[Idiopathic testicular infarction: a case report]

We herein report a case of idiopathic testicular infarction. The patient was a 20-year-old man with the chief complaint of right testicular swelling and pain. Ultrasonography and color Doppler sonography demonstrated a hypoechoic lesion without any blood supply. Torsion of the right spermatic cord was most suspected, but we could not exclude the possibility of testicular cancer judging from the findings obtained by computed tomography and magnetic resonance imaging. Surgical exploration did not reveal any torsion of the spermatic cord. Subsequently, right high orchiectomy was performed because of the risk of a testicular cancer. Histopathological examination revealed a hemorrhage and congestion of the testis and epididymis.

Clinical features of Creutzfeldt-Jakob disease with V180I mutation

The authors describe the clinical features of Creutzfeldt-Jakob disease (CJD) with the causative point mutation at codon 180. The symptoms never started with visual or cerebellar involvement. The patients showed slower progression of the disease compared with sporadic CJD. They never showed periodic sharp and wave complexes in EEG. MRI demonstrated remarkable high-intensity areas with swelling in the cerebral cortex except for the medial occipital and cerebellar cortices. These characteristic MRI findings are an important clue for an accurate premortem diagnosis.

Epitope analysis of the cerebrospinal fluid IgG in HTLV-I associated myelopathy patients using phage display method

We, for the first time, analyzed the binding motifs of immunoglobulin G (IgG) in the cerebrospinal fluid (CSF) of human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) patients with a phage library displaying 12-mer random peptides. As a result, the sequences highly homologous to HTLV-I gp46 192-199, 237-243 and 255-261 were the common linear epitopes of high affinity- IgG exclusively detected in both CSF and sera of the patients. These IgG responses were confirmed with corresponding HTLV-I peptides and serum antibody titers significantly correlated with disease severity or duration. Gp46 237-243 has not been detected in previous enzyme-linked immunosorbent assay (ELISA) studies using bound longer peptides, suggesting the usefulness of the phage display method.

MRI characteristics of sporadic CJD with valine homozygosity at codon 129 of the prion protein gene and PrPSc type 2 in Japan

Two Japanese sporadic Creutzfeld-Jakob disease (sCJD) patients with valine homozygosity at codon 129 of the prion protein gene and protease-resistant prion protein (PrP(Sc)) type 2 (VV2) are described. In contrast with Western countries, this type of sCJD is very rare in Japan. In 123 sCJD cases, only two were recognised as VV2 by the Japanese CJD surveillance committee. The clinical symptoms and pathological findings of the patients were similar to those of European and US patients. The noteworthy finding of diffusion weighted MRI (DWI) was that an abnormal high intensity covered a wide range of the thalamus including the dorsomedial nucleus, the pulvinar, and the ventral anterior, lateral, and posterolateral nuclei. This thalamic pattern has not been recognised in sCJD with methionine homozygosity and PrP(Sc) type 1 (MM1) or methionine/valine heterozygosity and PrP(Sc) type 1 (MV1) which comprises the vast majority of sCJD. This finding may be characteristic to VV2 and may distinguish it from MM1, MV1, and variant CJD. DWI can provide a very important clue for the antemortem diagnosis of VV2 subjects.

Case of alpha-fetoprotein-producing transitional cell carcinoma of the renal pelvis

An alpha-fetoprotein-producing transitional cell carcinoma of the renal pelvis is extremely rare. To our knowledge, this has not been reported previously. We present the first case of an alpha-fetoprotein-producing transitional cell carcinoma of the renal pelvis in a 70-year-old female.

CSF hypovolemia vs intracranial hypotension in "spontaneous intracranial hypotension syndrome"

OBJECTIVES

To investigate the role of CSF hypovolemia in spontaneous intracranial hypotension (SIH) syndrome because so-called SIH syndrome sometimes lacks intracranial hypotension.

METHODS

Ten women (aged from 28 to 49 years) with characteristic orthostatic headache without a previous history of dural tear were investigated. In addition to gadolinium (Gd)-enhanced brain MRI, spinal MRI with and without Gd enhancement was performed.

RESULTS

Gd-enhanced brain MRI demonstrated diffuse pachymeningeal enhancement in all patients. Sagittal T2-weighted spinal MRI revealed a variable amount of CSF in the extradural space in all patients. Sagittal T2-weighted MRI or axial Gd-enhanced T1-weighted MRI showed dilated epidural veins located in the high cervical portion in each patient. The intensity of dilatation of the epidural veins correlated significantly with the amount of CSF in the epidural space. This suggested that the Monro-Kellie doctrine was applicable in this circumstance.

CONCLUSIONS

Since some patients with SIH syndrome have normal CSF pressure and since a downward displacement of the brain due to a reduction of the buoyant action of CSF may induce symptoms, CSF hypovolemia, not intracranial hypotension, may be the cause. Based on the Monro-Kellie doctrine, detecting leaked CSF and venous engorgement (epidural vein dilatation and pachymeningeal enhancement) is an important clue to diagnose so-called SIH syndrome. Dilatation of epidural veins suggests CSF hypovolemia in appropriate conditions.

[Atresia hymenalis with acute urinary retention under the anti-histamine drug: a case report]

A case of atresia hymenalis with acute urinary retention under the administration of the anti-histamine drug for pollinosis was reported. The patient was an 11 year-old female, who complained with acute urinary retention under the administration of the anti-histamine drug. Ultrasonography and magnetic resonance imaging revealed an expansive urinary bladder and an intravaginal hematoma. Subsequently examination of the external genitalia revealed atresia hymenalis and hematocolpos. The symptoms disappeared completely after a hymenal incision and drainage. To our knowledge, approximately fifty cases of atresia hymenalis have been previously reported in Japan. For the urologists, atresia hymenalis may not be experienced because of the rarely gynecological disease. However, we believe it should be considered as one causative disease in pubescent girls who complaining of difficulty in urination. Subsequently an examination of the external genitalia should be performed.

Angiomyolipoma with regional lymph node involvement: a case report and literature review

A 28-year-old man without tuberous sclerosis, who complained of pollakisuria, consulted to our hospital for a left renal mass. Abdominal computed tomography revealed a solid mass without a lipid component, 10 cm in diameter, in the left kidney and with regional lymphadenopathy. Renal arteriography showed a hypervascular mass, demonstrating multiple tumor stains and aneurysms. Left radical nephrectomy and perihilar lymph node dissection were performed for an anticipated diagnosis of malignant tumor in November 2001. The histopathological diagnosis was an angiomyolipoma with lymph node involvement. Immunostaining for myogen markers was positive in the renal mass and lymph node tumors. He was free from disease ten months after surgery.

Renal oncocytomatosis in a long-term hemodialysis patient treated by laparoscopic surgery

A 50-year-old female, who had been on maintenance hemodialysis for 22 years, consulted our clinic because of a left renal mass detected incidentally by ultrasonography. Computed tomography (CT) demonstrated a solid hypervascular mass, suggesting a renal cell carcinoma (RCC), in the left atrophic kidney. Left hand-assisted laparoscopic nephrectomy (HALN) was performed. The histopathological diagnosis was renal oncocytomatosis. Renal oncocytomatosis in a long-term hemodialysis patient is extremely rare. We report the first case of renal oncocytomatosis in a long-term hemodialysis patient treated with hand-assisted laparoscopic nephrectomy.

Transitional cell carcinoma of the renal pelvis in a patient with cyclophosphamide therapy for malignant lymphoma: a case report and literature review

Cyclophosphamide is considered to be a bladder carcinogen and there are many reports of secondary bladder cancer, while only a few cases of upper urothelial cancer have been described. A 59-year-old man, who had received cyclophosphamide therapy for malignant lymphoma, was suffering from gross hematuria and consulted our institute. Computerized tomography (CT), intravenous pyelography (IVP) and retrograde pyelography (RP) revealed a left renal pelvic tumor. Urinary cytology showed class V and radical left nephroureterectomy was performed. Histopathological diagnosis of the left renal pelvic tumor was transitional cell carcinoma, invading the renal parenchyma. He is free from recurrence eight months after surgery. To our knowledge, this is the third case of cyclophosphamide-induced upper urothelial carcinoma reported in Japan, and the twelfth reported in the English literature.

[A low-fat and high soybean protein diet for patients with elevated serum PSA level: alteration of QOL and serum PSA level after the dietary intervention]

Considerable epidemiological evidence has indicated a relationship between diet and prostate cancer. Many studies have shown positive associations between dietary fat and prostate cancer, and inverse associations with soybean intake. To prevent prostate cancer, we have tried dietary intervention for patients showing an elevated prostate specific antigen (PSA) level. A total of 96 patients who did not show any evidence of prostate cancer by transrectal ultrasonography and/or prostate biopsy despite high serum PSA level were placed on a supervised dietary intervention program consisting of a low fat and high soybean protein diet. The primary endpoint was the alteration of quality of life (QOL) and PSA after 3 months of intervention. Response to the questionnaire indicated that 88% of the patients desired to join such a study, and that 90% of the patients continued the dietary control after 3 months of supervision. About 60% patients adhered strictly to the dietary menus, and 90% of the subject planed to continue. Less than 20% of the patients complained of deterioration of dietary QOL. The average serum PSA level decreased from 6.9 ng/ml to 5.6 ng/ml after 3 months, which was statistically significant (p = 0.01). This dietary intervention almost maintains the patient's QOL, decreases the serum PSA level, and indicates the possibility of prevention of prostate cancer by dietary intervention.

Mutation in the caveolin-3 gene causes a peculiar form of distal myopathy

The authors describe a patient with sporadic distal myopathy associated with reduced caveolin-3 in muscle fibers in which the muscle atrophy was restricted to the small muscles of the hands and feet. Gene analysis disclosed a heterozygous 80 G-->A substitution in the caveolin-3 gene that was identical to that of reported cases of elevated serum creatine kinase. This patient further demonstrated possible clinical heterogeneity of myopathies with mutations in the caveolin-3 gene.

[Successful treatment of emotional disturbances following non-herpetic limbic encephalitis by serotonergic agents. A case report]

We report a 19-year-old woman who developed refractory status epilepticus due to non-herpetic limbic encephalitis. Because ordinary anti-epileptics were ineffective, general anesthesia under mechanical ventilation was begun with pentobarbital, midazolam, and propofol. After 4 months, we could finally discontinue the intravenous anesthetics. Then, she gradually became conscious and several weeks later, could communicate verbally. Simultaneously, she began to manifest psychomotor agitation and emotional incontinence mimicking Klüver-Bucy syndrome. Brain MRI revealed cortical atrophy in the fronto-temporal lobes and dilated anterior and inferior horns of the lateral ventricles. Dopamine blockers and benzodiazepines failed to resolve these emotional symptoms. Oral tandospirone (30 mg/day dose) was initiated and a partial regression was observed. The following administration of fluvoxamine (started with 12.5 mg/day and maintained with 75 mg/day) resulted in a dramatic improvement of her symptoms within 3 days. This clinical course suggests that impaired serotonergic neurotransmission plays a key role in her emotional disturbances and that its modulation by serotonergic agents is useful to relieve such symptoms.

Decrement of N20 amplitude of the median nerve somatosensory evoked potential in Creutzfeldt-Jakob disease patients

We studied somatosensory evoked potentials (SSEPs) in eight Creutzfeldt-Jakob disease (CJD) patients presenting with subacute progressive dementia, generalized myoclonus, and characteristic periodic sharp wave complexes in EEG. Somatosensory evoked potentials were elicited by median nerve stimulation at the wrist. We compared SSEP findings with EEG and the clinical stage proposed by the Japanese Slow Virus Infection Research Committee (stage 1: early stage to stage 5: terminal stage). Until clinical stage 3, short-latency SSEPs showed normal findings despite the severely abnormal EEG. With the progression to clinical stages 4 and 5, however, the amplitude of N20 began to decrease and finally disappeared without prolongation of the latency of N20, whereas other short-latency components were preserved. We recorded giant SSEPs in two of three patients in stage 4, when the periodic sharp wave complex in EEG began to decrease in amplitude. The giant SSEPs decreased in amplitude with the progression of the illness. These findings suggest that the short-latency SSEP is relatively preserved until the middle phase of the disease but that it is eventually affected in the terminal phase. We conclude that our results are compatible with the CJD pathologic findings and that the amplitude of N20 reflects the extent of cortical damage in CJD patients.

Effects of stimulus intensity on latency and conduction time of short-latency somatosensory evoked potentials

We studied the effect of stimulus intensity on latencies of short-latency somatosensory evoked potentials (SSEP) by measuring both onset and peak latencies individually. The latencies of N9, N13, N20 and N9-N13 peripheral conduction time (PCT) of median nerve (MN) SSEP, and N8, N23, P37 and N8-N23 PCT of tibial nerve (TN) and sural nerve (SN) SSEP significantly shortened with increasing stimulus intensity by onset latency measurement. However, those latencies by peak latency measurement were less significantly shortened or had only a trend of latency shortening without statistical significance. In contrast to PCT, N13-N20 central conduction time (CCT) of MN-SSEP and N23-P37 CCT of TN- or SN-SSEP showed no latency changes with the increased stimulus intensity by both onset and peak latencies measurement. As peak latencies had greater interindividual variability than onset latencies shown by larger standard deviation, shortening of onset latencies were more consistent than that of peak latencies. We think shortening of onset latencies indicates the recruitment of faster conduction fiber along with increased stimulus intensity. As the degree of latency shortening was less if stimulus intensity was above 2.5 times sensory threshold, the stimulus intensity greater than 2.5 times the sensory threshold should be used for clinical application.

[Transverse myelopathy with renovascular hypertension caused by fibromuscular dysplasia]

An 18-year-old woman developed subacute transverse myelopathy with renovascular hypertension, hyperlipidemia, and proteinuria. Spinal magnetic resonance imaging(MRI) showed an intra-spinal cord lesion with severe spinal cord swelling at the C 2-Th 2 level. Increased plasma and cerebrospinal fluid interleukin-8(IL-8) levels and the presence of serum antineutrophil cytoplasmic antibody(ANCA) suggested the existence of an ischemic lesion due to vasculitis. Administration of corticosteroids ameliorated the clinical symptoms and MRI findings. Renovascular angiogram revealed the presence of fibromuscular dysplasia(FMD) at the left renal artery but no malformation was found at the cervical arteries. We discussed the possibility of relationships between myelopathy, FMD, IL-8, and ANCA.

[Hand motor cortical area reorganization following cerebral infarction evaluated with functional MRI, near infrared spectroscopic imaging, and transcranial magnetic stimulation]

A 60-year-old, right-handed man suffered from left hemiparesis with upper limb dominance. CT and MRI revealed cerebral infarction of the entire right middle cerebral artery territory. His hemiparesis recovered excellently and residual neurological deficits 6 years later were left hand weakness(grasping power 9 kg vs. 35 kg in the right) and clumsiness. Functional MRI was performed. During right(normal) hand grasping, activation was seen in the left sensorimotor cortex and supplementary motor area. During left(paretic) hand grasping, activation was seen in the left (ipsilateral) sensorimotor cortex, right parietal cortex, and bilateral supplementary motor areas. Near infrared spectroscopic imaging showed similar results. During right hand grasping, left sensorimotor cortex was activated, and during left hand grasping, bilateral sensorimotor cortices were activated with ipsilateral predominance. Transcranial magnetic stimulation of the left motor hand area evoked right hand movement and stimulation of a point near that area evoked ipsilateral left hand muscle movement. Thus, the findings of the three techniques consistently suggest that the recovery of left hemiparesis of this patient was promoted by motor cortical area reorganization including the ipsilateral motor cortex.

The formalin test: effects of formalin concentration and short-term halothane inhalation

BACKGROUND AND OBJECTIVES

In order to evaluate the effects of formalin concentration and inhalational anesthetics in formalin tests, we injected 5 concentrations of formalin into awake and anesthetized rats and investigated their behavior and the c-fos immunoreactivity of their spinal cords.

METHODS

Sixty adult male Sprague-Dawley rats were divided into 10 experimental groups. Each rat was either manually restrained or subdued through several minutes of 2% to 2.5% halothane inhalation, and then 1 of 5 concentrations of 0%, 5%, 10%, 27%, or 100% formalin (0%, 1.85%, 3.7%, 10%, or 37% formaldehyde solutions) was injected into its rear paw. Nociceptive behaviors were checked for 1 hour, 6 times for each 5-minute period. Two hours after the formalin injections, the rats were killed and c-fos immunoreactivity was measured.

RESULTS

Typical responses were observed in the 5% and 10% formalin (1.85% and 3.7% formaldehyde) groups, and nociceptive behaviors were lower in the 27% and 100% formalin (10% and 37% formaldehyde) groups. The number of c-fos-positive cells increased as the formalin concentration increased. Halothane inhalation affected the results of both the behavior and the c-fos immunoreactivity, especially in the 10% formalin (3.7% formaldehyde) group.

CONCLUSIONS

It is desirable to describe both formalin and formaldehyde concentrations simultaneously and to do formalin tests without inhalational anesthetics.

Structural and functional characterization of IS679 and IS66-family elements

A new insertion sequence (IS) element, IS679 (2,704 bp in length), has been identified in plasmid pB171 of enteropathogenic Escherichia coli B171. IS679 has imperfect 25-bp terminal inverted repeats (IRs) and three open reading frames (ORFs) (here called tnpA, tnpB, and tnpC). A plasmid carrying a composite transposon (Tn679) with the kanamycin resistance gene flanked by an intact IS679 sequence and an IS679 fragment with only IRR (IR on the right) was constructed to clarify the transposition activity of IS679. A transposition assay done with a mating system showed that Tn679 could transpose at a high frequency to the F plasmid derivative used as the target. On transposition, Tn679 duplicated an 8-bp sequence at the target site. Tn679 derivatives with a deletion in each ORF of IS679 did not transpose, finding indicative that all three IS679 ORFs are essential for transposition. The tnpA and tnpC products appear to have the amino acid sequence motif characteristic of most transposases. A homology search of the databases found that a total of 25 elements homologous to IS679 are present in Agrobacterium, Escherichia, Rhizobium, Pseudomonas, and Vibrio spp., providing evidence that the elements are widespread in gram-negative bacteria. We found that these elements belong to the IS66 family, as do other elements, including nine not previously reported. Almost all of the elements have IRs similar to those in IS679 and, like IS679, most appear to have duplicated an 8-bp sequence at the target site on transposition. These elements have three ORFs corresponding to those in IS679, but many have a mutation(s) in an ORF(s). In almost all of the elements, tnpB is located in the -1 frame relative to tnpA, such that the initiation codon of tnpB overlaps the TGA termination codon of tnpA. In contrast, tnpC, separated from tnpB by a space of ca. 20 bp, is located in any one of three frames relative to tnpB. No common structural features were found around the intergenic regions, indicating that the three ORFs are expressed by translational coupling but not by translational frameshifting.

[An autopsy case of atypical Friedreich's ataxia with chronic idiopathic intestinal pseudo-obstruction]

We report a 58-year-old man with slowly progressive muscle atrophy and weakness in the four extremities, accompanying cerebellar ataxia and sensory impairment of all modalities. He was a product of consanguineous marriage. His neurological manifestations began in childhood. He was admitted to our hospital because of marked abdominal distension and pretibial edema with hypoalbuminemia and hyperlipidemia. Neuroimaging studies showed marked atrophy of the cerebellum and spinal cord. Nerve conduction studies presented with slowing and sural nerve biopsy revealed demyelination with onion-bulbs. Abdominal distension was interpreted to be caused by chronic idiopathic intestinal pseudo-obstruction (CIIP), leading to protein-losing gastroenteropathy and hypalbuminemia caused by the CIIP. He died of DIC by myelodysplasic syndrome and DIC, two years later. Postmortem study demonstrated with severe loss of anterior horn cells and gliosis in the spinal cord. The Clarke's column was also affected. There was symmetrical degeneration in the dorsal column and corticospinal tracts. The cerebellum showed atrophy of molecular layer, prominent loss of Purkinje's cells and sparse granular cell layer, but no obvious change in the dentate nucleus. Neuronal loss in the dorsal root ganglia was remarkable. There were no alternations in the cerebral cortex, striatum, thalamus, subthalamic nucleus, and pontine nucleus, except for mild changes in substantia nigra and inferior olivary nucleus. This case was clinically suspected either of variant of Friedreich's ataxia or an early onset ataxia associated with hypoalbuminemia (EOAHA), although marked autonomic dysfunction was atypical. But the postmortem study, demonstrated with marked neuronal loss in anterior horn cells and cerebellan cortex and rather suggested an independent category of this case.

Adrenomedullin inhibits the pressor effects and decrease in renal blood flow induced by norepinephrine or angiotensin II in anesthetized rats

Adrenomedullin (AM), a hypotensive peptide originally isolated from human pheochromocytoma, has been reported to regulate renal functions. In patients with glomerulonephritis, the serum levels of AM are elevated as well as hypertensive agents norepinephrine (NE) and angiotensin II (AII). The effects of AM on the NE- or AII-induced pressor effects and renal blood flow responses, however, are not well clarified. We examined the effects of AM on blood pressure and renal blood flow induced by NE or AII in anesthetized rats. Arterial blood pressure and renal blood flow were measured using a calibrated pressure transducer and a laser Doppler flowmeter, respectively. Drugs were injected into the tail vein with a syringe. Intravenous administration of AM (1-3 nmol/kg) decreased the arterial blood pressure in anesthetized rats in a dose-dependent manner, whereas it did not affect the renal blood flow. NE or AII administration in anesthetized rats caused both increases in blood pressure and decreases in renal blood flow. Simultaneous administration of AM with NE or All prevented the increasing effects of blood pressure and inhibited the decreases in renal blood flow caused by NE or AII. These findings suggest that AM may have a protective role against the pressor effects and decrease in renal blood flow caused by NE or AII.

[A case of Tolosa-Hunt syndrome starting from abducens nerve palsy alone]

A 59-year-old man was admitted to our hospital because of right abducens nerve palsy without orbital pain. One month later right orbital pain appeared and two months later the pain changed to an aching severe pain and the right oculomotor, trochlear and trigeminal nerves were also involved. The administration of corticosteroid dramatically reduced these symptoms. The diagnosis was Tolosa-Hunt syndrome (THS) based on these findings. THS starting with abducens nerve palsy alone is rare, representing only 5.1% of 118 patients. In our patient, the newly developed dynamic MRI was able to reveal the right cavernous sinus lesion. The diagnostic usefulness of dynamic MRI for cavernous sinus lesions has been demonstrated for such cases.

Diabetogenic activity of 20 kDa human growth hormone (20K-hGH) and 22K-hGH in rats

To compare the diabetogenic activity of 20 kDa human growth hormone (20K-hGH) with that of 22K-hGH, we evaluated insulin sensitivity with a euglycaemic clamp in rats. The glucose infusion rate (GIR) in euglycaemic clamp studies was measured as an indicator of insulin sensitivity. [(14)C]glucose and 2-[(3)H] deoxy- D -glucose injection were used to calculate the rate of glucose utilization (R(d)), the hepatic glucose output (HGO), and the glucose metabolic index (R(g)'). Both 20K- and 22K-hGH were infused at equivalent rates (1.0 (mg/kg)/day). A 24 h infusion of 20K-hGH had no significant effects on the GIR, R(d), HGO and R(g)(')except for in gastrocnemius muscle. In contrast, 22K-hGH significantly lowered the GIR compared with the control (P< 0.001) and 20K-hGH groups (P< 0.01). The infusion of 22K-hGH also reduced R(d)compared with the controls and the 20K-hGH rats by 46.6% (P< 0.001) and 39.6% (P< 0.05) respectively, while no differences were observed in the HGO. Moreover, 22K-hGH inhibited glucose uptake, which was estimated from the insulin-stimulated R(g)' in some tissues. These results suggest that 22K-hGH inhibits the uptake and use of glucose in various tissues, which then leads to insulin resistance. In conclusion, the diabetogenicity of 20K-hGH is much weaker than that of 22K-hGH, and the reduced insulin-antagonizing action of 20K-hGH could have important clinical benefits.

Involvement of H-NS in transpositional recombination mediated by IS1

IS1, the smallest active transposable element in bacteria, encodes a transposase that promotes inter- and intramolecular transposition. Host-encoded factors, e.g., histone-like proteins HU and integration host factor (IHF), are involved in the transposition reactions of some bacterial transposable elements. Host factors involved in the IS1 transposition reaction, however, are not known. We show that a plasmid with an IS1 derivative that efficiently produces transposase did not generate miniplasmids, the products of intramolecular transposition, in mutants deficient in a nucleoid-associated DNA-binding protein, H-NS, but did generate them in mutants deficient in histone-like proteins HU, IHF, Fis, and StpA. Nor did IS1 transpose intermolecularly to the target plasmid in the H-NS-deficient mutant. The hns mutation did not affect transcription from the indigenous promoter of IS1 for the expression of the transposase gene. These findings show that transpositional recombination mediated by IS1 requires H-NS but does not require the HU, IHF, Fis, or StpA protein in vivo. Gel retardation assays of restriction fragments of IS1-carrying plasmid DNA showed that no sites were bound preferentially by H-NS within the IS1 sequence. The central domain of H-NS, which is involved in dimerization and/or oligomerization of the H-NS protein, was important for the intramolecular transposition of IS1, but the N- and C-terminal domains, which are involved in the repression of certain genes and DNA binding, respectively, were not. The SOS response induced by the IS1 transposase was absent in the H-NS-deficient mutant strain but was present in the wild-type strain. We discuss the possibility that H-NS promotes the formation of an active IS1 DNA-transposase complex in which the IS1 ends are cleaved to initiate transpositional recombination through interaction with IS1 transposase.

[A case of potassium-sensitive periodic paralysis with cardiac dysrhythmia controlled with imipramine and acetazolamide]

We report a patient with potassium-sensitive periodic paralysis with cardiac dysrhythmia. The patient was a 16-year-old man. He presented with asymptomatic ventricular dysrhythmia and periodic paralysis when he was 6 and 12 years old, respectively. Physical examination revealed slight dysmorphic features such as hypoplastic mandible, low-set ears and clinodactyly. Through an exercise test, a potassium tolerance test and a muscle biopsy, his illness was diagnosed as potassium-sensitive periodic paralysis with cardiac dysrhythmia. For the treatment of his episodic paralysis, we started acetazolamide, which improved both the incidence and the severity of paralysis. However, the incidence of cardiac dysrhythmia was increased after the use of acetazolamide. Routine anti-arrhythmic drugs such as lidocaine failed to control his ventricular dysrhythmia. Only imipramine showed its efficacy by improving the degree and the incidence of cardiac dysrhythmia without aggravating periodic paralysis. This syndrome is relatively rare and there have been no standard protocols for the treatment. We propose the combination of acetazolamide and imipramine as the first choice for this clinical entity. We also discussed the efficacy of the exercise test. It enabled us to confirm the diagnosis of periodic paralysis safely and easily by recording the change of compound muscle action potential amplitudes.

Effect of digoxin noncompliance on hospitalization and mortality in patients with heart failure in long-term therapy: a prospective cohort study

BACKGROUND

As outpatients with long-term chronic illness often show a high incidence of medication noncompliance, we investigated the influence of digoxin noncompliance on hospitalization, left ventricular ejection fraction, and mortality in outpatients in long-term therapy having congestive heart failure with tachycardia at a rate over 100 beats/min before starting digoxin therapy, but abnormal sinus rhythm.

METHODS

Before starting this study, the digoxin compliance/noncompliance of patients was determined by measuring the serum digoxin concentration (SDC). SDC was determined once a month, followed for six consecutive months, and patients were defined as noncompliant if their SDC was zero (0.0 ng/ml) on at least three consecutive occasions. According to SDC data, 218 patients were assigned to the compliant group and 213 patients were assigned to the noncompliant group. All 431 patients received diuretics, angiotensin converting-enzyme inhibitors, or nitrates as well as conventional therapy with digoxin throughout the trial. The duration of follow-up was 72 months.

FINDINGS

After 72 months of follow-up, the digoxin noncompliant patients showed significant increases in the number and duration of hospitalizations compared with the compliant patients. The digoxin noncompliant patients had a marked decrease in the left ventricular ejection fraction from 49.1% to 41.8%. The cumulative rate of mortality from any cause in noncompliant patients was twofold higher (15.0%) than in compliant patients (7.8%; risk ratio when noncompliant was compared with compliant: 1.95; 95% confidence interval 1.11, 3.45; P = 0.029) at the 72-month follow-up. The higher mortality in digoxin noncompliant patients was exclusively attributed to worsening heart failure rather than other cardiac and noncardiac causes (risk ratio 2.13; 95% confidence interval 1.12, 4.07; P = 0.033). In addition, multiple regression analyses demonstrated that patient noncompliance as well as lower left ventricular ejection fraction at baseline were significantly involved in increased mortality.

CONCLUSION

These results indicate that digoxin noncompliance, at least in part, increases the rate of both hospitalization and mortality due to worsening heart failure in outpatients who have congestive heart failure with tachycardia in long-term therapy.

Clinical and physiological significance of abnormally prolonged central motor conduction time in HAM/TSP

We measured the central motor conduction time (CMCT), central sensory conduction time (CSCT), F wave and mean F wave/M wave amplitude ratio in patients with HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) and controls. CMCTs in upper (U) and lower (L) limbs were significantly prolonged in HAM/TSP. L-CSCT was significantly prolonged in HAM/TSP, but U-CSCT in HAM/TSP and controls were not significantly different. CMCT and CSCT were significantly correlated in HAM/TSP. U-CMCT, but not L-CMCT, correlated with the clinical severity of HAM/TSP. Although F wave conduction velocity and its occurrence were normal in HAM/TSP, U- and L-mean F wave/M wave amplitude ratio tended to be higher in HAM/TSP, and the L-mean F wave/M wave amplitude ratio was significantly correlated with the L- and thoracic CMCT. These findings demonstrate that the prolongation of CMCT sensitively reflects the extension of the lesions and the disinhibition to the anterior horn cells in HAM/TSP.

Inhibitory effects of nicorandil on rat mesangial cell proliferation via the protein kinase G pathway

We investigated the effects of nicorandil, which is a hybrid between a nitrate and an ATP-sensitive potassium channel (K(ATP)) opener, on cultured rat mesangial cell proliferation. Nicorandil (1 microM to 1 mM inhibited [(3)H]thymidine incorporation into rat mesangial cells in a concentration-dependent manner. Nicorandil (1 microM to 1 mM) also inhibited the number of cells. Nicorandil increased cyclic guanosine 3',5'-cyclic monophosphate accumulation in mesangial cells. A protein kinase G inhibitor, KT5823, partially eliminated the inhibition of mesangial cell proliferation by nicorandil. Methylene blue, a guanylate cyclase inhibitor, blocked the inhibitory effect of nicorandil on mesangial cell proliferation. We also examined the effects of K(ATP) mediators. Cromakalim, a K(ATP) activator, and glibenclamide, a K(ATP) inhibitor, had little effect on the proliferation of mesangial cells. These results suggest that the inhibitory effects of nicorandil on mesangial cell proliferation are mediated via the protein kinase G pathway.

N-linked oligosaccharide processing enzyme glucosidase II produces 1,5-anhydrofructose as a side product

alpha-1,4-Glucan lyase cleaves alpha-1,4-linkages of nonreducing termini of alpha-1,4-glucans to produce 1,5-anhydrofructose (1,5-AnFru). The enzymes isolated from fungi and algae show high homology with glycoside hydrolase family 31. Purification of alpha-1,4-glucan lyase from rat liver using DEAE Cellulose chromatography resulted in separation of two enzymatic active fractions, one was bound to the column and the other was in the flow-through. Partial amino acid sequence determined from the lyase, retained on the anion exchange column, were identical with that of the N:-linked oligosaccharide processing enzyme glucosidase II. The lyase showed similar enzymatic properties as the microsomal glucosidase such as inhibition by 1-deoxynojirimycin and castanospermine. On the other hand, glucosidase II purified from rat liver microsomes produced not only glucose but also a small amount of 1,5-AnFru using maltose as substrate. Furthermore, CHO cells overexpressing pig liver glucosidase II showed a 1.5- to 2-fold higher lyase activity compared to the nontransfected CHO cells. Conversely, no lyase activity was detectable either in PHAR2.7, the glucosidase II-deficient mutant from a mouse lymphoma cell line, or in Saccharomyces cerevisiae strain YG427 having the glucosidase II gene disrupted. These data demonstrate that glucosidase II possesses an additional enzymatic activity of releasing 1,5-AnFru from maltose.

[A family with oculopharyngeal muscular dystrophy with (GCG)9 expansion in which a sister had neck as well as proximal and her brother proximal lower limb muscle weakness]

We report a 58-year-old woman (patient 1) and her 60-year-old brother (patient 2) with autosomal dominant oculopharyngeal muscular dystrophy. Patient 1 first noticed blepharoptosis and neck weakness at age 55. On neurological examination, she showed bilateral blepharoptosis and weakness in the neck and upper proximal limbs. Serum creatine kinase (CK) level was slightly elevated. Her older brother first noticed blepharoptosis and lower limb weakness at age 51. On neurological examination, he showed bilateral blepharoptosis, slight ophthalmoparesis and bilateral iliopsoas muscle weakness. Serum CK level was normal. Esophageal fluoroscopy disclosed dysfunction of the constrictor pharyngeal muscles. Muscle biopsy of them showed myopathic changes with rimmed vacuoles. The (GCG)9 mutation in the poly (A) binding protein 2 gene was identified, which was the same as seen in the large French-Canadian kindred in Quebec in Canada. The clinical phenotype in patient 2 is similar to that of French-Canadian patients but it in patient 1 is different in distribution of muscle weakness.

Two consecutive fasciculation potentials having different motor unit origins are an electromyographically pathognomonic finding of ALS

To electrophysiologically diagnose amyotrophic lateral sclerosis (ALS), fasciculation potentials (FPs) were evaluated in each wasted muscle in 12 ALS and 14 other neurogenic disorders (non-ALS patients). Various types of FPs were observed in ALS. The number of discharged FPs and firing rate of FPs were significantly increased in ALS compared to those in non-ALS. These findings indicate that more motor units take part in discharging FPs in ALS than in non-ALS, and that injured lower motor neurons exhibit hyperexcitability. Although nine of 12 ALS patients showed two consecutive FPs having different motor unit origins, non-ALS patients did not show such FPs. Since the two consecutive FPs having different motor unit origins reflect an involvement of both upper and lower motor neurons, these potentials are an electrophysiologically pathognomonic finding to ALS.

Hypoxic induction of prolyl 4-hydroxylase alpha (I) in cultured cells

Accumulated evidence indicates that hypoxia activates collagen synthesis in tissues. To explore the molecular mechanism of activation, we screened genes that are up-regulated or down-regulated by hypoxia. Fibroblasts isolated from fetal rat lung were cultured under hypoxia. Differential display technique showed that the mRNA level of prolyl 4-hydroxylase (PH) alpha(I), an active subunit that catalyzes the oxygen-dependent hydroxylation of proline residue in procollagen, increased 2-3-fold after an 8-h exposure to hypoxia. This elevated level was maintained over 40 h and returned to the basal level after reoxygenation. The transcription rate, protein level, and hydroxyproline content (an indicator of the prolyl hydroxylation) were all elevated by hypoxic culture. Analysis of the promotor region of PHalpha(I) gene indicated that a motif similar to hypoxia-responsive element (HRE) of hypoxia-inducible genes such as erythropoietin, was identified within a 120-base pair sequence upstream of the transcription start site. Luciferase reporter assay and mutational analysis showed that a site similar to the HRE in this motif is functionally essential to hypoxic response. Electrophoretic mobility shift assay revealed that hypoxia-inducible factor-1 was stimulated and bound to the PHalpha(I) HRE upon hypoxic challenge. Our results indicate that PHalpha(I), an essential enzyme for collagen synthesis, is a target gene for hypoxia-inducible factor-1.

Efficient production of N-terminally truncated biologically active human interleukin-6 by Bacillus brevis

cDNAs encoding human interleukin 6 (hIL-6) and its variants lacking the N-terminal Pro and Pro-Val-Pro-Pro, respectively, were expressed in Bacillus brevis by using the signal peptide fusion approach. The presence of Pro at the N-terminus of the mature protein hindered the action of the Bacillus brevis signal peptidase. hIL-6 lacking the N-terminal Pro-Val-Pro-Pro was most efficiently secreted in a biologically active form and accumulated in the culture medium to a level of 200 mg per liter, which is the highest level reported for the bacterial secretion of hIL-6.

Bronchial amyloidosis successfully treated with low-dose long-term erythromycin therapy

A 69-year-old man was admitted for evaluation of an abnormal chest X-ray. A diagnosis of primary bronchial amyloidosis was made on the basis of the chest X-ray, CT scans and bronchial biopsy specimens. The patient was treated with low-dose long-term erythromycin therapy (600 mg/day). After four months of therapy, chest CT scans, bronchoscopic findings and bronchial biopsy specimens revealed significant improvement of inflammatory changes. Low-dose erythromycin therapy may be helpful in terms of its anti-inflammatory effects for patients with bronchial amyloidosis.

Practical asymmetric synthesis of (S)-MA20565, a wide-spectrum agricultural fungicide

A practical asymmetric synthesis of a wide-spectrum agricultural fungicide, (S)-MA20565 (1), is described. The convergent synthesis was achieved starting from commercially available 3-(trifluoromethyl)aniline (7) in 44% overall yield through five steps and 2-bromobenzaldehyde (9) in 48% overall yield through four steps, respectively. (S)-O-[1-(3-Trifluoromethylphenyl)ethyl]hydroxylamine (2), a key intermediate of 1, was prepared via ruthenium(II)-catalyzed asymmetric transfer hydrogenation of 1-(3-trifluoromethylphenyl)ethanone (6) followed by chlorination using methanesulfonyl chloride and oxyamination using potassium acetohydroxamate with high level of stereocontrol.

The neuroprotective agent MS-153 stimulates glutamate uptake

We investigated the effect of (R)-(-)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), a novel neuroprotective agent, on L-[3H]glutamate uptake through GLT-1, a Na(+)/K(+)-dependent glial glutamate transporter, expressed in COS-7 cells. MS-153 (1-100 microM) accelerated the L-[3H]glutamate uptake through GLT-1 in a concentration-dependent and time-dependent manner. Eadie-Hofstee analysis revealed that MS-153 significantly decreased the K(m) of the glutamate uptake by COS-7 cells expressing GLT-1. In contrast, [3H]gamma-aminobutyric acid (GABA) uptake through a glial GABA transporter was not affected. In addition, MS-153 increased Na(+) currents through GLT-1 expressed in Xenopus oocytes. We also investigated the effect of MS-153 on amino acid efflux from rat hippocampal slices. The increase in glutamate efflux induced by 50 mM KCl was significantly attenuated by the treatment with MS-153 at 10 microM, while MS-153 had no significant effect on the K(+)-evoked efflux of GABA. Furthermore, the increase in glutamate efflux by ischemia (hypoxia/aglycemia) was partially, but significantly inhibited by MS-153. These results suggest that the cerebroprotective effect of MS-153 in this ischemic model in vivo is due to the specific reduction of the glutamate concentration in the extracellular space, which can probably be attributed to the acceleration of glutamate uptake by the indirect modulation of the glutamate transporter activity.

Therapeutic efficacy of transcranial magnetic stimulation for hereditary spinocerebellar degeneration

We applied transcranial magnetic stimulation (TMS) as a therapeutic approach for patients with spinocerebellar degeneration (SCD). The subjects were four familial SCD patients (three men and one woman) aged from 27 to 76 years old. They were genetically analysed as two spinocerebellar ataxia type 6 (SCA 6), one SCA 1, and one SCA 7. The durations of their illness ranged from 1 to 7 years. Ten consecutive magnetic pulses were delivered over the scalp corresponding to the right cerebellar hemisphere, the middle of the cerebellum and the left cerebellar hemisphere, respectively, every day for 21 days. In all patients, the time and the number of steps required for a 10 m walk examination were significantly decreased after TMS trial compared with those before TMS. The number of feasible steps in tandem gait test increased. The total length of tracing body balance for 30 seconds measured by gravinometer was significantly decreased. However, nystagmus, dysarthria or incoordination of the upper limbs did not change after TMS trial. It is of interest that the blood flow of the cerebellar hemisphere, putamen and pons were significantly increased during the TMS trial. Although we do not know the exact mechanism by which TMS improved the ataxic gait, we speculate the increase of blood flow in the cerebellum, putamen and pons takes part in the improvement. These findings suggest that TMS over the cerebellum may be an effective therapy for patients with SCD.

Transposition of IS1 circles

BACKGROUND

IS1, the smallest active transposable element in bacteria, encodes transposase. IS1 transposase promotes transposition as well as production of miniplasmids from a plasmid carrying IS1 by deletion of the region adjacent to IS1. The IS1 transposase also promotes production of IS1 circles consisting of the entire IS1 sequence and a sequence, 6-9 bp in length, as a spacer between terminal inverted repeats of IS1. The biological significance of the generation of IS1 circles is not known.

RESULTS

Plasmids carrying an IS1 circle with a spacer sequence 6-9 bp long transposed to target plasmids at a very high frequency when transposase was produced from a co-resident plasmid. The products were target plasmids with the donor plasmid inserted at the ends of IS1 in the IS1 circle. This insertion accompanied the removal of the spacer sequence and duplication of the sequence at the target site. IS1 circles with a much longer spacer sequence transposed less frequently. The SOS response was induced in cells harbouring a plasmid with an IS1 circle owing to transposase. IS1 circles could transpose in the strain deficient in H-NS, a nucleoid-associated DNA-binding protein known to be required for the transposition of IS1.

CONCLUSIONS

IS1 circles appear to act as intermediates for simple insertion into the target DNA via cleavage of the circles which induces the SOS response. H-NS may function in promoting the assembly of an active IS1 DNA-transposase complex at the terminal inverted repeats.

[Short- and long-term outcome after urethroplasty in the patients with hypospadias treated by Hodgson III method]

Between 1977 and 1997, 29 patients with hypospadias were surgically treated by Hodgson type III urethroplasty at Tsukuba University Hospital. The duration of surgery ranged from 150 to 535 minutes with an average of 269.3 minutes and the urethral catheter was removed between 4 and 14 days (average 8.7 day) after surgery. The postoperative hospital stay ranged from 10 to 29 days with an average of 18.4 days. The overall success rate of initial surgery was observed in 18 of the 29 patients (62.1%). As early postoperative complications, urethral fistula and stricture were seen in 10 (34%) and 3 (10%) patients, respectively; of these four fistulas persisted. As late complications revealed by questionnaire, erectile disorder was observed in one case. To obtain a higher success rate on initial treatment, skillful surgical technique and selection of appropriate cases are required.

1,5-Anhydroglucitol promotes glycogenolysis in Escherichia coli

Glycogen is a storage compound that provides both carbon and energy, but the mechanism for the regulation of its metabolism has not been fully clarified. Recently, we found a new glycogenolytic pathway in rat liver in which glycogen is first metabolized to 1, 5-anhydrofructose (AnFru) and then to 1,5-anhydroglucitol (AnGlc-ol). Because the amounts of glycogen and AnFru are closely related in various rat organs and the second reaction, AnFru to AnGlc-ol, is strongly inhibited in the presence of glucose, we expected that this pathway might play a regulatory role in glycogen metabolism. Here we evaluate the expected involvement of AnGlc-ol and AnFru in the regulatory mechanism in Escherichia coli C600. Having established the presence of this new glycogenolytic pathway in E. coli C600, we further show that the conversion of AnFru to AnGlc-ol is activated only after the exhaustion of glucose in the medium, and that as little as 5 microM AnGlc-ol in the medium acutely accelerates the degradation of glycogen by 40%. We consider the role of AnGlc-ol in the mechanism that controls glycogen metabolism in E. coli to be as follows. When glucose is abundant, E. coli accumulate glycogen, a fraction of which is steadily degraded so that the amount of AnFru is about 1/1,000 of glycogen on a weight basis. When glucose is depleted and the demand for glycogen utilization is elevated, AnFru, which has accumulated mostly in the medium, is promptly taken up and converted to AnGlc-ol, which accelerates glycogen degradation. We also suggest the possibility that AnGlc-ol is one of the extracellular signaling molecules for bacteria.

[Steroid-responsive diffuse cerebral white matter lesions in a case of intractable fungal meningoencephalitis]

We report a case of fungal meningoencephalitis with steroid-responsive diffuse cerebral white matter lesions. A 49-year-old male developed auditory hallucination, confusion and fever, on April, 1994. He was diagnosed as having cryptococcal meningoencephalitis based on the detection of cryptococcal antigens in the cerebrospinal fluid (CSF). Intravenous administration of fluconazole resulted in improvement of his neurologic symptoms and CSF findings. For the next seven months, he was treated with oral fluconazole and the neurological status was stable. However, soon after the dose of fluconazole was tapered, he became confused and febrile, which made him admitted to our hospital. Neurological examination on admission showed disturbance of consciousness, disorientation and meningeal irritation. The CSF examination revealed mild pleocytosis (mostly lymphocytes), elevated protein and normal glucose levels, although fungus was not detected. The T2-weighted image of brain MRI demonstrated diffuse hyperintense lesions in the bilateral cerebral white matters. GD-DTPA enhanced MRI showed spotty enhanced lesions in the periventricular white matters. The neurologic symptoms were once relieved after intravenous administration of fluconazole was started, but two months later, he became comatose and needed ventilatory support, despite amphotericine B therapy. Then, a needle brain biopsy targeting the white matter lesion was done. Histopathology of the specimen showed chronic inflammation with granuloma formation and T lymphycyte infiltrate around the small vessels, though fungus was not detected in the tissue. Combined therapy with corticosteroid and antifungal agents remarkably improved the neurological symptoms as well as the MRI findings. In the present case, fungal infection possibly induced an altered immune reactions which resulted in the steroid responsive diffuse cerebral white matter lesions.

Complement activation as a cause of transient hypotension during plasmapheresis

Hypotension is one of the most common adverse effect of plasmapheresis (PP) and often is attributed to hypovolemia due to extracorporeal circulation and the vasovagal reflex. Complements are activated during PP, and the activated complements are strong anaphylatoxins and potent vasodilators. Therefore, we studied the relationship between the transient hypotension and the plasma levels of activated complements during and after PP in 8 sessions of 7 patients using the Plasmafro OP-08 as a plasma separator. Five of the patients underwent immunoadsorption PP using the IM-TR 350 or IM-PH 350 as the adsorption column. The other underwent double filtration PP using the Evaflux 4A as a second filter. In 4 of 8 sessions, patients experienced transient hypotension with significantly elevated plasma levels of activated complements C3a and C5a. In contrast, patients without hypotension showed no increases in C3a and C5a values during PP. In this report, we emphasize the critical role of activated complements for hypotension during PP.

Histiocytic sarcoma of the spleen associated with hypoalbuminemia, hypo gamma-globulinemia and thrombocytopenia as a possibly unique clinical entity--report of three cases

We report three patients with histiocytic sarcoma of the spleen associated with severe hypoalbuminemia, hypo gamma-globulinemia and thrombocytopenia. After the clinical diagnosis of splenic tumor of unknown origin was made, all three patients underwent splenectomy. The histiocytic origin of the tumor was confirmed histopathologically and immunohistochemically using a panel of antibodies. In contrast to malignant histiocytosis (MH), which typically reveals severe generalized clinical manifestations and a rapidly fatal course caused by the disseminated proliferation of neoplastic histiocytes, these patients were asymptomatic or showed only mild clinical symptoms for a long period of time until the recurrence was detected by which time the tumor cells had already spread to other organs. All three cases were characteristically associated with hypoalbuminemia, hypo gamma-globulinemia and thrombocytopenia, which returned to normal after splenectomy. Splenic histiocytic sarcoma with the features described here may represent a unique clinical entity, distinct from MH.

An assay system for detecting environmental toxicants with cultured cladoceran eggs in vitro: malformations induced by ethylenethiourea

An in vitro assay system using cladoceran eggs was developed for the detection of toxic compounds in the aquatic environment. Parthenogenetic eggs of Daphnia magna were removed from the brood chambers of female adults and cultured individually in 96-well microtiter plates with Elendt M7 medium at 23 degrees C. Embryonic development proceeded completely in vitro with more than 95% hatchability. Egg development time in vitro was 2 days, which was almost equal to that in the brood chamber of the mother. Ethylenethiourea, a compound teratogenic to mammals, was investigated for toxicity to development of eggs. Isolated eggs were cultured in the presence of ethylenethiourea during the period of embryonic development for 3 days. Treatment with ethylenethiourea induced morphological abnormalities in the cladoceran carapace. Parthenogenetic eggs of Cladocera are genotypically identical, which makes them useful biological materials for a toxicity test on aquatic pollutants.

Development of new tester strains derived from E. coli WP2uvrA for the determination of mutational specificity

We have developed a set of multipurpose tester strains (WP3101 to WP3106) derived from E. coli WP2uvrA for the detection and classification of mutagens. Six kinds of F' plasmid (lacI, lacZ, proAB+) in strains CC101-CC106, each of which carried a different lacZ allele, were transferred to a delta(lac-pro) derivative of WP2uvrA. Assays for transitions and transversions are based upon Lac+ reversion of a specific mutation located within the lacZ gene on an F' plasmid in strains WP3101-WP3106. In addition, the trpE65(ochre) allele in the same strains is available for Trp+ reversion assays. Using the new tester strains, we investigated the mutational specificities of various chemical mutagens. Base analog mutagens and alkylating mutagens induced specific types of base substitutions. G:C-->A:T transitions and G:C-->T:A transversions predominated in mutagenesis induced by 4-nitroquinoline 1-oxide. Only a slight increase in G:C-->T:A transversions was observed in cells treated with 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), although the potent mutagenicity of AF-2 was detected in a concurrent Trp+ reversion assay in the same strain. Sodium azide, on the other hand, was negative in the Trp+ reversion assay but specifically induced G:C-->A:T transitions. Present finding suggested that target sites for AF-2- and azide-induced lesions may largely depend on sequence context.