Chiral discrimination of N-carbazole-carbonyl derivatives of alpha-amino acids with a short linear alkyl side chain by bovine serum albumin

Chiral discrimination of racemic carbazole carbonyl (CC)-amino acids with linear alkyl sidechain (C(1)-C(4)) by bovine serum albumin (BSA) was investigated by competitive replacement experiments using dansyl-L-proline and dansyl-D-norvaline as fluorescent probes. It was found that the CC derivatives of the D-forms of alanine (C(1)), amino butyric acid (C(2)), norvaline (C(3)), and norleucine (C(4)) bound to the dansyl-L-proline site much more strongly than their L-forms, whereas the interactions between both enantiomers of these amino acids with dansyl-D-norvaline site were slight.

Tuning of the porin expression under anaerobic growth conditions by his-to-Asp cross-phosphorelay through both the EnvZ-osmosensor and ArcB-anaerosensor in Escherichia coli

BACKGROUND

Widespread bacterial signal transduction circuits are generally referred to as 'two-component systems' or 'histidine (His)-to-aspartate (Asp) phosphorelays.' In Escherichia coli, as many as 30 distinct His-to-Asp phosphorelay signalling pathways operate in response to a wide variety of environmental stimuli, such as medium osmolarity and anaerobiosis. In this regard, it is of interest whether or not some of them together constitute a network of signalling pathways through a physiologically relevant mechanism (often referred to as 'cross-regulation'). We have addressed this issue, with special reference to the osmo-responsive EnvZ and anaero-responsive ArcB phosphorelay signalling pathways in E. coli.

RESULTS

Under standard aerobic growth conditions, it is well known that the osmoregulatory profile of the outer membrane porins (OmpC and OmpF) is mainly regulated by the EnvZ-OmpR phosphorelay system in response to medium osmolarity. In this study, it was found that, under anaerobic growth conditions, E. coli cells exhibit a markedly altered expression profile of OmpC and OmpF This profile was significantly different from that observed for the cells grown aerobically. Results from extensive genetic studies showed that, under such anaerobic growth conditions, the arcB gene encoding the anaero-sensory His-kinase appears to be an auxiliary genetic determinant that regulates the expression profile of porins. We then provided several lines of in vivo and in vitro evidence, which taken together, supported the following conclusions.

CONCLUSIONS

Under anaerobic growth conditions, porin expression is tuned not only by the authentic osmo-resposive EnvZ sensor, but also by the anaero-responsive ArcB sensor, in an OmpR-dependent manner. It is suggested that such ArcB-mediated cross-regulation plays a physiological role by integrating anaerobic respiratory signals into the porin regulation in E. coli anaerobiosis. The proposed model is a clear example of the interplay of two distinct His-to-Asp phosphorelay signalling pathways.

Japanese individuals do not harbor the T594M mutation but do have the P592S mutation in the C-terminus of the beta-subunit of the epithelial sodium channel: the Ohasama study

OBJECTIVE

To assess the implications of polymorphisms of the amiloride-sensitive epithelial sodium channel in essential hypertension in the Japanese population by determining the incidence of the T594M mutation in the , subunit of the epithelial sodium channel, and by screening the C-terminus of the epithelial sodium channel.

METHODS

Single-strand confirmational polymorphism (SSCP) analysis using two sets of primers which cover the last two-thirds of the last exon coding the B epithelial sodium channel and modification of a specific enzyme restriction site (NlaIII) for the T594M mutation were performed on 803 Japanese subjects. They were randomly selected from the study participants representative of a general population of Ohasama, Japan, who measured their home blood pressure. Polymerase chain reaction (PCR) products presenting a shift in SSCP gel, as well as controls, were directly sequenced by autoanalyser to identify the mutation.

RESULTS

SSCP analysis identified altered migration in five subjects. Four SSCP variants found by sequencing were heterogeneous for the P592S (CCT to TCT) mutation conserving the PY motif, although it was not significantly associated with either home or casual blood pressure values. The resting polymorphism was at codon Thr 594, leading to no change in the amino acid sequence (ACG to ACA). None of the PCR products were modified by NlaIII, indicating the absence of the T594M mutation.

CONCLUSIONS

The epithelial sodium channel variants at the C-terminus are not involved in the common form of essential hypertension in Japanese.

[A very elderly autopsy case of cecal cancer with pulmonary lymphangitis carcinomatosa]

A 91-year-old man was admitted with colliquative diarrhea, anorexia and weight loss. He had a history of healed tuberculosis, hypertension and atherosclerotic abdominal aortic aneurysms. On admission, shortness of breath without cough, exertional dyspnea, and ascites were also noticed. His chest X-ray and CT showed almost normal findings in the lung fields except for calcified old pleurisy. Since laboratory tests revealed thrombocytopenia, low fibrinogen, and increased CA19-9. DIC induced by an unknown cancer was diagnosed. He died on the eighth day due to progressive respiratory failure which did not respond to oxygen therapy. Autopsy revealed that he had a poorly differentiated adenocarcinoma in the cecum complicated with pulmonary lymphangitis carcinomatosa. Lymphangitis should be considered in the case of unexplained progressive respiratory failure developing in patient with cancer, even in the absence of X-ray findings.

Effects of semotiadil, a novel calcium antagonist, on the retina and optic nerve head circulation

The effects of semotiadil, a novel benzothiazine calcium antagonist, on the retinal and optic nerve head (ONH) tissue circulation were evaluated using the noninvasive laser speckle method. In urethane-anesthetized Dutch or albino rabbits, before and up to 90 min following intravenous injection of 400 microg/kg semotiadil fumarate (semotiadil group) or vehicle (control group), normalized blur value, a quantitative index of tissue blood velocity, in the retina (NB(retina)) or ONH (NB(onh)), was serially obtained with monitoring intraocular pressure (IOP) and systemic parameters: arterial pressure, pulse rate, arterial blood gas, and body temperature. There were no significant differences in IOP and the systemic parameters except arterial pressure between semotiadil and control groups during the experiments. Arterial pressure showed an acute and transient drop during the first 5 min after semotiadil administration. The time courses of the normalized blur value were significantly different between semotiadil and control groups in the retina (P = 0.0001, repeated measures two-way ANOVA), but not in the ONH (P = 0.6724). Changes in NB(retina) from the baseline in the semotiadil group was significantly greater than those in the control group 50 min or later after the administration (P < 0.0500, Mann-Whitney test). NB(onh) showed no significant differences between the two groups except during the first few min when arterial pressure acutely decreased in the semotiadil group. In conclusion, intravenously injected semotiadil increased the tissue blood velocity in the retina, but not in the ONH. This vascular selectivity in the ocular neural tissues differs from those of other calcium antagonists, such as nicardipine.

Effect of ifenprodil on aqueous humor dynamics and optic nerve head circulation in rabbits

The purpose of this study was to study the effects of ifenprodil, a cerebral vasodilator with alpha and N-methyl-D-aspartate (NMDA) receptor antagonistic activities, on aqueous humor dynamics and optic nerve head (ONH) circulation in rabbits. Experiments were performed during the dark phase in rabbits conditioned to a schedule of alternating 12-hr periods of light and dark. Effects on blood-aqueous barrier permeability (K(d)), aqueous flow rate (F), outflow facility to general blood circulation (C(gen)), and uveoscleral outflow (F(u) were determined fluorophotometrically. Effects on ONH tissue circulation were estimated using the laser speckle method. Unilateral topical administration of 0.5% ifenprodil solution decreased intraocular pressure (IOP) with a maximum reduction of 3.4 mmHg and an effect duration of 3 hr without effects on the contralateral eye. A single instillation of 0.5% ifenprodil had no significant effect on K(d), F, or C(gen), whereas it substantially increased F(u). Twenty-day, twice-daily unilateral 0.5% ifenprodil instillation significantly increased tissue blood velocity in the ONH only in the treated eye.

Cardiac infarcts increase sodium transporter transcripts (rBSC1) in the thick ascending limb of Henle

BACKGROUND

Enhanced expression of the kidney-specific sodium transporter, rBSC1, in the thick ascending limb of Henle (TAL) and of the renal water channel, aquaporin-2 (AQP2), in collecting duct has been identified in rats with congestive heart failure (CHF) as a cause for enhanced sodium and water retention in this condition. However, the mechanism of impaired urinary sodium excretion observed even in rats with mild cardiac dysfunction remains unknown.

METHODS

Male Sprague-Dawley rats with myocardial infarctions measuring 15 to 30% of the left ventricular circumference with no overt CHF were prepared. We measured the amount of rBSC1 or AQP2 mRNA using competitive polymerase chain reaction (PCR) by inducing a point mutation at the middle of the PCR product for rBSC1 or by deleting 180 bp from the 760 bp PCR product for AQP2, respectively. The results were confirmed by in situ hybridization. rBSC1 protein expression was examined by immunohistochemistry and Western blot analysis using a specific antibody against rBSC1.

RESULTS

Although plasma renin activity was slightly elevated in rats with myocardial infarction (MI), no significant differences in lung weight or plasma concentrations for aldosterone and atrial natriuretic peptide were observed between control rats and MI rats. Competitive PCR showed a significant increase in rBSC1 mRNA in the renal outer medulla and cortex of MI rats, which was confirmed by in situ hybridization. However, the AQP2 mRNA of these rats remained unchanged throughout the kidney. Renin-angiotensin II blockade by oral captopril administration did not influence the alteration in rBSC1 mRNA induced by myocardial infarction. Immunohistochemistry and Western blots showed the enhanced expression of rBSC1 protein in TAL of rats with small to moderate cardiac infarcts.

CONCLUSIONS

rBSC1 is up-regulated even in rats with small to moderate myocardial infarctions, which may enhance the sodium transport in the TAL in this pathophysiologic condition.

Chronic clinical course of two patients with severe corneal dystrophy caused by homozygous R124H mutations in the betaig-h3 gene

PURPOSE

To report the chronic clinical course of two patients with homozygous R124H mutations in the betaig-h3 gene.

METHODS

Case reports.

RESULTS

Two patients with homozygous R124H mutations in the betaig-h3 gene developed severe juvenile corneal opacities that required keratoplasty. After surgery, corneal opacities recurred and limited the recovery of visual acuity in the chronic follow-up.

CONCLUSION

In patients with homozygous R124H mutations in the betaig-h3 gene, recurrence of corneal opacities after keratoplasty limits the recovery of visual acuity in the chronic follow-up.

A patient with mitochondrial myopathy associated with isolated succinate dehydrogenase deficiency

We report on a boy with normal mental development who had muscle hypotonia and congenital dislocation of the hip and knee joints. Histochemical and biochemical examinations of his muscle specimen revealed no succinate dehydrogenase (SDH) activity. Since the NADH cytochrome c reductase and cytochrome c oxidase activities were normal, we concluded that he had an isolated SDH deficiency. Our patient provides further evidence for the clinical variability of this disorder.

The SixA phospho-histidine phosphatase modulates the ArcB phosphorelay signal transduction in Escherichia coli

The Escherichia coli SixA protein is the first discovered prokaryotic phospho-histidine phosphatase, which was implicated in a His-to-Asp phosphorelay. The sixA gene was originally identified as the one that interferes with, at its multi-copy state, the cross-phosphorelay between the histidine-containing phosphotransmitter (HPt) domain of the ArcB anaerobic sensor and its non-cognate OmpR response regulator. Nevertheless, no evidence has been provided that the SixA phosphatase is indeed involved in a signaling circuitry of the authentic ArcB-to-ArcA phosphorelay in a physiologically meaningful manner. In this study, a SixA-deficient mutant was characterized with special reference to the ArcB signaling, which allows E. coli cells to respond to not only external oxygen, but also certain anaerobic respiratory conditions. Here evidence is provided for the first time that the SixA phosphatase is a crucial regulatory factor that is involved in the ArcB signaling, particularly, under certain anaerobic respiratory growth conditions. We propose a novel mechanism, involving an HPt domain and a phospho-histidine phosphatase, by which a given multi-step His-to-Asp signaling can be modulated.

Advanced glycation end products in diabetic corneas

PURPOSE

Corneal complications are often associated with diabetes mellitus and can be vision threatening. Corneas in diabetic patients are exposed to increased glucose concentration despite cornea's avascular property, and this condition may contribute to the accumulation of advanced glycation end products (AGEs). The focus of this study was to examine the role of AGEs in the pathogenesis of diabetic keratopathy.

METHODS

An anti-AGE monoclonal antibody (6D12), which recognizes a N(epsilon)-carboxymethyl lysine (CML)-protein adduct as an epitope, was prepared. Immunohistochemical localization of CML was examined in human age-matched diabetic and nondiabetic corneas (8 of each). In vitro, type I collagen-, type IV collagen-, or laminin-coated 96-well plates were glycated by glucose-phosphate. In some experiments, aminoguanidine was present in the incubation mixture. The amounts of CML-protein adducts in the extracellular matrix (ECM) were determined by enzyme-linked immunosorbent assay using 6D12. SV40-immortalized human corneal epithelial cells were seeded onto modified or unmodified ECM in 96-well plates and allowed to attach for 3 hours. Attached cells were fixed, and the areas of attached cells in each condition were measured. Attached cells without fixation were removed, and cell number was counted.

RESULTS

In all of the 8 diabetic corneas, CML immunoreactivity was observed in the epithelial basement membrane, whereas CML immunoreactivity was not found in the corresponding area in 7 of 8 nondiabetic corneas. In vitro, nonenzymatic glycation of laminin on the culture dish attenuated adhesion and spreading of corneal epithelial cells. The presence of amninoguanidine in the incubation mixture during glycation inhibited CML formation and promoted the adhesion and spreading of corneal epithelial cells in a dose-dependent manner.

CONCLUSIONS

The accumulation of AGEs on the basement membrane, particularly on laminin, may play a causative role in the corneal epithelial disorders of diabetic patients.

The acute effects of cigarette smoking on human optic nerve head and posterior fundus circulation in light smokers

PURPOSE

To study the acute effects of cigarette smoking on tissue circulation in the optic nerve head (ONH) and posterior fundus in smokers with a short smoking history.

METHODS

Ten healthy smokers whose length of smoking history was within 2 years (age 25 +/- 1 years; smoking index (number of cigarettes smoked per day x length of smoking history in years) 16 +/- 4, mean +/- SE) were included in the study. Using the laser speckle method, normalised blur (NB) value, a quantitative index of tissue blood velocity, was measured every 0.125 s and averaged over three pulses across an area located in the temporal site of the ONH free of visible surface vessels (NBONH) and across an area located halfway between the macula and the ONH with no discrete vessels visible (NBch-ret). NBONH, NBch-ret and intraocular pressure (IOP) in one randomly chosen eye, and blood pressure (BP) and pulse rate (PR) were measured before, and 1, 5, 10, 15, 20, 25, 30, 45, 60 and 90 min after sham smoking. One week later, NBONH, NBch-ret and IOP in the same eye, and BP and PR were measured after cigarette smoking according to the same time schedule as in the control experiment.

RESULTS

After sham smoking, no parameter showed a significant change during the experiment. Differences in NBONH from the baseline were not significant between the smoking experiment and sham smoking experiment, while NBch-ret showed a significant difference at 30 min. Inter-group difference in the time course of the difference from baseline was significant (ANOVA, p = 0.0246, 0.0021). BP and PR were significantly increased between 1 and 20 min after smoking while IOP showed no significant change at any time of measurement.

CONCLUSIONS

In light smokers, cigarette smoking showed little effect on tissue blood velocity in the ONH and slightly decreased that in the posterior fundus, suggesting a significant increase in vascular resistance in these tissues.

[Neuroprotective effect of N-methyl-D-aspartate receptor antagonists in an experimental glaucoma model in the rat]

PURPOSE

To evaluate the neuroprotective effect of memantine and dizocilpine, which are noncompetitive open-channel blockers of the N-methyl-D-aspartate (NMDA) receptor, on glaucomatous optic neuropathy in an experimental glaucoma model in the rat.

METHODS

Experimental glaucoma was induced in the right eyes of 30 Wistar albino rats by intracameral injection of India ink followed by laser trabecular photocoagulation 4 days later. The left eye served as a control. Either memantine, dizocilpine, or phosphate-buffered saline (PBS) was injected intraperitoneally just before trabecular photocoagulation. Five days later, 3% fast blue was injected into both superior colliculi. The eyes were enucleated another 3 days later and flat mounts of the retinas were prepared. Labeled ganglion cells were counted in the area 1 mm away from the optic disc.

RESULTS

Five days after laser application, no significant intraocular pressure (IOP) change in the right eye was found among the 3 groups. In eyes treated with memantine or dizocilpine, significantly more ganglion cells were labeled.

CONCLUSION

Systemically applied memantine and dizocilpine had a neuroprotective effect against experimental glaucomatous optic neuropathy in the rat.

Media selection for refolding of thermolysin by use of immobilized preparation

Selection of the most effective medium for the correct refolding of thermolysin was performed. Thermolysin that had been denatured with 6 M guanidinium chloride at pH 2.0 could not be recovered to its activity larger than ca. 10% even when the denaturant was diluted with a conventional buffer solution. The amount of activity recovered by this method decreased with time. The recovered activity was ca. 20% at most where 1 M calcium chloride or 1.6 M calcium acetate was employed as the refolding medium instead of the conventional buffer solution. In this case also, the activity decreased with time. Not only the low recovered activity or yield, but also the elimination of the activity once recovered, was probably mainly due to the intermolecular interactions between protein molecules such as autolysis and aggregation. In order to exclude the influence of the intermolecular interactions and to select the effective media for the correct refolding of thermolysin, immobilized thermolysin was prepared using agarose gel. Employment of the immobilized preparation made it possible to quantitatively determine the refolding of thermolysin and results revealed that the salts of organic acid, such as potassium acetate and sodium acetate, were excellent media for refolding. The immobilization was confirmed to be available for the selection of protein refolding media and indispensable, especially in the case of proteases. Since these results were partly similar to those obtained in the case of subtilisin reported previously, results of both cases were compared.

Topographic distribution of aquaporin 2 mRNA in the kidney of dehydrated rats

BACKGROUND

Stimulation of arginine vasopressin results in an immediate redistribution of water channels (aquaporin 2; AQP2) in the apical membrane of the collecting ducts, leading to water reabsorption. Water restriction for >/=24 h increases AQP2 proteins in the whole collecting duct which is highest in the inner medulla of the kidney, indicating that dehydration enhances synthesis of this protein. Although increased expression of AQP2 mRNA under this condition has been reported, the increased ratio of mRNA expression in the three regions of the kidney, cortex, outer medulla, and inner medulla, during the dehydration is still unclear.

METHODS

We investigated the AQP2 transcripts using male Sprague-Dawley rats deprived of water for 24 h. Mimic cDNA for competitive polymerase chain reaction (PCR) was constructed by deleting 180 bp at the middle of a 780-bp partial PCR product for rat AQP2 cDNA. In situ hybridization of the kidney and Northern blotting of inner medulla were performed using a 60-bp oligo-cDNA probe which identified rat AQP2 transcripts in the collecting duct.

RESULTS

Dehydration resulted in a significant increase in plasma osmolality and arginine vasopressin concentration and urinary osmolality. Competitive PCR demonstrated that dehydration increased AQP2 transcripts in all parts of the kidney, but was highest in the inner medulla. Northern blotting confirmed the high increased rate of AQP2 transcription in the inner medulla. In situ hybridization showed markedly intensified signals in the inner medulla of dehydrated rats.

CONCLUSIONS

Our data indicate that dehydration increases the abundance of AQP2 transcripts which may be closely associated with enhancement in AQP2 protein synthesis reported previously. This topographically variable increase in transcription is considered to be one of the mechanisms involved in long-term regulation of water permeability in the collecting duct.

Non-invasive assessment of bone quality

A morphological filter and pipeline analysis was applied to computed radiographs (CR) to abstract the geometrical characteristics of the trabecular pattern and to analyze bone mechanical properties. By applying a morphological filter to the CR images, trabecular patterns were divided into 8 subset groups (n=O through 7) by the trabecular thickness. Sumset images were also derived from the thicker trabeculae group (n=2-5, 3-6, and 4-7) to examine the criteria relating the percentage of thicker trabeculae to the strength of the bone. A method to analyze the bone mechanical properties was developed, based on the hypothesis that data of connective line segments were loaded mechanically. By this method, trabeculae were analyzed in the fifth lumbar vertebrae from etidronic acid-treated and non-treated ovariectomized osteoporosis rat models, and in human third lumbar vertebrae. Consequently, it was shown that total loss of bone mass accompanied a reduction of consecutive trabecular number in the rat osteoporosis model, especially in parts of the bone having thick trabeculae. The reduction in number of connective trabeculae, from one cortical side to the other, occurred at a similar rate, along both the craniocaudal and anteroposterior axes in the vertebral bodies of the experimental osteoporosis rats. In the dynamic study with human third vertebral blocks, no significant correlation was observed between the bone mineral density of the bone specimens and their ultimate strength (R2=0.093). In contrast, the abstracted percentage of thicker trabeculae, derived from the sumset (n=2-5) images, showed a strong correlation with bony mechanical properties (Young's modulus: R2=0.915, maximum point load: R2=0.815). The result calculated by this methodology can serve as an excellent index to indicate bone strength under non-destructive, living conditions.

Relationships among blood pressures obtained using different measurement methods in the general population of Ohasama, Japan

To examine the relationships between casual, ambulatory and home blood pressure measurements in the general population, these measurements were obtained in 1,695 of 3,744 subjects aged 20 yr or older in Ohasama, Japan. Of these 1,695 subjects, 1,207 measured their home blood pressure more than 14 times in each of the morning and evening (881 untreated subjects including normotensives and untreated hypertensives, 56.4 +/- 11.5 yr of age; 326 treated subjects, 66.0 +/- 9.2 yr of age). We analyzed data in these 1,207 subjects, examining the distribution of each measurement, the relationships among measurements, and the factors affecting the blood pressure differences among the measurements. For systolic pressure, the casual measurement was the highest among the methods examined. The daytime ambulatory measurement was significantly higher than morning and evening home measurements. Morning home measurements were significantly higher than those in the evening. For diastolic pressure, however, the morning home measurement was the highest among the methods examined. Short-term pressure variability (standard deviation and variation coefficient of ambulatory measurements) was greater than long-term pressure variability (standard deviation and variation coefficient of home measurements). The pressure variability in treated subjects was greater than that in untreated subjects. The correlation between casual pressure and the other pressures was not as strong (r<0.567). Among the relationships between ambulatory and home measurements, the strongest correlation was observed between the 24-h ambulatory measurement and the morning home measurement (r=0.738) in untreated subjects. The morning home measurement was highly correlated with the evening home measurement (r>0.814). The differences among the methods examined were affected by blood pressure level and age. It should be noted that in elderly and treated subjects, blood pressure measurement using one method does not necessarily correlate with that obtained using the other methods. This information is useful for the estimation of the value of one type of blood pressure measurement from values obtained with other methods.

Characteristics of blood pressure measured at home in the morning and in the evening: the Ohasama study

OBJECTIVE

To determine the qualitative and quantitative differences of blood pressure measured at home (home measurement) in the morning versus the evening.

METHODS

Of 3744 participants, aged 20 years or older in the Ohasama population, more than 14 home measurements in the morning and in the evening, respectively, were obtained in each of 1207 individuals (881 untreated, 56.1 +/- 11.4 years and 326 treated, 66.0 +/- 9.2 years). A casual/screening measurement was also obtained in these individuals.

RESULTS

The home measurements in the morning were significantly higher than those in the evening. The bivariate linear regression analysis demonstrated that the difference between diastolic home measurement in the morning and that in the evening increased with an increase in diastolic home measurements. The multiple step-wise linear regression analysis, however, demonstrated that male sex, the use of antihypertensive medication, and SD of home measurements in individuals (blood pressure variability), but not level of home measurements, were positively associated with the difference between home measurement in the morning and that in the evening. The SD of home measurement in the evening in individuals was significantly larger than that in the morning, and the SD in treated individuals was significantly larger than that in untreated individuals. The correlations between casual and home measurements were moderate in untreated individuals (r = 0.509-0.567) but poor in treated subjects (r= 0.223-0.384). The correlations between home systolic measurements in the morning and in the evening were very close in both treated and untreated subjects (r = 0.814-0.902). The correlations between the SD of home measurements in the morning and in the evening were moderate in both treated and untreated individuals (r = 0.585-0.657).

CONCLUSIONS

Qualitative and quantitative differences in home blood pressure measurement, due to the differential time of measurement, should be taken into consideration in clinical use of home blood pressure measurements.

Herpes simplex virus in the trabeculum of an eye with corneal endotheliitis

PURPOSE

To report an eye with corneal endotheliitis and increased intraocular pressure in which the trabeculum demonstrated immunoreactivity for herpes simplex virus.

METHOD

Case report. A 62-year-old man presented with increased intraocular pressure, keratic precipitates, and corneal stromal edema in his left eye. The tissue excised during trabeculectomy was immunohistochemically examined for herpetic viruses.

RESULT

Immunoreactivity for herpes simplex virus was identified in the trabeculum.

CONCLUSION

Herpes simplex virus may cause trabeculitis and increased intraocular pressure in patients with corneal endotheliitis.

Identification of the calmodulin-binding domain of neuron-specific protein kinase C substrate protein CAP-22/NAP-22. Direct involvement of protein myristoylation in calmodulin-target protein interaction

Various proteins in the signal transduction pathways as well as those of viral origin have been shown to be myristoylated. Although the modification is often essential for the proper functioning of the modified protein, the mechanism by which the modification exerts its effects is still largely unknown. Brain-specific protein kinase C substrate, CAP-23/NAP-22, which is involved in the synaptogenesis and neuronal plasticity, binds calmodulin, but the protein lacks any canonical calmodulin-binding domain. In the present report, we show that CAP-23/NAP-22 isolated from rat brain is myristoylated and that the modification is directly involved in its interaction with calmodulin. Myristoylated and non-myristoylated recombinant proteins were produced in Escherichia coli, and their calmodulin-binding properties were examined. Only the former bound to calmodulin. Synthetic peptides based on the N-terminal sequence showed similar binding properties to calmodulin, only when they were myristoylated. The calmodulin-binding site narrowed down to the myristoyl moiety together with a nine-amino acid N-terminal basic domain. Phosphorylation of a single serine residue in the N-terminal domain (Ser5) by protein kinase C abolished the binding. Furthermore, phosphorylation of CAP-23/NAP-22 by protein kinase C was also found myristoylation-dependent, suggesting the importance of myristoylation in protein-protein interactions.