AB0429 SAFETY AND OBSTETRIC OUTCOMES OF BELIMUMAB IN SYSTEMIC LUPUS ERYTHEMATOSUS-ASSOCIATED IMMUNE THROMBOCYTOPENIC PURPURA PATIENTS WITH PREGNANCY

Background

Immune thrombocytopenia purpura (ITP) is not uncommon in systemic lupus erythematosus (SLE) patients and may lead to severe complications during pregnancy, such as pregnancy loss, and peripartum hemorrhage. 1 However, the treatment options during pregnancy was limited due to fetal safety concerns. Belimumab was approved for SLE and appeared to be safe in pregnant patients 2. A phase II trial also reported efficacy of rituximab-belimumab combination in treating ITP 3. However, the safety, influence on pregnancy outcomes, and effects on ITP in SLE patients with pregnancy was unclear.

Objectives

To evaluate the safety and obstetrics outcomes of SLE patients with pregnancy receiving belimumab for ITP.

Methods

This was a retrospective study in National Taiwan University Hospital. Eligible patients were more than 20 years old, had history of ITP, and fulfilled either the 1997 American College of Rheumatology or 2012 Systemic Lupus International Collaborating Clinics classification criteria. The belimumab was administered at 400 mg every 3-4 weeks. The serial full blood counts and immunological markers, unintended hospitalizations, infection episodes, pregnancy complications, and pregnancy outcomes were recorded.

Results

From April 2018 to November 2021, 7 SLE patients were identified. The median (IQR) age at conception was 35.6 (33.0 - 39.5) years. Three (43%) patients had secondary antiphospholipid syndrome, and none had lupus nephritis. The median (IQR) platelet count at conception was 187,000 (146,000 - 195,000) per microliter. The median (IQR) cycle of belimumab was 5 (4.5 - 8.5).

Successful delivery was achieved in all patients. The median (IQR) gestational age was 36 (34 - 37) weeks, and four (57%) patients had preterm labor. The median birth weight was 2362 (2269-2477) grams, and three (43%) were small for gestational age. Pre-eclampsia developed in one patient, and none had premature preterm rupture of membrane or peripartum infections, or postpartum hemorrhage.

The median platelet count at labor was 75,000 (59,000 - 116,000) per microliter. During the pregnancy, severe thrombocytopenia with a platelet counts less than 10000 per microliter occurred in two (29%) patients, and one received prophylactic preoperative platelet transfusion. None of the patients had major or minor bleeding episodes throughout the pregnancy. Remarkably, one patient developed severe thrombocytopenia to 15,000 per microliter in the first trimester of pregnancy, and the platelet count recovered to normal range after 4 doses of belimumab administration. (Figure 1)

Figure 1.

Serial blood platelet count during pregnancy in one patient. Arrow: belimumab 400 mg infusion.

During the pregnancy courses, no patient developed bacterial infections, two (29%) patients developed viral infections (one with upper respiratory tract infection and the other with acute gastroenteritis), and two (29%) had herpes zoster reactivation, which resolved smoothly after five-day course of oral valacyclovir.

Conclusion

The belimumab appeared to be safe in ITP patients with pregnancy, with no obvious increase in the infections and obstetric complications. Based on these observations, belimumab may be considered as one of the pharmacological options for SLE with ITP patients during pregnancy.

References

[1]Xu X, Liang MY, Wang JL, et al. Clinical features and outcome of pregnancy with SLE-associated thrombocytopenia. J Matern Fetal Neonatal Med 2016;29(5):789-94. doi: 10.3109/14767058.2015.1018169

[2]Kao JH, Lan TY, Lu CH, et al. Pregnancy outcomes in patients treated with belimumab: Report from real-world experience. Semin Arthritis Rheum 2021;51(5):963-68. doi: 10.1016/j.semarthrit.2021.06.005

[3]Mahévas M, Azzaoui I, Crickx E, et al. Efficacy, safety and immunological profile of combining rituximab with belimumab for adults with persistent or chronic immune thrombocytopenia: results from a prospective phase 2b trial. Haematologica 2021;106(9):2449-57. doi: 10.3324/haematol.2020.259481

Disclosure of Interests

None declared

Obstructive sleep apnoea is associated with diabetes in sleepy subjects

BACKGROUND

Although obstructive sleep apnoea (OSA) has been linked to insulin resistance and glucose intolerance, it is unclear whether there is an independent association between OSA and diabetes mellitus (DM) and whether all patients with OSA are at risk. The objective of this study was to determine the association between OSA and DM in a large cohort of patients referred for sleep diagnostic testing.

METHODS

A cross-sectional analysis of participants in a clinic-based study was conducted between July 2005 and August 2007. DM was defined by self-report and concurrent use of diabetic medications (oral hypoglycaemics and/or insulin). Sensitivity analysis was performed using a validated administrative definition of diabetes. OSA was defined by the respiratory disturbance index (RDI) using polysomnography or ambulatory monitoring. Severe OSA was defined as an RDI > or = 30/h. Subjective sleepiness was defined as an Epworth Sleepiness Scale score > or = 10.

RESULTS

Complete data were available for 2149 patients. The prevalence of DM increased with increasing OSA severity (p<0.001). Severe OSA was associated with DM following adjustment for patient demographics, weight and neck circumference (odds ratio (OR) 2.18; 95% CI 1.22 to 3.89; p<0.01). Following a stratified analysis, this relationship was observed exclusively in sleepy patients (OR 2.59 (95% CI 1.35 to 4.97) vs 1.16 (95% CI 0.31 to 4.37) in non-sleepy patients).

CONCLUSIONS

Severe OSA is independently associated with DM in patients who report excessive sleepiness. Future studies investigating the impact of OSA treatment on DM may wish to focus on this patient population.

Obstacle avoidance for autonomous land vehicle navigation in indoor environments by quadratic classifier

A vision-based approach to obstacle avoidance for autonomous land vehicle (ALV) navigation in indoor environments is proposed. The approach is based on the use of a pattern recognition scheme, the quadratic classifier, to find collision-free paths in unknown indoor corridor environments. Obstacles treated in this study include the walls of the corridor and the objects that appear in the way of ALV navigation in the corridor. Detected obstacles as well as the two sides of the ALV body are considered as patterns. A systematic method for separating these patterns into two classes is proposed. The two pattern classes are used as the input data to design a quadratic classifier. Finally, the two-dimensional decision boundary of the classifier, which goes through the middle point between the two front vehicle wheels, is taken as a local collision-free path. This approach is implemented on a real ALV and successful navigations confirm the feasibility of the approach.

The effects of early postnatal dexamethasone therapy on pulmonary outcome in premature infants with respiratory distress syndrome: a two-year follow-up study

AIM

To evaluate the pulmonary outcome at corrected age of 2 y on preterm infants who participated in a double-blind trial of early postnatal dexamethasone therapy (< 12 h after birth) for the prevention of chronic lung disease.

METHODS

Clinical respiratory status, blood gases, acid-base balance and pulmonary function were evaluated at corrected age of 2 y in 116 preterm infants (59 infants in the control group; 57 in the dexamethasone-treated group). In the dexamethasone-treated group, dexamethasone was administered intravenously every 12 h in tapering doses: 0.25 mg/kg on days 1 through 7, 0.12 mg/kg on days 8 through 14, 0.05 mg/kg on days 15 through 21, and 0.02 mg/kg on days 21 through 28.

RESULTS

The clinical and laboratory characteristics in the perinatal period were comparable between the groups. At the time of follow-up (mean +/- SD corrected age was 25.1 +/- 4.8 mo for the control group and 24.6 +/- 5.1 mo for the dexamethasone-treated group), there was a slightly lower mean body weight and body length, and a lower psychomotor developmental index in the dexamethasone-treated group than in the control group (10.9 +/- 2.1 vs 11.5 +/- 1.9 kg, 84.4 +/- 6.1 vs 85.9 +/- 5.8 cm, and 82 +/- 24 vs 89 +/- 26, respectively); however, these differences were not statistically significant. There were no significant differences between the control and dexamethasone-treated groups in clinical respiratory status, blood gases, acid-base balance or in lung mechanics (V(T): 9.5 +/- 2.0 vs 9.4 +/- 1.9 ml/kg; V(min): 0.23 +/- 0.04 vs 0.23 +/- 0.03 l/min/kg; C(RS): 13.1 +/- 3.9 vs 12.6 +/- 3.6 ml/kPa/kg; R(RS): 1.56 +/- 0.64 vs 1.62 +/- 0.58 kPa/l/s, respectively).

CONCLUSION

There was no apparent adverse respiratory outcome associated with early postnatal dexamethasone therapy.

Chinese dialect identification using segmental and prosodic features

Several approaches to Chinese dialect identification based on segmental and prosodic features of speech are described in this paper. When using segmental information only, the system performs phonotactic analysis after speech utterances have been tokenized into sequences of broad phonetic classes. The second scheme comprises prosodic models which are trained to capture tone sequence information for individual dialects. Also proposed is a novel approach that examines differences between Chinese dialects at broad phonetic and prosodic levels. These algorithms were evaluated via a multispeaker read-speech mode. Simulation results indicate that the combined use of segmental and prosodic features allows the proposed system to discriminate among three major Chinese dialects spoken in Taiwan with 93.0% accuracy.

Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnoea

BACKGROUND

The gold standard diagnostic test for obstructive sleep apnoea (OSA) is overnight polysomnography (PSG) which is costly in terms of time and money. Consequently, a number of alternatives to PSG have been proposed. Oximetry is appealing because of its widespread availability and ease of application. The diagnostic performance of an automated analysis algorithm based on falls and recovery of digitally recorded oxygen saturation was compared with PSG.

METHODS

Two hundred and forty six patients with suspected OSA were randomly selected for PSG and automated off line analysis of the digitally recorded oximeter signal.

RESULTS

The PSG derived apnoea hypopnea index (AHI) and oximeter derived respiratory disturbance index (RDI) were highly correlated (R = 0.97). The mean (2SD) of the differences between AHI and RDI was 2.18 (12.34)/h. The sensitivity and specificity of the algorithm depended on the AHI and RDI criteria selected for OSA case designation. Using case designation criteria of 15/h for AHI and RDI, the sensitivity and specificity were 98% and 88%, respectively. If the PSG derived AHI included EEG based arousals as part of the hypopnea definition, the mean (2SD) of the differences between RDI and AHI was -0.12 (15. 62)/h and the sensitivity and specificity profile did not change significantly.

CONCLUSIONS

In a population of patients suspected of having OSA, off line automated analysis of the oximetry signal provides a close estimate of AHI as well as excellent diagnostic sensitivity and specificity for OSA.

Clinical and epidemiological implications of swine hepatitis E virus infection

In nonendemic areas, most patients with acute hepatitis E were infected through traveling to endemic areas. However, some patients did not have a history of foreign travel before infection. Furthermore, high seroprevalence rates of antibody to hepatitis E virus (anti-HEV) were found in the general adult population in some countries without any recorded outbreak of hepatitis E. The significance of anti-HEV assay in these subjects remains obscure. To study if swine might be a source of HEV infection, HEV was tested in sera of 235 pigs in Taiwan, and from 5 patients with acute HEV infection who either denied or did not provide any foreign travel history. Three (1.3%) pigs had detectable swine HEV RNA. The swine and human HEV strains from Taiwan formed a monophyletic group, distinct from three previously reported groups: the United States human and swine HEV strains, the Mexico strain, and the largest group composed of the Asian and the African strains. The identity of nucleotide sequences was 84-95% between swine and human HEV strains in Taiwan, and 72-79% between Taiwan strains and those from different areas. The predicted amino acid sequence of a Taiwan swine HEV strain within the peptide 3-2 used in commercial anti-HEV assay showed a high identity (91-94%) with those of other human and swine HEV strains. Swine may be a reservoir of HEV and subclinical swine HEV infection may occur. Cross-reactivity of current anti-HEV assay may account for the high prevalence rate of anti-HEV in the general population in nonendemic areas.

Circulating levels of thrombopoietic and inflammatory cytokines in patients with clonal and reactive thrombocytosis

The regulation of megakaryocytopoiesis and thrombopoiesis appears to be under the control of an array of hematopoietic growth factors. To determine the relationship between endogenous cytokine levels and circulating platelet counts, we measured the serum levels of both thrombopoietic and inflammatory cytokines in the peripheral blood and bone marrow samples from 70 patients with clonal thrombocytosis (CT) caused by myeloproliferative disorders, 28 patients with reactive thrombocytosis (RT), and 35 normal control subjects. The levels of thrombopoietin (TPO), interleukin-6 (IL-6), soluble IL-6 (sIL-6) receptor, IL-11, stem cell factor (SCF), IL-3, and IL-8 were determined by enzyme-linked immunosorbent assay (ELISA). Platelet counts were significantly higher in both CT and patients with RT (699+/-399x10(9)/L, P<.001; 642+/-200 x 10(9)/L, P<.001; respectively) as compared with the normal control subjects (240+/-47x10(9)/L). The concentrations of cytokines in the bone marrow correlated well with those in the peripheral blood. The endogenous levels of TPO, IL-6, and sIL-6 receptor were significantly higher in both CT and patients with RT than those in normal control subjects. The median level of IL-6 was significantly higher in patients with RT than in patients with CT (40 pg/mL vs. 5 pg/mL; P<.001); however, there was no detectable difference in TPO and sIL-6 receptor levels between the two groups. Significantly higher levels of SCF and IL-8 were also found in patients with CT as compared with those found in normal control subjects (median 2460 pg/mL vs 1995 pg/mL, P<.05; 20 ng/mL vs. 5 ng/mL, P = .001; respectively). Finally, IL-11 and IL-3 levels were undetectable in most patients with thrombocytosis. Our results reveal that the endogenous levels of TPO, IL-6, sIL-6 receptor, IL-8, and SCF are elevated in patients with CT or RT. These cytokines appear to be active mediators involved in the regulation of thrombopoiesis during clonal and reactive thrombocytosis.

In vitro effect of granulocyte-colony stimulating factor and all-trans retinoic acid on the expression of inflammatory cytokines and adhesion molecules in acute promyelocytic leukemic cells

Differentiation therapy with all-trans retinoic acid (ATRA) represents a landmark approach in the treatment of acute promyelocytic leukemia (APL). However, a potentially fatal complication of retinoic acid (RA) syndrome occurs in about a quarter of patients and its pathophysiology is still unclear. In order to investigate whether or not the treatment with ATRA leads to increased elaboration of inflammatory cytokines and adhesion molecules by the APL cells, the expression of interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, IL-8, L-selectin and intercellular adhesion molecule-1 (ICAM-1) was examined in the APL cells after induction of differentiation with ATRA in the presence or absence of granulocyte-colony stimulating factor (G-CSF) or IL-3 in the present study. Cytokine elaboration by the treated cells was detected using both Northern blotting and enzyme-linked immunosorbent assay. Our results have shown that ATRA induces an increased expression of IL-8, IL-1beta, TNF-alpha and ICAM-1 in APL cells, which can be amplified by the addition of G-CSF. These data imply that the induction of inflammatory cytokines in APL cells may play an important role in the pathogenesis of RA syndrome. Furthermore, G-CSF, through its potent differentiating activity, may increase the risk of such complications during ATRA treatment.

A comparison of apnea-hypopnea indices derived from different definitions of hypopnea

We examined the effects of arousal- and desaturation-based scoring criteria on the apnea-hypopnea index (AHI) and on the measured prevalence of obstructive sleep apnea (OSA). Ninety-four randomly selected patients underwent overnight polysomnography. Studies were scored according to three different criteria for hypopnea, as defined by a >= 10 s discernible reduction in thoracoabdominal movement associated with: (1) >= 4% decrease in oxygen saturation (SaO2) (Type A); (2) either a >= 4% decrease in SaO2 or an arousal (Type B); or (3) electroencephalographically based arousal alone (Type C). Excellent correlation existed between AHI-A, AHI-B, and the oxygen desaturation index (ODI) (r > 0.98). AHI-A and AHI-B differed by only 2.04 +/- 1.72/h (2 SD). AHI-A and AHI-B differed from the ODI by 1.04 +/- 4.07/h and 3.07 +/- 4.30/h, respectively. Despite these small differences, use of the Type B rather than Type A definition resulted in an extra case of OSA being diagnosed for every 14 to 31 patients tested, depending on the definition of OSA (AHI: >= 5, 10, 15, or 20/h). The addition of arousal-based scoring criteria for hypopnea causes only small changes in the AHI, but if OSA is defined solely by an AHI value, the measured prevalence of OSA will increase.

Identification of heterogeneous nuclear ribonucleoprotein K (hnRNP K) as a repressor of C/EBPbeta-mediated gene activation

Transcription factor C/EBPbeta has been known to regulate a wide array of genes including those involved in the acute-phase response. One of the molecular mechanisms underlying transcription activation by C/EBPbeta is through protein-protein interaction with other transcription factors. Here we report the identification and characterization of physical and functional interactions between C/EBPbeta and heterogeneous nuclear ribonucleoprotein (hnRNP) K. This interaction results in the repression of C/EBPbeta-dependent trans-activation of the agp gene. Footprinting assays indicate that hnRNP K cannot bind to the promoter region of agp gene or interfere with the binding of C/EBPbeta to its cognate DNA site. Furthermore, agp gene activation by the synergistic interaction of Nopp140 and C/EBPbeta is abolished by hnRNP K. The kinetics of appearance of C/EBPbeta-hnRNP K complex in the nuclear extract after initiation of acute-phase reaction indicates that hnRNP K functions as a negative regulator of C/EBPbeta-mediated activation of agp gene.

Transcriptional induction of the agp/ebp (c/ebp beta) gene by hepatocyte growth factor

Hepatocyte growth factor (HGF) is a pleiotropic factor with mitogenic, morphogenic, motogenic, cytotoxic, or growth inhibitory activity. Although the signaling of HGF is mediated through the cell membrane receptor c-Met, the molecular mechanism of downstream signal transduction remains obscure. In this report, we present evidence that shows HGF can stimulate the expression of AGP/EBP (C/EBP beta) and NF-kappaB, which are both key transcription factors responsible for the regulation of many genes under stress conditions or during the acute-phase response. Biochemical and functional analysis indicates that the HGF-responsive element is located in the region -376 to -352 (URE1) of the 5'-upstream regulatory sequence of agp/ebp. Activation of NF-kappaB by HGF was observed to precede the induction of agp/ebp. Further studies indicate that NF-kappaB can cooperate with AGP/EBP or other members of the C/EBP family to activate the agp/ebp gene in both URE1 and URE2-dependent manner. These results suggest that the induction of the agp/ebp gene by HGF is mediated at least in part by its activation of NF-kappaB. The activated NF-kappaB then interacts with AGP/EBP, resulting in the induction of agp/ebp.

Primary transplantation of allogeneic peripheral blood stem cell for severe aplastic anemia

Primary allogeneic peripheral blood stem cell transplantation (allo-PBSCT) has not been previously described in the treatment of severe aplastic anemia (SAA). We report a patient with SAA who underwent primary allo-PBSCT with cells from her HLA-identical sibling and achieved rapid bone marrow reconstitution. The patient has been in complete remission with normal blood counts for 9 months following allo-PBSCT. This suggests that primary allo-PBSCT is a safe and effective alternative in the treatment of SAA.

Identification and characterization of a nucleolar phosphoprotein, Nopp140, as a transcription factor

Expression of the alpha-1 acid glycoprotein (AGP) gene (agp) is activated by a key transcription factor, AGP/enhancer-binding protein (AGP/EBP, commonly called C/EBP beta), in the liver during the acute-phase response. In addition to this positive regulation, agp is negatively regulated by nucleolin (T. H. Yang et al., Mol. Cell. Biol. 14:6068-6074, 1994). Other factors involve in positive regulation of the agp gene are poorly characterized. In a systematic search for factors that may interact with AGP/EBP, we have identified Nopp 140, a phosphoprotein of 140 kDa, by immunoaffinity chromatography. Nopp 140 not only functions as a transcriptional activator per se but also interacts with AGP/EBP to synergistically activate the agp gene in an AGP/EBP-binding motif-dependent manner. In addition to interacting with AGP/EBP, Nopp140 interacts specifically with TFIIB. Distinct regions of Nopp140 that interact with AGP/EBP and TFIIB have been characterized. The sequence of Nopp140 contains several stretches of serine- and acidic amino acid-rich sequences which are also found in ICP4 of herpes simplex virus type 1, a known transcription factor that interacts with TFIIB. The physical interaction between TFIIB and wild-type Nopp140 or several deletion mutants of Nopp140 correlates with the ability of Nopp140 to activate the agp gene synergistically with AGP/EBP. Thus, the molecular mechanism for agp gene activation may involve the interaction of AGP/EBP and TFIIB mediated by coactivator Nopp140.

Identification of a novel variant hepatocyte growth factor secreted by spleen-derived stromal cells

Stromal cells can interact with parenchymal cells by secreting various cytokines to affect the growth, differentiation or movement of the latter. Here we report the identification and characterization of a novel variant hepatocyte growth factor (HGF) from the conditioned medium of stromal cells derived from mouse spleen. Compared to human HGF, it has much lower heparin-binding activity and lacks the beta-chain. Its molecular weight, 70 kDa, is very close to that of the alpha-chain of HGF. Human HGF homologue was not found in the conditioned medium. The conditioned medium of stromal cells, like recombinant HGF, could inhibit the growth of rat hepatoma cells. The inhibitory activity was presumably attributed to this novel HGF because the inhibitory activity, as the existence of this novel HGF, was confined to the identical fractions after heparin-column chromatography. Furthermore, this activity could be specifically abrogated by neutralizing anti-HGF antibodies.

Responsiveness of hepatocytes from dichloroacetic acid or phenobarbital treated mice to growth factors in primary culture

Hepatocytes isolated from male B6C3F1 mice and maintained in primary culture were exposed to epidermal growth factor (EGF), hepatocyte growth factor (HGF), acidic fibroblast growth factor (aFGF) alone or in combination with the mitoinhibitory transforming growth factor beta 1 (TGF-beta 1). Groups of mice were exposed to 3.5 g/l dichloroacetic acid (DCA), 0.1% phenobarbital (PB) or the drinking water vehicle for 0, 2, 5, 10, 20, 30, 60, or 90 days. Following a 2 h attachment period, the growth factors with or without TGF-beta 1 were added together with [3H]thymidine. The cells were harvested 48 h later and the incorporation of the labeled thymidine into cellular DNA was determined. Basal DNA synthesis was enhanced following 2 days of PB treatment after which it declined to levels significantly below that in the untreated mice. No early time enhancement of DNA synthesis was measured in the hepatocyte cultures for animals exposed to DCA, but the late time inhibition was also seen. Primary cultures of hepatocytes isolated from control and DCA treated mice exhibited similarly enhanced DNA synthesis in response to eGF, HGF, or aFGF alone or in combination with TGF-beta 1. In contrast, hepatocytes from PB treated animals were refractory to the effects of the growth factors at all time periods. These data suggest that the early depression of cell proliferation we have seen during DCA induced hepatocellular cancer is not due to an impaired ability of hepatocytes to respond to growth factors and that the mechanisms of liver tumorigenesis in the mouse induced by PB and DCA are dissimilar.

Effects of colony-stimulating factors on the all-trans retinoic acid-induced differentiation of acute promyelocytic leukemic cells

BACKGROUND

NB4, a cell line derived from a patient with t(15;17) acute promyelocytic leukemia (APL) that undergoes granulocytic differentiation when treated with pharmacological doses of all-trans retinoic acid (ATRA), was used as a model for induction of differentiation. In this study, we examined the interaction of colony-stimulating factors (CSF) and ATRA in affecting the proliferation and differentiation of NB4 cells.

METHODS

Nitroblue tetrazolium (NBT) reduction was used as a functional marker of leukemia cell differentiation. The number of viable cells was counted by trypan blue exclusion test.

RESULTS

Proliferation of NB4 cells increased when exposed to 10(-9)M of ATRA, but reduced progressively when exposed to ATRA at the concentrations of 10(-8)M to 10(-6)M. After culture for 5 days, NBT-positive cell was not detectable in the control cultures with medium alone, but its percentage apparently increased to 84% at 10(-7)M ATRA. Granulocyte (G)-CSF per se had no effect on the granulocytic differentiation of NB4 cells, but it could enhance the NBT reduction when used in combination with various concentrations (10(-9)M -10(-6)M) of ATRA. Interleukin (IL)-3 or granulocyte-macrophage-CSF (GM-CSF) alone also had no effect on the NBT reduction in NB4 cells. However, when combined with ATRA, both caused a slight suppression of NBT reduction. No synergistic effect was noted between IL-3 and G-CSF on the ATRA-induced granulocytic differentiation.

CONCLUSIONS

G-CSF, but not IL-3 or GM-CSF, can enhance the differentiating activity of ATRA. Further investigations are necessary to evaluate its clinical use.

Neuritogenesis, not receptor expression, of NG108-15 cells can be modulated by monosialoganglioside GM1

In this study, involvement of gangliosides in neurite outgrowth and receptor expression of the neuroblastoma X glioma hybrid NG108-15 cloned cells was investigated. Monosialoganglioside GM1 (100 microM) and disialoganglioside GD1a (100 microM) were applied to the culture medium at different concentrations of fetal bovine serum, 1-10%, with or without addition of dibutyryl adenosine 3',5'-cyclic monophosphate (500 microM). In some experiments, 5 mg/ml of cholera toxin B was added to the media to block endogenous GM1. The results indicated that GM1 had an influence on cell proliferation and neuritogenesis but did not induce muscarinic receptor expression of NG108-15 cells.

Production of hematopoietic regulatory cytokines by peripheral blood mononuclear cells in patients with aplastic anemia

The aim of this study was to measure the level of cytokines produced by peripheral blood mononuclear cells (PBMNC) in patients with aplastic anemia (AA) and determine their effect on normal bone marrow (BM) colony growth. Thirty-five patients with AA and 21 normal controls were enrolled in the study. Medium conditioned by PBMNC of AA patients in the presence of phytohemagglutinin (PHA) was found to be suppressive to the clonal growth of normal BM cells. Thus, we further determined the presence in the PBMNC conditioned medium (CM) of inhibitory cytokines (macrophage inflammatory protein-1 alpha [MIP-1 alpha], transforming growth factor-beta 2 [TGF-beta 2], interferon-gamma [IFN-gamma], and tumor necrosis factor-alpha [TNF-alpha]) and stimulatory cytokines (granulocyte-macrophage colony-stimulatory factor [GM-CSF], interleukin-3 [IL-3], and stem cell factor [SCF]). The results show no significant difference between AA patients and normal controls in the spontaneous production of all cytokines by PBMNC. After PHA stimulation, the production of MIP-1 alpha, IFN-gamma, TNF-alpha, and GM-CSF significantly increased in the cultures of AA patients (p = 0.0009, 0.0002, 0.0022, and 0.0156, respectively). However, both TGF-beta 2 and SCF were undetectable in most of the tested samples. IL-3 was measured in the conditioned medium only after PHA stimulation, but without significant difference between the two groups (p = 0.67). Furthermore, the myelopoietic suppressing effect of AA-PBMNC CM could be significantly blocked by pretreatment with specific antibodies to the corresponding inhibitory cytokines (MIP-1 alpha, IFN-gamma, and TNF-alpha). After antibody neutralization, an apparent change occurred in the clonal growth of normal BM cells incubated with AA-PBMNC CM, resulting in colony enhancement of 205, 131, and 237% by anti-MIP-1 alpha, anti-IFN-gamma, and anti-TNF-alpha, respectively. These results suggest that overproduction of inhibitory cytokines, rather than underproduction of stimulating cytokines, may play a role in the progression of at least some patients with AA.

Overproduction of inhibitory hematopoietic cytokines by lipopolysaccharide-activated peripheral blood mononuclear cells in patients with aplastic anemia

The aim of this study was to measure the level of cytokines produced by peripheral blood mononuclear cells (PBMNC) in patients with aplastic anemia (AA) and to determine their effect on the clonal growth of normal bone marrow (BM) cells. Twenty-one patients with AA and 11 normal controls were enrolled in this study. Medium conditioned by PBMNC of AA patients in the presence of lipopolysaccharide (LPS) was found to be suppressive to the colony growth of normal BM cells. Thus, we further determined the presence in the PBMNC-conditioned medium (CM) of both inhibitory cytokines: macrophage inflammatory protein-1 alpha (MIP-1 alpha), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 2 (TGF-beta 2), and interferon-gamma (IFN-gamma), and stimulatory cytokines: interleukin-3 (IL-3) and stem cell factor (SCF). Spontaneous production of MIP-1 alpha was higher in the AA patients than the normal controls (1887 +/- 174 pg/ml vs 1643 +/- 93 pg/ml), but the difference was not significant. After LPS stimulation, the production of MIP-1 alpha was markedly increased in the AA patients, and its level was significantly higher than that of the normal controls (2360 +/- 149 pg/ml vs 1517 +/- 92 pg/ml, p = 0.0022). The level of TNF alpha was also higher in the AA patients. However, IFN-gamma, TGF-beta 2, SCF, and IL-3 were not detectable in the PBMNC-CM of either AA patients or normals. The myelopoietic suppressing effect of AA-PBMNC-CM from each AA patient was significantly blocked by pretreatment with anti-TNF-alpha, resulting in a colony-forming enhancement of 174% +/- 12%. A similar effect was noted in six of 11 AA patients by pretreatment with anti-MIP-1 alpha. We conclude that TNF alpha and MIP-1 alpha can be overproduced by the PBMNC of some AA patients, which may play a role in the progression of AA.

Neural and hormonal regulation of growth of corpora allata in the cockroach, Diploptera punctata

DNA synthesis and mitosis in the corpora allata (CA) of adult Diploptera punctata males were investigated with total cell count after 5'-bromo-2'-deoxyuridine immunodetection and colchicine arrestment both in vivo and in vitro. The CA exhibited a single wave of DNA synthesis followed by cell division during the first 4 days after the imaginal ecdysis. A second mitotic wave was experimentally induced after the nervous connections between the CA and the brain were severed on day 4. Spontaneous mitosis was abolished in cockroaches treated with a juvenile hormone (JH) analog. This inhibitory regulation in vivo appeared to act through brain neurosecretory cells since in the denervated CA mitotic activity was unaffected by JH treatment. An in vitro system supporting growth of the corpus allatum was established to study direct hormonal effects. By using continuous bromodeoxyuridine labeling in vitro for 6 days, we showed that DNA synthesis of corpus allatum cells was unaffected by direct contact with JH. In contrast, 20-hydroxyecdysone exerted direct mitogenic action on allatal cells. These and previous results suggest that CA cells alternate between JH synthesis and a proliferative state in which they divide in a self-renewing fashion to yield differentiated progeny. We propose that in newly enclosed adult Diploptera punctata males, low JH titer and high ecdysteroid titer promote mitosis in CA cells. As the ecdysteroid titer declines, JH produced by the CA acts on brain neurosecretory cells which dispatch inhibitory signals through nerves to prevent continuous proliferation of CA cells.

In vitro growth of corpora allata from Diploptera punctata

An in vitro organ culture system was established to support growth of corpora allata from the cockroach Diploptera punctata. During a 1-wk incubation in L-15B medium supplemented with 10% fetal bovine serum (FBS) and 10% cockroach hemolymph, adult male corpora allata exhibited a cycle of de novo DNA synthesis followed by cell division. The number of S-phase cells and metaphase cells per corpus allatum were counted from whole-mount monolayers after labeling in vitro with 5'-bromo-2'-deoxyuridine and exposure to colchicine, respectively. While both FBS and cockroach hemolymph were essential for proliferation of allatal cells, the growth-promoting effect of insect hemolymph was not species-specific and adult female hemolymph was more potent than hemolymph from adult males. Furthermore, DNA synthesis of corpus allatum cells was stimulated in vitro by 20-hydroxyecdysone. This sensitive assay system will be of immense utility in the search for allatal growth factors.

Purification and characterization of nucleolin and its identification as a transcription repressor

Expression of the acute-phase response genes, such as that for alpha-1 acid glycoprotein (AGP), involves both positive and negative transcription factors. A positive transcription factor, AGP/EBP, and a negative transcription factor, factor B, have been identified as the two most important factors responsible for the induction of the AGP gene. In this paper we report the purification, characterization, and identification of a B-motif-binding factor from the mouse hepatoma cell line 129p. The purified factor has been identified as nucleolin by amino acid sequence analysis. Biochemical and functional studies further established that nucleolin is a transcription repressor for regulation of AGP and possibly other acute-phase response genes. Thus, in addition to the many known functions of nucleolin, such as rRNA transcription, processing, ribosome biogenesis, and the shuttling of proteins between the cytoplasmic and nuclear compartments, it may also function as a transcriptional repressor.

Endothelin-mediated calcium response and inositol 1,4,5-trisphosphate release in neuroblastoma-glioma hybrid cells (NG108-15): cross talk with ATP and bradykinin

Addition of endothelins (ETs) to neuroblastoma-glioma hybrid cells (NG108-15) induced increases in cytosolic free Ca2+ ([Ca2+]i) levels of labeled inositol monophosphates and inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. The increases in [Ca2+]i elicited by the three ETs (ET-1, ET-2, and ET-3) were transient and did not show a sustained phase. Chelating extracellular Ca2+ in the medium by adding excess EGTA decreased the ET-mediated Ca2+ response by 40-50%. This result indicates that a substantial portion of the increase in [Ca2+]i was due to influx from an extracellular source. However, the increase in [Ca2+]i was not affected by verapamil or nifedipine (10(-5) M). A rank order potency of ET-1 > ET-2 > ET-3 is shown for the stimulated increase in [Ca2+]i, as well as labeled inositol phosphates, in these cells. ATP (10(-4) M) and bradykinin (10(-7) M) also induced the increases in [Ca2+]i and Ins(1,4,5)P3 in NG108-15 cells, albeit to a different extent. When compared at 10(-7) M, bradykinin elicited a five- to sixfold higher increase in the level of Ins(1,4,5)P3, but less than a twofold higher increase in [Ca2+]i than those induced by ET-1. Additive increases in both Ins(1,4,5)P3 and [Ca2+]i were observed when ET-1, ATP, and bradykinin were added to the cells in different combinations, suggesting that each receptor agonist is responsible for the hydrolysis of a pool of polyphosphoinositide within the membrane. ET-1 exhibited homologous desensitization of the Ca2+ response, but partial heterologous desensitization to the Ca2+ response elicited by ATP. On the contrary, ET-1 did not desensitize the response elicited by bradykinin, although bradykinin exhibited complete heterologous desensitization to the response elicited by ET-1. Taken together, these results illustrate that, in NG108-15 cells, a considerable amount of receptor cross talk occurs between ET and other receptors that transmit signals through the polyphosphoinositide pathway.

The effect of octreotide on hepatic regeneration in rats

The effect of the long-acting somatostatin analog octreotide on liver regeneration was studied in rats in vitro and in vivo. The effect of continuous subcutaneous octreotide infusion on regenerative liver weight and relative DNA synthesis was examined in rats that had undergone 70% hepatectomy. Administration of octreotide resulted in a 33% reduction of regenerating liver weight at 72 hours and a 67% reduction of regenerative hepatocellular hyperplasia at 24 hours. This effect was reversed within 12 hours after withdrawal of the drug. The mechanism for the inhibitory effect of octreotide appears to be indirect, because experiments in hepatocyte cultures did not demonstrate a direct inhibitory effect on serum-free or epidermal growth factor-induced regenerative hepatocyte proliferation. Because insulin levels were suppressed by octreotide in the in vivo experiments, suppression of hepatotrophs may be the mechanism by which octreotide inhibits liver regeneration.

Induction of liver alpha-1 acid glycoprotein gene expression involves both positive and negative transcription factors

Expression of the alpha-1 acid glycoprotein (AGP) gene is liver specific and acute phase responsive. Within the 180-bp region of the AGP promoter, at least five cis elements have been found to interact with trans-acting factors. Four of these elements (A, C, D, and E) interacted with AGP/EBP, a liver-enriched transcription factor, as shown by footprinting analysis and by an anti-AGP/EBP antibody-induced supershift in a gel retardation assay. Modification of these sites by site-directed mutagenesis coupled with transfection analysis indicated that AGP/EBP binding to all of these sites resulted in positive regulation of the promoter. Dose-response data suggest that AGP/EBP binding to these sites results in the cooperative activation of the promoter. In contrast, functional assays showed that element B is a negative regulatory element; this element is recognized by heat-stable DNA-binding factors which are found in many cells and tissues. The regulation of these binding proteins was studied in rat liver treated with lipopolysaccharide (LPS), which induced an acute-phase reaction. We found that LPS treatment resulted in a two- to threefold increase in AGP/EBP activity and a severalfold decrease in the activity of factors that bind to element B in the liver. These results indicate that expression of the AGP gene can be regulated by both positive and negative factors and that the modulation of these factors can account for the LPS induction of the AGP gene.

Plasma levels of HGF in rats treated with tumor promoters

Hepatocyte growth factor (HGF), mol. wt 105,000 is a potent mitogen for hepatocytes. HGF is strongly associated with compensatory regeneration in the liver after two-thirds partial hepatectomy and carbon tetrachloride administration. Plasma levels of HGF increase markedly during early stages of compensatory hyperplasia caused by these treatments. This is followed by an increase in HGF mRNA in the liver. This is in contrast to other growth factors for liver (epidermal growth factor, transforming growth factor alpha and acidic fibroblast growth factor) whose levels in plasma remain virtually undetectable during compensatory hyperplasia. We have shown that during augmentative hyperplasia caused by the tumor promoters alpha-hexachlorocyclohexane, phenobarbital and ciprofibrate, plasma levels of HGF also increase. This increase of HGF occurs during the transient wave of DNA synthesis caused by administration of these xenobiotics, providing further support for HGF as being the stimulator of DNA synthesis during both augmentative and compensatory hyperplasia.

Taurine receptor: kinetic analysis and pharmacological studies

A new procedure for the preparation of the taurine receptor from mammalian brain is described. The taurine receptor thus prepared shows a Kd of 92 nM, Bmax of 6.0 pmol/mg protein and Hill coefficient of 0.90 suggesting a single site model for the binding of 3H-taurine to the receptor. The binding of 3H-taurine to the receptor is highly specific and is not affected by agonists and antagonists of other receptors such as glutamate, quisqualic acid, kainate and NMDA for the glutamate receptor; glycine and strychnine for the glycine receptor; FNZP for the benzodiazepine receptor; picrotoxin and bicuculline for the GABAB receptor. However, analogues of taurine (e.g., homotaurine and hypotaurine) are potent inhibitors inhibiting more than 50% of 3H-taurine binding at 0.1 microM. Taurine receptor binding is not significantly affected by monovalent cations (e.g., Na+, K+, Li+ and NH4+) at 1 mM or divalent cations (e.g., Mg2+, Ca2+, Ba2+ and Mn2+) at 0.1 mM. However, the binding was completely abolished by Co2+, Zn2+ and Hg2+ at 0.1 mM, suggesting the presence of free sulfhydryl groups near or at the ligand binding site. Among the amino acids tested, cysteic acid was the most potent inhibitor, followed by beta-alanine, valine, tyrosine and cysteine inhibiting 3H-taurine to an extent of 84, 66, 63, 62, and 58% of 1 mM, respectively. Nucleotides and second messengers (e.g., ATP, ADP, cAMP, GTP, cGMP and diacyl glycerol) do not inhibit 3H-taurine binding significantly at 0.1 mM. From above studies, it seems that the taurine receptor is not up- or down-regulated by ions or second messengers at the taurine binding site. Whether the taurine receptor is coupled to a G-protein mediated second messenger system is currently under investigation.

Isolation and characterization of endogenous modulators for GABA system

Pig brain extracts from both soluble and membrane fractions were found to contain potent inhibitors for GABA synthesizing enzyme, GAD, referred to as endogenous GAD inhibitors (EGIs) and for the binding of GABA agonist, muscimol, referred to as muscimol binding inhibitors (MBIs). EGIs and MBIs were first purified through gel-filtration Bio-Gel P-2 columns, in which multiple activity peaks were observed. One of them appears to be co-eluted with either L-glutamate or GABA. However, others are clearly separated from L-glutamate or GABA. EGIs were found to be low MW (less than 1,800 dalton), heat and acid-base stable, negatively charged, non hydrophobic substances. MBIs were found to be low MW (less than 1,800 dalton) neutral or positively charged substances. MBIs had no effect on [3H]flunitrazepam (FNZP) binding, indicating that they are not endogenous benzodiazepine receptor ligands and they may act specifically on GABA binding site.

Long-term treatment with hepatic tumor promoters inhibits mitogenic responses of hepatocytes to acidic fibroblast growth factor and hepatocyte growth factor

Studies with hepatocyte cultures have defined four hepatocyte mitogens which can transmit a complete mitogenic signal in cultures kept in completely defined conditions. These four mitogens are epidermal growth factor (EGF), acidic fibroblast growth factor (aFGF), hepatopoietin A/hepatocyte growth factor (HPTA/HGF) and hepatopoietin B (HPTB). In this study, we investigated the effect of aFGF, HGF and the mito-inhibitor transforming growth factor beta (TGF-beta) on cultured hepatocytes isolated from livers of rats treated with the xenobiotic hepatic tumor promoters phenobarbital (PB) and alpha-hexachlorocyclohexane (alpha-HCH). Male F344 rats were treated with each of these two xenobiotics to stimulate hepatic DNA synthesis and augmentative hepatomegaly. At different times on the regimens with tumor promoters, hepatocytes were isolated and placed in primary culture. DNA synthesis of hepatocytes in culture stimulated by these two growth factors and the suppression of DNA synthesis affected by TGF-beta were examined as a function of time of treatment in vivo with these two promoters. Following day 10, hepatocytes from both promoter regimens became unresponsive to these two growth factors for the rest of the duration of the treatment (day 90). TGF-beta suppressed DNA synthesis stimulated by growth factors but did not affect the high background DNA synthesis stimulated by xenobiotics themselves.

Responsiveness of hepatocytes to epidermal growth factor, transforming growth factor-beta and norepinephrine during treatment with xenobiotic hepatic tumor promoters

Previous studies with xenobiotic hepatic tumor promoters have shown that prolonged treatment with these substances decreases the level of epidermal growth factor (EGF) receptors and the response of hepatocytes to EGF. In this study we show that, in contrast to prolonged exposure, the early stage of exposure to tumor promoters is associated with enhanced responsiveness to EGF. Differences in the patterns of responsiveness to EGF are noticed between two tumor promoters, phenobarbital (PB) and alpha-hexachlorocyclohexane (alpha-HCH). Norepinephrine is one of the strongest comitogens (mitogenic amplifiers) for hepatocytes. In addition to altering responsiveness to EGF, treatment with the tumor promoters eliminated the response to norepinephrine during the early stage of treatment. Transforming growth factor-beta (TGF-beta), a well known inhibitor of EGF mitogenesis in hepatocytes, inhibited the EGF-induced DNA synthesis but did not affect the DNA synthesis stimulated directly by the tumor promoters. Long term treatment with the tumor promoters inhibited responsiveness to both EGF and norepinephrine. The implications of these findings for mechanisms of tumor promotion in the liver are discussed.

Structure and function of L-glutamate decarboxylase

Membrane bound L-glutamate decarboxylase (GAD) has been solubilized and partially purified from hog brain. The solubilized GAD appears to exist in two forms, alpha and beta, differing in their size and electrophoretic mobility. The alpha form has similar mobility as that of the soluble GAD in 7.5% and 5-25% gradient polyacrylamide gel electrophoresis suggesting that they are similar in size and charge. In addition, gene encoding for mouse brain GAD has been cloned and characterized. Mouse brain GAD cDNA consists of two DNA fragments with 1.6 and 1.0 Kb. The 1.6 and 1.0 Kb fragments contain 1657 and 974 bP, respectively. The significance of multiple forms of GAD is also discussed.

Blockade of alpha-1 adrenergic receptor inhibits hepatic DNA synthesis stimulated by tumor promoters

Studies with regenerating liver and hepatocyte cultures have shown that the alpha-1 adrenergic receptor (A1AR) is involved in the early events which transmit a mitogenic signal to hepatocytes after 2/3 partial hepatectomy. In this study, we investigated the role of A1AR in DNA synthesis associated with the augmentative hyperplasia stimulated by the xenobiotic hepatic tumor promoters phenobarbital (PB) and alpha-hexachlorocyclohexane (alpha-HCH), and the peroxisome proliferator ciprofibrate. Male F344 rats were treated with each of the three xenobiotics to stimulate hepatic DNA synthesis. When either phenobarbital or alpha-HCH administration was preceded and accompanied by the A1AR antagonist prazosin, DNA synthesis was significantly inhibited, as measured by [3H]thymidine incorporation or 5-bromo-2'-deoxyuridine (BrdU) nuclear labeling index. There was no inhibition of DNA synthesis by prazosin in the ciprofibrate treated group. The inhibition of hepatic DNA synthesis by prazosin was accompanied by non-significant changes in the number of alpha-1 binding sites in the PB and alpha-HCH treated groups, but a significantly reduced number of alpha-1 binding sites in the ciprofibrate treated group. These studies suggest that A1AR is involved in generating the mitogenic signal leading to hepatic DNA synthesis induced by xenobiotic hepatic tumor promoters phenobarbital and alpha-HCH. A1AR is not involved in the mitogenic pathway generated by the peroxisome proliferator ciprofibrate.

Noradrenaline induces short and long duration potentiation of glutamate excitations of cultured Purkinje neurons

The effects of iontophoretic application of noradrenaline on spontaneous or glutamate-evoked activity were studied in Purkinje neurons in explant cultures. The most frequently observed effect of noradrenaline was a depression of glutamate responses, and this was sometimes observed in the absence of apparent changes in spontaneous activity. In 30 out of 80 cells, glutamate responses were increased during or following noradrenaline application. In 21 of the 30 cells, these potentiations were of relatively short duration (less than 4 min), while in the other 9, the potentiations had a much longer duration. beta-Adrenergic antagonists blocked the long duration potentiations in four out of five cells, while short duration potentiation was blocked in only one of eight cells. The alpha-adrenergic antagonist prazosin blocked the short duration potentiations in six of eight cells. The results indicate that long duration potentiations by noradrenaline as reported in the hippocampus are also observable in the cerebellum, and that short and long duration potentials of glutamate responses may be pharmacologically distinct.

Epinephrine regulates cholinergic transmission mediated by rat retinal neurons in culture

The purpose of this study was to investigate the effects of epinephrine on neurotransmission mediated by cholinergic neurons derived from the rat retina. We used a culture system in which striated muscle cells served as postsynaptic targets for cholinergic neurons of the embryonic retina. This culture system permitted the physiological monitoring of acetylcholine released by retinal neurons. Here, we report that epinephrine facilitates evoked transmission across retina-muscle synapses. This facilitation of cholinergic transmission by epinephrine is reversible, can be mimicked by isoproterenol (a beta adrenoceptor agonist) and blocked by propranolol (a beta adrenoceptor antagonist). Neither the alpha-2 adrenoceptor blocker, yohimbine, nor the dopamine receptor antagonist, haloperidol, blocked this effect of epinephrine. Since epinephrine was found not to influence the membrane potential of muscle cells nor the responses of myotubes to acetylcholine, epinephrine appeared to have mediated its facilitatory effect on cholinergic transmission by affecting retinal cells. Because previous findings indicated that adenosine 3',5'-cyclic monophosphate may be involved in the modulation of transmission at retina-muscle synapses, the effect of epinephrine on adenosine 3',5'-cyclic monophosphate levels was investigated. Our biochemical studies demonstrated that epinephrine could increase adenosine 3',5'-cyclic monophosphate levels markedly in cultured retinal cells. The accumulation of adenosine 3',5'-cyclic monophosphate induced by epinephrine could be blocked by propranolol, but not by yohimbine nor haloperidol. Taken together, the results indicate that the facilitatory effect of epinephrine is mediated via a beta adrenoceptor and may involve an increase in adenosine 3',5'-cyclic monophosphate levels. Our findings are in agreement with the hypothesis that epinephrine may be a modulatory neurotransmitter in the rat retina.

Dopamine modulates evoked transmission at cholinergic synapses formed by rat retinal neurons with muscle cells

The purpose of this study was to investigate the effect of dopamine on synaptic transmission mediated by cholinergic neurons derived from the rat retina. We used a cell culture system that permitted the physiological monitoring of acetylcholine released at synapses formed between retinal neurons and striated muscle cells. Dopamine was found to facilitate evoked transmission by a mechanism mediated by D1 dopamine receptors. The results support the hypothesis that dopamine may have a modulatory role in information processing by the mammalian retina.

Attributed string matching with merging for shape recognition

A new structural approach to shape recognition using attributed string matching with merging is proposed. After illustrating the disadvantages of conventional symbolic string matching using changes, deletions, and insertions, attributed strings are suggested for matching. Each attributed string is an ordered sequence of shape boundary primitives, each representing a basic boundary structural unit, line segment, with two types of numerical attributes, length and direction. A new type of primitive edit operation, called merge, is then introduced, which can be used to combine and then match any number of consecutive boundary primitives in one shape with those in another. The resulting attributed string matching with merging approach is shown useful for recognizing distorted shapes. Experimental results prove the feasibility of the proposed approach for general shape recognition. Some possible extensions of the approach are also included.

Mesencephalic reticular formation stimulation effects on hypothalamic neuronal activity

The effects of mesencephalic reticular formation (RF) single pulse, 0.5 msec and 0-500 microA, stimulation on lateral preoptic-lateral hypothalamic (LPA-LH) neuronal activity were determined in anesthetized rats. In addition, the effects of LH stimulation on neural activity in the RF and periaqueductal gray (PAG) were evaluated. Recordings from 117 neurons indicate reciprocal connections between the LPA-LH and the mesencephalon. Stimulation of the RF affected 70% of the LPA-LH neurons tested. Short latency decreases in activity predominated indicating an inhibitory synaptic input from the RF to the LPA-LH. Short latency increases in discharge frequency were observed infrequently. Stimulation of the LH affected only 32% of the mesencephalic neurons tested. Short latency decreases in activity were usually observed indicating reciprocal inhibitory synaptic connections between the LPA-LH and the RF and periaqueductal gray. Antidromic responses verified these interconnections and revealed relatively slow conduction velocities of approximately 1.0 m/sec. Results are discussed in terms of the involvement of the LPA-LH and RF in sensorimotor functions, spinal motor excitability, and ingestive behavior.