Vagovagal reflex motility patterns of the rat esophagus

Esophageal reflex motility and its neural correlates were investigated in 94 urethan-anesthetized adult male albino rats. When distended by means of a stationary balloon, the cervical and thoracic esophageal portion responded with a single pressure wave (type I response), whereas the diaphragmatic (intercrural) segment exhibited rhythmic contractions (type II response). Balloon deflation resulted in an off response aboral to the balloon. Bilateral cervical vagotomy or systemic D-tubocurarine abolished all types of reflex responses. Both type I and type II responses were associated with multiunit discharges in the central subnucleus of the solitary tract complex (NTSC) and the compact formation of the nucleus ambiguus (AMBC). Type I discharges, consisting of single bursts, and type II discharges, consisting of rhythmic 0.6-Hz bursts, preceded intraesophageal pressure waves in a fixed phase relationship, persisted after contralateral vagotomy, and were eliminated by ipsilateral vagotomy. During neuromuscular paralysis, peak intraburst discharge rates were reduced in both the NTSC and AMBC, with a concomitant decrease in rhythmicity. It is concluded that bolusevoked peristalsis of the rat esophagus is 1) segmentally organized; 2) effected by a bilateral uncrossed reflex arc consisting of vagal viscerosensory, NTSC premotor, and AMBC motoneurons innervating the striated muscle tunic and 3) strongly facilitated by reafferent feedback.

Neurotrophin modulation of NMDA receptors in cultured murine and isolated rat neurons

Neurotrophin modulation of NMDA receptors in cultured murine and isolated rat neurons. J. Neurophysiol. 78: 2363-2371, 1997. Patch-clamp and calcium imaging techniques were used to assess the acute effects of the neurotrophins, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and nerve growth factor (NGF), on the responses of cultured and acutely isolated hippocampal and cultured striatal neurons to the glutamate receptor agonist N-methyl--aspartic acid (NMDA). The effects of BDNF on NMDA-activated currents were examined in greater detail. Currents evoked by NMDA, and the accompanying changes in intracellular calcium, were enhanced by low concentrations of the neurotrophins (1-20 ng/ml). The potentiation by the neurotrophins was rapid in onset and offset (<1 s). The neurotrophins also reduced desensitization of these currents in most cells. The enhancement of NMDA-activated currents by BDNF was observed using both perforated and whole cell patch recording techniques and could be demonstrated in outside-out patches. Furthermore, its effects were not attenuated by pretreatment with the protein kinase inhibitors genistein or 1-(5-isoquinolynesulfony)2-methylpiperazine (H7). Therefore, the actions of BDNF do not appear to be mediated by phosphorylation. Similar enhancements were observed with NT-3 and NT-4 and with NGF despite the fact that hippocampal neurons lack TrkA receptors. All together this evidence suggests that the enhancement of NMDA-evoked currents is unlikely to be mediated through the activation of growth factor receptors. Modulation of NMDA responses by BDNF was dependent on the concentration of extracellular glycine. The most pronounced potentiation by BDNF was observed at low concentrations, whereas no potentiation was observed in saturating concentrations of glycine, suggesting that BDNF may have increased the affinity of the NMDA receptor for glycine. However, the competitive glycine-site antagonist 7-chloro-kynurenic acid blocked the enhancement by BDNF without shifting the dose-inhibition relationship for this antagonist, and Mg2+ consistently depressed the potentiation of NMDA-evoked currents by BDNF, indicating that BDNF does not alter glycine affinity. BDNF also reversibly increased the probability of opening of NMDA channels recorded from outside-out patches taken from cultured hippocampal neurons. Other unrelated peptides including dynorphin and somatostatin also caused a glycine-dependent enhancement of NMDA currents and depressed the currents in saturating concentrations of glycine. In contrast, a shortened analogue dynorphin (6-17), which lacks N-terminus glycine residues, and another peptide met-enkephalin were without effects on NMDA currents recorded in low concentrations of glycine. Our results suggest that neurotrophins and other peptides can serve as glycine-like ligands for the NMDA receptor.

Recruitment of functional GABA(A) receptors to postsynaptic domains by insulin

Modification of synaptic strength in the mammalian central nervous system (CNS) occurs at both pre- and postsynaptic sites. However, because postsynaptic receptors are likely to be saturated by released transmitter, an increase in the number of active postsynaptic receptors may be a more efficient way of strengthening synaptic efficacy. But there has been no evidence for a rapid recruitment of neurotransmitter receptors to the postsynaptic membrane in the CNS. Here we report that insulin causes the type A gamma-aminobutyric acid (GABA[A]) receptor, the principal receptor that mediates synaptic inhibition in the CNS, to translocate rapidly from the intracellular compartment to the plasma membrane in transfected HEK 293 cells, and that this relocation requires the beta2 subunit of the GABA(A) receptor. In CNS neurons, insulin increases the expression of GABA(A) receptors on the postsynaptic and dendritic membranes. We found that insulin increases the number of functional postsynaptic GABA(A) receptors, thereby increasing the amplitude of the GABA(A)-receptor-mediated miniature inhibitory postsynaptic currents (mIPSCs) without altering their time course. These results provide evidence for a rapid recruitment of functional receptors to the postsynaptic plasma membrane, suggesting a fundamental mechanism for the generation of synaptic plasticity.

A review of stress ulcer prophylaxis in the neurosurgical intensive care unit

STRESS ULCERS OCCUR frequently in intensive care unit patients who have intracranial disease. After major physiological stress, endoscopic evidence of mucosal lesions of the gastrointestinal tract appears within 24 hours of injury; 17% of these erosions progress to clinically significant bleeding. Gastrointestinal hemorrhage has been associated with mortality rates of up to 50%. The pathogenesis of stress ulcers may not be completely understood, but gastric acid and pepsin appear to play significant roles. Antacids, H2 antagonists, and sucralfate are effective prophylactic agents in the medical/surgical intensive care unit. Appropriate therapy for neurosurgical patients remains unclear, however. This review summarizes the current literature regarding the pathogenesis and therapy of stress ulcers in neurosurgical patients.

Clarification of an uncertain intron within the cDNA sequences of arrowhead proteinase inhibitors A and B

An uncertain intron of 87 bp within the cDNA sequences of arrowhead proteinase inhibitors A and B was clarified. By site-directed mutation with either a stop codon inside the uncertain intron or mutated codons at both its 5' and 3' ends, it was proved that there was neither a translation intron nor a protein intron present in the cDNA sequences of proteinase inhibitors A and B. The primary structure of inhibitor B was then reexamined by mass spectrometry molecular weight determination and partial amino acid sequencing. A 38 residue peptide was derived by degradation of inhibitor B with lysylendopeptidase, and purified, which was not found in the previous work, and its N-terminal part was none other than the missed 29 residue peptide encoded by the uncertain intron. The 38 residue peptide was very hydrophobic, while the 29 residue peptide it included was even more hydrophobic. The N-terminal part of the missed peptide was also aligned within a BrCN-degraded fragment of the inhibitor. In this paper the cause of the overlooking of this 29 residue peptide in the previous work and some unexpected problems which arose during the former sequence analysis are explained.

A step-wise protocol for stress ulcer prophylaxis in the neurosurgical intensive care unit

BACKGROUND

Neurosurgical patients are at risk for stress induced gastric erosion. Clinical criteria for monitoring stress ulcer prophylaxis (SUP) efficacy and predicting clinical bleeding are limited. SUP in the neurosurgical intensive care unit (NSICU) was evaluated utilizing a multidisciplinary quality assurance program with defined criteria for therapy.

METHODS

All patients admitted to the NSICU were managed using this protocol. Therapy was initiated with a single drug (cimetidine 300 mg IV every 6 hours, or continuous infusion up to 2400 mg/day) in 136 evaluable cases. Combination therapy was implemented if continued gastric pH < 4 and guaiac positive aspirates occurred (N = 45).

RESULTS

Significant correlations were observed between low gastric pH values and both GCS < 8 (P < or = 0.01) and length of ventilatory support (P < or = 0.005). Single agent therapy was more effective in patients with GCS > or = 8 (P < or = 0.001). Endoscopy was performed in 25 patients. No patient with GCS < 8 had pathologic lesions. The presence of asymptomatic gastrointestinal lesions was higher in patients requiring longer ventilatory support (P < or = 0.001) and intensive care unit stay (P < or = 0.0001). Patients requiring pentobarbital and vasopressors had statistically higher rates of clinical bleeding (P < 0.05). Patients with GCS < 8 had increased rates of pneumonia (P < or = 0.005) with a higher pneumonia rate when treated with combination therapy (P < or = 0.05). Overall, the incidence of clinical bleeding was 3.7%.

CONCLUSIONS

This protocol was effective for prospective monitoring of SUP efficacy and limited multiple drug therapy to patients at risk for clinical bleeding.

Inhibition of nicotinic cholinoceptor mediated current in vagal motor neurons by local anesthetics

The effects of local anesthetics on ligand-gated cation channel currents were examined in rat brainstem vagal motoneurons. Etidocaine (0.1-20 microM) blocked nicotinic cholinoceptor gated currents in cells voltage-clamped at -60 mV in a concentration-dependent manner, but at concentrations up to 100 microM did not inhibit glutamate receptor currents induced by (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA), N-methyl-D-aspartate (NMDA), or glutamate. Relative to etidocaine, procaine displayed about 10-fold lower potency in antagonizing acetylcholine and its inhibitory effect, unlike that of etidocaine, was rapidly reversed by washout. Ketamine (10 microM) caused a 2-fold larger decrease in NMDA current than acetylcholine current, but did not affect AMPA current. In conclusion, (i) etidocaine and procaine possess a moderately potent blocking activity at nicotinic cholinoceptor gated channels in brainstem vagal motoneurons and (ii) in contrast with ketamine, both agents showed similar selectivity in that neither inhibited glutamate receptor gated channels at concentrations up to 0.1 mM.

[Target therapy by monoclonal antibody against ovarian carcinoma conjugated with liposomes and adriamycin]

Conjugates of monoclonal antibody COC166-9 and adriamycin entrapped in liposome (MLA) were prepared in our laboratory. In vitro growth inhibition of SKOV3 ovarian carcinoma cell line was carried out by MLA and controls. Target therapies by MLA, adriamycin, normal mouse IgG instead of MAb, and control were given for 24 nude mice models with subcutaneous human ovarian carcinoma xenografts and 16 ascitic ovarian carcinoma respectively. MLA group showed the best therapeutic effect than all the other groups which gave a helpful clue to clinical use.

[Target therapy by monoclonal antibody against ovarian carcinoma conjugated with liposome and adriamycin]

Conjugates of monoclonal antibody (MAb) and adriamycin entrapped in liposome (MLA) were prepared by COC166-9. The MAb against ovarian serous adenocarcinoma was generated in our laboratory. Target therapies were done in nude mice model with subcutaneous tumor xenografts in 24 and ascitic carcinoma in 16 by MLA. The results demonstrated that MLA group presented the best therapeutic effect than all the other groups, which gave a very helpful clue to clinical target therapy of ovarian carcinoma in the future.

Anti-idiotypic monoclonal antibodies against anti-ovarian carcinoma monoclonal antibody COC166-9. Generation and application

Anti-idiotypic monoclonal antibody (Mab Ab2) by MAb COC166-9 against ovarian serous papillary adenocarcinoma was prepared. Hybridomas of Ab2 screened by sandwich ELISA and immunocompetitive inhibition tests were procured and named as 6B11 and 1H12. The number of their chromosomes were 93 and 91, and DNA analysis also proved the characteristics of hybridomas. These Ab2s could induce delayed type hypersensitivity (DTH), the cellular immune response. The results of the immune reaction of 6B11 with SKOV3 (ovarian carcinoma cell line) were similar to OC166-9 (Ag), the positive control, while 1H12 was weaker. Anti-anti-idiotypic antibody (Ab3) was also raised by 6B11 and 1H12 respectively. They all showed positive immunohistochemical stainings with ovarian serous adenocarcinoma tissue sections and immunocytochemical stainings with SKOV3 cells as was shown by COC166-9. In the antibody dependent cell mediated cytotoxicity (ADCC) tests, they showed no differences against SKOV3 as compared with COC166-9. We anticipate that 6B11 and 1H12 may be used as vaccines against ovarian carcinoma and may provide a clue for its prevention and treatment.

[The induction of specific immunity to human ovarian carcinoma cells by anti-idiotypic antibodies]

Monoclonal anti-idiotypic antibodies, 6B11 and H12, were employed instead of the tumor antigen to induce a specific cellular immunity to ovarian carcinoma cell line SKOV3. 6B11 and 1H12 carring the internal image of ovarian carcinoma antigen. BALB/c mice were immunized with 6B11 or 1H12 and then the mouse foot pad was attacked by the injection of target cell SKOV3 to stimulate a specific delayed-type hypersensitivity (DTH). The results showed that 6B11 induced a severe foot pad swelling (Mean thickness 0.93mm) as seen in the positive control (P > 0.05) induced by ovarian carcinoma antigen; the 1H12 induced swelling was significantly lower than the positive control (P < 0.05). Both 6B11 and 1H12 expressed the effective responses only to SKOV3, but not to the unrelated target cells. Pathological examinations found that there was marked infiltration of inflammatory cells in foot pad of mice primed by 6B11, while by 1H12, only induced a narrow pathological changes. These observations indicated that there would be some essential differences between 6B11 and 1H12 in the behavior of inducing the specific DTH to SKOK3. And as an idiotypic vaccine, 6B11 would be more powerful against ovarian carcinoma.

[Antigen mimicry of anti-idiotypic antibodies for human ovarian carcinoma antigen: generation and characterization of anti anti-idiotype antibodies]

The antigen mimicry of monoclonal anti-idiotypic antibodies 6B11 and 1H12 was investigated, which carrying the internal image of human ovarian carcinoma antigen. Anti-anti-idiotypic antibodies, obtained from the mice immunized with 6B11 or 1H12, binded to ovarian tumor antigen OC 166-9 specifically by enzyme linked immunosorbent assay (ELISA). Western blot analysis showed that Ab3 and Ab1 recognized the same antigenic protein. Through antibody dependent cell-mediated cytotoxicity (ADCC), Ab3 sera killed the ovarian carcinoma cell line SKOV3 specifically in vitro. These results suggest that 6B11 and 1H12 may substitute for the nominal antigen to stimulate a specific immune response and that they are potential candidates as idiotype vaccines against ovarian carcinomas.

Optic nerve ganglioglioma. Case report

Gangliogliomas of the optic nerve are extremely rare. The case is reported of a 38-year-old man who presented with a visual field deficit and was discovered to have an optic nerve ganglioglioma. The possible embryological origins of this neoplasm, its histological and immunohistochemical features, and its appearance on magnetic resonance imaging are examined. The prognoses of optic nerve glioma and of gangliogliomas occurring elsewhere in the nervous system are compared.

Amino acid sequences of ovomucoid third domain from 25 additional species of birds

Ovomucoids were isolated from 25 avian species other than the 101 studied in Laskowski et al. (1987, Biochemistry 26, 202-221). These were subjected to limited proteolysis with an appropriate enzyme, and connecting peptide extended ovomucoid third domains were isolated and sequenced to the end in a protein sequencer. Of the 25 new sequences, 13 duplicate ones were already known, and 12 are unique. Probably the most striking findings are a Pro14----Ser14 replacement in weka, an Ala14----Thr15 replacement in Bulwer's pheasant, the discovery of two additional amino acid residues Ile18 and Gly18 at the P1 reactive site position in Kalij pheasant and tawny frogmouth, respectively, and the first finding of a negative (Glu34) rather than positive (Lys34 or Arg34) amino acid residue at the NH2 terminus of the alpha helix in caracara ovomucoid third domain. These results complete the determination of all the sequences of ovomucoid third domains in the four species genus Gallus, in the five species genus Syrmaticus, and in the two species genera Aix and Pavo.

Hemodynamics during PEEP ventilation in patients with severe left ventricular failure studied by transesophageal echocardiography

The effects of mechanical ventilation with PEEP were investigated in five patients with normal cardiopulmonary function (group A) and in 11 patients with severe left ventricular failure (group B). Cross-sectional area of the right and left atrium (RA/LA), left ventricle (LV), and right ventricle (RV) was determined at EDA/ESA using transesophageal echocardiography. Hemodynamic parameters and transesophageal pressure were measured simultaneously at PEEP levels 0, 4, 8, 12, and 16 cm H2O. End-diastolic area of the right atrium decreased significantly in both groups. The RA pressure increased, while transmural pressure remained unaltered. The CI decreased in both groups. The decrease in cardiac output by PEEP ventilation was related to the decrease in RV filling volume by external compression. In patients with congestive heart failure, PEEP ventilation with 8 to 10 cm H2O did not worsen LV function.

Studies on the inspiratory generating effect of the dorso-medial area of nucleus facialis

The responses in phrenic nerve activity resulting from stimulation and successive focal block of the dorso-medial area of nucleus facialis (dmNF) were studied in urethane anaesthetized rabbits. It was found that: (1) Long train stimulation (0.025-0.2 mA, 100 Hz) delivered to the dmNF caused marked prolongation in inspiratory duration and distinct increase in amplitude of phrenic discharge. Continuous inspiration with increased amplitude was usually observed during stimulation. (2) Short train stimulation (10 pulses, 100 Hz, 0.025-0.2 mA) during inspiration increased the duration and amplitude of inspiration. When the short train stimulation was delivered during expiration, inspiration would be initiated prematurely. (3) Microinjection of L-glutamate (0.5 M, 0.5-2 microliters) into the dmNF also increased inspiratory duration and amplitude. (4) Focal block of the dmNF by microinjection of lidocaine (2%, 1-2 microliters) produced strong depression or complete cessation of inspiration. In conclusion, the results of the present study show that the dmNF may play an important role in the neurogenesis of respiratory rhythm.