A review: the active peptide of lactoferrin

A potent antimicrobial peptide, 'lactoferricin', was found to be generated upon gastric pepsin cleavage of lactoferrin. The active peptide consists mainly of a loop of 18 amino acid residues, derived from the N-terminal region of the lactoferrin molecule. Like various other antimicrobial peptides that display membrane-disruptive properties, it contains a high proportion of basic amino acid residues. A physiologically diverse range of micro-organisms was tested and found to be susceptible to inhibition by this natural peptide including Gram-negative and Gram-positive bacteria, yeasts and filamentous fungi. Its antimicrobial effect against sensitive micro-organisms was lethal. Electron microscopy studies revealed that it induces a profound change in cell ultrastructural features and causes substantial cell damage in bacteria and fungi. These findings suggest the possibility that active peptides of lactoferrin may have a role in the host defense against microbial disease. If produced in substantial quantities in vivo such peptides could have important physiological significance, especially in nursing infants.

Lactoferrin inhibits cholesterol accumulation in macrophages mediated by acetylated or oxidized low-density lipoproteins

When macrophages are incubated with acetylated or oxidized low-density lipoproteins (Ac- or OxLDL), cellular cholesteryl esters (CE) increase significantly. In the present study, we investigated the effect of whey protein on Ac- or OxLDL mediated accumulation of CE in macrophages and found that lactoferrin (Lf), a minor protein component of whey, inhibits the accumulation of CE dose-dependently. In the presence of bovine Lf (1 mg/ml), CE accumulation in macrophages incubated with AcLDL (100 micrograms of protein/ml) decreased by more than 80%. Human Lf was less potent than bovine Lf, and bovine transferrin had no effect. Binding of 125I-AcLDL to macrophages was also inhibited by Lf. Agarose gel electrophoresis revealed that Lf binds to Ac- or OxLDLs and neutralizes their negative charges. These results indicate that Lf inhibits the binding of modified LDLs to macrophages by direct interaction with modified LDLs, resulting in their loss of function as ligands of the scavenger receptor. Modification of the arginine residues of Lf with 1,2-cyclohexanedione abolished its ability to bind to AcLDL, suggesting that a region rich in basic amino acid residues near the N-terminus of Lf, which resembles the ligand-binding site of the scavenger receptor, may be responsible for this binding ability. As a result, the inhibitory effect of Lf on CE accumulation in macrophages was significantly weakened by this modification. Our results suggest the possibility that Lf in the blood stream may act as an anti-atherogenic agent in vivo.

[Neurophysiological study of hemifacial spasm--F wave of the facial muscles]

We studied the F wave of the facial muscles on both the normal side and the spastic side in 14 patients with hemifacial spasm. The purpose of this study was to determine if the mechanism of hemifacials spasm originates in ephaptic transmission in the facial nerve at the site of vascular compression or in a hyperexcited facial motor nucleus. Larger amplitude, longer duration and shorter latency F waves in the peripheral nerves than in normals indicate anterior horn cell hyperexcitability. We found abnormal potentials exhibiting synkinesis (lateral spread), a typical electrophysiological finding in hemifacial spasm, in the facial nerve evoked electromyograms of the 14 patients, none of whom had experienced facial palsy or facial nerve block. Electrical stimulation was delivered transcutaneously to the most distal portion of the marginal mandibular branch of the facial nerve. Using surface electrodes the F waves were obtained over the mentalis muscle as the second response after the M wave. While the F waves were normal on the patients' normal side, on the spastic side, their duration was longer (mean duration about 1.9 times that of the normal side), their onset latency was slightly shorter, and their F/M amplitude latency was greater than on the normal side. After microvascular decompression, the facial spasm and abnormal F-wave findings resolved. Onset latency was not increased, and on the spastic side some patients displayed facial spasm clinically and electrophysiologically for one year after MVD. In other words, there was hardly any focal demyelination of the facial nerve, so it is possible that ephaptic transmission and ectopic excitation are the mechanism of HFS.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization and purification of serum albumin in the testis of Xenopus laevis

The distribution of serum albumin is of interest in the Xenopus (X.) laevis testis, since albumin is probably a major protein that binds testosterone (T) in the plasma and interstitial fluid. This study was undertaken to determine the localization and purification of serum albumin in the X. laevis testis. The interstitial tissue and spermatogenia immunoreacted strongly with a sheep antiserum raised against X. laevis albumin. A weak staining was also seen in spermatocytes and early spermatids, but there was no staining in Sertoli cells. In order to clarify whether serum albumin was really localized on the surface of testicular cells in the X. laevis testis, a membrane-rich fraction was prepared from testes and extracted with 0.6 M KCl. The KCl extract was then subjected to gel filtration, ammonium sulfate precipitation and high-performance liquid chromatography (HPLC). A protein with M(r) = 74 kD was obtained by this procedure and its NH2-terminal amino acid sequence was determined. The sequence of the first 19 amino acids was DTDADXXKXIADVYTALTE, suggesting that this protein was identical to serum albumin (M(r) = 74 kD). When the membrane fraction of blood cells in this animal was handled in the same manner, no appreciable amount of albumin was detected. These results suggest that the 74 kD serum albumin, possibly associated with bound T, may play an important role in the differentiation of germ cells during spermatogenesis of X. laevis testis.

Physicochemical and antibacterial properties of lactoferrin and its hydrolysate produced by heat treatment at acidic pH

In order to apply functionally active lactoferrin (Lf) to food products, the effect of pH on the heat stability of Lf was studied. Lf was easily denatured to an insoluble state by heat treatment under neutral or alkaline conditions, above pH 6. In contrast, it remained soluble after heat treatment under acidic conditions at pH 2 to 5, and the HPLC pattern of Lf heat-treated at pH 4 at 100 degrees C for 5 min was the same as that of native Lf. Lf was found to be very thermostable at pH 4, and could be pasteurized or sterilized without any significant loss of its physicochemical properties. Lf was hydrolyzed by heat treatment at pH 2 to 3 at above 100 degrees C, and its iron binding capacity and antigenicity were lost. But the antibacterial activity of the hydrolysate was found to be much stronger than that of native Lf. The antibacterial component of Lf hydrolysate produced by heat treatment at acidic pH was verified to be a peptide including the sequence of residues 1-54 from the N-terminal end of the bovine Lf molecule.

Antimicrobial peptides of lactoferrin

Lactoferrin was found to contain an antimicrobial sequence near its N-terminus which appears to function by a mechanism distinct from iron chelation. Antimicrobial peptides representing this domain were isolated following pepsin cleavage of human lactoferrin and bovine lactoferrin. The antimicrobial sequence was found to consist mainly of a loop of 18 amino acid residues formed by a disulfide bond between cysteine residues 20 and 37 of human lactoferrin, or 19 and 36 of bovine lactoferrin. The identified domain contains a high proportion of basic residues, like various other antimicrobial peptides known to target microbial membranes and it appears to be located on the surface of the folded protein allowing its interaction with surface components of microbial cells. The isolated domain, "lactoferrin", was shown to have potent broad spectrum antimicrobial properties and its effect was lethal causing a rapid loss of colony-forming capability. Such evidence points to the conclusion that this domain is the structural region responsible for the microbicidal properties of lactoferrin. The evidence also suggests the possibility that active peptides produced by enzymatic digestion of lactoferrin may contribute to the host defense against microbial disease.

Lactoferrin promotes nerve growth factor synthesis/secretion in mouse fibroblast L-M cells

Fibroblast cells are known to have an ability to synthesize and secrete nerve growth factor (NGF). To investigate the mechanism of action of the iron-binding protein, lactoferrin (Lf), on cultured animal cells, the effect of bovine Lf (bLf) on NGF synthesis/secretion in mouse fibroblast cells was examined. Both apo- and holo-bLf induced an increase in NGF content in the cell-conditioned medium(CM) of mouse L-M cells, a line derived from L929 fibroblast cells, with similar effectiveness. The increase in NGF content in the CM of L-M cells cultured with bLf was not dependent on the induction of increase in cell numbers, but was due to induction of de novo synthesis of NGF in individual cells by bLf. Human Lf(hLf) also increased NGF content. However, apo- and holo-bovine transferrin (bTf) failed to stimulate the NGF synthesis. The time-dependent induction of NGF in L-M cells by bLf was different from that induced by basic fibroblast growth factor (bFGF) and bLf showed an additive effect with bFGF. These results suggest that the induction of NGF synthesis depends on a mechanism different from iron transport or bFGF.

Role of cell-binding in the antibacterial mechanism of lactoferricin B

The antibacterial cell-binding properties of lactoferricin B, a potent bactericidal peptide derived from bovine lactoferrin, were investigated for the first time. To facilitate measurements of binding the peptide was radiolabelled by reduction and treatment with iodo-[1-14C]acetamide. 14C-lactoferricin B bound rapidly to the surface of Escherichia coli and Bacillus subtilis. The rate of binding was consistent with the rapid rate of killing caused by this peptide. The extent of binding was reduced in the presence of Mg2+ or Ca2+ ions which act to reduce its antimicrobial effectiveness. The optimal pH for binding was strain-dependent and the killing effect was maximal near the optimal pH for cell binding with each strain tested. These observations indicate that direct interaction of lactoferricin B with the cell surface is necessary for its lethal effect. The number of peptide molecules bound (> 10(6) per cell) was more than would be expected for binding to specific protein receptors. Lactoferricin B inhibited bacterial uptake of 3H-proline with effectiveness similar to polymyxin B, a known membrane-disruptive agent. The cell-binding event appears to lead to a disruption of normal permeability functions of the cytoplasmic membrane.

Lysozyme in cervical mucus of patients with chorioamnionitis

Lysozyme and lactoferrin, antimicrobial substances present in cervical mucus, play an important role in defense mechanisms against ascending infections in development of chorioamnionitis (CAM). In this study, we measured the concentration of lysozyme in cervical mucus, and studied its relationship with other factors, and obtained following results. The concentration of lysozyme in cervical mucus decreased more significantly in positive CAM in preterm labor than in negative CAM and control subjects (P < 0.001). A direct correlation between the concentrations of lysozyme and lactoferrin was observed (r = 0.709). In positive CAM, the concentration of elastase in cervical mucus reached a significantly high level (more than 8,000 micrograms/L), and a no correlation between the concentrations of elastase and lysozyme was observed. These findings suggest a reduction of the defense mechanism occurred because the concentrations of both lysozyme and lactoferrin in cervical mucus during preterm labor (positive CAM) decreased.

[Transcranial magnetic stimulation of the facial nerve--identification of the actual excitation site in the cat]

The site where transcranial magnetic stimulation excites the facial nerve was studied in 6 cats. Transcranial magnetic stimulation of the facial nerve was recorded from the left mentalis muscle. A figure-of-eight shaped magnetic coil was used, and coil induction direction had more influence on the facial nerve evoked compound muscle action potentials (CMAPs) than the coil position. No change could be detected in the CMAPs before and after craniotomy, after cerebellar lobectomy and after exposure of the facial nerve in the facial canal. The facial nerve was stimulated electrically at the porus, meatal portion, geniculum and horizontal portion. The latencies of the CMAPs for each portion were measured and compared with the magnetic response, which was coincidental with that of the meatal portion. The facial nerve was then transected distally from the porus, and CMAPs following magnetic stimulation were recorded at each step. The CMAPs disappeared when the nerve was transected at the fundus. The results of both approaches in this study led to the conclusion that transcranial magnetic stimulation excites the facial nerve at the meatal portion.

Killing of Candida albicans by lactoferricin B, a potent antimicrobial peptide derived from the N-terminal region of bovine lactoferrin

Candida albicans was found to be highly susceptible to inhibition and inactivation by lactoferricin B, a peptide produced by enzymatic cleavage of bovine lactoferrin. Effective concentrations of the peptide varied within the range of 18 to 150 micrograms/ml depending on the strain and the culture medium used. Its effect was lethal, causing a rapid loss of colony-forming capability. 14C-labeled lactoferricin B bound to C. albicans and the rate of binding appeared to be consistent with the rate of killing induced by the peptide. The extent of binding was diminished in the presence of Mg2+ or Ca2+ ions which acted to reduce its anticandidal effectiveness. Binding occurred optimally at pH 6.0 and killing was maximal near the same pH. Such evidence suggests the lethal effect of lactoferricin B results from its direct interaction with the cell surface. Cells exposed to lactoferricin B exhibited profound ultrastructural damage which appeared to reflect its induction of an autolytic response. These findings suggest that active peptides of lactoferrin could potentially contribute to the host defense against C. albicans.

MKK1 and MKK2, which encode Saccharomyces cerevisiae mitogen-activated protein kinase-kinase homologs, function in the pathway mediated by protein kinase C

The PKC1 gene of Saccharomyces cerevisiae encodes a homolog of mammalian protein kinase C that is required for normal growth and division of yeast cells. We report here the isolation of the yeast MKK1 and MKK2 (for mitogen-activated protein [MAP] kinase-kinase) genes which, when overexpressed, suppress the cell lysis defect of a temperature-sensitive pkc1 mutant. The MKK genes encode protein kinases most similar to the STE7 product of S. cerevisiae, the byr1 product of Schizosaccharomyces pombe, and vertebrate MAP kinase-kinases. Deletion of either MKK gene alone did not cause any apparent phenotypic defects, but deletion of both MKK1 and MKK2 resulted in a temperature-sensitive cell lysis defect that was suppressed by osmotic stabilizers. This phenotypic defect is similar to that associated with deletion of the BCK1 gene, which is thought to function in the pathway mediated by PCK1. The BCK1 gene also encodes a predicted protein kinase. Overexpression of MKK1 suppressed the growth defect caused by deletion of BCK1, whereas an activated allele of BCK1 (BCK1-20) did not suppress the defect of the mkk1 mkk2 double disruption. Furthermore, overexpression of MPK1, which encodes a protein kinase closely related to vertebrate MAP kinases, suppressed the defect of the mkk1 mkk2 double mutant. These results suggest that MKK1 and MKK2 function in a signal transduction pathway involving the protein kinases encoded by PKC1, BCK1, and MPK1. Genetic epistasis experiments indicated that the site of action for MKK1 and MKK2 is between BCK1 and MPK1.

[Lactoferrin in cervical mucus of patients with chorioamnionitis]

The antimicrobial activity of cervical mucus is regarded as a local defense mechanism against ascending infections by the vaginal bacterial flora. In this study, the content of lactoferrin in cervical mucus of patients with chorioamnionitis (CAM) and its correlation with other indicators of infection were determined. The results obtained are summarized as follows: 1. The lactoferrin content in cervical mucous was higher in pregnant than in non-pregnant women. It was significantly lower in CAM(+) patients than in CAM(-) patients (P < 0.001) in preterm labor and was lower in preterm labor than in full-term control (P < 0.002). Elastase contents in cervical mucus of CAM(+) patients were significantly higher than full-term control levels (P < 0.001), and showed a negative correlation with lactoferrin contents. 2. With regard to other indicators of infection, CRP, ESR, and WBC were higher in CAM(+) patients and fibronectin was detected (> 50 ng/ml) in the cervical mucus of all CAM(+) patients.

Effects of a novel thyrotropin-releasing hormone analogue, JTP-2942, on extracellular acetylcholine and choline levels in the rat frontal cortex and hippocampus

The effects of a novel thyrotropin-releasing hormone (TRH) analogue, N alpha-[(1S,2R)-2-methyl-4-oxocyclopentanecarbonyl]-L-histidyl-L-pr olinamide (JTP-2942) on acetylcholine (ACh) release and on the extracellular choline level were investigated in rat frontal cortex and hippocampus by microdialysis, and were compared with effects of TRH. JTP-2942 (0.3 mg/kg i.p.) produced a marked (> 300%) and persistent increase of ACh release in both the frontal cortex and hippocampus, while TRH (3 mg/kg i.p.) caused a significant but transient increase of ACh to about 200% in the frontal cortex. Both drugs significantly decreased the choline levels in both brain regions. Investigation of the effects of JTP-2942 (0.001-1 mM) and TRH (1 and 10 mM) on ACh release and choline levels when perfused through the dialysis probe revealed that JTP-2942 had a greater effect than TRH in both the frontal cortex and the hippocampus. The action of JTP-2942 was about 1000-fold more potent than that of TRH in both brain regions. Oral administration of JTP-2942 at a dose of 10 mg/kg markedly and persistently increased the release of ACh and at doses of 1-10 mg/kg decreased the extracellular choline level in the frontal cortex and hippocampus. These results also suggest that JTP-2942 has some selectivity for the hippocampus compared to the frontal cortex after both systemic administration and local injection. The increase of ACh release caused by JTP-2942 was completely antagonized by perfusion with tetrodotoxin (TTX, 1 microM), suggesting that the action of JTP-2942 on cholinergic neurons was mediated via neuronal activity.

Relationship between clinical symptoms and EEG findings in borderline personality disorder

Borderline personality disorder (BPD) was diagnosed in female patients (N = 41) between the ages of 18 and 30 using the Diagnostic Interview for Borderline Patients (DIB) and DSM-III. Comparing the EEG findings of BPD (N = 18) and non-BPD (N = 21) groups, there were no EEG findings characteristic of BPD. We also assessed the relationship between the EEG findings and DIB items. Positive spikes appeared in patients with high scores for Impulse Action Patterns, while wave and spike phantoms were observed in patients with high scores for Interpersonal Relations. Dividing the patients into BPD and non-BPD groups, a similar tendency to that observed from an analysis of all patients was observed in the non-BPD group, but no such tendency was observed in the BPD group. The results suggest that BPD patients include those in whom vulnerability of cerebral function plays an important role in the development of these two clinical symptoms as well as those in whom vulnerability of cerebral function plays almost no pathogenic role.

A gene, SMP2, involved in plasmid maintenance and respiration in Saccharomyces cerevisiae encodes a highly charged protein

The smp2 mutant of Saccharomyces cerevisiae shows increased stability of the heterologous plasmid pSR1 and YRp plasmids. A DNA fragment bearing the SMP2 gene was cloned by its ability to complement the slow growth of the smp2 smp3 double mutant (smp3 is another mutation conferring increased stability of plasmid pSR1). The nucleotide sequence of SMP2 indicated that it encodes a highly charged 95 kDa protein. Disruption of the genomic SMP2 gene resulted in a respiration-deficient phenotype, although the cells retained mitochondrial DNA, and showed increased stability of pSR1 like the original smp2 mutant. The fact that the smp2 mutant is not always respiration deficient and shows increased pSR1 stability even in a rho0 strain lacking mitochondrial DNA suggested that the function of the Smp2 protein in plasmid maintenance is independent of respiration. The SMP2 locus was mapped at a site 71 cM from lys7 and 21 cM from ilv2/SMR1 on the right arm of chromosome XIII.

Antibacterial spectrum of lactoferricin B, a potent bactericidal peptide derived from the N-terminal region of bovine lactoferrin

A physiologically diverse range of Gram-positive and Gram-negative bacteria was found to be susceptible to inhibition and inactivation by lactoferricin B, a peptide produced by gastric pepsin digestion of bovine lactoferrin. The list of susceptible organisms includes Escherichia coli, Salmonella enteritidis, Klebsiella pneumoniae, Proteus vulgaris, Yersinia enterocolitica, Pseudomonas aeruginosa, Campylobacter jejuni, Staphylococcus aureus, Streptococcus mutans, Corynebacterium diphtheriae, Listeria monocytogenes and Clostridium perfringens. Concentrations of lactoferricin B required to cause complete inhibition of growth varied within the range of 0.3 to 150 micrograms/ml, depending on the strain and the culture medium used. The peptide showed activity against E. coli O111 over the range of pH 5.5 to 7.5 and was most effective under slightly alkaline conditions. Its antibacterial effectiveness was reduced in the presence of Na+, K+, Mg2+ or Ca2+ ions, or in the presence of various buffer salts. Lactoferricin B was lethal, causing a rapid loss of colony-forming capability in most of the species tested. Pseudomonas fluorescens, Enterococcus faecalis and Bifidobacterium bifidum strains were highly resistant to this peptide.

Cloning and sequencing of the cDNA encoding tyrosinase of the Japanese pond frog, Rana nigromaculata

We cloned and sequenced the cDNA encoding tyrosinase (TYN) of the Japanese pond frog, Rana nigromaculata. The 3511-bp cDNA contained a 54-bp 5'-noncoding region, a 1596-bp open reading frame encoding TYN of 532 amino acids (aa), and a 1861-bp 3'-noncoding region. The aa sequence of frog TYN predicted from the cDNA sequence was homologous to that of mouse and human TYNs. The aa sequence including the copper-binding domain, which is likely the active center of TYN, was highly conserved among these three species and Neurospora crassa, Streptomyces antibioticus, and S. glaucescens. The frog TYN also contains possible glycosylation sites and conserved Cys at sites similar to those in the mouse and human TYNs. There are two hydrophobic regions at the N-terminus and near the C-terminus, which are likely the signal (leader) peptide and a transmembrane domain, respectively.

Absorption enhancement of polypeptide drugs by cyclodextrins. I. Enhanced rectal absorption of insulin from hollow-type suppositories containing insulin and cyclodextrins in rabbits

The absorption of insulin (from porcine pancreas) from the rectum of rabbits after the administration of hollow-type suppositories containing insulin and five kinds of cyclodextrins (CyDs) was investigated. Three types of suppositories were employed: suppository I containing insulin (approximately 26 IU/mg) and various amounts of each CyD in citric buffer solution at pH 3.0 or powder in its cavity, suppository II containing CyD without insulin, and suppository III containing insulin without CyD. Without CyD, the insulin and glucose levels in plasma were unchanged, whereas a significant increase in the plasma insulin concentration and a marked decrease in the glucose levels were found following simultaneous administration of insulin and CyDs by suppository I. The enhancing effect of CyD on rectal insulin absorption (absorption-enhancing effect) by chemically modified CyDs (heptakis(2,6-di-O-methyl)-beta-CyD (DM-beta-CyD) and 2-hydroxypropyl-beta-CyD (HP-beta-CyD)) was higher than those by natural CyDs (alpha-, beta-, and gamma-CyD). The area under the plasma concentration-time curve (AUC) and Cmax of insulin significantly decreased with the preadministration (administration of CyD 6, 24 and 48 h before rectal insulin administration) of DM-beta-CyD. The absorption-enhancing effect disappeared 24 h after preadministration. These results suggest that CyDs enhance insulin absorption from the rectum, and that attenuation of the membrane transport barrier function in the rectum recovers at a maximum of 24 h after administration of CyDs.

[Ocular effects of topical instillation of UF-021 ophthalmic solution in healthy volunteers]

Phase I studies, as divided into two stages, were conducted in healthy volunteers with the ophthalmic solution of UF-021, a novel prostaglandin metabolite-related compound, that was reported to exhibit potent intraocular pressure (IOP)-reducing activity in various species of animals. In the first stage, the vehicle as well as UF-021 ophthalmic solutions at concentration of 0.03%, 0.06% and 0.09% were applied topically to the eyes of 8 healthy volunteers to determine their respective effects through observations on the IOP, and local ocular and systemic side effects. In the second stage, 2 dosages of UF-021 ophthalmic solution, 0.06% and 0.12%, were applied topically to 11 healthy volunteers to investigate the IOP-reducing activities and local ocular side effects. The results revealed that ophthalmic solutions of UF-021 at concentrations ranging from 0.03% to 0.12% reduced IOP in a dose-dependent manner with neither systemic nor local ocular controversial side effects at those dosage levels. In summary, UF-021 ophthalmic solutions, when administered to healthy volunteers through single instillation, reduced IOP significantly without causing any side effects.

[Quantitative analyses of the normal throat flora of children with upper respiratory tract infections]

Relationship between the normal throat flora and pathogenic bacteria recovered from the throat in 139 children with upper respiratory tract infections in winter were studied using quantitative analyses. Pathogenic bacteria examined include S. pyogenes, H. influenzae, S. aureus, and S. pneumoniae, and the normal floras include alpha-streptococci, gamma-streptococci, Neisseria species, and Micrococci. Children with S. pyogenes in their throats (S. pyogenes group) were examined with anti-streptococcal antibodies such as anti-streptolysin O, anti-streptokinase, and anti-deoxyribonuclease B. Eighty seven pathogenic bacteria were recovered from 72 children (51.8%) out of 139. S. pyogenes and S. pneumoniae groups showed significantly lower alpha-streptococci and gamma-streptococci in incidence of appearance when compared with children with the no pathogenic bacteria in their throats (no bacteria group). H. influenzae group showed significantly lower gamma-streptococci and higher Neisseria sp. in incidence of appearance compared with the no bacteria group. Positive cases for anti-streptococcal antibodies showed a significantly lower alpha-streptococci in number compared with negative cases for antibodies and the no bacteria group, and a significantly lower gamma-streptococci in incidence of appearance compared with the no bacteria group. These data suggest that the normal throat flora may have a role in prevention of colonization by the pathogenic bacteria in vivo, as were shown in vitro by many authors, and that the quantitative analysis of the normal flora is useful because this methodology might reveal whether the bacteria recovered from the throat show the pathogenicity.

Identification of the bactericidal domain of lactoferrin

We report the existence of a previously unknown antimicrobial domain near the N-terminus of lactoferrin in a region distinct from its iron-binding sites. A single active peptide representing this domain was isolated following gastric pepsin cleavage of human lactoferrin, and bovine lactoferrin, and sequenced by automated Edman degradation. The antimicrobial sequence was found to consist mainly of a loop of 18 amino acid residues formed by a disulfide bond between cysteine residues 20 and 37 of human lactoferrin, or 19 and 36 of bovine lactoferrin. Synthetic analogs of this region similarly exhibited potent antibacterial properties. The active peptide of bovine lactoferrin was more potent than that of human lactoferrin having effectiveness against various Gram-negative and Gram-positive bacteria at concentrations between 0.3 microM and 3.0 microM, depending on the target strain. The effect of the isolated domain was lethal causing a rapid loss of colony-forming capability. Our studies suggest this domain is the structural region responsible for the bacterial properties of lactoferrin.

In vivo anti-tumor activity of arginine deiminase purified from Mycoplasma arginini

Arginine deiminase (EC 3.5.3.6) was purified to homogeneity from the cell extract of Mycoplasma arginini by molecular-sieve, anion-exchange and arginine-affinity chromatographies. The purified enzyme was composed of 2 identical sub-units with a molecular weight of 45.000 and had a pI of 4.7. Its Vmax value and Km value for L-arginine were estimated to be 50 units/mg protein and 0.2 mM, respectively. It exerted maximal enzyme activity at pH 6.0-7.5 and at 50 degrees C. The arginine deiminase was stable at neutral pH. When injected i.v. into mice, the half-life of the arginine deiminase in blood was about 4 hr. In culture, the enzyme strongly inhibited the growth of 6 kinds of mouse tumor cell lines by depleting L-arginine in the culture media. When the in vivo growth-inhibitory activity of arginine deiminase was tested for the 6 tumor cell lines, i.p. administration of the purified enzyme effectively prolonged the survival time of the mice injected with all kinds of the tumor cell lines. Especially, the in vivo growth of a hepatoma cell line, MH134, was completely prevented by the daily administration at a dose of 0.2 mg/mouse for 14 days. These results raise the possibility of the use of the arginine deiminase derived from Mycoplasma arginini as a new anti-tumor drug.

Spontaneous disappearance of arteriovenous fistula between the vertebral artery and deep cervical vein--case report

A 58-year-old female was readmitted with pulsatile tinnitus in the right ear 8 months after subtemporo-occipital transtentorial clipping of a peripheral superior cerebellar artery aneurysm. On examination, she was normal except for pulsatile bruit over the right mastoid region. Angiography showed a fistulous communication between the muscular branches of the right vertebral artery and the deep cervical vein. The incision of the aneurysm surgery was supratentorial, so the only possible cause of the upper cervical arteriovenous (AV) fistula was fine gold acupuncture needles implanted for bronchial asthma 18 years before. The AV fistula disappeared spontaneously after 1 month, possibly because of thrombosis of the affected veins.