Adrenoleukomyeloneuropathy presenting as cerebellar ataxia in a young child: a probable variant of adrenoleukodystrophy

A child aged 5 years 7 months was diagnosed as suffering from adrenoleukomyeloneuropathy (ALMN). The first sign was ataxia, and high intensity lesions were observed in the cerebellar hemispheres on T2-weighted brain MRI. His condition progressed rapidly to a vegetative state in 1 year. When aged 7 years 3 months adrenal insufficiency supervened and his skin turned dark. Rectal biopsy revealed linear cytoplasmic inclusions in macrophages in the rectal membrane. At the age of 8 years 2 months, an analysis of very long-chain fatty acids of sphingomycin in plasma led to the final diagnosis. At the age of 10 years, cerebellar and cerebral atrophy were prominent and diffuse high intensity lesions were noted in the cerebellum and cerebrum. An onset below 9 years of age has not previously been documented in ALMN.

New approach to the estimation of the extent of myocardial fibrosis in patients with dilated cardiomyopathy: use of signal-averaged electrocardiography

To determine whether the extent of myocardial fibrosis in dilated cardiomyopathy could be estimated noninvasively, signal-averaged electrocardiograms were recorded in 32 patients with dilated cardiomyopathy, followed by left ventricular endomyocardial biopsy. The root mean square voltage for the last 40 msec (V40), the duration of the filtered QRS complex (fQRSd) and the duration of low amplitude signals < 40 microV (LAS) were obtained by signal-averaged electrocardiography. The extent of fibrosis in all biopsy samples was measured by the point-counting method. The extent of myocardial fibrosis closely correlated with fQRSd (r = 0.623, p < 0.001), LAS (r = 0.570, p < 0.001), and V40 (r = -0.355, p < 0.05). When fibrosis was classified into intercellular and interfascicular types, the extent of intercellular fibrosis more closely correlated with fQRSd (r = 0.695, p < 0.0001), LAS (r = 0.640, p < 0.0001), and V40 (r = -0.533, p < 0.005). These results suggest that signal-averaged electrocardiograms might be useful for estimation of the extent of myocardial fibrosis, especially intercellular fibrosis in patients with dilated cardiomyopathy.

PC-766B, a new macrolide antibiotic produced by Nocardia brasiliensis. II. Isolation, physico-chemical properties and structure elucidation

A new macrolide antibiotic, PC-766B, was isolated from the cells of Nocardia brasiliensis SC-4710 by acetone extraction, and purified by gel filtration, silica gel chromatography, HPLC and TLC. The structure of PC-766B was determined by NMR spectral analysis to be a new class of the hygrolidin family antibiotics. PC-766B had a 16-membered macrocyclic lactone ring, a 6-membered hemiketal ring and a 2-deoxy-D-rhamnose moiety. DL-alpha-Tocopherol, known as an antioxidant agent, significantly improved the stability of PC-766B and prevented the decomposition of PC-766B during the storage of the antibiotic.

Leukemogenesis-associated antigen in HTLV-I-transformed rabbit cells

The presence of a leukemogenesis-associated antigen was investigated in an experimental model of adult T-cell leukemia in (B/J x Chbb:HM)F1 rabbits, where adult rabbits develop leukemia within 1-2 weeks following inoculation with HTLV-I-transformed syngeneic cell lines. Leukemogenic activity was found in some but not all HTLV-I-transformed cell lines, and was associated with leukocytosis-inducing activity which was assayed by inoculating these cells into adult rabbits of the parental Chbb:HM strain. The leukemogenic cell line diminished or lost the leukemogenic and leukocytosis-inducing activities during prolonged culture in vitro. A mouse mAb was raised which recognized an antigen uniquely expressed on the cell surface of the leukemogenic cell lines. This antigen was present, however, in all HTLV-I-transformed cells examined and the mAb immunoprecipitated the same 65 kD glycoproteins from both leukemogenic and non-leukemogenic cell lines. Taken together, the antigenic epitope seemed to be expressed on the cell surface in such a manner as to be accessible to the mAb in leukemogenic but not non-leukemogenic cells. The analyses of various cell lines revealed that this antigen was an endogenous antigen and not a viral antigen. The antibody was cytotoxic in vitro against leukemogenic cell lines in the presence of complement, and administration of this antibody to leukemic rabbits resulted in an abrupt decrease in the peripheral blood leukocyte number, leading to remission of the disease.

Induction of acute arthritis in mice by peptidoglycan derived from gram-positive bacteria and its possible role in cytokine production

The activities of a water-soluble peptidoglycan fragment derived from Staphylococcus epidermidis (SEPS) were examined as to their role in proliferation of spleen mononuclear cells (SMNC) from various strains of mice, the production of cytokines in vitro, and the induction of an inflammatory reaction in vivo. The proliferation of SMNC from C3H/HeN, C57BL/6, AKR, DBA/2, and ddY mice in reaction to SEPS in vitro showed a peak on day 3 and was greater than that of SMNC from BALB/c mice. The cells of SMNC from C3H/HeN mice responsive to SEPS were indicated to be mainly macrophages. A time kinetics experiment showed a coincidence in the proliferation of SMNC in reaction to SEPS and the detection of colony-stimulating factor (CSF) activity. Interleukin 2 (IL-2) activity was not detected during the incubation periods. When SEPS was administered to mice, much stronger mRNA transcripts of granulocyte-macrophage (GM)-CSF were detected in the lungs of C3H/HeN mice than in BALB/c mice. On the other hand, the amounts of IL-1 and PGE2 produced by SMNC of BALB/c mice stimulated by SEPS were greater than those produced in C3H/HeN mice. SEPS was confirmed to induce arthritis in BALB/c mice, but not in C3H/HeN mice. Our findings suggest that the production of GM-CSF is involved in the in vitro proliferation of SMNC in reaction to SEPS and that along with IL-1 and PGE2 production, contributes to the inflammation by SEPS in vivo.

Vibrio parahaemolyticus has a homolog of the Vibrio cholerae toxRS operon that mediates environmentally induced regulation of the thermostable direct hemolysin gene

In an effort to identify the regulatory gene controlling the expression of the tdh gene, encoding the thermostable direct hemolysin of Vibrio parahaemolyticus, we examined total DNA of AQ3815 (a Kanagawa phenomenon-positive strain) for sequences homologous to that of the toxR gene of Vibrio cholerae. The extracted DNA gave a weak hybridization signal under reduced-stringency conditions with a toxR-specific DNA probe. Cloning and sequence analysis of the probe-positive sequence revealed an operon (Vp-toxRS) which was highly similar to the toxRS operon of V. cholerae (Vc-toxRS) (52 and 62% similarities in the two genes, respectively). The deduced amino acid sequences of the Vp-toxRS gene products (Vp-ToxRS) contained regions similar to the proposed transmembrane and activity domains of the Vc-toxRS gene products (Vc-ToxRS). All clinical and environmental strains of V. parahaemolyticus examined possessed the Vp-toxRS genes. In the presence of Vp-ToxS, Vp-ToxR promoted expression of the tdh2 gene, one of two tdh genes (tdh1 and tdh2) carried by Kanagawa phenomenon-positive strains. The DNA sequence located 144 bp upstream of the tdh2 coding region was shown to be important for the Vp-ToxR-stimulated expression of the tdh2 gene in an Escherichia coli background. Comparative analysis of AQ3815 and its isogenic Vp-toxR null mutant gave the following results: (i) Vp-ToxR promoted, in an AQ3815 background, expression of the tdh gene to different degrees in various culture media, with KP broth (2% peptone, 0.5% NaCl, 0.03 M KH2PO4, pH 6.2) being most effective (12-fold); (ii) the promotion of tdh gene expression in KP broth was at the level of transcription; and (iii) Vp-ToxR was essential for demonstration of enterotoxic activity of AQ3815 in the rabbit ileal loop, a model previously used to demonstrate thermostable direct hemolysin-mediated enterotoxic activity of AQ3815. These results demonstrate that Vp-ToxR and Vc-ToxR share a strikingly similar function, i.e., direct stimulation at the transcriptional level of the gene encoding a major virulence determinant (enterotoxin) of a Vibrio species.

PC-766B, a new macrolide antibiotic produced by Nocardia brasiliensis. I. Taxonomy, fermentation and biological activity

An actinomycete strain SC-4710, a new soil isolate, was found to produce a new macrolide antibiotic, PC-766B. Chemotaxonomic analysis of the producing organism revealed that the cells of SC-4710 had type IV cell wall, type A whole cell sugar pattern, type PII phospholipids, menaquinone MK-8(H4), cellular fatty acids comprising straight-chain saturated, unsaturated and tuberculostearic acids, and mycolic acids. The strain was identified as Nocardia brasiliensis (Lindenberg) Pinoy. The antibiotic, PC-766B, was active against Gram-positive bacteria, and some fungi and yeasts, but inactive against Gram-negative bacteria. It also showed antitumor activity against murine tumor cells in vitro and in vivo, and a weak inhibitory activity against Na+, K(+)-ATPase in vitro.

Induction of specific tolerance by hepatic double-negative CD4-8- alpha beta T cells of mice immunized with allogeneic cells via the portal vein in vivo [corrected]

We immunized AKR/n (H-2k) spleen cells in BALB/c (H-2d) mice via the portal vein (pv) and investigated the role of hepatic mononuclear cells (MNC) in the induction of alloantigen-specific immune tolerance. MNC in the liver and spleen of pv-administered mice were demonstrated to abrogate the responses to AKR/n alloantigens in allogeneic MLR. On the contrary, MNC in the liver and spleen of mice administered subcutaneously with the same antigens showed greater responses than those of control mice. The tolerance induced by pv administration was alloantigen-specific and appeared earlier in hepatic MNC than in splenic MNC. Furthermore, hepatic MNC of pv-administered mice had a suppressive effect when these cells were added to allogeneic MLR, in which mitomycin C (MMC)-treated AKR/n splenic MNC were used as stimulator and control BALB/c splenic MNC were used as responder. Splenic MNC of pv-administered mice and hepatic MNC of control mice did not show such suppressive effects. Such suppression was alloantigen-specific, since no suppression was induced when hepatic MNC of pv-administered mice were added to a system using MMC-treated C57BL/6 (H-2b) splenic MNC. The alloantigen-specific suppression induced by hepatic MNC was abrogated by a depletion of TcR-alpha beta + cells but not of CD4+, CD8+, nor B220+ cells from hepatic MNC. These results suggested that alloantigen-specific suppressor cells appeared predominantly in the hepatic MNC of pv-administered mice and displayed the phenotype of TcR-alpha beta +CD4-8- double-negative T cells, although alloantigen-specific tolerance was induced in both hepatic and splenic MNC.

Proarrhythmic effects of class Ic drugs

Three cases managed with class Ic antiarrhythmic drugs but with subsequent aggravation of arrhythmias are reported herein. A 58-year-old man given 300 mg of flecainide for atrial flutter developed sinus arrest and transient ventricular fibrillation. A 42-year-old man with a postoperative condition of tetralogy of Fallot who received 300-mg doses of flecainide for sustained ventricular tachycardia had spontaneous sustained ventricular tachycardia. A 74-year-old man given 150 mg of propafenone for atrial tachycardia developed sustained ventricular tachycardia. The present cases illustrate that class Ic drugs may exacerbate ventricular arrhythmias, and their use may reveal concealed sinus node dysfunction. This may be due to marked slowing of conduction and prolonged ventricular refractoriness, which are characteristic of the class Ic drugs; also, it is probable that the patients' underlying cardiac conditions served as contributing factors.

Elevated production of interleukin 6 by hepatic MNC correlates with ICAM-1 expression on the hepatic sinusoidal endothelial cells in autoimmune MRL/lpr mice

MRL/lpr mice, which are a model of SLE and rheumatoid arthritis in humans, develop profound lymphadenopathy resulting from the accumulation of CD3+ 4-8- double-negative (DN) alpha beta T cells in peripheral lymphoid tissues. We previously indicated that these DN alpha beta T cells preferentially proliferate in the liver and migrate to the periphery. In this study, we analyzed whether any kind of cytokine was produced by hepatic mononuclear cells (MNC) in MRL/lpr mice. The evidence obtained indicates that interleukin 6 (IL-6) was vigorously produced by hepatic MNC in diseased MRL/lpr mice under unstimulated conditions. MNC in the spleen of these mice produced small amounts of IL-6, while those in the lymph nodes did not produce any appreciable amounts of IL-6. These activities of hepatic MNC in diseased MRL/lpr mice were almost completely neutralized by anti-mouse IL-6 monoclonal antibody (mAb). On the other hand, immunohistochemical staining of light- and electron-microscopic analyses revealed that the intracellular cell adhesion molecule 1 (ICAM-1) was expressed on the hepatic sinusoidal endothelial cells of diseased MRL/lpr mice. Moreover, ICAM-1 was newly induced in the hepatic sinusoids of control C3H/He mice by an intravenous injection of 50 units of recombinant mouse IL-6. These data suggest that ICAM-1 expressed on the hepatic sinusoidal endothelial cells in MRL/lpr mice is induced by IL-6, which is produced by hepatic MNC, and that such ICAM-1 may be responsible for the saturation of inflammatory cells and the proliferation of lymphocytes in the liver of MRL/lpr mice.

[The roles of cytokine in organ-specific tumor metastasis]

The production of cytokines by tumor cells has been suggested as the molecular perturbation responsible for the development of malignant tumors. The behavior of tumor cells in animals is presumed to be affected by these factors, which include such hematopoietic cytokines as GM-CSF, IL-1, and IL-6. Here, we report findings demonstrating that GM-CSF is produced by many murine transplantable tumors with metastatic ability in the lungs, and IL-6 and/or IL-1 are produced by the tumors metastatic in the liver. We discuss the notion that the particular organ or organs in which tumor cells metastasize may be associated with the type of cytokines produced by the tumors. Metastatic spread requires interactions of tumor cells with components of the extracellular matrix of host tissues or with other cells, almost all of which depend on cell surface determinants such as cell adhesion molecules. We also discuss the possibility that the expression and adhesive potentials of adhesive protein (CD44) may be regulated by the cytokine (GM-CSF) excreted from the tumor cells. We then emphasize the possibility that both gene expression of cytokines and adhesive proteins play a critical role in tumor metastasis and in determining organ specificity in metastasis.

Age-associated increase of CD5+ B cells in the liver of autoimmune (NZB x NZW) F1 mice

The liver has been demonstrated to be a major site for extrathymic differentiation of T cells. In this study, an identification of CD5+ B cells, which are responsible for the onset of autoimmune disease by virtue of autoantibody production, was performed in autoimmune (NZB x NZW) F1 mice. An age-associated increase of CD5+ B cells was demonstrated in the liver of these mice. Although CD5+ B cells (i.e., CD5+IgM+ and CD5+B220+) constituted a minor population of hepatic mononuclear cells (MNC) (< 5%) when mice were young (8 weeks), a large population of CD5+ B cells (10 to 30% of whole MNC) was identified in the liver of mice aged 25 to 30 weeks after the onset of disease. Such age-dependent increase of CD5+ B cells was not observed in any other strains including NZB, NZW, C3H/He and BALB/c mice. The phenotype of hepatic CD5+ B cells was the same as that of CD5+ B cells in the peritoneal cavity and spleen, showing dull-CD5, bright-IgM and dull-B220. High levels of CD5+ B cells were observed in the peritoneal cavity and liver, but not in the spleen nor in any other lymphoid organs in mice aged 30 weeks. Radioimmunoassay of autoantibodies in the 5-day culture supernatants demonstrated that hepatic MNC were unable to produce any amounts of IgM- and IgG-autoantibodies against double-stranded DNA and single-stranded DNA, despite the increased proportion of CD5+ B cells. On the other hand, peritoneal exudate cells produced only IgM-, but not IgG-, autoantibodies, whereas splenic cells were able to produce both IgM- and IgG-autoantibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminoalkylbisphosphonates, potent inhibitors of bone resorption, induce a prolonged stimulation of histamine synthesis and increase macrophages, granulocytes, and osteoclasts in vivo

Aminoalkyl derivatives of bisphosphonates are potent inhibitors of bone resorption. A single I.P. injection of 4-amino-1-hydroxybutylidene-1,1-bis-phosphonate (AHBuBP) induced a prolonged enhancement of histidine decarboxylase (HDC) activity in the bone marrow, spleen, lung, and liver of mice and resulted in an increase in histamine. The induction of HDC by the agent was dose dependent (16-80 mumol/kg) and peaked 3-4 days after its injection (40 mumol/kg). Repeated S.C. injections of smaller doses of AHBuBP (0.32 or 1.6 mumol/kg/day) for 4 days also enhanced HDC activity. However, the minimum dose capable of inhibiting bone resorption (0.064 mumol/kg/day) was lower than that inducing HDC. Unexpectedly, AHBuBP, at the doses inducing HDC, increased macrophages, granulocytes, and even osteoclasts. The size of osteoclasts was also enlarged by the agent. Another aminobisphosphonate, 3-amino-1-hydroxypropylidene-1,1-bisphosphonate, but none of non-amino derivatives, also exhibited essentially the same effects as those of AHBuBP. These results indicate that in spite of increase in osteoclasts and their enlargement, bone resorption is still inhibited by amino bisphosphonates. As granulocyte and granulocyte-macrophage colony-stimulating factors and interleukin-3 induce HDC in hematopoietic organs, and histamine has a hematopoietic activity, the HDC induction by aminobisphosphonates may be relevant to the proliferation of progenitor cells of macrophages, granulocytes, and osteoclasts.

Which subgroup of patients with dilated cardiomyopathy would benefit from long-term beta-blocker therapy? A histologic viewpoint

OBJECTIVES

The purpose of this study was to elucidate whether the effectiveness of long-term beta-blocker therapy could be predicted before this therapy is started.

BACKGROUND

Long-term beta-blocker therapy has recently been reported to provide a favorable effect in treatment of congestive heart failure due to dilated cardiomyopathy.

METHODS

Several measurements including histologic variables before administration of metoprolol were retrospectively compared among 18 good responders (showing improvement of at least one New York Heart Association functional class or an increase in ejection fraction > or = 0.10 12 months after drug administration) and 12 poor responders without such improvement.

RESULTS

Although there were no significant differences between the two groups in age, gender, functional class, heart rate, blood pressure, pulmonary capillary wedge pressure, cardiac index, left ventricular end-diastolic dimension and ejection fraction, percent fibrosis estimated by the point-counting method in endomyocardial biopsy specimens was significantly lower in good than in poor responders (7.6 +/- 5.7 vs. 14.2 +/- 9.7%, p < 0.05). Moreover, when the types of fibrosis were classified as interfascicular and intercellular by the dominance of counted points, there were 13 cases of interfascicular fibrosis and 5 cases of intercellular fibrosis in good responders and 1 case of interfascicular fibrosis and 11 cases of intercellular fibrosis in poor responders (p < 0.001, sensitivity 72%, specificity 91%, predictive accuracy 80%). These results suggest that improvement with long-term beta-blocker therapy may be more likely to occur in patients with less myocardial fibrosis, with interfascicular fibrosis the dominant type.

CONCLUSIONS

The extent and type of fibrosis may be important factors in the prediction of the effectiveness of long-term beta-blocker therapy for dilated cardiomyopathy.

Effects of verapamil on electrophysiological properties in paroxysmal atrial fibrillation

Verapamil is used to control ventricular response during atrial fibrillation (AF). Limited data is available on the effects of verapamil on atrial vulnerability in human AF. The effects of intravenous verapamil (0.15 mg/kg) on electrophysiological properties of the atrium were investigated in 12 patients with documented paroxysmal AF by electrophysiological studies. Sinus cycle length, sinus node recovery time, and the effective refractory period of the right atrium were not significantly affected by verapamil. The intraatrial conduction delay zone was significantly increased (33 +/- 20 msec before verapamil versus 50 +/- 22 msec after verapamil, P < 0.01), and the maximal intraatrial conduction delay was also significantly prolonged by verapamil, both to the His bundle region (30 +/- 12 msec before verapamil versus 42 +/- 15 msec after verapamil, P < 0.01) and to the coronary sinus (40 +/- 15 msec before verapamil versus 53 +/- 17 msec after verapamil, P < 0.01). The fragmented atrial activity zone was significantly increased (15 +/- 14 msec before verapamil versus 25 +/- 22 msec after verapamil, P < 0.02), and the percentile fragmented atrial activity was also significantly increased by verapamil (149 +/- 18 msec before verapamil versus 174 +/- 44 msec after verapamil, P < 0.05). The repetitive atrial firing zone remained unchanged. Sustained AF spontaneously occurred in only one patient after the administration of verapamil. Thus, verapamil may modulate the abnormal atrial electrophysiology in paroxysmal AF, and would favor production of atrial reentry.

Use of monophasic action potentials to evaluate postpacing T wave changes

We examined the relationship between postpacing T wave changes and monophasic action potentials recorded from the ventricle in dogs. MAPs were recorded from the right and left ventricle before and after cessation of pacing. The duration of the MAP was calculated as the time in milliseconds from the upstroke to 90% repolarization (MAPD90). T waves in limb leads were flat or had a biphasic pattern, eventually becoming negative after pacing. The Q-T interval of the escape beat after pacing was prolonged compared with the control. After right ventricular pacing, the average duration of MAPD90 in the right ventricle, but not in the left ventricle, was prolonged. (right MAPD: control 275 +/- 10 ms; after pacing: 311 +/- 17 ms, p < 0.05; left MAPD: control: 266 +/- 23 ms, after pacing: 284 +/- 26 ms, NS). After left ventricular pacing, the average duration of MAPD90 in the left ventricle, but not in the right ventricle, was prolonged (right MAPD: control: 247 +/- 75 ms, after pacing: 287 +/- 39 ms, NS; left MAPD: control: 257 +/- 23 ms, after pacing: 303 +/- 25 ms, p < 0.05). Furthermore, the average duration of MAPD90 at the pacing site became progressively prolonged over time. These results suggest that myocardial cells retain the memory of abnormal repolarization associated with pacing.

[Rate of in vitro degradation of vecuronium in plasma of patients with renal failure and pregnancy]

The half-life of vecuronium in plasma by spontaneous desacetylation is about 120 minutes. We have to consider this degradation for examining the cause of prolonged duration of action of vecuronium. Therefore the rate of in vitro plasma spontaneous desacetylation of vecuronium bromide was measured in healthy women (n = 10), patients with renal failure (n = 10) and pregnant women (n = 10). There were no significant differences between three groups. It was concluded that the rate of spontaneous desacetylation was not responsible for the cause of prolonged neuromuscular blockade of vecuronium in patients with renal failure and pregnancy.

Characterization of a unique scrambled peptide derived from the CD4 CDR3-related region which shows substantial activity for blocking HIV-1 infection

We have previously identified CD4 peptides that exhibited blocking activity on human immunodeficiency virus type 1 (HIV-1) infection, i.e. CD4(68-130) and CD4(66-92) which include the region corresponding to the third complementarity-determining region of IgG. Here we describe a unique peptide derived from CD4(66-92), altered in amino acid sequence but not in composition, which was found to have increased anti-HIV-1 activity. The acidic amino acid residues in this scrambled peptide, S1, localized at the N-terminus, while in the native peptide they clustered at the C-terminus. On the other hand, a second scrambled peptide, S2, in which the acidic amino acid residues were fully dispersed, did not show any anti-HIV-1 activity. However, we could not identify any correlation between CD4(66-92) and S1 peptides by their hydrophobic or circular dichroism spectrum analyses. The results provide insight into the mechanisms of HIV-1 gp120 and CD4 interaction and may be useful as a new approach to AIDS therapy.

The usefulness of postoperative continuous epidural morphine in abdominal surgery

The influence of continuous epidural morphine on the recovery course of intestinal activity, urinary function, and ambulation after surgery was studied in 40 patients who underwent either gastrectomy for gastric cancer or cholecystectomy for cholelithiasis. Compared with a control group of patients whose postoperative pain was managed by pentazocine or hydroxyzine as before, the length of time before passing flatus or faeces was significantly shortened in the morphine groups (P < 0.05). Following gastrectomy, the urinary catheter was able to be removed significantly earlier in the morphine group (P < 0.05) although there was no statistical difference between both cholecystectomy groups. The morphine group experienced no difficulty with postoperative ambulation and exercise, although the difference in time before ambulation between the two groups was not considered significant. The results of this study led us to conclude that the postoperative continuous epidural infusion of morphine would be more beneficial following major abdominal surgery than the conventionally used methods of administering postoperative analgesia.

Effect of treatment at night with S-1452, a thromboxane A2 receptor antagonist, on the morning rise in platelet aggregation

It is well known that platelet aggregation shows a morning rise, which may contribute to the increase in the onset of ischaemic heart diseases during the morning period. The present study was undertaken to determine whether nocturnal dosage with S-1452, a thromboxane A2 receptor antagonist, would blunt the morning rise in platelet aggregability. S-1452 50 mg or placebo were given orally to 8 healthy subjects at 10.00 h (day trial) or 22.00 h (night trial) according to a cross-over design. Plasma concentrations of S-1452 and its metabolites, bisnor-(+)-S-145 and tetranor-(+)-S-145, and platelet aggregation were determined during the 12-hour period following the dose. Mean plasma concentrations of S-1452, bisnor-(+)-S-145 and tetranor-(+)-S-145 during the absorption phase were lower after the nocturnal dose than after the morning dose. The maximum plasma concentration and area under the plasma concentration-time curve of the compounds were also lower and the time to the maximum concentration were delayed after the treatment at night. A morning rise in platelet aggregation was observed following placebo treatment. The inhibitory effect of S-1452 on platelet aggregation was observed at 3 hours and persisted for up to 9 h in both trials. The results suggest that S-1452 is absorbed more slowly after the nocturnal dose than after the morning dose. However nocturnal treatment with 50 mg S-1452 may blunt the morning rise in platelet aggregability.

Effects of antihypertensive agents on arterial baroreceptor reflexes in conscious rats

The effects of antihypertensive treatment with four currently used agents (trichlormethiazide, atenolol, nicardipine, and enalapril) on the arterial baroreceptor reflex control of renal sympathetic nerve activity and heart rate were investigated in 45 conscious spontaneously hypertensive rats and 37 age-matched Wistar-Kyoto rats. Antihypertensive agents were administered for 2 weeks beginning at 8 weeks of age to treat and prevent the development of hypertension. Blood pressure was reduced to a similar level (-13 +/- 3 mm Hg, p < 0.05) by each antihypertensive agent. Blood pressure, heart rate, and renal sympathetic nerve activity were recorded in the conscious state during phenylephrine and nitroglycerin ramp infusion. The gain in the baroreceptor reflex was determined from the maximum slope of logistic function curves. Untreated spontaneously hypertensive rats exhibited decreased sensitivity of reflex control of renal sympathetic nerve activity and heart rate (-1.78 +/- 0.07% of control/mm Hg and -2.16 +/- 0.05 beats per minute/mm Hg, respectively) compared with untreated Wistar-Kyoto rats (-3.62 +/- 0.18% of control/mm Hg, p < 0.01, and -3.46 +/- 0.11 beats per minute/mm Hg, p < 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphotoxin activates hepatic T cells and simultaneously induces profound thymic atrophy

We have recently demonstrated that the liver may be a major site of extrathymic T-cell differentiation. This hepatic pathway was shown to be activated in mice injected with heat-killed bacteria. It is conceivable that the resulting activation of macrophages or lymphocytes, and the production of cytokines may be responsible for a subsequent activation of hepatic T cells. In this context, we investigated the possibility of whether certain cytokines may activate hepatic T cells. It was demonstrated that the administration of lymphotoxin [tumour necrosis factor-beta (TNF-beta)] more than doubled the number of hepatic mononuclear cells (MNC) yielded 3-5 days after the treatment. More strikingly, such treatment induced profound thymic atrophy and resulted in a decrease of more than 95% in the number of thymocytes. Spontaneous proliferation in an in vitro culture of hepatic MNC from treated mice increased, and inversely such activity of thymocytes decreased. The increased number of hepatic MNC was mainly due to an increase in intermediate alpha beta T-cell receptor (TcR) cells, which are extrathymic T cells uniquely seen in the liver. On the other hand, the thymic atrophy was caused by the prompt apoptotic death of dull alpha beta TcR cells with double-positive (DP) CD4+ CD8+ phenotype. These results indicate that lymphotoxin may be one of the factors that activates extrathymic T cells in the liver and at the same time inhibits intrathymic T-cell differentiation.