Basic imaging properties of a new screen-film system for chest radiography

To evaluate the potential clinical usefulness of a new screen-film system (advanced screen-film system; AD system) for chest radiography, its fundamental imaging properties compared with a conventional screen-film system (HR-4/HR-S) were investigated. The basic imaging properties were evaluated by measuring characteristic (H&D) curves, relative speeds, MTFs (modulation transfer functions), WS (Wiener spectra), and x-ray attenuations of screens. The detail visibilities and pathological details of various diseases in chest radiographs of patients were evaluated subjectively. The film gradient of the AD system was slightly lower at low radiographic density, and higher at high density, as compared with a conventional screen-film system. The screen speed of the AD system was 212% greater than that of the conventional system, and the film speed was 53% that of the conventional film. As the result, the total speed of the AD system was slightly higher compared with the conventional system. The spatial resolution of the AD system was comparable to or slightly lower than that of the conventional system. The noise level of the AD system was considerably lower than that of the conventional system at low (D = 0.5) and middle (D = 1.0) radiographic density levels. However, it was high at high radiographic density (D = 1.8). The radiographic densities in the underpenetrated areas with the AD system were greater than those of the conventional system when the lung densities are matched comparable. Improvement in noise level with the AD system at low and middle density levels may be useful for detection of various diseases in chest radiographs.

Age-related alterations in the auditory brainstem responses and the compound action potentials in guinea pigs

The auditory brainstem response (ABR) and the eight nerve compound action potential (CAP) were measured using click click stimuli to investigate the age-related alteration in the auditory function in 66 guinea pigs consisting of four age groups. With advancing age, a gradual elevation of the thresholds in both the ABR and CAP was clearly seen, together with the prolonged latencies for waves I, II, III, and IV to clicks at 95 dBpeSPL in the ABR. There were some individual differences in either threshold elevation or latency prolongation of both the ABR and CAP in aged guinea pigs. These findings suggest that the effect of individual differences on degenerative aging processes of the auditory system should be considered in selected aged animals, although a significant elevation of the neural auditory threshold is clearly found with advancing age as a whole.

Alpha-adrenergic stimulation enhances inducible nitric oxide synthase expression in rat cardiac myocytes

We investigated the effects of alpha 1-adrenergic stimulation on nitric oxide (NO) production by cardiac myocytes. Incubation of cultured neonatal rat cardiac myocytes with interleukin-1 beta (IL-1 beta) caused a significant increase in the production of nitrite, a stable metabolite of NO. Addition of phenylephrine significantly augmented nitrite production by IL-1 beta-stimulated but not by unstimulated myocytes in a dose-dependent manner. The effect of phenylephrine was completely abolished in the presence of NG-monomethyl-L-arginine (L-NMMA) or actinomycin D. Northern blotting revealed increased inducible NO synthase mRNA accumulation in cardiac myocytes treated with IL-1 beta and phenylephrine compared with those treated with IL-1 beta alone. After protein kinase C activity was functionally depleted by treating cells with phorbol 12-myristate 13-acetate for 24 h, phenylephrine did not augment IL-1 beta-induced NO production. The effect of phenylephrine was also abolished in the presence of protein kinase C inhibitor calphostin C. These observations suggest that alpha 1-adrenergic stimulation causes an upregulation of cytokine-induced NO production by cardiac myocytes, which is mediated at least partially via activation of protein kinase C.

Porphyromonas gingivalis fimbrillin is one of the fibronectin-binding proteins

In this study, we demonstrate that Porphyromonas gingivalis fimbrillin, a major component of bacterial fimbriae, is one of the fibronectin-binding proteins and that fibronectin is a potent inhibitor of the adherence of the bacteria to host cells and of the pathogenesis of the bacterium that acts by binding to the fimbriae. A Western blotting (immunoblotting) assay showed that fibronectin binds strongly to P. gingivalis fimbrillin. The fimbrial binding to fibronectin was also evidenced by a binding assay involving 125I-labeled fimbriae. Furthermore, fibronectin markedly inhibited the fimbria-induced expression of interleukin-1beta and neutrophil-specific chemoattractant KC genes in macrophages. The inhibitory action depended on the fimbrial interaction with heparin-binding and cell attachment domains in the fibronectin structure. The binding of P.gingivalis to mouse peritoneal macrophages via its fimbriae was inhibited by fibronectin. Fibronectin also inhibited the bacterial cell-induced expression of interleukin-1beta and KC genes in the macrophages. These results demonstrate the importance of fibronectin as a modulator of the pathogenic mechanism of P. gingivalis, a pathogen that causes adult periodontal disease.

Effects of oxotremorine and pilocarpine on striatal acetylcholine release as studied by brain dialysis in anesthetized rats

1. The effects of oxotremorine and pilocarpine on striatal acetylcholine (ACh) release were investigated using brain microdialysis techniques in urethan-anesthetized rats. 2. Oxotremorine (0.1 and 0.5 mg/kg, IV), a preferential M2 agonist, dose-dependently decreased ACh release in the striatum. On the other hand, pilocarpine, at 5 mg/kg (IV), showed a tendency to decrease ACh release in the striatum but, at 7.5 and 10 mg/kg (IV), significantly enhanced release in a dose-dependent manner. 3. The effect of oxotremorine was blocked by scopolamine (0.1 mg/kg, IV) but not by pirenzepine (10 mg/kg, IV), a selective M1 antagonist. 4. Pilocarpine (10 mg/kg, IV) enhancement of striatal ACh release was not affected by 10 mg/kg pirenzepine, but 5 mg/kg pilocarpine significantly increased ACh release in scopolamine (0.1 mg/kg)-pretreated rats without affecting the release by itself. 5. These results suggest that oxotremorine-induced decrease in striatal ACh release is due to stimulation of presynaptic M2 autoreceptor, and that the increase of striatal ACh release by pilocarpine is mediated by mechanism(s) other than effects on muscarinic ACh receptors.

Inactive allele-specific methylation and chromatin structure of the imprinted gene U2af1-rs1 on mouse chromosome 11

The imprinted U2af1-rs1 gene that maps to mouse chromosome 11 is predominately expressed from the paternal allele. We examined the methylation of genomic sequences in and around the U2af1-rs1 locus to establish the extent of sequence modifications that accompanied the silencing of the maternal allele. The analysis of HapII or HhaI sites showed that the silent maternal allele was hypermethylated in a block of CpG sequences that covered more than 10 kb. By comparison, the expressed paternal allele was unmethylated from a CpG island upstream of the transcribed region through 2 kb. An analysis of DNaseI hypersensitivity of a putative promoter of U2af1-rs1 showed an open chromatin conformation only on the unmethylated, expressed paternal allele. These results suggest that allele-specific hypermethylation covering the gene and its upstream CpG island plays a role in maternal allele repression of U2af1-rs1, which is reflected in altered chromatin conformation of DNaseI hypersensitive sites.

Proteasome pathway operates for the degradation of ornithine decarboxylase in intact cells

Ornithine decarboxylase (ODC) is degraded in an ATP-dependent manner in vitro by the 26 S proteasome in the presence of antizyme, an ODC destabilizing protein induced by polyamines. In the present study we examined whether the proteasome catalyses ODC degradation in living mammalian cells. Lactacystin, the most selective proteasome inhibitor, strongly inhibited the degradation of ODC that had been induced in hepatoma tissue-culture (HTC) cells by refeeding with fresh medium. Furthermore the inhibitor inhibited the rapid degradation of ODC that had been induced by hypotonic shock. Interestingly, hypertonic shock was found to increase the proportion of OD present as a complex with antizyme (the ratio of ODC-antizyme complex to total ODC). Cycloheximide, which partly inhibited rapid ODC degradation caused by hypertonic shock, also part inhibited the increase in the ratio of ODC-antizyme complex total ODC. These results suggest that a common ODC degradation pathway, namely the antizyme-dependent and 26 proteasome-catalysed ODC degradation pathway, is also operating in intact cells for osmoregulated ODC degradation.

Usefulness of thallium-201 single photon emission computed tomography to quantify the malignancy grade of brain tumors

Preoperative thallium-201 (201Tl) single photon emission computed tomography (SPECT) was used to evaluate the histological malignancy in 24 patients with brain tumors. A corrected L/E ratio was calculated based on the ratio of thallium uptake in the tumor on early images versus the tumor in the delayed images (L/E ratio) corrected for thallium uptake in the contralateral cerebral hemisphere. The corrected L/E ratio in benign brain tumors was 0.79 +/- 0.23, significantly different to 1.32 +/- 0.25 in high grade astrocytomas (p < 0.01) and 1.19 +/- 0.05 in metastatic brain tumors (p < 0.01), respectively. The corrected L/E ratio in low grade astrocytomas was 0.64 +/- 0.32, significantly lower than that in high grade astrocytomas (p < 0.01) and metastatic brain tumors (p < 0.05). There was one false positive result among 24 patients using a threshold of 1.0 to separate malignant and benign tumors. 201Tl SPECT using the corrected L/E ratio is effective for determining the malignant viability of tumors.

Tetrahydrobiopterin and GTP cyclohydrolase I in a rat model of endotoxic shock: relation to nitric oxide synthesis

Induction of the inducible isoform of nitric oxide synthase (iNOS) in various types of cells is implicated as the cause of septic shock. We evaluated the concentration of tetrahydrobiopterin (BH4), a cofactor of NOS, in plasma and various other tissues of rats treated with lipopolysaccharide (LPS; 10 mg/kg I.V.). The activity of GTP cyclohydrolase I (GTPCH), the first and rate-limiting enzyme in the de novo synthesis of BH4, in rat tissues was also determined. Three hours after administration of LPS, rats showed plasma levels of BH4 and NOx (NO3- and NO2-) that were elevated by 137 and 206%, respectively. GTPCH was expressed in liver and, to a lesser extent, in the lung, heart and kidney of control rats. In control rats, although a high concentration of BH4 was detected in the liver, its level was lower in lung, heart, kidney and aorta. Three hours after LPS administration, a significant increase in BH4 concentration and/or GTPCH activity was observed in all tissues examined except the liver. Our results demonstrate that the de novo synthesis of BH4 is upregulated by LPS in the rat in vivo, which may, at least in part, account for the increases in plasma level and tissue concentration of BH4 after the administration of LPS.

A nonneuronal isoform of cell adhesion molecule L1: tissue-specific expression and functional analysis

The cell adhesion molecule L1 is a multifunctional protein in the nervous system characterizing cell adhesion, migration, and neurite outgrowth. In addition to full-length L1, we found an alternatively spliced variant lacking both the KGHHV sequence in the extracellular part and the RSLE sequence in the cytoplasmic part of L1. This L1 variant was expressed exclusively in nonneuronal cells such as Schwann cells, astrocytes, and oligodendrocytes, in contrast to the expression of the full-length L1 in neurons and cells of neuronal origin. To investigate the functions of the L1 variant, we established cell lines transfected with a cytoplasmic short L1 (L1cs) cDNA that lacks only the 12-bp segment encoding for the RSLE sequence. The promoting activities of homophilic cell adhesion, neurite outgrowth, and neuronal cell migration of L1cs-transfected cells (L4-2) were similar to those of full-length L1-transfected cells (L3-1), but the cell migratory activity of L4-2 itself was clearly lower than that of L3-1. In conclusion, the short form of L1 is a nonneuronal type, in contrast to the neuronal type of the full-length L1. Deletion of the four amino acids RSLE in the cytoplasmic region of L1 markedly reduced cell migratory activity, suggesting an importance of the RSLE sequence for the signaling events of neuronal migration mediated by L1.

Synthetic cationic amphiphile for liposome-mediated DNA transfection with less cytotoxicity

A cationic peptide amphiphile comprising an L-alanine residue interposed between a charged head group and a double-chain segment, N,N-dihexadecyl-N alpha-[6-(trimethylammonio)- hexanoyl]-L-alaninamide bromide (NC5Ala2C16), was synthesized and used to prepare sonicated liposomes. We examined the efficiency of this liposome in gene transfer according to the transient expression of chloramphenicol acetyltransferase (CAT). This cationic liposome reagent facilitates efficient DNA transfection in COS-7 cells. We determined the optimum conditions for NC5Ala2C16 liposome-mediated transfection. The optimal amounts of the amphiphile and plasmid DNA were determined to be about 100 micrograms and 10 micrograms per 35-mm dish, respectively. The activity of this liposome was greater than that of commercial reagents, lipofectin, and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethyl-ammonium methylsulfate (DOTAP), and it was less toxic than lipofectin and DOTAP in COS-7 cells.

Preparation of virus-infection-associated (VIA) antigen of foot-and-mouth disease (FMD) virus from inactivated vaccine

Virus-infection-associated (VIA) antigen of foot-and-mouth disease (FMD) virus was prepared from an inactivated FMD vaccine. The VIA antigen coupled with an adjuvant of aluminium hydroxide gel supplemented vaccine was efficiently eluted by suspending and stirring in high concentration of phosphate buffer solution (0.3M, pH 7.6). The final elute purified by DEAE-Sephadex A50 from the vaccine was concentrated in 1/500-1/1,000 of the original volume. VIA antigens prepared from two kinds of vaccine (Type O and Asia-1) were antigenically identical to one prepared from a cell culture infected with live virus. Two cattle were infected with FMD virus (Type O) and sera were obtained from each cattle every week. The VIA antigens from the inactivated vaccine were compared with the ones from the cell culture infected with live virus in agar gel diffusion tests using sera from cattle infected with live virus. The antibodies against the VIA antigen were detected between the second week and the 13th or 14th week after infection. The VIA antigen from an inactivated vaccine would be very useful in FMD free countries like Japan to avoid the risk of using live FMD viruses.

Psychosomatic aspects of healthy young women with orthostatic dysregulation

The Japanese Edition of the Cornell Medical Index-Health Questionnaire and the Yatabe-Guilford personality test (Y-G Test) was given to 56 young women (mean age 19.2 years) who were identified as having orthostatic dysregulation among a total of 280 healthy young women. The percentage classed as types III (possible neurotic) and IV (probable neurotic) according to the Health Questionnaire was 37.5% in the 56 with orthostatic dysregulation and 9.2% in the controls (n = 65). The percentage classed as types B and E, suggestive of emotional or psychological disturbance according to the personality test, was 59.0% in those with orthostatic dysregulation and 23.1% in the controls. These differences were statistically significant (P < 0.01). Furthermore, there was a significant correlation (P < 0.01) between the two test results for the frequency distribution of the 280 women. These results suggest a possibility that psychosomatic factors influence the occurrence of orthostatic dysregulation in young women, even if these subjects have not sought treatment for dizziness or vertigo, nor for psychosomatic disorders.

[Pre-emptive analgesia from intravenous administration of opioid: no effect with pentazocine]

The influence of timing of administration of preoperative pentazocine on pain and analgesic requirements after surgery was studied in 46 patients undergoing total abdominal hysterectomy. Twenty-three patients received thiamylal 5 mg.kg-1 on induction of anesthesia, followed by pentazocine 30 mg or 60 mg before surgical incision (group A). Twenty-three control patients received pentazocine 30 mg or 60 mg, 5 min after abdominal incision (group B). The visual analogue scales for pain 24 h after operation were 6.0 cm at 30 mg dose in group A or 5.3 cm at 60 mg dose in group A and 5.7 cm at 30 mg dose in group B or 4.7 cm at 60 mg dose in group B. There were no differences in the visual analogues scales. Pentazocine consumption in the first 24 h after surgery was 67.5 mg at 30 mg dose in group A or 52.5 mg at 60 mg dose in group A and 70.9 mg at 30 mg dose in group B or 51.8 mg at 60 mg dose in group B. We conclude that postoperative pentazocine consumption and pain scores are no different when pentazocine is given before or after skin incision for abdominal hysterectomy and that there is no clinically useful pre-emptive analgesic effect with these doses of pentazocine.

Increased serotonin release across the coronary bed during a nonischemic interval in patients with vasospastic angina

BACKGROUND

Platelet activation and coagulation abnormality have been observed during coronary spasm. It is crucial whether platelet activation occurs even during a nonischemic period.

HYPOTHESIS

This study was designed to determine whether platelets might be activated across the coronary bed during a nonischemic interval in patients with vasospastic angina.

METHODS

Plasma levels of serotonin, 6-keto-prostaglandin F1 alpha, and catecholamines in the aorta and the coronary sinus were simultaneously measured in 16 patients with vasospastic angina and 13 control patients with nonischemic heart disease.

RESULTS

None of these patients showed myocardial ischemia during sampling. The difference in transcardiac plasma levels of serotonin in patients with vasospastic angina was significantly higher than that in controls (1.48 +/- 1.08 ng/ml vs. 0.07 +/- 0.12 ng/ml, respectively, p < 0.001). Coronary sinus plasma norepinephrine levels in these two groups were almost the same (204.8 +/- 110.8 pg/ml vs. 190.4 +/- 131.6 pg/ml, respectively). The ratio of 6-keto-prostaglandin F1 alpha in the coronary sinus and the aorta was not different between the two groups (1.17 +/- 0.96 in patients with vasospastic angina vs. 1.15 +/- 0.68 in controls).

CONCLUSIONS

These data suggest that platelet activation across the coronary bed should be ascribed to endothelial dysfunction. Lack of compensatory enhancement of prostacyclin production might be concerned with dysfunction of coronary endothelial cells in these patients.

Sensitization of T-cell receptor-alpha beta+ T cells recovered from long-term T-cell receptor downmodulation

Although the survival of fully allogeneic skin grafts was prominently prolonged by adult thymectomy in anti-T-cell receptor-alpha beta monoclonal antibody (TCR-alpha beta mAb)-treated mice compared with that of non-adult thymectomized (ATX) mice, the skin allografts were eventually rejected. In the anti-TCR-alpha beta mAb-treated ATX mice, as shown in the present study, most of TCR-alpha beta+ cells were promptly activated on day 2 and then rapidly disappeared by day 7, but some TCR-alpha beta- Thy-1+ cells remained at that time. These TCR-alpha beta- Thy-1+ cells which have downmodulated their TCR-alpha beta expression may be refractory to depletion events by the mAb treatment. Although these downmodulated T cells re-expressed their TCR-alpha beta on day 50, they could not respond to stimuli via TCR such as TCR cross-linking or alloantigens. However, they recovered the reactivity to donor antigens on day 85. These results indicate that the downmodulated T cells by anti-TCR-alpha beta mAb treatment are long-lived and re-express their TCR-alpha beta at a late stage to be sensitized to donor antigen, which suggests that additional regimens may be required to get permanent, or very long-term, graft acceptance.

[Estimation of pathways of 5-fluorouracil anabolism in human cancer cells in vitro and in vivo]

Possible pathways of intracellular phosphorylation of 5-fluorouracil (5-FU) in human cancer cells were investigated in vitro and in vivo. We used two inhibitors which regulate the anabolism of 5-FU for the purpose of elucidation of its pathways; one is oxonic acid (Oxo), an inhibitor of orotate phosphoribosyltransferase (OPRTase), catalizing a formation of FUMP from 5-FU, and another is 2, 6-dihydroxypyridine (DP), an inhibitor of uracil ribosyltransferase which catalizes a conversion of 5-FU to 5-fluorouridine. Although the pathway of 5-FU phosphorylation in murine tumor cells was varied, about 80% of human cancer cells tested were found to utilize the first pathway in which 5-FU was converted to FUMP by OPRTase. Thus, the phosphorylation of 5-FU via the first pathway was markedly inhibited by Oxo in 4 strains of 5 gastric cancer cells, 7 of 8 colorectal cancer cells and 3 of 4 lung cancer cells. In xenografts of human gastric and colorectal adenocarcinoma in which 5-FU phosphorylation is regulated by Oxo in vitro, the production of 5-fluoronucleotides and its incorporation into RNA after iv administration of 5-FU significantly decreased by co-administration of Oxo, suggesting that the nature of an anabolic pathway of 5-FU in the tumor cells in vitro reflects in vivo behavior. We also confirmed that the phosphoribosylpyrophosphate level in tumor cells was importantly related to determination of the metabolic pathway of 5-FU. These results would suggest that possible modulation of 5-FU lies on the augmentation of 5-FU efficacy.

A variant of adenomatous goiter with characteristic histology and possible hereditary thyroglobulin abnormality

A variant type of adenomatous goiter was identified in 24 of 2160 patients with adenomatous goiter who underwent thyroidectomy. The characteristics of the thyroid gland in these 24 patients included large goiter, small follicles, scant colloid, and columnar follicular cells containing yellow-green granules on hematoxylin-eosin staining. The thyroid gland was slightly orange-red, and electron microscopic examination showed abundant lysosomes with colloid droplets. When comparing the features of this group with those of 24 patients with common adenomatous goiter, the incidence of familial predisposition to thyroid diseases in the former group was higher. The age at the time of detection of goiter was lower, i.e. 17 +/- 15 vs. 44 +/- 17 yr (P < 0.001, variant type vs. common type), the serum total T4 concentrations were lower (84 +/- 21 vs. 103 +/- 18 nmol/L; P < 0.01), and the serum TSH concentrations were higher (2.4 +/- 2.1 vs. 1.0 +/- 0.9 mU/L; P < 0.01). Thyroid radioiodine uptake was remarkably increased (49 +/- 22 vs. 16 +/- 9%; P < 0.001), and lower levels of serum thyroglobulin were noted (33 +/- 51 vs. 484 +/- 603 micrograms/L; P < 0.01). The thyroglobulin content was low in the thyroid gland studied. The data suggest that the etiology of this variant type of goiter is a hereditary abnormality in thyroglobulin synthesis, and this type of goiter may be distinguished from common adenomatous goiter by the characteristic morphology of the thyroid gland in addition to clinical findings.

The nasopharyngeal bacterial flora in children with otitis media with effusion

A study was undertaken to evaluate the incidence of nasopharyngeal alpha-streptococci with inhibitory activity against pathogens, as a defense mechanism of the normal bacterial flora against infection. Cultures were taken from the nasopharynges of 43 children with otitis media with effusion (OME). The detection rates of alpha-streptococci with inhibitory activity against Haemophilus influenzae, Streptococcus pneumoniae, Staphylococus aureus and group A streptococci were significantly lower in the nasopharynx than those isolated from the tonsils of the same patients. Moreover, the detection rates of alpha-streptococci with inhibitory activity against all of these pathogens derived from the nasopharynx were lower than those in healthy children, streptococcal strains with activity against H. influenzae and Strep, pneumoniae were also lower than that in patients with tonsillitis. These findings suggest that low nasopharyngeal levels of alpha-streptococci with inhibitory activity against respiratory pathogens may render children susceptible to OME. Further studies are needed to investigate the relationships between the prevalence of pathogens in the nasopharynx and the inhibitory activities of alpha-streptococci against them in order to devise and select optimal treatment for patients with OME.

Investigation of the nasopharyngeal bacterial flora in children with otitis media with effusion

A study was undertaken to evaluate the incidence of alpha-streptococci with inhibitory activity against pathogens, a defense mechanism of the normal flora against bacterial infection, in the nasopharynx and tonsils of 37 children with otitis media with effusion (OME). In the patients with OME, the detection rates of alpha-streptococci with inhibitory activity against Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus and group A streptococci in the nasopharynx were significantly lower than those of alpha-streptococci isolated from the tonsils. Furthermore, the detection rates of nasopharyngeal alpha-streptococci with inhibitory activity against H. influenzae and S. pneumoniae in OME patients were lower than those in patients with tonsillitis. In conclusion, low nasopharyngeal levels of alpha-streptococci with inhibitory activity against pathogens appear to render children susceptible to attacks of OME. We suggest that it is important to investigate the relationships between the prevalence of pathogens and the inhibitory activity of alpha-streptococci against them in the nasopharynx.

Involvement of pituitary adenylate cyclase-activating polypeptide in growth hormone secretion induced by serotoninergic mechanisms in the rat

Pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) stimulated GH secretion in superfused rat anterior pituitary cell in vitro and in conscious male rats in vivo. PACAP-38-induced GH secretion was inhibited by PACAP-(6-38), an N-terminal-deleted analog, at 100-fold concentrations of PACAP-38 both in vitro and in vivo. In contrast, a GH-releasing hormone antagonist did not affect the action of PACAP-38 to stimulate GH release in vitro. Plasma GH increase induced by i.v. injection of 5-hydroxy-L-tryptophan (1 mg/100 g BW), a precursor of serotonin, was blunted by PACAP-(6-38) (1 nmol/100 g BW, i.v.), whereas spontaneous pulsatile GH secretion in conscious male rats, which is governed by hypothalamic GH-releasing hormone and somatostatin, was not affected by repeated i.v. injection of PACAP-(6-36). These findings suggest that PACAP-(6-38) is a potent antagonist of PACAP-38 to stimulate GH secretion both in vivo and in vitro. Taken together with the facts that PACAP-38 is highly concentrated in the hypothalamus and that is released into the hypophysial portal blood, our present findings suggest that PACAP-38 might play a stimulatory role on GH secretion induced by serotoninergic mechanisms in the rat.