from various compartments behave differently in response to hyperthermia treatment. Moreover, it suggests that hyperthermia treatment does not irreversibly comprise the host natural killer response and may even in some cases increase NK cell responsiveness to biological response modifiers (BRM).

Effects of streptozotocin-induced diabetes mellitus on growth and hepatic insulin-like growth factor I gene expression in the rat

Poorly controlled diabetes mellitus in humans and animals is often accompanied by impaired growth. We undertook this study in young rats to determine whether the reduction in growth rate associated with streptozotocin (STZ)-induced diabetes might be related to changes in both serum insulin-like growth factor I (IGF-I) and IGF-II levels, and, if so, whether these changes reflect alterations in serum growth hormone (GH) and in hepatic IGF-I and IGF-II gene expression. Serum rat GH (rGH) levels were variable during the first 4 days after STZ administration, but during the subsequent 5- to 11-day period the mean (+/- SEM) levels in insulin-treated (DI) (21.4 +/- 4.9 ng/mL) and untreated (D) (8.5 +/- 1.5 ng/ml) diabetic rats were significantly (P less than .001) lower than in controls (C) (117.8 +/- 22.9 ng/mL). Multiple transcripts of IGF-I (7.0, 4.0, 1.9, 1.0 kb), but barely detectable amounts of IGF-II mRNA, were found in the livers of normal and diabetic rats by Northern blot analysis. Using dot blot analysis, we have shown that the abundance of total hepatic IGF-I mRNA in untreated, growth-retarded diabetic animals decreases rapidly over a period of 3 days after STZ administration. Both serum IGF-I and IGF-II levels are also diminished during this interval in these markedly hyperglycemic rats. Insulin treatment for 3 to 4 days, started either immediately (6 hours) or within 3 days after administering STZ, blunts diabetes-induced impairment of growth and restores mean hepatic IGF-I mRNA abundance to control levels, but does not normalize serum IGF-I and IGF-II concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

[Application of ion chromatography to identification of anaerobic bacteria]

The fatty acids of anaerobic bacteria were detected by ion chromatography (IC). The results showed that 11 kinds of standard fatty acids could be analyzed within 15 min, and just needed 1 injection sample. The fatty acids patterns of 40 strains of anaerobic bacteria detected by IC were essentially the same as that by gas chromatography (GC) reported by VPI. In comparison with GC, IC has further advantages: pretreatment is simpler, both volatile and non-volatile fatty acids can be analyzed at the same time, and formic and lactic acid can be well analyzed.

Role of acetylcholine, histamine and gastrin in the acid response to intracisternal injection of TRH analog, RX 77368, in the rat

The role of gastrin, acetylcholine and histamine in the acid response to central vagal activation induced by intracisternal injection of the stable analog, RX 77368, was further investigated in urethane-anesthetized rats with gastric fistula. The gastrin monoclonal antibody 28-2 injected intravenously, at a dose previously shown to prevent gastrin-induced stimulation of acid secretion, did not alter the peak acid response to intracisternal injection of RX 77368 (15 ng). The TRH analog (30 ng) injected into the cisterna magna increased levels of histamine measured in the hepatic portal blood. Cimetidine administered at a dose which completely blocked the stimulation of gastric acid secretion produced by intravenous infusion of histamine, inhibited by 62% the stimulatory effect of intracisternal RX 77368 (30 ng). The M1 muscarinic antagonist, pirenzepine, completely prevented the acid secretion induced by intracisternal RX 77368 (30 ng). These results indicate that the acid response to central vagal activation by the TRH analog in rats involved M1 muscarinic receptors along with histamine release acting on H2 histaminergic receptors whereas gastrin does not appear to play an important role.

[Dynamic changes of superoxide dismutase in patients with myocardial infarction. A clinical study]

The activity of serum superoxide dismutase (SOD) was studied in 35 cases of acute myocardial infarction (AMI) and 12 cases of angina pectoris (AP). The results suggested that serum MnSOD activity reached its peak value (18.7 +/- 6.39) immediately after AMI attack and gradually dropped down on the second day. The activity was no more detected on the seventh day. The value of serum MnSOD in patients with AMI within 24 hours was significantly different (P less than 0.05) or very significantly different (P less than 0.01-0.001) from that in patients with AMI after 2 days and AP and in the control group. The positive rate of early diagnosis in the three groups was 100%, 71% and 66% respectively. It was found that the height of serum MnSOD activity was closely correlated with the seriousness of myocardial damage, therefore, serum MnSOD activity may be one of the sensitive indices for the early diagnosis of AMI. In has also certain clinical value in the judgement of the extent of infarction and of prognosis.

Morphological and functional studies on microencapsulated human fetal pancreatic tissue

Fifty human fetal pancreases of 4-6 months gestation obtained from legal abortions were microencapsulated with alginate, poly-lysine after culture for 4-7 days. The microcapsules were studied morphologically and functionally. Immunocytochemical staining for insulin indicated B-cells were morphologically intact at 48 days. Insulin and C-peptide of the culture medium measured with radioimmuno-assay (RIA) showed that the microcapsules still retained the function of insulin secretion after culture for 25 days. There was no statistical difference when compared with noncapsulated tissues. No exocrine function was detected as evidenced by the amylase determination. We conclude that microencapsulated human fetal pancreatic tissues retain viability in culture for more than 25 days and can be used as transplants in the treatment of diabetes mellitus.

Synthesis and antiviral activity of several 2,5'-anhydro analogues of 3'-azido-3'-deoxythymidine, 3'-azido-2',3'-dideoxyuridine, 3'-azido-2',3'-dideoxy-5-halouridines, and 3'-deoxythymidine against human immunodeficiency virus and Rauscher-murine leukemia virus

Several 2,5'-anhydro analogues of 3'-azido-3'-deoxythymidine (AZT), 3'-azido-2'3'-dideoxyuridine (AZU), 3'-azido-2'3'-dideoxy-5-bromouridine, 3'-azido-2',3'-dideoxy-5-iodouridine, and 3'-deoxythymidine and the 3'-azido derivative of 5-methyl-2'-deoxyisocytidine have been synthesized for evaluation as potential anti-HIV (human immunodeficiency virus) agents. These 2,5'-anhydro derivatives, compounds 13-17, demonstrated significant anti-HIV-1 activity with IC50 values of 0.56, 4.95, 26.5, 27.1, and 48 microM, respectively. Compared to that of the parent compounds AZT and AZU, the respective 2,5'-anhydro analogues, compounds 13 and 14, were somewhat less active. Whereas AZT was cytotoxic with a TCID50 of 29 microM, the toxicity of the 2,5'-anhydro derivative of AZT, compound 13, was reduced considerably to a TCID50 value of greater than 100 microM. The 2,5'-anhydro analogue of 5-methyl-2'-deoxyisocytidine also demonstrated anti-HIV-1 activity with an IC50 value of 12 microM. These compounds were also evaluated against Rauscher-Murine leukemia virus (R-MuLV) in cell culture. Among them, AZT, 3'-azido-2',3'-dideoxy-5-iodouridine, 3'-azido-2',3'-dideoxy-5-bromouridine, and 2,5'-anhydro-3'-azido-3'-deoxythymidine (13) were found to be most active, with IC50 values of 0.023, 0.21, 0.23, and 0.27 microM, respectively.

In vitro culture and transplantation of encapsulated human fetal islets as an artificial endocrine pancreas

There has been increasing evidence indicating that islet transplantation may offer an ideal endocrine replacement therapy for patients with Type I diabetes mellitus. However, allogenic islets are susceptible to immune rejection. In 1980, Lim and Sun first reported a novel technique of microencapsulation by which pancreatic islets used as transplants could be encapsulated and immunoisolated so as to survive and function for a period of 2-3 weeks. By further improving the biocompatibility of the capsular membrane, Sun's group demonstrated that islet allografts can be protected from rejection for up to 21 months in nonimmunosuppressed, streptozotocin-induced diabetic rats. The biocompatible polymer capsule membrane constitutes a physical barrier to the host's immune system. Permeability of the membrane can be controlled to allow free diffusion of small molecular nutrients, hormones, and metabolites, but exclude lymphocytes, leukocytes, and macromolecular immunoglobulins and complement. Darquy and Reach, in 1985, disclosed the role of the microcapsule membrane in protecting islets from cytotoxic antibodies. Sun's group further demonstrated that the microencapsulation technique effectively protected xenografts of rat islets transplanted into diabetic mice. In a previous report, we described the success of allotransplanted microencapsulated rat islets in treating streptozotocin-induced diabetes in Wistar rats. We now report the in vitro study of human fetal islets microencapsulated within an alginate-polylysine membrane. A preliminary clinical trial of allotransplants for the treatment of insulin-dependent diabetics is also presented.

Intrathecal injection of bombesin inhibits gastric acid secretion in the rat

Bombesin (100-500 ng) injected intrathecally (T9-10) inhibited gastric acid secretion stimulated by pentagastrin and the GABAB agonist baclofen in urethane-anesthetized rats and basal gastric acid secretion in conscious, pylorus-ligated rats. Peptide action was dose-related, occurred within 30 min, and lasted for greater than 1 h. Bombesin-induced inhibition of pentagastrin-stimulated gastric acid secretion was not altered by cervical cord transection. Intravenous infusion of the monoclonal bombesin antibody 2A11 abolished intravenous bombesin (10 micrograms/kg.h)-induced 33% inhibition of gastric response to pentagastrin but did not alter intrathecal bombesin (200 ng)-induced 38% inhibition of gastric response to pentagastrin. The inhibitory effect of bombesin (200 ng) on pentagastrin-stimulated gastric secretion was reversed by bilateral adrenalectomy or removal of celiac and mesenteric ganglia. Intrathecal injections of rat calcitonin gene-related peptide, neuromedin B, neuromedin U, and the stable substance P analogue (pGlu5, MePhe8, MeGly9)-substance P(5-11) did not alter pentagastrin-stimulated gastric acid secretion. These results demonstrate that bombesin injected into the subarachnoid space of the spinal cord inhibits vagally stimulated and pentagastrin-stimulated gastric secretion in rats. Bombesin action is peptide specific, exerted at a spinal site, and expressed through the sympathetic nervous system.

Autoradiographic study of smooth muscle cell proliferation in spontaneously hypertensive rats

1. The rate of smooth muscle cell proliferation in age-matched 1-4-week-old spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats was compared using autoradiography. 2. Labelling index, defined as labelled cells/sum of labelled and unlabelled cells x 1000, was obtained from perfusion-fixed superior mesenteric and large mesenteric arteries. 3. In the large mesenteric arteries, the smooth muscle cell labelling indices were similar between the SHR and WKY at all age groups, except at 1 week of age when the smooth muscle labelling index was higher in the SHR. 4. In the superior mesenteric arteries, labelling indices were similar between the rat strains at all age groups. 5. We conclude that, in the SHR, a rapid proliferation of smooth muscle cells in the large mesenteric arteries occurred during the first week of life. This resulted in a higher number of smooth muscle cell layers in the media of muscular arteries. 6. The increased proliferation may play a role in the subsequent development of hypertension in the SHR.