Selective loss of sphingosine 1-phosphate signaling with no obvious phenotypic abnormality in mice lacking its G protein-coupled receptor, LP(B3)/EDG-3

Sphingosine 1-phosphate (S1P) exerts diverse physiological actions by activating its cognate G protein-coupled receptors. Five S1P receptors have been identified in mammals: LP(B1)/EDG-1, LP(B2)/H218/AGR16/EDG-5, LP(B3)/EDG-3, LP(B4)/NRG-1/EDG-8, and LP(C1)/EDG-6. One of these receptors, LP(B1), has recently been shown to be essential for mouse embryonic development. Here we disrupted the lp(B3) gene in mice, resulting in the complete absence of lp(B3) gene, transcript, and LP(B3) protein. LP(B3)-null mice were viable and fertile and developed normally with no obvious phenotypic abnormality. We prepared mouse embryonic fibroblast (MEF) cells to examine effects of LP(B3) deletion on S1P-induced signal transduction pathways. Wild-type MEF cells expressed lp(B1), lp(B2), and lp(B3) but neither lp(B4) nor lp(C1), and they were highly responsive to S1P in phospholipase C (PLC) activation, adenylyl cyclase inhibition, and Rho activation. Identically prepared LP(B3)-null MEF cells showed significant decreases in PLC activation, slight decreases in adenylyl cyclase inhibition, and no change in Rho activation. Retrovirus-mediated rescue of the LP(B3) receptor in LP(B3)-null MEF cells restored S1P-dependent PLC activation and adenylyl cyclase inhibition. These results indicate a nonessential role for LP(B3) in normal development of mouse but show nonredundant cellular signaling mediated by a single type of S1P receptor.

[Retrospective evaluation of PSA density for selection of biopsy candidates with prostate specific antigen in the gray zone]

PURPOSE

We examined the usefulness of prostate specific antigen density (PSAD) for selection of biopsy candidate with prostate specific antigen levels between 4.1 and 10.0 ng./ml. in prostate cancer screening retrospectively.

MATERIALS AND METHODS

The screening was conducted on male candidates in Natori city, aged 55 years or older, for 6 years from 1994 through 1999. We could analyze serum PSA levels and PSA density in 118 men with PSA levels between 4.1 and 10.0 ng./ml. All of 118 men underwent ultrasound guided systematic prostate biopsy regardless of findings of digital rectal examination and transrectal ultrasound. Prostate volume was estimated by transrectal ultrasound measurements using the prolate ellipse formula (pi/6 x length x width x height). PSAD was calculated by dividing serum PSA level by prostate volume. Serum PSA levels were determined by Tandem-R assay.

RESULTS

In 118 men, twenty-five men had prostate cancer. There was no significant difference in mean PSA between those with prostate cancer and those without prostate cancer, but the difference was significant in the mean PSA density (mean 0.26 and 0.16, respectively, p < 0.0001). Receiver operating characteristic curves for PSA and PSAD demonstrated superior benefit for PSAD in 118 men. A sensitivity, a specificity, a positive predictive value and a negative predictive value of PSAD cut-off of 0.15 were 88%, 52.7%, 33.3% and 94.2%. PSAD cut-off of 0.18 showed the highest sum of sensitivity and specificity, which gave a sensitivity of 80%, a specificity of 72%, a positive predictive value of 43.5% and a negative predictive value of 93.1%. PSAD cut-off of 0.15 would seem to be preferable to cut-off of 0.18 because of less cancer missing.

CONCLUSIONS

Although further studies are needed to determine optimal cut-off value to be used in clinical practice, PASD seems to be useful for the selection of biopsy candidates with PSA levels of 4.1 to 10.0 ng./ml. in the prostate cancer screening.

Relationship between serum TNF activity and insulin resistance in dairy cows affected with naturally occurring fatty liver

To clarity the relationship between tumor necrosis factor (TNF) and insulin resistance in dairy cows affected with fatty liver, naturally occurring cases were investigated. The affected cows were classified into following three groups according to histopathologic findings of the liver: mild fat droplet deposition (group 1; n=11), severe fat droplet deposition (group 2; n=10), and cloudy swelling (group 3; n=8). Serum TNF activities in Group 2 (8.67 +/- 2.16 U/ml) and Group 3 (11.65 +/- 1.92 U/ml) were significantly higher than that in Group 1 (3.57 +/- 0.81 U/ml) (p<0.05). The insulin-tolerance tests showed that the insulin-stimulated glucose disposal rates (GDR) in Group 2 (27.6 +/- 7.8%) and Group 3 (15.8 +/- 9.1%) were significantly lower than that in Group 1 (41.7 +/- 9.8%). There was a significant negative correlation between serum TNF activity and GDR in affected cows (r=-0.56, p<0.01). These results indicate that serum TNF activity is correlated with insulin resistance in cows with fatty liver.

Ischemic preconditioning attenuates cardiac sympathetic nerve injury via ATP-sensitive potassium channels during myocardial ischemia

BACKGROUND

During myocardial ischemia, massive norepinephrine (NE) is released from the cardiac sympathetic nerve terminals, reflecting the sympathetic nerve injury. A brief preceding ischemia can reduce infarct size; this is known as ischemic preconditioning (PC). The effect of PC on sympathetic nerves, however, including its underlying mechanisms in dog hearts, has remained unclear. Thus, this study was designed to elucidate whether the activation of ATP-sensitive potassium (K(ATP)) channels is involved in the mechanism of cardiac sympathetic nerve protection conferred by PC.

METHODS AND RESULTS

Interstitial NE concentration was measured by the in situ cardiac microdialysis method in 45 anesthetized dogs. Five minutes of ischemia followed by 5 minutes of reperfusion was performed as PC. In the controls, the dialysate NE concentration (dNE) increased 15-fold after the 40-minute ischemia. PC decreased dNE at 40-minute ischemia by 59% (P<0.01), which was reversed by glibenclamide. A K(ATP) channel opener, nicorandil (25 microg. kg(-1). min(-1) IV), decreased dNE at 40 minutes of ischemia by 76% (P<0.01), which was also reversed by glibenclamide. During the PC procedure, no significant increase in dNE was detected, even with the uptake-1 inhibitor desipramine.

CONCLUSIONS

Cardiac sympathetic nerve injury during myocardial ischemia was attenuated by PC via the activation of K(ATP) channels, but the trigger of the PC effect is unlikely to be NE release in dog hearts.

Genomic and spectral analyses of long to middle wavelength-sensitive visual pigments of common marmoset (Callithrix jacchus)

The genetic basis of red-green color vision of common marmoset (Callithrix jacchus) is not fully understood. Here, we have cloned and characterized the three alleles at a locus that encode the long to middle wavelength-sensitive (LWS/MWS) visual pigments of this species. Using in situ hybridization, we localized this locus to the telomeric region of the long arm of X chromosome. The three visual pigments achieve the wavelengths of maximal absorption at 561, 553, and 539 nm and fully explain the red-green color vision of the common marmoset. The 'tri-allelic single-locus X-chromosome' model operates under the unique phenomenon, known as blood chimerism.

Physicochemical properties of a novel alpha-L-arabinofuranosidase from Rhizomucor pusillus HHT-1

The zygomycete fungus Rhizomucor pusillus HHT-1, cultured on L(+)arabinose as a sole carbon source, produced extracellular alpha-L-arabinofuranosidase. The enzyme was purified by (NH4)2SO4 fractionation, gel filtration, and ion exchange chromatography. The molecular mass of this monomeric enzyme was 88 kDa. The native enzyme had a pI of 4.2 and displayed a pH optimum and stability of 4.0 and 7.0-10.0, respectively. The temperature optimum was 65 degrees C, and it was stable up to 70 degrees C. The Km and Vmax for p-nitrophenyl alpha-L-arabinofuranoside were 0.59 mM and 387 micromol x min(-1) x mg(-1) protein, respectively. Activity was not stimulated by metal cofactors. The N-terminal amino acid sequence did not show any similarity to other arabinofuranosidases. Higher hydrolytic activity was recorded with pnitrophenyl alpha-L-arabinofuranoside, arabinotriose, and sugar beet arabinan; lower hydrolytic activity was recorded with oat-spelt xylan and arabinogalactan, indicating specificity for the low molecular mass L(+)-arabinose containing oligosaccharides with furanoside configuration.

Organ Doses from Radiation Therapy in Atomic Bomb Survivors

Previous surveys of radiation therapy among the Life Span Study (LSS) population at the Radiation Effects Research Foundation (RERF) revealed that 1,670 (1.4%) of the LSS participants received radiation treatments before 1984. The data on therapeutic radiation doses are indispensable for studying the relationship between radiation treatments and subsequent cancer occurrences. In this study, the radiation treatments were reproduced experimentally to determine the scattered radiation doses. The experiments were conducted using a female human phantom and various radiation sources, including a medium-voltage X-ray machine and a (60)Co gamma-ray source. Doses were measured using thermoluminescence dosimetry and ionization chambers. Radiation doses were determined for the salivary glands, thyroid gland, breast, lung, stomach, colon, ovary and active bone marrow. The results have been used for documenting the organ doses received by patients in previous surveys. The contribution of therapeutic irradiation to the occurrence of chromosome aberrations was studied using data on doses to active bone marrow from both radiation treatments and atomic bomb exposures in 26 RERF Adult Health Study participants. The results suggest that radiation treatments contributed to a large part of their frequencies of stable-type chromosome aberrations. The therapeutic radiation doses determined in the present study are available for investigating the effects of therapeutic irradiation on the subsequent primary cancers among atomic bomb survivors who received radiation treatments.

Acute phase response in naturally occurring coliform mastitis

Changes in the activities of serum cytokines and in acute phase response were observed in dairy cows with naturally occurring coliform mastitis. Seven cows with severe mastitis showed systemic and mammary inflammatory response throughout the observation period, and 11 cows with mild mastitis recovered and were able to be milked within 3 days of onset of mastitis. Serum interleukin (IL)-I and tumor necrosis factor (TNF) activities were higher in the severe group than in the mild group at the first appearance of symptoms. Elevated IL-1 activity was evident in the severe group throughout the observation period. Serum alpha-1-acidglycoprotein (alpha1AG) concentration began to rise with the beginning of mastitis in the severe group, and peaked at 9 days. Serum haptoglobin (Hp) concentrations peaked at 3 days, and decreased gradually after 3 days in the severe group. These results showed that there are dynamic changes in serum IL-1 activity and in serum alpha1AG and Hp concentrations in cows with severe coliform mastitis.

Ribosomal protein L5 has a highly twisted concave surface and flexible arms responsible for rRNA binding

Ribosomal protein L5 is a 5S rRNA binding protein in the large subunit and plays an essential role in the promotion of a particular conformation of 5S rRNA. The crystal structure of the ribosomal protein L5 from Bacillus stearothermophilus has been determined at 1.8 A resolution. The molecule consists of a five-stranded antiparallel beta-sheet and four alpha-helices, which fold in a way that is topologically similar to the ribonucleoprotein (RNP) domain. The molecular shape and electrostatic representation suggest that the concave surface and loop regions are involved in 5S rRNA binding. To identify amino acid residues responsible for 5S rRNA binding, we made use of Ala-scanning mutagenesis of evolutionarily conserved amino acids occurring in the beta-strands and loop regions. The mutations of Asn37 at the beta1-strand and Gln63 at the loop between helix 2 and beta3-strand as well as that of Phe77 at the tip of the loop structure between the beta2- and beta3-strands caused a significant reduction in 5S rRNA binding. In addition, the mutations of Thr90 on the beta3-strand and Ile141 and Asp144 at the loop between beta4- and beta5-strands moderately reduced the 5S rRNA-binding affinity. Comparison of these results with the more recently analyzed structure of the 50S subunit from Haloarcula marismortui suggests that there are significant differences in the structure at N- and C-terminal regions and probably in the 5S rRNA binding.

Retroperitoneal fibrosis and immune-complex glomerulonephritis

A 63-year-old man with rapidly progressive glomerulonephritis of the immune-complex type showed typical findings of idiopathic retroperitoneal fibrosis involving the left ureter resulting in hydronephrosis. Treatment with steroid improved both conditions. Our case and previously reported cases showing the same association of conditions support the hypothesis that the association is not fortuitous but reflects a common immunological mechanism.

Application of computer-assisted sperm analysis system to elucidate lack of effects of cyclophosphamide on rat epididymal sperm motion

A computer-assisted sperm analysis (CASA) system was used to examine the motion of epididymal spermatozoa derived from cyclophosphamide (CP)-treated male rats. Male rats were orally dosed daily for 1 week with 20 mg/kg of CP. Males were euthanized or were mated 3 times with untreated females at 1 day, 3 weeks, and 8 weeks after the final treatment. Significant decreases in testicular and epididymal weights and epididymal sperm counts of the treated animals were noted after 8-week recovery. Histopathological morphometry of the testis revealed minimal damage to spermatogonia at 1 day after the final treatment and to spermatocytes after 3-week recovery in the CP-treated group. On Caesarian section, increased post-implantation losses were found in females mated with CP-treated males in matings starting 1 day and 3 weeks after the final treatment. On the other hand, none of the sperm motion parameters of treated males derived from the CASA system exhibited significant changes at any time points, although the spermatozoa of treated males at 1 day and 3 weeks after the final treatment were damaged at the DNA level, and the spermatozoa of males after 8-week recovery had been the target cells of CP when they were spermatogonia in the testis. It was thus found that damaged spermatozoa could exhibit no changes on their motion when the damage was confined to the nuclei, and that the effect of CP on sperm nuclei was reversible.

Stable operation of a 300-m laser interferometer with sufficient sensitivity to detect gravitational-wave events within our galaxy

TAMA300, an interferometric gravitational-wave detector with 300-m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations; the interferometer was operated for over 10 hours stably and continuously. With a strain-equivalent noise level of h approximately 5x10(-21)/sqrt[Hz], a signal-to-noise ratio of 30 is expected for gravitational waves generated by a coalescence of 1.4M-1.4M binary neutron stars at 10 kpc distance. We evaluated the stability of the detector sensitivity with a 2-week data-taking run, collecting 160 hours of data to be analyzed in the search for gravitational waves.

Cerebral blood flow and oxygen metabolism during mild hypothermia in patients with subarachnoid haemorrhage

Cerebral blood flow and O2 metabolism during hypothermia (33-34 degrees C) was evaluated in 5 patients with aneurysmal subarachnoid haemorrhage by positron emission tomography (PET). Their preoperative clinical condition was WFNS scale IV or V. The patients received surface cooling postoperatively, and were maintained in a hypothermic state during transfer for radiological examination. Positron emission tomography revealed a decrease in cerebral blood flow and O2 metabolic rate. Cerebral blood flow was 34.8+/-15.1 ml/100 ml/min and the O2 metabolic rate was 1.85+/-0.61 ml/100 ml/min in areas of the middle cerebral artery ipsilateral to the ruptured aneurysms, whereas these values were 30.8+/-7.1 and 2.21+/-0.45 ml/100 ml/min, respectively, on the contralateral side. This represents a decrease of 37+/-27% compared to normal cerebral blood flow and 52+/-16% compared to normal O2 metabolic rate (p < 0.02) in the ipsilateral areas, and decreases of 44+/-13% and 43+/-12%, respectively, on the contralateral side. The present results reflected the luxury perfusion state in almost all cases and provide the first PET evidence of decreased cerebral blood flow and metabolic rate of O2 during hypothermia in humans.

Determination of canine beta2-microgloblin in plasma and urine by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay was developed for the determination of canine beta2-microglobulin (beta2-m) in plasma and urine. The detectable sensitivity for pure canine beta2-m was 0.05 microg/l and the analytical range was 0.1 to 50 microg/l. The mean analytical recovery when pure canine beta2-m was added to normal plasma was 101.9%. The mean analytical recovery in the urine was 102.1%. The intra-day variation coefficient was 3.1% in plasma, 4.3% in serum and 1.9% in urine. No difference was found between the concentration of beta2-m in plasma and serum (n=17). The concentration of beta2-m in the plasma of normal dogs was 1.82 +/- 0.57 mg/l (n=31). The mean excretion in 24 hr urine collected from normal dogs was 17.6 +/- 9.2 microg/l, 0.22 +/- 0.12 microg/kg of body weight or 14.2 +/- 9.4 microg/g of urine creatinine. The beta2-m creatinine index of random urine samples was 23.5 +/- 16.6 microg/g (n=26). There was a close correlation between the beta2-m creatinine index of 24 hr urine samples and that of random urine samples (r=0.872).

Effects of in vivo gene transfer of fibroblast growth factor-2 on cardiac function and collateral vessel formation in the microembolized rabbit heart

The effects of gene transfer of the secreted form of fibroblast growth factor-2 (FGF-2) were tested using an adenovirus vector in the microembolized rabbit heart. Japanese white rabbits underwent an intracoronary injection of 25-microm microspheres followed by recombinant adenovirus vectors encoding a secreted form of FGF-2 (FGF group), LacZ (LacZ group), or saline (saline group). Left ventricular (LV) systolic function was serially assessed by echocardiography. Vascular density was measured at 14 days with Azan and CD31 staining. The development of collateral vessels was assessed by measuring myocardial blood flow before and after the occlusion of the left anterior descending coronary artery. Percent fractional shortening (%FS) decreased after the microembolization, and improved gradually for 14 days in the FGF group only (41+/-1% (FGF) vs 32+/-1% (LacZ), 31+/-1% (saline), p<0.01). The vascular density and myocardial collateral blood flow were significantly higher in the FGF group in comparison with other groups. Transcoronary arterial gene transfer of the secreted form of FGF-2 was beneficial for the recovery of LV systolic function and development of collateral vessels in the microembolized rabbit heart.

Massive bleeding from multiple jejunal diverticula associated with an angiodysplasia: report of a case

We report herein the case of a 70-year-old woman who presented with massive bleeding from multiple jejunal diverticula. She was initially admitted to our hospital with massive melena. An upper gastrointestinal endoscopic examination revealed no bleeding site. Colonoscopy revealed clotted and red blood throughout the colon, and a small diverticulum in the ascending colon which was thought to be the source of bleeding. Following admission, she was treated conservatively at first, but melena continued and the anemia did not improve despite blood transfusions. A laparotomy was performed and multiple jejunal diverticula, distributed from 10 to 40 cm distal to the ligament of Treitz, were found. A segment of the jejunum containing all diverticula was resected. The most distal diverticulum contained a clot of blood, but no ulceration was observed. A histological examination revealed many dilated blood vessels in the mucosa and submucosa of this diverticulum, which were compatible with the findings of angiodysplasia. Based on these findings, we believe that angiodysplasia was the cause of bleeding from the jejunal diverticula in this case.

Mut-Test to detect substances suppressing spontaneous mutation due to oxidative damage

Since it has been considered that suppression of spontaneous mutation in cells is related to suppression of spontaneous carcinogenesis, it is significant to detect substances which suppress spontaneous mutation in bacterial cells such as Escherichia coli and Salmonella typhimurium in the environment. However, since the frequency of spontaneous mutation in bacteria is usually very low, generally 10(-8)-10(-10),it is difficult to determine significant suppressive ability of such substances on spontaneous mutation. A new method, Mut-Test, was developed by us, applying Luria & Delbruck fluctuation test, to detect substances which suppress spontaneous mutation using E. coli mutT mutant in which spontaneous mutation frequency due to oxidative damage is enhanced to approximately 500-1000 times of the wild type strain. Suppressive abilities of two hydroxyl radical scavengers: D(-)-mannitol and thiourea, were examined and clear positive results were obtained, suggesting that the radical scavengers are suitable as the positive control for the test. Using Mut-Test, suppressive abilities of four vitamins: L-ascorbic acid, beta-carotene, folic acid and riboflavin; 10 polyphenols: caffeic acid, ellagic acid, (-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, gallic acid, pyrocatechol, pyrogallol, quercetin and tannic acid which are recognized as antimutagens, were examined. Furthermore, the concentrations for 50% of suppressive abilities of five positive samples, L-ascorbic acid, folic acid, caffeic acid, pyrocatechol and pyrogallol were compared. Negative results were obtained in nine samples, riboflavin, tannic acid, etc. suggesting that their antimutagenic effect on cells may not be related to oxidative damage in cells.

Involvement of spinal NK2 and NMDA receptors in aversive behavior induced by intra-arterial injection of capsaicin

The spinal processing by which intra-arterial injection of capsaicin (CAP) induces vocalization response (VOR) was investigated in guinea pigs. Intrathecal pre-treatment with CP-96,345 (a selective NK(1) receptor antagonist, 50 nmol) did not affect the CAP-induced VOR. However, significant attenuation of the VOR was observed by intrathecal pre-treatment with a selective NK(2) receptor antagonist MEN-10,376 (40 nmol) accompanied with a significant change in the response modality. MK-801 [an N-methyl-D-aspartate (NMDA) receptor antagonist, 20 and 40 nmol] inhibited the CAP-induced VOR dose-dependently without affecting the response modalities. Furthermore, intrathecal co-treatment with 40-nmol MEN-10,376 and 40-nmol MK-801 resulted in a marked inhibitory effect on the VOR followed by a significant alteration of response modalities. Intrathecal pre-treatment with neurokinin A (NKA; a tachykinin NK(2) receptor agonist, 1 nmol) enhanced the CAP-induced VOR. These behavioral results suggested that spinal NK(2) and NMDA receptors might have priority over NK(1) receptors in the spinal processing of nociceptive information from the CAP-sensitive nociceptor.

Senile plaques in an aged western lowland gorilla

Senile plaques (SPs) were found in the cerebral cortex of a 44-year-old Western lowland gorilla (Gorilla gorilla gorilla). All the SPs were obtained as dense assemblies consisting of fibrous materials by silver impregnation, but were not detected by Congo red. More SPs were detected by immunostaining for amyloid beta protein (A beta) and a half of A beta-positive-SPs were also immunoreactive for apolipoprotein E. Moreover, all SPs were immunoreactive for A beta 42 and A beta 43, but not for A beta 40. SPs also did not contain A beta precursor protein-positive structures. These findings suggested that SPs in this case were diffuse plaques. To our knowledge, this is the first report of SPs in the gorilla.

Mild hypothermia mitigates post-ischemic neuronal death following focal cerebral ischemia in rat brain: immunohistochemical study of Fas, caspase-3 and TUNEL

Mild hypothermia is considered to have a protective effect during ischemic neuronal cell death. The present study provides experimental evidence for this beneficial role of mild hypothermia using reversible middle cerebral artery occlusion (MCAo) in a Sprague-Dawley (SD) rat model. MCAo was induced in rats for 1 h followed by reperfusion at different periods. Hematoxylin-eosin (HE) staining in normothermic (NT) 37 degrees C and hypothermic (HT) 33 degrees C groups of rats confirmed cerebral infarcts. The mean per cent infarct area was significantly reduced in the HT group of rats. Immunohistochemical analysis was done using anti-Fas and caspase-3 antibodies. The immunohistochemical expression of Fas and caspase-3 was demonstrable as early as 5 h after reperfusion, but the expression pattern maximized at 24 h after reperfusion. The expression of Fas and caspase-3 proteins showed a clear decrease in the HT group over the NT group. In situ detection of DNA fragmentation was done using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling method (TUNEL). TUNEL-positive cells were first observed at 5h after reperfusion and progressively increased by 24h. A higher number of TUNEL-positive cells was found in the NT group, but they were significantly decreased in the HT group. Further, DNA fragmentation was confirmed by size fractionation in agarose gel. These findings demonstrate a positive relation between the expression of Fas, caspase-3 and TUNEL-positive cells.

[A case of polypoid form of parameatal urethral cyst]

A 45-year-old man first noticed a soft tumor on his left lip of the urethral meatus at the age of 15. The lesion had gradually been increasing in size during the last 10 years. He presented to our clinic with division of urinary stream which had been persisting for about nine months. The tumor was resected, and histopathological examination revealed that it was a mucous cyst. The cyst had an outer wall of stratified squamous epithelium and an inner wall of stratified columnar epithelium. Since the inner wall was covered with epithelium originating from the urethral mucosa and the lesion was located outside the urethral meatus, a diagnosis of parameatal urethral cyst was made. Recently, parameatal urethral cyst has rarely been reported since it is often clinically in significant and remains asymptomatic. In our patient, the tumor showed polyploid growth and caused difficulty in urination. The mechanism of its development is considered based on a review of the literature.

Survival rate of microbes after freeze-drying and long-term storage

The survival rates of 10 species of microorganisms were investigated after freeze-drying and preserving in a vacuum at 5 degrees C. The survival rates varied with species. The survival rates immediately after freeze-drying were different among yeast, gram-positive bacteria, and gram-negative bacteria, and the change in the 10-year survival rate was species-specific. The survival rate of yeast, Saccharomyces cerevisiae, was about 10% immediately after drying, and the rate did not decrease significantly during the 10-year storage period. Survival rates after the drying of gram-positive bacteria, i.e., Brevibacterium flavum, B. lactofermentum, Corynebacterium acetoacidophilum, C. gultamicum, and Streptococcus mutans, were around 80%. The survival rate of Brevibacterium and Corynebacterium did not decrease greatly during the storage period, whereas the rate of S. mutans decreased to about 20% after 10 years. Survival rates after the drying of gram-negative bacteria, i.e., Escherichia coli, Pseudomonas putida, Serratia marcescens, and Alcaligenes faecalis, were around 50%. The survival rate decreased for the first 5 years and then stabilized to around 10% thereafter.

[Vascular and metabolic reserve in a case of hypoplasia of bilateral internal carotid arteries]

We report a 64-year-old right-handed man who presented with a hypoplasia of bilateral internal carotid arteries (ICAs). The patient complained of a vertigo and was diagnosed as having a benign paroxysmal positional vertigo. Upon neurological examination, he was completely free from neurological deficits. MR angiogram revealed an occlusion of both ICAs. On conventional angiogram, the right ICA was occluded about 3 cm distal from its origin, and the left ICA was occluded at the precavernous portion. There was an abundant collateral blood flow to the frontal, temporal and parietal lobes through the posterior communicating arteries. Both carotid canals were hypoplastic on 3D-CT. The patient was then diagnosed as having a hypoplasia of both ICAs. Using a positron emission tomography (PET), cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF), and vascular transit time (VTT) were measured during resting state, and the vascular reactivities to carbon dioxide inhalation (VRCO2), and to the intravenous administration of Acetazolamide (VRACZ) were also evaluated. There was no global or focal reduction in CBF and VTT was within normal limit, whereas a global reduction of CMRO2 caused mild decrease in OEF. Moreover, VRACZ was significantly decreased and an intracerebral steal phenomenon was observed in the parietal cortical areas, whereas VRCO2 was preserved. The discrepancy between VRACZ and VRCO2 observed could be related to the differences in the mechanisms underlying the vasodilating effects of carbon dioxide and ACZ.