Evaluation of essential and variable residues of nukacin ISK-1 by NNK scanning.

Nukacin ISK-1, a type-A(II) lantibiotic, comprises 27 amino acids with a distinct linear N-terminal and a globular C-terminal region. To identify the positional importance or redundancy of individual residues responsible for nukacin ISK-1 antimicrobial activity, we replaced the native codons of the parent peptide with NNK triplet oligonucleotides in order to generate a bank of nukacin ISK-1 variants. The bioactivity of each peptide variant was evaluated by colony overlay assay, and hence we identified three Lys residues (Lys1, Lys2 and Lys3) that provided electrostatic interactions with the target membrane and were significantly variable. The ring structure of nukacin ISK-1 was found to be crucially important as replacing the ring-forming residues caused a complete loss of bioactivity. In addition to the ring-forming residues, Gly5, His12, Asp13, Met16, Asn17 and Gln20 residues were found to be essential for antimicrobial activity; Val6, Ile7, Val10, Phe19, Phe21, Val22, Phe23 and Thr24 were relatively variable; and Ser4, Pro8, His15 and Ser27 were extensively variable relative to their positions. We obtained two variants, Asp13Glu and Val22Ile, which exhibited a twofold higher specific activity compared with the wild-type and are the first reported type-A(II) lantibiotic mutant peptides with increased potency.

Change in vasoconstrictive function during prolonged nonpulsatile left heart bypass.

We investigated changes in vasoconstrictive function accompanying prolonged nonpulsatile left heart bypass (NLHB). After 2-week pulsatile left heart bypass (PLHB) in 11 goats, NLHB was conducted for another 4 weeks (Group N) in 6 goats. In the other 5 goats, PLHB was continued for another 4 weeks (Group P). Systemic vascular resistance at rest (rSVR) was measured on the last days of the second and sixth postoperative week (W2 and W6, respectively). Subsequently, phenylephrine was injected, and the maximum values (SVRmax) and the maximum increasing change in SVR (DeltaSVR) were measured. No significant difference was observed in rSVR between groups at W2 or W6. The SVRmax and the DeltaSVR at W2 were consistent in both groups. However, at W6, the SVRmax and the DeltaSVR of Group N were significantly lower than those of Group P. In conclusion, prolonged NLHB caused a significant decrease in the SVR response to phenylephrine, indicating a dimunition of vasoconstrictive function.

[Clinical and neuroradiological evaluation of the long-term surviving siblings of Sanfilippo syndrome A type].

The siblings of Sanfilippo syndrome type A (MPS III A) have been reported. The relationship of their parents was the first cousins. Case 1: A 30-year-old Japanese man was hospitalized because of gait disturbance and mental impairment. His early somatic and mental development was normal until 9 years of age when mental deterioration had developed. Speech and gait disturbances and double incontinence occurred at 18 years of age. He could not walk at 21 years of age. Those symptoms were slowly progressive. Case 2: A 32-year-old Japanese man, the elder brother of case 1, had a similar clinical history to that of case 1. Their neurological findings revealed mental impairment, coarse face, positive forced grasp and sucking reflexes, and pyramidal signs. Lumbar X-ray showed platyspondylitis, compression fracture of L 1 and osteoporotic changes. Brain MRI of both cases showed brain atrophy, ventricular dilatation and abnormal high intensity signals near the posterior horn of the lateral ventricles on T2 weighted image. Low perfusion images of fronto-parietal regions were seen in the early phase of SPECT using 123I-IMP. This siblings were diagnosed as Sanfilippo syndrome type A because of heparan sulfaturia and deficiency of heparan sulfate sulfamidase of the lymphocytes. Average life span of Sanfilippo syndrome type A is not so long but the age of our cases is over 30 years of age.

Fast and highly parallel content addressing of a large amount of information recorded in a holographic memory.

It has recently become possible to fabricate spatial light modulators for holographic information retrieval. We analyze the signal-to-noise ratios in two typical holographic information retrieval systems, serial and inverted, and we discuss the possibilities of implementing holographic information retrieval with a newly proposed spatial light modulator that uses a Fabry-Perot étalon with a piezoelectrically driven mirror.

[A case of myasthenia gravis occurring in the period of remission of chronic inflammatory demyelinating polyradiculoneuropathy].

A 31-year-old woman noticed progressive muscular weakness in the limbs and paresthesia in the fingers in February 1989. Paresthesia worsened and improved 4 times during 2 months. Intravenous edrophonium chloride failed to improve her muscular weakness. She had high antiacetylcholine receptor antibody titer in serum. We made a diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) because of slow nerve conduction velocity (NCV), increased CSF protein, and the clinical course. Treatment with prednisolone improved muscular weakness and the slow NCV. Two years later she acutely had dyspnea, dysphagia, and muscular weakness after upper respiratory infection. Intravenous edrophonium chloride dramatically improved her symptoms. The diagnosis was made as myasthenia gravis (MG). After thymectomy her weakness was getting better without any medications. There may exist an autoimmune mechanism common, at least in part, to both CIDP and MG in our patient.

Effects of carbamate, BPMC, on the central cholinergic functions and behavior of mice.

O-sec-butylphenyl methylcarbamate (BPMC), an anticholinesterase carbamate, was injected once (100 mg/kg, s.c.) or repeatedly (50 mg/kg/day for 10 days) into mice. Animals were examined for their behavior and for parameters of cholinergic activity in the forebrain. Mice that received only a single injection exhibited reduced ambulation, hypothermia, and impairment of rotarod performance for up to 3 hr after a single injection. BPMC increased levels of acetylcholine (ACh) in the forebrain for up to 6 hr, and decreased acetylcholinesterase (AChE) activity for up to 24 hr. Both high-affinity choline uptake (HACU) and binding of [3H]quinuclidinyl benzilate (QNB) were reduced 20 min after a single injection without any effect on choline acetyltransferase (ChAT) activity. In behavioral tests conducted 10 min prior to the daily injections, rotarod performance and ambulation were slightly impaired for a few days before and after cessation of injection. Repeated treatment decreased HACU and binding of [3H]QNB for 24 hr after the final injection without any changes in levels of ACh content, AChE activity and ChAT activity. BPMC may reversibly impair cholinergic functions through effects not only on AChE activity but also on HACU and binding of [3H]QNB.

Myotonia induced by low chloride solution: intracellular studies by Cl liquid ion exchanger microelectrode.

By exposing the rat hemidiaphragm preparations to various low chloride solutions, it was demonstrated that myotonia can be induced when the extracellular chloride concentration was reduced below 82 mEq/L. Myotonia can be induced simply by reducing the extracellular chloride concentration without any significant reduction of RMP. The intracellular and extracellular chloride activity was measured by the liquid ion exchanger microelectrode. The control intracellular chloride activity was 10.8 mEq/L and that of myotonic specimen in a low chloride solution of 47 mEq/L was 4.4 mEq/L. Chloride conductance was closely related to the extracellular chloride concentration and myotonia was induced when gc1 was 38.3% of the control.