Higher-order structure of bovine mitochondrial tRNA(SerUGA): chemical modification and computer modeling

On the basis of enzymatic probing and phylogenetic comparison, we have previously proposed that mammalian mitochondrial tRNA(sSer) (anticodon UGA) possess a slightly altered cloverleaf structure in which only one nucleotide exists between the acceptor stem and D stem (usually two nucleotides) and the anticodon stem consists of six base pairs (usually five base pairs) [Yokogawa et al. (1991) Nucleic Acids Res. 19, 6101-6105]. To ascertain whether such tRNA(sSer) can be folded into a normal L-shaped tertiary structure, the higher-order structure of bovine mitochondrial tRNA(SerUGA) was examined by chemical probing using dimethylsulfate and diethylpyrocarbonate, and on the basis of the results a tertiary structure model was obtained by computer modeling. It was found that a one-base-pair elongation in the anticodon stem was compensated for by multiple-base deletions in the D and extra loop regions of the tRNA(SerUGA), which resulted in preservation of an L-shaped tertiary structure similar to that of conventional tRNAs. By summarizing the findings, the general structural requirements of mitochondrial tRNAs necessary for their functioning in the mitochondrial translation system are considered.

Multiple proline substitutions cumulatively thermostabilize Bacillus cereus ATCC7064 oligo-1,6-glucosidase. Irrefragable proof supporting the proline rule

Nine residues of Bacillus cereus ATCC7064 oligo-1,6-glucosidase were replaced stepwise with proline residues. Of the nine residues, Lys121, Glu208 and Glu290 were at second sites of beta turns; Asn109, Glu175 and Thr261 were at N-caps of alpha helices; Glu216, Glu270 and Glu378 were in coils within loops. The replacements were carried out in the order, Lys121-->Pro, Glu175-->Pro, Glu290-->Pro, Glu208-->Pro, Glu270-->Pro, Glu378-->Pro, Thr261-->Pro, Glu216-->Pro and Asn109-->Pro. The resultant nine active mutant enzymes contained 1-9 more proline residues than B. cereus oligo-1,6-glucosidase. The thermostability of these mutants was additively enhanced with the increase in the number of proline residues introduced. The increase in the thermostability was most remarkable when proline residues were introduced at second sites of beta turns or at N-caps of alpha helices. The above results afforded irrefragable proof for the proline rule as an effective principle for increasing protein thermostability [Suzuki, Y., Oishi, K., Nakano, H. & Nagayama, T. (1987) Appl. Microbiol. Biotechnol. 26, 546-551].

Effect of 6-hydroxydopamine injection into the arcuate hypothalamic nucleus on the osmotic release of vasopressin in conscious rats

The aim of the present study was to evaluate a role in vasopressin secretion of the catecholaminergic neurons, including the tuberohypophysial dopaminergic neurons situated in the arcuate hypothalamic nucleus. A neurotoxin, 6-hydroxydopamine (6 g/l), was injected locally into the arcuate nucleus and its effects on catecholamine levels of the hypothalamic tissue and the neurointermediate lobe, and on the plasma vasopressin concentrations before and during i.v. infusion (0.1 ml kg-1 min-1) of isotonic (0.15 mol/l) or hypertonic saline (2.5 mol/l), were examined in conscious rats. The infusion of hypertonic saline produced increases of plasma vasopressin 15 and 30 min later, accompanied by elevations of plasma osmolality, sodium, chloride and arterial pressure. The vasopressin response was potentiated markedly by the 6-hydroxydopamine injection performed 8 days before, which hardly affected the responses of the other variables. Histological examination indicated that the injection sites of 6-hydroxydopamine in those rats had been located in the area ranging from rostral to medial arcuate nucleus. The i.v. infusion of isotonic saline did not change plasma vasopressin, osmolality, sodium, chloride or arterial pressure, regardless of the presence or absence of pretreatment with 6-hydroxydopamine. It was confirmed that when 6-hydroxydopamine was injected into the arcuate nucleus region 8 days before, noradrenaline and adrenaline concentrations of the hypothalamic tissue containing the injection site were decreased remarkably, although we could not detect any significant alteration in the dopamine concentration of the hypothalamic tissue or the neurointermediate lobe. On the basis of these results, we concluded that catecholaminergic neurons in the arcuate nucleus may act to inhibit osmotic vasopressin secretion.

The relationship between the glucose uptake system and growth cessation in Candida albicans

It is thought that dimorphic Candida albicans undergoes changes in its intracellular metabolic state prior to yeast-mycelial transformation. Cells grown in budding form to mid-exponential phase could not be induced to form germ tubes when grown in glucose medium. However, cells in which growth was initially inhibited by either starvation or inhibitors (0.1% hydroxyurea, 4% sodium malonate or 4% 2-deoxy-D-glucose) could be induced to form germ tubes in the same medium. The effects of these initial treatments on the intracellular state in mid-exponential phase cells were analysed by measuring the kinetics of D-glucose uptake. D-glucose uptake in mid-exponential phase and stationary phase cells was measured. The untreated mid-exponential phase cells exhibited only a high Km (6.9 mM). However, mid-exponential phase cells, in which growth was initially inhibited, exhibited both a high Km (3.2-6.2 mM) and a low Km (0.40-0.78 mM) simultaneously. In addition, the stationary phase cells exhibited both a high Km (5.6 mM) and a low Km (0.56 mM). These results suggest that there are two kinetically distinct systems of glucose transport in C. albicans and that changes in the glucose uptake system in C. albicans may be related to intracellular changes prior to transition from the budding to the mycelial form.

Effects of anti-ulcer agents on antibiotic activity against Helicobacter pylori

OBJECTIVE

To investigate the mechanism of action of a series of potential combination therapies for use against Helicobacter pylori.

DESIGN

The effects of certain anti-ulcer agents on the antimicrobial activity of antibiotics effective against H. pylori were determined in vitro.

METHODS

H. pylori was cultured on Skirrow's agar. Amoxycillin, clarithromycin, erythromycin and tetracycline were used. The anti-ulcer agents studied comprised aluminum chloride, sofalcone [2'-carboxymethyl 4,4'-bis(3-methyl-2-butenyloxy)chalcone] and zinc chloride. Urease activity was measured by the urease-indophenol method. The minimum inhibitory concentration was determined by a plating method, with H. pylori streaked on plates containing various concentrations of the antibiotics plus sublethal doses of the anti-ulcer agents.

RESULTS

This in vitro study showed that sofalcone had a direct antibacterial effect and, in addition, inhibited the adhesive property of H. pylori. It did not inhibit the antimicrobial activity of the antibiotics amoxycillin, clarithromycin, erythromycin or tetracycline against H. pylori. The metal ions had inhibitory effects on the antimicrobial activity of amoxycillin, erythromycin and tetracycline, but not on that of clarithromycin.

CONCLUSION

This study suggests that sofalcone is a suitable candidate for combination therapy.

A case of common variable immunodeficiency associated with cyclic thrombocytopenia

A 12 year old boy was found to be deficient in immunoglobulins (Ig) A, G2 and G4, and common variable immunodeficiency was diagnosed. He also had cyclic thrombocytopenia at intervals of approximately 28-30 days. His bone marrow revealed normocellular with slightly decreased megakaryocytes. In vitro colony assays showed markedly imparied megakaryocytopoiesis, erythropoiesis and granulopoiesis. Platelet-associated IgG was elevated at his thrombocytopenic phase. Direct Coombs' test was repeatedly positive. Although not defined at present, we suggest the autoimmune nature of the disease.

[Suprasellar ectopic pituitary adenoma: report of a case]

An extremely rare case of an ectopic pituitary adenoma in the suprasellar region is reported. A 57-year-old man was referred to us in March, 1993, because of bitemporal hemianopsia. Magnetic resonance imaging (MRI) and computed tomography (CT) revealed a well-circumscribed enhancing mass in the suprasellar region. Sagittal tomography of the skull showed normal-sized sella turcica. Endocrinological tests were almost within normal range. The tumor was totally removed by combined right subfrontal and interhemispheric approach. At the time of the operation, we confirmed that the tumor did not continue to the pituitary gland and that the diaphragma sellae was intact. Histological diagnosis of the tumor specimen was pituitary adenoma. Post-operative MRI showed a normal pituitary gland, thus supporting the diagnosis of ectopic pituitary adenoma. To our knowledge, only ten cases of suprasellar ectopic pituitary adenoma have been reported, including our case. Pathogenesis of ectopic pituitary adenoma was briefly discussed.

Contribution to antibody-antigen interaction of structurally perturbed antigenic residues upon antibody binding

For elucidating the contribution of structurally perturbed antigenic residues upon antibody binding to antigen-antibody interaction, the interaction between hen egg white lysozyme (HEL) and HyHEL10 Fv fragment, which is one of several monoclonal antibodies against HEL and structurally well defined (Padlan, E.A., Silverton, E. W., Sheriff, S., Cohen, G. H., Smith-Gill, S. J., and Davies, D. R. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 5938-5942), was investigated. Asp-101 and Trp-62 of HEL, whose conformations are perturbed by the binding of antibody HyHEL10 in this interaction, were replaced with Gly, and the resulting interactions were studied by assay of the inhibition of the lysozyme activity with the Fv fragment and by titration calorimetry. The results can be summarized as follows. 1) It was possible to prepare the fully functional Fv fragment of HyHEL10 using a secretory expression system in Escherichia coli. Its inhibition profile for HEL activity was almost indistinguishable from that of HyHEL10 IgG, and the contribution of enthalpy to driving the interaction was shown to be significant. 2) A thermodynamic study of the interaction between the D101G mutant HEL and the Fv fragment revealed that, although the negative enthalpy change was smaller than that for the wild type, the Gibbs energy was almost identical to that of the wild type, which resulted from the smaller entropy loss. 3) Study of the interaction between the W62G mutant HEL and this Fv fragment indicated that the rotation of the Trp-62 indole ring upon binding of the antibody made an enthalpic contribution to antibody-antigen interaction, although Trp-62 of HEL was proposed not to be the direct contact residue in the HyHEL10.HEL complex. 4) From these results, it was confirmed experimentally that structural perturbations of antigenic residues upon antibody binding of antigen would contribute to the gain of enthalpic energy, in spite of partial offset by entropic loss, and to driving the interaction.

The three dimensional structure of rat cytokine CINC/Gro in solution by homonuclear 3D NMR

The solution conformation of rat cytokine-induced neutrophil chemoattractant (CINC/Gro), a small protein consisting of 72 amino acid residues with proinflammatory activities, and a member of the interleukin 8 family corresponding to a counterpart of human Gro, was investigated with homonuclear 2D and 3D NMR spectroscopy. At each phase of the structural analysis, the homonuclear 3D NOESY-HOHAHA and HOHAHA-NOESY spectra afforded valuable data, removing ambiguities intractable by conventional 2D NMR techniques. CINC/Gro exists as a dimer in solution and contains a triple stranded anti-parallel beta-sheet and C-terminal alpha-helix in the monomer structure, as observed in human IL-8, but non-trivial differences are also observed.

Clustered lipid droplets in the endomyocardial biopsies from a patient with neuroleptic malignant syndrome

Neuroleptic malignant syndrome is caused by serious adverse effects of antipsychotic agents and occurs only rarely. Endomyocardial biopsies documented unique clustered lipid droplets in a Japanese man with this disease. After administration of haloperidol, he had symptoms of high fever, respiratory dysfunction, and cardiogenic shock, and subsequently suffered from multiple organ failure. Fortunately, he was completely cured with intensive therapy. In the convulsant stage, left ventricular endomyocardial biopsies were performed that yielded the interesting discovery of unique clustered lipid droplets among the myofibrils. It was suggested that although the pathomechanism of neuroleptic malignant syndrome is unknown, this disease may be characterized by a lipid metabolic disorder of the cardiac muscle cell.

[Results of one-stage hypospadias repair]

We reviewed 17 patients who had first undergone one-stage hypospadias repair. According to the criteria proposed by Keating and Duckett, the operative procedure performed was the MAGPI procedure in 2 patients, the pyramid procedure in 2, the Mathieu procedure in 1, the onlay island flap procedure in 6, the transverse preputial island flap and glans channel procedure (Duckett) in 4 and a combined method using the buccal and bladder mucosa graft in 2. The age of the patients ranged from 11 months to 22 years (median age 3.2 years). Postoperative follow-up ranged from 3 to 30 months (mean 7 months). Postoperative complications requiring revision occurred in 4 patients; urethrocutaneous fistula developed in 1 patient with the onlay island flap, urethral sticuture at the anastomosis and meatus in 1 patient with the transverse preputial island flap, meatal retraction in 1 patient with the mucosal graft, and urethral stricture at the distal anastomosis and bladder stone in the other patient with the mucosal graft. These complications were successfully revised by simple operations. Ventral skin tethering caused by scar contracture developed in 2 patients with the preputial island flap, and spontaneously improved with time in 1 patient. These results indicate that the criteria proposed by Keating and Duckett is proper to select an operative procedure for hypospadias.

[Early phase II clinical study of RP56976 (docetaxel) in patients with primary pulmonary cancer. Docetaxel Cooperative Study Group for Lung Cancer]

An early phase II clinical study of RP56976 (Docetaxel), a new anticancer agent of plant origin, was conducted in patients with primary pulmonary cancer as a multicentered study involving 28 Japanese institutions. Docetaxel was administered at an intravenous dose of 60 mg/m2 based on the results of a phase I clinical study, and efficacy and safety were examined. Of the 65 patients enrolled, 57 patients were evaluated to have completed the scheduled course of treatment by the Evaluation Committee. The antitumor effect in patients with non-small cell lung cancer was 21.4% (9/42). In patients not previously treated, the antitumor effect was 30.0% (6/20), in patients previously treated the antitumor effect was 13.6% (3/22), and in 13.3% (2/15) of patients with small cell lung cancer. This shows that docetaxel had an efficacy for non-small cell lung cancer. Hematological adverse reactions included leukopenia and neutropenia of Grade III or more as specified in the Adverse Event Reporting Form proposed by the Japan Society for Cancer Therapy in 53.3% (32/60) and 78.3% (47/60) patients, respectively. Other major adverse reactions included alopecia and anorexia. Neurological symptoms developed at a low frequency and were mild in severity.

[Effect of shear stress on hemostatic regulation in endothelium]

The vascular endothelium plays a pivotal role in regulating the hemostatic system. Various cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor (TNF) are known to perturb endothelial cells to reduce antithrombogenicity. On the other hand, blood flow has been shown to affect the endothelium to maintain its antithrombogenicity under some levels of shear stress in the laminar flow system. We examined the role of hemodynamic forces on the vascular system under cytokine stimulation using a cone-plate type viscometer. Treatment of endothelial cells with either IL-1 beta or TNF-alpha under static conditions increased PAI-1, vWF and prostacyclin release, while t-PA secretion was unchanged. When cells were exposed to steady shear stress of 0, 6, 12, 18 and 24 dyne/cm2, the release of t-PA, t-PA-PAI complex and prostacyclin elevated with the increase of shear stress intensity, while a gradual decrease of total PAI-1 secretion was observed and vWF secretion was unchanged. On the contrary, active PAI-1 secretion was significantly decreased under the shear stress of over 18 dyne/cm2. Interestingly, cytokines, which did not affect t-PA secretion of resting cells, increased the t-PA secretion and had an additive effect on prostacyclin secretion with shear stress under the shear stress of over 18 dyne/cm2. PAI-1 elevation induced by cytokines was markedly abolished under the same shear forces. No additive effect was observed in the secretion of vWF. Thus, shear stress attenuates the alteration of the balance in the fibrinolytic and coagulation system induced by cytokines. These findings clearly indicate that hemodynamic forces play a crucial role in regulating the hemostatic activity in vivo.

Bone scintigraphy as a prognostic factor in patients with adult T-cell leukemia-lymphoma

Bone scintigraphy in 26 patients with adult T-cell leukemia-lymphoma (ATLL) was evaluated. Abnormally high accumulations were observed in 7 of 26 patients (skull, 5; vertebra, 1; rib, 6; bony pelvis, 1; scapula, 2; lower extremities, 1). Serum calcium levels were significantly elevated in patients with abnormally high accumulations on bone scintigraphy. Survival rates of the patients with positive results on bone scintigraphy were significantly lower than were those with negative results on bone scintigraphy (P < 0.05). Survival rates of patients with high serum calcium levels, high WBC counts, and high serum lactate dehydrogenase (LDH) levels were also significantly lower than were those of the negative groups, in this order of significance. Bone scintigraphy was useful for detecting bone marrow involvement in ATLL and it can be one of the better indicators of the prognoses of patients with ATLL.

[The prognostic value of brain CT scan in infants with periventricular leukomalacia]

Brain CT scan was performed at 40 weeks of conceptional age in 17 preterm infants with periventricular leukomalacia (PVL). The finding of periventricular low density was not useful in differentiating patients with PVL from normal infants, because this finding was seen in 40% of normal infants. The following findings were characteristic of PVL: (1) a marked low density area in centrum semiovale, (2) an irregular outline of ventricular wall, and (3) low density spots in periventricular white matter. The findings of ventricular dilation with irregular wall and marked low density area in centrum semiovale were correlated with a finding of volume loss on MRI during late infancy and the severity of neurological impairment, especially in severely affected patients. Marked low density area in centrum semiovale was characteristic of severe PVL demonstrated on brain CT scan.

A case of bullous pemphigoid with antidesmoplakin autoantibodies

Paraneoplastic pemphigus, a recently identified disease entity, is associated with autoantibodies against a variety of epidermal proteins including desmoplakins I and II, and the 230-kDa bullous pemphigoid (BP) antigen. We report an 84-year-old Japanese man who had typical clinical and histopathological features of BP, but in whom indirect immunofluorescence, using normal human skin as the substrate, revealed concomitant serum antibasement membrane zone and antikeratinocyte cell surface autoantibodies. His serum showed reactivity similar to that which is seen with antidesmoplakin monoclonal antibody on immunofluorescence of cardiac muscle and urinary bladder. With immunoblotting, using various antigen sources, the patient's serum reacted with desmoplakins I and II, and with both the 230- and 180-kDa BP antigens. Immunogold electron microscopy also indicated the presence of antidesmoplakin antibodies. Although the significance of the antidesmoplakin antibodies in this patient is unknown, the findings in this case may provide an insight into understanding the occurrence of antidesmoplakin antibodies in paraneoplastic pemphigus.

Stage-specific expression of alkaline phosphatase during neural development in the mouse

The expression pattern of tissue nonspecific alkaline phosphatase (TNAP) in the developing neural tube of mouse is reported. Homogeneous AP activity in the neuroepithelium becomes prominent at E8.5. At E9.5, distinctly AP-positive cells appear in the brain and spinal cord area. At stages E10.5 to E12.5, AP positivity is observed between the mesencephalon and the rhombencephalon, along the entire spinal cord and cranial nerves emerging from the myelencephalon. At E13.5, strongly AP positive fibers become prominent in the pons. At E14.5, AP expression in brain tissue is considerably reduced and there is a complete absence of AP activity in the nerve cells and glial cells of adult brain. The choroid plexus remains distinctly positive for AP expression until the adult stage. Northern blot analysis and reverse-transcriptase polymerase chain reaction amplification of RNA indicate that this AP activity results from the expression of the Akp-2 locus. This AP expression pattern is distinct from those reported for the expression of GD3, nestin, Hox 2.3, and Wnt-1 during brain development. We conclude that AP is a useful marker of a subpopulation of neuroectodermal cells present in the neural tube as early as E8.5, at which stages there are no other AP positive intraembryonic cells except PGCs.