In vivo evidence for non-universal usage of the codon CUG in Candida maltosa

An alkane-assimilating yeast Candida maltosa had been studied in order to establish systems suitable for biotransformation of hydrophobic compounds. However, functional expression of heterologous genes tested for this purpose had not been successful in several cases. On the other hand, it had been reported that the codon CUG, a universal leucine codon, is read as serine in C. cylindracea. The same altered codon usage had also been suggested by in vitro experiments in some Candida yeasts which are phylogenetically closely related to C. maltosa. In this study we have shown that the failure in functional expression of a heterologous gene is due to the fact that the codon CUG is read as serine in C. maltosa. This conclusion was drawn from the following experimental results: (1) when a cytochrome P450 gene of C. maltosa containing a CTG codon was expressed in C. maltosa, the corresponding amino acid was found to be serine, and not leucine; (2) a tRNA gene with an almost identical structure to that of the tRNASerCAG gene of C. albicans could be isolated from the genome of C. maltosa; (3) the Saccharomyces cerevisiae URA3 gene, which has one CTG codon, could not complement the ura3 mutation of C. maltosa as itself, but when the CTG codon was changed to another leucine codon, CTC, the mutated gene could complement the ura3 mutation. The last result is the first example of succeeding in functional expression of a heterologous gene in Candida species having an altered codon usage by changing the CTG codon in the gene to another codon.

Observation of head-shaking nystagmus with an infrared Frenzel's glass

It has been reported that a head-shaking test is very useful in clinical practice. To observe head-shaking nystagmus (HSN) a Frenzel's glass and electronystagmography (ENG) have been used. Although observation with Frenzel's glass is a simple method, it tends to suppress after shaking nystagmus, as gazing is not completely eliminated with Frenzel's glass. An electronystagmogram in darkness can eliminate gazing completely, but it requires much trouble in routine use. We therefore tried to use Frenzel's glass with an infrared CCD camera. We observed highly provoked HSN like ENG in darkness and were able to use it without difficulty. We recognized the second phase in several cases with only an infrared Frenzel's glass and the rotatory component of the nystagmus. This method is more convenient and valuable for clinical use than ENG and Frenzel's glass.

Renal protective effect of efonidipine hydrochloride (NZ-105), a new calcium antagonist, in spontaneously hypertensive rats

1. We investigated the renal protective effect of efonidipine hydrochloride (NZ-105) in spontaneously hypertensive rats (SHR). SHR were given a diet containing 0.075% NZ-105 from 8 weeks old for 20 weeks. 2. 24-hr urinary protein excretion in the control SHR (drug-free diet) increased with age (from 77.3 mg/kg/day at 8 weeks old to 385.4 mg/kg/day at 28 weeks old), while that in NZ-105-treated SHR was maintained at almost the same level as that in Wistar-Kyoto rats (WKY), matched control animals throughout the experimental period. 3. The histological changes of the kidney were examined by light microscopy at the end of the treatment period. In control SHR, swelling and hyalinization of glomeruli, dilatation of renal tubules containing hyaline casts and arteriolosclerosis were revealed. The long-term administration of NZ-105 markedly suppressed these changes. 4. The kidney weights and plasma creatinine concentration in control SHR were higher than those in WKY, while they were significantly reduced in NZ-105-treated SHR. The long-term administration of NZ-105 also suppressed the elevation of systolic blood pressure and the increases of plasma renin activity and aldosterone concentration. 5. These findings suggest that NZ-105 inhibits the development of proteinuria and progressive kidney damage in SHR and may become a useful antihypertensive drug with the renal protective effect.

Heterogeneity of Epstein-Barr virus infection in angioimmunoblastic lymphadenopathy type T-cell lymphoma

To investigate the relationship of Epstein-Barr virus (EBV) and angioimmunoblastic lymphadenopathy with dysproteinemia, we performed DNA analysis using the polymerase chain reaction (PCR), Southern blot, in situ hybridization, and immunohistochemical analysis of lymph nodes in five patients who were followed up and biopsied more than once. In the course of the disease, nodal architecture diminished, cellular atypia worsened, and clear cells increased in number. In the DNA analysis of the receptor genes, the clonal population increased in number. EBV nucleic acid sequences were found by either PCR or in situ hybridization in all examined nodes. The number of EBV-positive cells varied widely among the cases and throughout the course of the disease in the same patients. The analysis of EBV terminal repeats or lymphocyte-determined membrane antigen genes showed polyclonal populations of EB-infected cells. EBV-positive cells possessed intermediate- to large-sized nuclei, and the cells with large nuclei, especially, expressed latent membrane protein of EBV. These large cells varied among the cases. Double-labelling immunohistochemistry/in situ hybridization studies demonstrated that most of the EBV-positive cells expressed B-cell antigen (CD20). The presence of EBV seems to be associated with the selective defects of the immune system, rather than with the direct pathogenesis of angioimmunoblastic lymphadenopathy.

[Clinical significance of P-glycoprotein expression and multidrug resistance assessed by in vitro thymidine incorporation assay in patients with gastric carcinoma]

Drug resistance in chemotherapy is a significant problem in the treatment of gastric carcinomas as well as other malignant tumors. Multidrug resistant cells frequently overexpress the 170 kDa P-glycoprotein (P-gp). Twenty-four fresh tumor specimens of gastric carcinoma were assessed by flow cytometric detection of P-gp using monoclonal antibody C219. Eight patients were P-gp positive. Differentiated gastric carcinomas contained significantly higher concentrations of P-gp positive. Incidence of P-gp positive case was high in advanced stage. Sixteen cases received in vitro chemosensitivity test assessed by thymidine incorporation assay (TIA). Seven of 9 multidrug resistant cases by TIA were P-gp positive, and all of 7 non-multidrug resistance were negative. Expression of P-gp and multidrug resistance were closely correlated (p < 0.01). Also, in 89 patients with operable gastric carcinoma, the relationship between multidrug resistance by TIA and their clinicopathologic features as well as their survival lengths were examined. Thirty-one of 89 specimens from gastric carcinoma patients were multidrug resistant by TIA. Patients with multidrug resistant group had a significantly poorer cumulative survival rate than non-multidrug resistant cases (p < 0.01). The multivariated analyses showed that multidrug resistance analyzed is useful indicator for prognosis (p < 0.1). We suggest that multidrug resistance cases or P-gp-positive cases of gastric carcinoma are highly malignant, and these determinations are clinically useful.

Inhibitory properties of NIP-121, a potassium channel opener, on high potassium- and norepinephrine-induced contraction and calcium mobilization in rat aorta

We examined the effects of NIP-121, a potassium channel opener, on KCl- and norepinephrine (NE)-induced contraction, the phasic-contraction under the Ca(2+)-free condition and cytosolic free-Ca2+ mobilization using isolated rat aorta. NIP-121 as well as cromakalim inhibited, in the KCl- and NE-contractions concentration dependently. Glibenclamide, an ATP-sensitive potassium channel blocker, competitively reversed their inhibition. On the other hand, they did not inhibit the phasic-contractions induced by NE in Ca(2+)-free medium. In Fura-2-loaded rat aorta, NIP-121 inhibited only the late phase of the NE-induced cytosolic Ca2+ level ([Ca2+]cyt) increases that were inhibited by nicardipine. However, it did not inhibit the first [Ca2+]cyt increase, which was completely abolished by repeated applications of NE in Ca(2+)-free medium. Neither did it inhibit phorbol ester-induced contraction. The vasorelaxant mechanism of NIP-121 is attributable to the decrease in Ca2+ influx passing through the membrane Ca2+ permeable systems. In addition, inhibition of Ca2+ release from sarcoplasmic reticulum (SR) and of protein kinase C (PKC) activation may not be involved in vasorelaxation induced by NIP-121.

Potassium channel openers relax A23187-induced nifedipine-resistant contraction of rat aorta

We investigated the vasorelaxant mechanisms of three potassium channel openers (PCOs: NIP-121, cromakalim, and nicorandil) using rat aortic strips precontracted with calcium ionophore A23187. A23187 (10(-6) M)-induced contraction was fully relaxed by NIP-121, cromakalim, and nicorandil, but not by the calcium channel blocker nifedipine. The effective concentration range and potency of these relaxant effects were the same as those previously reported for relaxation caused by potassium channel opening in the presence of 30 mM K+ or for relaxation of agonist-induced contraction. Relaxation induced by NIP-121 or cromakalim was competitively antagonized by glibenclamide, with apparent pA2 values for NIP-121 and cromakalim of 7.28 and 7.47, respectively. However, these PCOs did not relax A23187-induced contraction in the presence of 50 mM K+ and 10(-6) M nifedipine. These PCOs but not nifedipine significantly inhibited calcium-induced contraction in the presence of A23187 (10(-6)M). NIP-121, cromakalim, and nicorandil induced full relaxation of A23187-precontracted arteries, which might be attributable (partially for nicorandil) to their potassium channel opening activity. This relaxant effect might be related to inhibition of A23187-induced calcium influx resulting from opening of glibenclamide-sensitive potassium channels.

Muscarinic receptor-mediated calcium efflux from cultured bovine adrenal chromaffin cells

The effect of stimulation of the muscarinic receptor on Ca2+ mobilization in cultured bovine adrenal chromaffin cells was examined. Acetylcholine (ACh) increased the uptake of 45Ca2+ and [Ca2+]i whose levels decreased with time after reaching peaks. It also enhanced the efflux of 45Ca2+ from the cells. Its effect was inhibited by the specific muscarinic receptor antagonist atropine (Atr), but not by the nicotinic receptor antagonist hexamethonium (C6). The increase in muscarine (Mus)-stimulated 45Ca2+ efflux was reduced concentration-dependently by deprivation of extracellular Na+. These results suggest that muscarinic stimulation of the ACh receptor stimulates Na+/Ca2+ exchange in cultured bovine adrenal chromaffin cells.

Effects of efonidipine hydrochloride (NZ-105), a new calcium antagonist, against acute renal failure in rats

1. We investigated the effect of efonidipine hydrochloride (NZ-105) against acute renal failure (ARF) in male Wistar rats. ARF was produced by ischemia or glycerol. 2. Ischemia-induced ARF was produced by right nephrectomy and clamping of the left renal artery for 60 min, followed by reperfusion. NZ-105 (20 mg/kg) was orally administered twice a day for 3 days before ARF. The plasma creatinine and urea nitrogen concentrations were markedly elevated in the ischemia ARF group on the 1st day, but the elevation was significantly suppressed by NZ-105 treatment. 3. Glycerol-induced ARF was produced by intramuscular injection of 50% (v/v) glycerol (10 ml/kg) in rats which were restricted to drinking water for 24 hr. NZ-105 (20 mg/kg) was orally administered twice a day for 3 days before ARF. NZ-105 significantly attenuated the severe impairment of creatinine and urea nitrogen clearances and the elevated fractional sodium excretion (FENa) caused by ARF. 4. In the kidney homogenate, NZ-105 (10(-6)-10(-4) M) inhibited lipid peroxidation induced by ascorbic acid and Fe or by NADPH and the inhibitory effect of NZ-105 was stronger than alpha-tocopherol, an antioxidant agent. NZ-105 (10(-5)-10(-3) M) showed radical scavenging action against diphenyl-p-picrylhydrazyl and galvinoxyl induced radicals. 5. These findings suggest that NZ-105 prevents the renal damage caused by the two kinds of ARF. Moreover, the inhibitory effects of NZ-105 against lipid peroxidation and radical formation may be one of the mechanisms involved in the prevention of ARF.

Effects of highly toxic organochlorine compounds retained in human body on induction of sister chromatid exchanges in cultured human lymphocytes

In this study, we investigated the effect of mixture of the organochlorine compounds, which very resembled their contamination of healthy Japanese people in its composition, on the induction of sister chromatid exchanges (SCEs) in human whole-blood cultures in order to clarify their genotoxicity as a whole. The following results were obtained. Regardless of the presence or absence of 7,8-benzoflavone (ANF) in the blood culture system, we could observe a fairly good dose-response relationship between the concentration of the mixture of organochlorine compounds and the induction of SCEs/cell. In particular, we found that 50% effective concentration of the mixture of the organochlorine compounds was considered to be only about 3 times greater level over the average concentration in the healthy people, namely 70ppt as 2,3,7,8-TCDD, in the absence of ANF and about 8 times more than that in the presence of ANF.

Influence of efonidipine hydrochloride, calcium antagonist on the epithelium of prostates in spontaneously hypertensive rats

The hypertensive effect on the development of the prostatic abnormality in spontaneously hypertensive rats (SHRs) was examined using Efonidipine hydrochloride, a calcium antagonist. The control SHRs were given a high sodium and potassium diet (SP-diet) alone, and the treated SHRs were given a SP-diet with 0.15% Efonidipine hydrochloride from 8 to 28 weeks of age. The systolic blood pressure (SBP) in the control SHRs increased with age, while the elevation of SBP was significantly prevented in the treated SHRs. Light-microscopically, the prostatic lesion was observed both in the control and treated SHRs. The glandular lumen was narrowed with papillary protrusions, and the epithelium was composed of tall columnar epithelial cells. However, hypertension-induced complications in kidneys and hearts were not observed in the treated SHRs. These results suggested that the prostatic abnormality of SHRs might not be the consequent lesions upon hypertension.

Stimulatory effect of pituitary adenylate cyclase-activating polypeptide on catecholamine synthesis in cultured bovine adrenal chromaffin cells: involvements of tyrosine hydroxylase phosphorylation caused by Ca2+ influx and cAMP

In cultured bovine adrenal chromaffin cells, pituitary adenylate cylase-activating polypeptide (PACAP) stimulated [14C]catecholamine synthesis from [14C]tyrosine (but not from [14C]DOPA) in a concentration-dependent manner, causing maximal stimulation at 10(-7) M. The stimulatory action of PACAP was not affected by staurosporine (an inhibitor of protein kinase C) or in the cells in which protein kinase C was down-regulated by prolonged exposure to TPA (an activator of protein kinase C), whereas it was partially attenuated in Ca(2+)-free medium. PACAP (10(-7) M) increased the formation of [3H]inositol phosphates, [Ca2+]i and 45Ca2+ uptake as well as cAMP. The peptide also stimulated the phosphorylation of tyrosine hydroxylase, the enzyme catalyzing the rate-limiting step in catecholamine synthesis. Catecholamine synthesis and tyrosine hydroxylase phosphorylation stimulated by the maximal effective concentration of dibutyryl cAMP or high K+, which activates Ca2+ uptake, were further enhanced by PACAP, suggesting that both cAMP- and Ca(2+)-dependent protein kinases may be involved in the stimulation of tyrosine hydroxylase phosphorylation and catecholamine synthesis caused by PACAP.

[Diagnosis of coronary artery dehiscence and pseudoaneurysm after modified Bentall operation by Doppler color flow imaging: a case report]

This 48-year-old man presented with anterior chest and back pain in 1981. He was treated with replacement of the ascending aorta and aortic valve under a diagnosis of dissection of the ascending aorta with severe aortic regurgitation. He underwent modified Bentall reoperation for the dilation of the aortic root in 1991. Postoperative two-dimensional echocardiography was performed because of sustained atrial flutter. An echo-free space was detected between the aorta graft and aorta wrapping on the short-axis view. Doppler color flow imaging revealed blood flow from the left coronary artery graft into the echo-free space. This leakage was suspected to be the cause of the echo-free space. Transesophageal echocardiography was performed to conform this hypothesis, which revealed blood flow from the left coronary artery graft into the echo-free space in systole and flow into the left coronary artery graft from the echo-free space in diastole.

Dose escalation of biweekly cyclophosphamide, doxorubicin, vincristine, and prednisolone using recombinant human granulocyte colony stimulating factor in non-Hodgkin's lymphoma

BACKGROUND

Several uncontrolled trials have suggested that dose intensity of chemotherapy is a crucial determinant of treatment outcome for patients with non-Hodgkin's lymphoma (NHL). To explore the possibility of increasing dose intensity, a dose-escalation study of cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) using recombinant human granulocyte colony stimulating factor (rhG-CSF) was initiated.

METHODS

First, the feasibility of standard dose CHOP (750 mg/m2 cyclophosphamide intravenously [i.v.] on Day 1;50 mg/m2 doxorubicin i.v. on Day 1; 1.4 mg/m2 vincristine i.v. on Day 1; and 100 mg/body prednisolone orally on Days 1-5) repeated biweekly at the original dose was assessed. rhG-CSF was given subcutaneously at doses of 2-5 micrograms/kg every day or every other day on Days 3-13. The safety of increasing the dose of cyclophosphamide during biweekly CHOP then was tested. Besides the standard dose (750 mg/m2), two dose levels of cyclophosphamide were set (1200 mg/m2 and 1500 mg/m2 in patients younger than 61 years of age, and 1200 mg/m2 in patients 61-75 years old).

RESULTS

Twenty-seven patients with NHL who had received minimal or no previous treatment were enrolled in this study. In the 750 mg/m2 group, 9 patients received 3-6 cycles of treatment (mean, 3.9 cycles), in the 1200 mg/m2 group, 10 patients received 3-6 cycles (mean, 4.8), and in the 1500 mg/m2 group, all 8 patients received 6 cycles. No significant differences among the groups were observed in the extent and the duration of neutropenia in each cycle, and a leukocyte count of more than 3000/microliters on Day 15 was achieved in all 131 cycles. Hemoglobin values and platelet counts, however, decreased in the later cycles in the 1500 mg/m2 group. Two patients were hepatitis-B virus carriers, one of whom died of fulminant hepatitis after completion of six cycles. Another patient developed a transient increase of transaminases after the second cycle. One other patient developed Grade 4 mucositis (World Health Organization scale). The numbers of patients who achieved complete and partial responses, respectively, were 4 (50%) and 2 (25%) in the 750 mg/m2 group, 8 (80%) and 2 (20%) in the 1200 mg/m2 group, and 8 (100%) and 0 (0%) in the 1500 mg/m2 group.

CONCLUSIONS

The dose of cyclophosphamide in biweekly CHOP can be increased up to 1500 mg/m2 with no increase in the incidence of treatment-related early mortalities without any organ damage in younger patients. The efficacy of this dose intensification of CHOP currently is being investigated in a multicenter prospective randomized trial using three different dose levels of cyclophosphamide.

Radial arm maze behavior in mice when a return to the home cage serves as the reinforcer

Male ddY mice were housed in a cage with an eight arm radial maze apparatus for 6 h a day. A water bottle was placed at the central platform. The end of each arm ran to the home cage through a guillotine door (G). Food was placed at the home cage. During the housing in the apparatus, one G was raised and the remaining seven G were lowered. The raised G was changed every 45 min in random order. Mice housed in this apparatus learned efficient strategy to return the home cage by trial and error. When they chose the arm in which the G was lowered on their way to the home cage from the platform, they returned to the platform, then chose a different arm until they were able to enter the home cage. The mice housed in this apparatus mastered the radial maze task on the 7th day. When scopolamine (SCO) was injected, SCO butylbromide had no effect on performance, but SCO hydrobromide (0.2 and 0.4 mg/kg) impaired working memory, dose dependently. These results show that the apparatus is useful for ease in estimating working memory in mice without the use of severe food or water deprivation.

Rapid HPLC assay with coulometric detection for norepinephrine and 3-methoxy-4-hydroxyphenylglycol in the mouse brain

For the rapid assay of norepinephrine (NE) and its major metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG) in the mouse brain, we developed a simple method using isocratic HPLC with coulometric detection. This method permits NE and MHPG assay within 5 min in one chromatographic run. Within-run coefficients of variation for NE and MHPG in the working standard solution were 0.8% and 0.6% (n = 50), respectively. The detector responses were linear from 0.025 to 100 pmol for NE and from 0.05 to 100 pmol for MHPG in the working standard solution. Using this method, the NE and MHPG concentrations were measured in discrete brain areas of the mouse prior treatment with or without alpha-methyl-p-tyrosine or N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4).

Expression of human T-cell leukaemia virus type I and associated antigens, and interleukin-2 and receptor in lymph nodes of adult T-cell leukaemia/lymphoma

To examine the relationship between the expression of human T-cell leukaemia virus type (HTLV-I) mRNA and associated antigens and clinicopathological features, we studied 31 lymph nodes of patients with adult T-cell leukaemia/lymphoma (ATLL) and related diseases, using in situ hybridization and immunohistochemistry. We classified the patients into four types on the basis of their clinicopathological features (HTLV-I associated lymphadenitis, incipient ATLL, ATLL with complete HTLV-I provirus, and ATLL with defective HTLV-I provirus. The expression of HTLV-I mRNA was detected in all 3 patients with incipient ATLL, in 5 of 10 patients with defective-provirus ATLL, in 5 of 11 patients with complete-provirus ATLL, and 3 of 7 with HTLV-I associated lymphadenitis, but the amounts were very small; approximately 1 in 10000-200000 lymph node cells express the viral genomes. This suggests that expression of viral genomes may not be important for immortalization, but it is important that to note the capacity for HTLV-I infection is preserved in each group of non-neoplastic and neoplastic states. HTLV-I mRNA was detected only in lymphocytes and/or lymphoma cells, but the HTLV-I associated antigens (env, gag and pX) were found in histiocytes and endothelial cells, as well as in lymphocytes and/or lymphoma cells. Anti-interleukin 2 receptor (IL-2R) antibody reacted with the giant cells of incipient ATLL and with the transformed lymphocytes and immunoblast-like cells of the HTLV-I-associated lymphadenitis but not with the lymphocytes in the background. Of the typical ATLL, IL-2R was found in both lymphoma cells and giant cells. IL-2 was rarely detected.

Progression and regression of atherosclerotic findings in the descending thoracic aorta detected by enhanced computed tomography

Reports evaluating the progression and regression of atherosclerosis by non-invasive procedure are still limited. We investigated the progression and regression of atherosclerotic intimal thickening of the descending thoracic aorta non-invasively measured by enhanced computed tomography in 83 patients (average age 51.0 years) at the beginning and end of a 2.5 year period. The patients were not taking anti-hypertensive, lipid-lowering or hypoglycemic drugs and therefore we consider them as a natural history cohort. At entry, the extent of aortic intimal thickening was 35.2% of the circumference of the cross-section of the wall, which increased to 39.7% after 2.5 years. Spontaneous progression was associated directly with age, elevated levels of total cholesterol, LDL-cholesterol, LDL/HDL cholesterol ratio, diastolic blood pressure, and inversely to HDL-cholesterol. There was little correlation with triglycerides, systolic blood pressure, fasting glucose or body mass index. In 65 of the patients, aortic atherosclerosis progressed, while in 9 patients it remained unchanged, and in a further 9 it regressed. The levels of lipid variables, apart from HDL-cholesterol, and diastolic blood pressure in the patients with spontaneous progression were significantly higher than in the unchanged and spontaneous regression. Thus, this study verified the natural history of aortic atherosclerosis non-invasively measured by enhanced CT.

Allergens of the house dust mite, Dermatophagoides pteronyssinus, in patients with mite allergic rhinitis: a clinical investigation by intracutaneous skin tests and nasal provocation tests

To determine the allergens of mite allergic rhinitis, we studied 31 patients with mite allergic rhinitis by skin tests and nasal provocation tests (15 for skin and 16 for nasal tests) using 6 fractions of Dermatophagoides pteronyssinus (Dp) extract differing in molecular weights (15, 25, 32, 53, 95 and 190 kDMW). In skin testing, patients showed intense positive reactions to the fractions of 15, 25, 32, 95 and 190 kDMW, among which the most patients showed positive reactions to the fractions of 15 and 25 kDMW. Significant differences were found in patients' positive reactivity among each fraction and between low (15 and 25 kD) and high (95 and 190 kD) molecular weight fractions as well. In nasal provocation tests, patients showed intense positive reactions to the fractions of 15, 32, 53 and 95 kDMW, especially to the fractions of 15 and 95 kDMW. Furthermore, the insidence of positive reactions to the 15 kDMW fraction was significantly higher than that to any other fraction in the skin tests (P < 0.05). From these results, the low molecular weight fraction, 15 kDMW, is considered to be the main allergen of this mite and the high molecular weight fractions, 95 and 190 kDMW, may also be considered to be allergens of this mite.

Effects of nefiracetam on deficits in active avoidance response and hippocampal cholinergic and monoaminergic dysfunctions induced by AF64A in mice

The effects of nefiracetam [DM-9384; N-(2,6-dimethyl-phenyl)-2-(2-oxo-pyrrolidinyl)acetamide] and of phosphatidylcholine on a step-up active avoidance response, locomotor activities and regional brain cholinergic and monoaminergic neurotransmitters in AF64A-treated mice were investigated. Intracerebroventricular (i.c.v.) injection of AF64A (ethylcholine mustard aziridinium ion; 8 nmol/ventricle) impaired acquisition and retention of the avoidance task, and increased vertical and horizontal locomotor activities. Regional levels of acetylcholine, noradrenaline, 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were significantly decreased and homovanillic acid (HVA) levels were increased in the hippocampus but not in the septum, cerebral cortex or striatum of AF64A-treated animals. Administration of nefiracetam (3 mg/kg, p.o.) twice daily for 9 days to AF64A-treated animals ameliorated the deficit in active avoidance response in addition to attenuating the increase in locomotor activities. In parallel with these behavioural effects, nefiracetam reversed AF64A-induced alterations in the hippocampal profiles of cholinergic and monoaminergic neurotransmitters and their metabolites. In contrast, administration of phosphatidylcholine (30 mg/kg, p.o.) twice daily for 9 days had no significant effect on the deficit in active avoidance response, despite significantly reversing the decrease in acetylcholine levels in the hippocampus. These results indicate that the effects of nefiracetam on AF64A-induced behavioural deficits are probably due to its ability to facilitate both cholinergic and monoaminergic neurotransmitter systems.

Tubular dilatation in the repair process of ischaemic tubular necrosis

To elucidate the mechanisms of renal tubular dilatation in acute tubular necrosis (ATN), morphological findings after 60 min ischaemia were studied in rats. The characteristics of the tubular basement membrane (BM) were also examined. A morphometric analysis of cell proliferation, epithelial cellularity and the circumference of damaged tubules was performed. The ischaemic injury resulted in widespread necrosis of renal tubules at day 1, and the BM of damaged tubules appeared thin. The intensity of the immunohistochemical staining for BM components decreased. The epithelial cell proliferation was particularly active in the early phase. Dilatation of the damaged tubules began at day 2, and the degree of dilatation increased up to day 6. Regenerative epithelial hyperplasia occurred and abnormalities of tubular BM were seen. Epithelial hyperplasia and dilatation of damaged tubules was most prominent at day 6 and the tubular BM was thickened by newly produced BM components. Tubular obstruction was not seen and tubules returned to normal size by day 28. Epithelial hyperplasia and abnormalities of tubular BM disappeared progressively. Regenerative tubular epithelial hyperplasia and abnormalities of tubular BM may play an important role in pathogenesis of tubular dilatation in ATN, and tubular dilatation is not due to tubular obstruction.

Mapping and disruption of the chpB locus in Escherichia coli

The chpB locus is a chromosomal homolog of the pem locus, which is responsible for stable maintenance of plasmid R100 within the host cells. Like pem, chpB codes for two genes, chpBK and chpBI, encoding a growth inhibitor and a suppressor for the killing action of the ChpBK protein, respectively. Here, we determined the precise location of the chpB locus, which is linked to ileR and ppa in the order ileR-chpB-ppa, at 95.7 min on the map of Escherichia coli. We then constructed mutants with an insertion of a (cat) fragment within chpBK or chpBI on the E. coli chromosome. These mutants grew normally, indicating that chpB is dispensable for cell growth.

Magnetic resonance imaging for aspirated peanut in the bronchus

Peanut inhalation in the right main bronchus of a 15-month-old boy was diagnosed using a T1-weighted image produced by magnetic resonance imaging (MRI) because of the high fat content of the peanut. The T1-weighted MRI image may also be useful in diagnosing other kinds of aspirated nuts with high lipid content as well as peanuts. This method does not involve any X-ray exposure.