Fast-ion-induced secondary ion emission from submicron droplet surfaces studied using a new coincidence technique with forward-scattered projectiles.

A mass spectrometric study of secondary ions emitted from droplet surfaces by MeV-energy heavy ion impact was performed to investigate fast-ion-induced molecular reaction processes on liquid surfaces. Herein, a new coincidence technique was developed between secondary ions and scattered projectile ions at a small forward angle. The advantages of this technique were demonstrated by measurement of the collision between 4-MeV C3+ and ethanol droplets. Secondary ion emission probabilities were obtained directly from the coincidence data. Notably, this technique enabled positive fragment ions that had not been identified in previous measurements to be observed by suppressing the strong background originating from gas-phase molecules more than 104-fold. H+, H3O+, C2H5 +, and C2H5O+ were found to be produced as major positive fragment ions, in addition to minor fragments H2 +, C2H3 +, and CH2OH+. Production of these ions suggests that competition between rapid hydrogen ion emission from multiply ionized states and intermolecular proton transfer accompanied by fragmentation through protonated ethanol occurs after fast heavy-ion collisions. Clarification of the positive fragment ions also revealed the characteristic features of negative ions. Negative ions were realized to exhibit higher degrees of fragmentation and reactivity compared with positive ions. Furthermore, the energy loss by forward-scattered ions during droplet penetration was used to evaluate the target thickness at a submicron level. Variations in secondary ion yield, mass distribution, and kinetic energies depending on the penetration length were observed below 1 µm. These results highlight the unknown mechanism of these "submicron effects" observed in secondary ion emission processes as a new phenomenon.

Positive and negative cluster ions from liquid ethanol by fast ion bombardment.

Secondary ion mass spectra have been measured for the first time for a liquid ethanol target bombarded by 2.0 MeV He(+) ions. Positive and negative ion spectra exhibit evidently a series of cluster ions of the forms [(EtOH)(n)H](+) and [(EtOH)(n)-H](-), respectively, in addition to light fragment ions from intact parent molecules. It was found that these cluster ions are produced only from liquid phase ethanol. Both positive and negative secondary ion spectra show similar cluster size distributions with almost the same decay slope. We also present for the first time the cluster ion distribution emitted from the liquid at different liquid temperatures.

Hepatic pre-sinusoidal vessels contract in anaphylactic hypotension in rabbits.

AIM: The purpose of this study was to determine whether anaphylactic hypotension in rabbits is accompanied by hepatic venoconstriction, and the effects of anaphylaxis on hepatic segmental vascular resistances and liver weight in isolated perfused rabbit livers. METHODS: The rabbits were sensitized by subcutaneous injection of antigen of 2.5 mg ovalbumin with complete Freund's adjuvant three times at 1 week interval. One week after sensitization, anaphylaxis was induced by an injection of 2.5 mg ovalbumin into the jugular vein of pentobarbital anaesthetized rabbits or the perfusate of rabbit livers perfused via the portal vein at a constant flow. Using the double occlusion technique to estimate the hepatic sinusoidal pressure, pre- (R(pre)) and post-sinusoidal (R(post)) resistances were calculated for the isolated perfused livers. RESULTS: An antigen injection into the sensitized rabbits caused not only a decrease in systemic arterial pressure from 79 +/- 2 to 40 +/- 4 mmHg, but also an increase in portal venous pressure (P(pv)) from 9.5 +/- 2.2 to 24.1 +/- 3.9 cmH(2)O. Portal hypertension persisted for 8 min after the antigen injection. An injection of antigen into the perfusate caused a marked increase in P(pv) from 5.4 +/- 0.1 to 28.6 +/- 2.4 cmH(2)O at 6 min, but only a slight increase in double occlusion pressure from 2.2 +/- 0.2 to 3.8 +/- 0.2 cmH(2)O, resulting in a selective increase in R(pret) rather than R(post). Concomitant with the hepatic pre-sinusoidal constriction, liver weight loss occurred. CONCLUSION: Anaphylactic hypotension in rabbits is accompanied by hepatic venoconstriction which is characterized by pre-sinusoidal contraction.

Effect of low-density lipoprotein apheresis on patients with peripheral arterial disease. Peripheral Arterial Disease LDL Apheresis Multicenter Study (P-LAS).

AIM: The effectiveness of low-density lipoprotein (LDL) apheresis for patients with peripheral arterial disease (PAD) was investigated to confirm a hypothesis based on subjective evidence that the amelioration of blood rheology would be the most contributing factor for improvement in clinical symptoms. Evaluation of the severity of intermittent claudication is difficult because of the lack of an accurate parameter to assess muscle ischemia during exercise, thus we objectively evaluated by non-invasive near-infrared spectroscopy (NIRS) on a treadmill in this study. METHODS: Thirty-one patients with PAD were evaluated for hemostatic function and physiological parameters such as ankle-brachial pressure index (ABI), maximum tolerated walking distance (MTWD) and recovery time (RT) or recovery ability index (RAI) on NIRS. Laboratory tests included plasma assays of total cholesterol, LDL-cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, and fibrinogen. The change in red-cell filtration rate was evaluated for the improvement of microcirculation. Statistical analysis was performed using the paired Student's t-test with Bonferroni's correction. RESULTS: A significant improvement in ABI and MTWD was observed after average 9.6+/-0.8 sessions of LDL apheresis treatment and the amelioration of microcirculation in ischemic muscle was objectively evaluated as significant improvement in RAI on NIRS. Rest pain was improved in all 5 patients with Fontaine's classification III or IV. A severe ulcer refractory to usual medications was dramatically diminished in the area by 10 sessions of LDL apheresis and fully healed 5 months after the final LDL apheresis treatment followed by medication. No angiographical change was observed in the arterial occlusive lesions in any patients. CONCLUSIONS: The effectiveness of LDL apheresis on the improvement in physiological parameters such as ABI, MTWD and clinical symptoms in patients with PAD was confirmed. The severity of intermittent claudication was objectively evaluated using non-invasive NIRS. The RT or RAI was useful parameter to evaluate the improvement in the ischemic symptoms of the extremities.

Injuries in professional motor car racing drivers at a racing circuit between 1996 and 2000.

BACKGROUND: Research on injuries in racing drivers is limited. OBJECTIVE: To gain more information about such injuries. METHODS: Injuries recorded during and after races between 1996 and 2000 were investigated using the medical charts from the circuit medical centre at Fuji Speedway, which is one of the biggest circuits in Japan. Races were in either single seat/formula cars or saloon cars. RESULTS: Data were obtained from 39 races in single seat cars (1030 participating cars) and 42 races in saloon cars (1577 cars). Fifty injuries were recorded during the single seat car races, and 62 during the saloon car races (injury rate 1.2 per 1000 competitors per race and 0.9 per 1000 competitors per race respectively). Thirteen injuries were recorded after the race, 12 of them in saloon car racing. Bruises were the major injury in single seat car racing (58%). Lower limb bruising was more common than upper limb bruising. Most of the injuries in saloon car racing (53.2%) were neck sprains. The incidence of concussion was high in both groups compared with other high risk sports. CONCLUSIONS: There were some differences in injuries between the two types of car. No serious injuries occurred except for one death. However, the driver's body is subjected to large forces in a crash, hence the high incidence of concussion. The injuries recorded after the race emphasise that motor racing is a demanding sport.

Different hepatic vascular response to noradrenaline and histamine between guinea-pig and rat.

AIM: Hepatic xenotransplantation from guinea-pig to rat has not been established. This failure is partly ascribed to differences in hepatic vascular characteristics between two species. However, the differences in hepatic vascular resistance distribution and responses to vasoconstrictors are not known. The present study was designed to determine basal levels of segmental vascular resistances and the responses to histamine and noradrenaline in isolated guinea-pig and rat livers. METHODS: The livers were haemoperfused (Hct 8.3%) via the portal vein at a constant flow. The sinusoidal pressure was measured by the double occlusion pressure, and was used to determine the pre- (Rpre) and post-sinusoidal (Rpost) resistances. RESULTS: There was no significant difference in basal total hepatic vascular resistance (Rt) between two species, whereas Rpre in rat (69% of Rt) was significantly greater than that in guinea-pig (61% of Rt). The responses to noradrenaline were similar; Rpre increased in a greater magnitude than Rpost, and liver weight was reduced. However, the noradrenaline-induced increase in Rt was greater in rats than in guinea-pigs. In contrast, histamine increased predominantly Rpost over Rpre, and increased liver weight in guinea-pig, while it affected no haemodynamic variables in rat. CONCLUSION: There exist species differences in the hepatic vasculature between rat and guinea-pig. Basal pre-sinusoidal resistance in rat is greater than that in guinea-pig. Although noradrenaline predominantly contracts pre-sinusoidal vessels in both species, histamine causes predominant post-sinusoidal vasoconstriction in guinea-pig liver, while it has no vasoactive effects on rat liver.

Stenting for atherosclerotic stenosis of the intracranial or skull base cerebral arteries. Effectiveness and problems.

SUMMARY: Since May 1992, we have performed percutaneous transluminal angioplasty (PTA) or stenting 70 times for 65 lesions in 62 patients with atherosclerotic stenosis of the intracranial or skull base cerebral arteries. Stenting was carried out nine times for nine lesions in nine cases. Stenting was performed on patients with an average age of 62. The patients were eight men and one woman. The stenotic lesions involved the internal carotid artery (petrous portion) in four cases, the internal carotid artery (cavernous portion) in two cases, the internal carotid artery (supraclinoid portion) in one case, the middle cerebral artery (M1) in one case, and the vertebral artery (V4) in one case. The degree of stenosis ranged from 70% to 99%, with a mean of 80%. A stent for coronary arteries was used in all cases. After PTA was carried out in four cases, their initial extension was inadequate, and dissection was performed in five cases after PTA. As for the results of the treatment, subarachnoid haemorrhage occurred in one case due to perforation by the guidewire, and a major deficit was accepted. During the operation, asymptomatic cerebral infarction by distal embolism occurred in one case. Although obstruction of the lesion occurred three months after treatment in one case, symptoms did not appear. Stents used for atherosclerotic stenosis of the intracranial or skull base cerebral arteries still do not have sufficient performance. Although the stenting had problems, such as a prolonged patent, in the present condition, it was effective in terms of recovery from complications due to PTA.

Education and propagation of intravascular surgery in okinawa.

SUMMARY: Okinawa is an island located on the southwest edge of the Japanese Islands in which about 1,300,000 people live, and is an area where selfconclusion type medical treatment is desired. In this area, intravascular surgery was only performed for several cases per year until 1998. From May 1999, intravascular surgery started being performed in earnest, and 140 or more cases of intravascular surgery per year were performed in 2002. In the meantime, various measures for the propagation and development of intravascular surgery that we undertook led to the increase in the number of cases. As a result, the choice of medical treatment has increased by propagating these medical treatments, and it seems that this has contributed to the welfare of the people of Okinawa.

After-pulse-discarding in single-photon detection to reduce bit errors in quantum key distribution.

We demonstrate fiber-optic quantum key distribution (QKD) at 1550 nm using single-photon detectors operating at 5 MHz. Such high speed single-photon detectors are essential to the realization of efficient QKD. However, after-pulses increase bit errors. In the demonstration, we discard after-pulses by measuring time intervals of detection events. For a fiber length of 10.5 km, we have achieved a key rate of 17 kHz with an error of 2%.

Significant accumulation of C(4)-specific pyruvate, orthophosphate dikinase in a C(3) plant, rice.

The C(4)-Pdk gene encoding the C(4) enzyme pyruvate, orthophosphate dikinase (PPDK) of maize (Zea mays cv Golden Cross Bantam) was introduced into the C(3) plant, rice (Oryza sativa cv Kitaake). When the intact maize C(4)-Pdk gene, containing its own promoter and terminator sequences and exon/intron structure, was introduced, the PPDK activity in the leaves of some transgenic lines was greatly increased, in one line reaching 40-fold over that of wild-type plants. In a homozygous line, the PPDK protein accounted for 35% of total leaf-soluble protein or 16% of total leaf nitrogen. In contrast, introduction of a chimeric gene containing the full-length cDNA of the maize PPDK fused to the maize C(4)-Pdk promoter or the rice Cab promoter only increased PPDK activity and protein level slightly. These observations suggest that the intron(s) or the terminator sequence of the maize gene, or a combination of both, is necessary for high-level expression. In maize and transgenic rice plants carrying the intact maize gene, the level of transcript in the leaves per copy of the maize C(4)-Pdk gene was comparable, and the maize gene was expressed in a similar organ-specific manner. These results suggest that the maize C(4)-Pdk gene behaves in a quantitatively and qualitatively similar way in maize and transgenic rice plants. The activity of the maize PPDK protein expressed in rice leaves was light/dark regulated as it is in maize. This is the first reported evidence for the presence of an endogenous PPDK regulatory protein in a C(3) plant.

Relationship between regional cerebral blood flow and verbal fluency in Alzheimer's disease.

Category and letter verbal fluency tests are widely used for dementia detection and severity measure. Performances of these tasks have been regarded to be mainly associated with the left frontal lobe function. However, some recent studies suggest that there are different neuropsychological bases between these two tasks, and the brain region which contributes to these performances still remains unclear in Alzheimer's disease (AD). To clarify the neural basis of verbal fluency in AD, we examined the relationship between performances of these tasks and regional cerebral blood flow (rCBF). Twenty-five AD patients were administered verbal fluency tasks and single photon emission computed tomography (SPECT) scans. Thirteen cortical regions of interest were symmetrically defined in each hemisphere. Letter fluency scores were correlated significantly only with the left prefrontal (Brodmann's area (BA) 10-46) regional cerebral blood flow (rCBF). In contrast, category fluency scores were correlated most strongly with the left temporal rCBF and also with the left prefrontal (BA 10-46) rCBF. In conclusion, the present study suggests that left prefrontal (BA 10-46) dysfunction contributes to decline in both letter and category fluency scores in AD, while typical posterior dysfunction of AD has a closer relationship with decline in category fluency scores.

Urinary type IV collagen excretion reflects renal morphological alterations and type IV collagen expression in patients with type 2 diabetes mellitus.

AIM: We tried to establish the significance of quantifying urinary type IV collagen (IV-C) excretion for the evaluation of renal involvement of type 2-diabetic patients. METHODS: Twenty patients (13 males and 7 females; age range 31 to 69 years) with type 2 diabetes mellitus had undergone renal biopsy and relationship between the severity of morphological alteration, IV-C expression and urinary IV-C excretion were examined. RESULTS: Urinary IV-C excretion significantly correlated with mesangial expansion score (p = 0.49, p < 0.05) and tubulointerstitial injury score (p = 0.56, p < 0.05). Furthermore, urinary IV-C excretion significantly correlated with both glomerular (r = 0.56, p < 0.01) and tubulointerstitial IV-C expression areas. Urinary protein excretion also correlated with mesangial expansion score and tubulointerstitial injury score. However, it did not correlate with the expression of IV-C in the kidney. CONCLUSIONS: These results suggest that urinary IV-C excretion reflects the pathogenetic process of diabetic nephropathy, which urinary protein excretion alone cannot do sufficiently. It can be concluded that urinary IV-C excretion could be a more useful marker for the evaluation of renal involvement of type 2-diabetic patients.

Mechanism of sodium load-induced hypertension in non-insulin dependent diabetes mellitus model rats: defective dopaminergic system to inhibit Na-K-ATPase activity in renal epithelial cells.

Obesity-related non-insulin dependent diabetes mellitus (NIDDM) is frequently accompanied by hypertension. The present study was designed to clarify this mechanism. We first determined the blood pressure in male Wistar fatty rats (WFR), one of the NIDDM model rats, and in Wistar lean rats (WLR) as the control, with a normal (0.7% NaCl) or high (7% NaCl) salt diet. We observed no difference in systolic and mean blood pressures between WFR and WLR. WFR, however, became extremely hypertensive as a result of ingesting the high salt diet. We next investigated the mechanism for sodium sensitivity in WFR. Although the urinary excretion of dopamine (DA), a potent natriuretic factor, which reflects the ability for renal DA production, was preserved in WFR, the sodium balance with the high salt diet was positive. Moreover, Na-K-ATPase activity in isolated proximal convoluted tubules (PCT) from WFR with a normal salt diet was significantly (p<0.05) higher than that from WLR. A high salt load produced a significant (p<0.05) decrease in Na-K-ATPase activity in WLR but not in WFR. Similarly, Na-K-ATPase activity in WLR with a normal salt diet was significantly (p<0.05) inhibited by DA (10(-5) M), but this was not true in WFR. Furthermore, urinary excretion of norepinephrine in WFR with a high salt diet was the highest among all the groups. These results indicate that WFR tend to develop salt-sensitive hypertension that could be caused by the excessive sodium retention occurring as the results of a defective dopaminergic system in the kidney that fails to inhibit Na-K-ATPase activity. Augmentation of the renal sympathetic nervous system may play some role in this setting.

High level expression of C4-specific NADP-malic enzyme in leaves and impairment of photoautotrophic growth in a C3 plant, rice.

The chloroplastic NADP-malic enzyme (NADP-ME) is a key enzyme of the C4 photosynthesis pathway in NADP-ME type C4 plants such as maize. To express the chloroplastic NADP-ME in leaves of a C3 plant, rice, full-length cDNAs encoding the rice C3-specific isoform and the maize C4-specific isoform of the enzyme were expressed under the control of the rice CAB: promoter. Transformants carrying the rice cDNA showed the NADP-ME activities in the leaves less than several-fold that of non-transformants, while those carrying the maize cDNA showed activities up to 30-fold that of non-transformants or about 60% of the NADP-ME activity of maize leaves. These results indicate that expression of the rice C3-specific NADP-ME is suppressed at co- and/or post-transcriptional levels by some regulation mechanisms intrinsic to rice, while that of the foreign C4-specific isoform can escape from such suppression. The accumulation of the maize C4-specific NADP-ME led to bleaching of leaf color and growth hindrance in rice plants under natural light. These deteriorative effects resulted from enhanced photoinhibition of photosynthesis due to an increase in the level of NADPH inside the chloroplast by the action of the maize enzyme.

Tracer studies on the incorporation of [2-14C]-DL-mevalonate into chlorophylls a and b, alpha-chaconine, and alpha-solanine of potato sprouts.

Chlorophyll and glycoalkaloids are synthesized in different parts of the potato plant including leaves, tubers, and sprouts. Although light stimulates the biosynthesis of both constituents, the question of whether the two biosynthetic pathways are under the same genetic control has not been resolved. This study investigated the dynamics of incorporation of labeled [2-(14)C]-DL-mavalonate into chlorophyll a, chlorophyll b, and the glycoalkaloids alpha-chaconine and alpha-solanine in potato sprouts after 7 and 14 days of storage in the light and in the dark. No chlorophyll synthesis occurred in the dark. Fractionation of the "glycoalkaloid" extract followed by high-performance liquid chromatography produced four peaks. The fractions were collected and analyzed for radioactivity. About 80% of the radioactivity resided in fraction 1, the composition of which is unknown. Two of the fractions, with 1-14% of the original label, were alpha-chaconine and alpha-solanine. The radioactivity derived from mevalonate largely resides in unidentified compound(s) eluting as a single peak on the HPLC column before the peaks associated with the glycoalkaloids. The specific radioactivity of alpha-chaconine and alpha-solanine increased approximately 2-fold in going from 7 to 14 days of exposure in the light and in the dark. These and additional observations point to the near identity of the dynamics of biosynthesis of the two glycoalkaloids. These data also implicate a non-mevalonate pathway for the synthesis of both chlorophylls and the glycoalkaloids and are consistent with independent genetic control of the concurrent formation of the two classes of compounds during greening of potatoes.

Cloning of a D-serine-regulated transcript dsr-1 from the rat cerebral cortex.

To obtain insight into the molecular mechanisms underlying the metabolism and functions of endogenous d-serine, we have explored d-serine-regulated transcripts in the neocortex of the infant rat treated with acute d-serine administration by using an RNA fingerprinting technique. Cloning and sequence analysis of the corresponding cDNAs to the identified transcripts have revealed that the dsr-1 (d-serine responsive transcript-1) mRNA is presumed to contain a novel sequence at the 5'-region, while the 631-base nucleotide sequence of its 3'-end is identical with that of rat M9.2 mRNA encoding a subunit of vacuolar type proton-ATPase. The predicted two open reading frames and their deduced amino acid sequences suggest that the dsr-1 product has a membrane spanning domain. The dsr-1 transcript was detected as a single band around 2.1 kb on the Northern blot. RT-PCR analyses have indicated that the dsr-1 transcript is expressed predominantly in the brain, lung, and testis, and that acute intraperitoneal injection of d-serine significantly upregulates dsr-1 expression in the neocortex 3 and 15 h later without affecting the levels of the M9.2 gene transcript. These results suggest that dsr-1 products may be involved in the d-serine-related metabolic or signaling pathways in mammalian brains.

Efficacy of alkalinized lidocaine for reducing pain on intravenous and epidural catheterization.

PURPOSE: To investigate whether increasing the pH of lidocaine could reduce the pain caused by its skin infiltration as well as that caused by intravenous and epidural needle insertion. METHODS: A randomized, double-blind trial was undertaken in patients who were allocated to receive topical anesthesia with either plain (plain group; n = 25) or alkalinized lidocaine (alkalinized group; n = 25). An alkalinized lidocaine solution was prepared by adding 8.4% sodium bicarbonate to a plain 1% lidocaine solution at a ratio of 1 : 10. Pain was assessed using the verbal analog scale (VAS). RESULTS: In the alkalinized group, the VAS scores on skin infiltration in the hand (2.5 +/- 1.4) and the back (2.7 +/- 1.4) were significantly lower than the respective scores in the plain group (3.5 +/- 1.4, and 4.9 +/- 1.9). Although the VAS score on intravenous needle insertion did not differ between the two groups, the VAS score on epidural needle insertion was significantly lower in the alkalinized group (1.3 +/- 1.0) than in the plain group (3.6 +/- 1.3). CONCLUSIONS: Alkalinization of lidocaine was effective in attenuating pain on skin infiltration and on epidural needle insertion.

Propofol improves recovery from paraquat acute toxicity in vitro and in vivo.

OBJECTIVE: To investigate whether the antioxidative sedatives propofol and thiopental can improve recovery from acute paraquat toxicity in A549 cells and in mice. DESIGN: Prospective, controlled, dose-response, in vitro study and prospective, controlled animal study. SETTING: A university animal research laboratory. SUBJECTS: Established human lung cultured cells and male SPF ICR mice. INTERVENTIONS: Paraquat-treated (0.2 mM) A549 cells were incubated either with the antioxidative sedatives propofol (0-0.56 mM) or thiopental (0-2.0 mM), or the nonantioxidative sedatives diazepam (0-3.0 mM), midazolam (0-3.0 mM) and ketamine (0-9.0 mM), as well as the antioxidative drugs, trolox (0-2.0 mM), alpha-tocopherol (0-4.4 mM), antioxidative-processed food (AOB; 0-1.0 mg/ml), superoxide dismutase (SOD; 0 and 3,000 U/ml) and ulinastatin (0 and 50,000 U/ml), for 48 h. Paraquat-treated mice received i.v. injections of 10 mg/kg propofol, 5 mg/kg thiopental, 4.0 mg/kg trolox, 100 mg/kg alpha-tocopherol, 10 mg/kg AOB or 5,000 U/kg SOD, b.i.d. for 4 days (n = 10 each). MEASUREMENTS AND RESULTS: Post-administered propofol and thiopental, as well as the antioxidative drugs, trolox, alpha-tocopherol and AOB, improved A549 cell survival in vitro. The non-antioxidative sedatives SOD and ulinastatin were not protective. An i.p. injection of 50 mg/kg of paraquat resulted in a survival rate of 40% in mice at day 6. Propofol, trolox, alpha-tocopherol and AOB significantly lowered the mortality rate (80% survival), while thiopental did not. CONCLUSION: Post i.v. injection of propofol is protective against paraquat-induced damage. Propofol can be given during mechanical ventilatory support after paraquat poisoning.

Natural progression of osteochondritis dissecans of the humeral capitellum: initial observations.

PURPOSE: To determine the earliest findings, subsequent changes, and natural course of osteochondritis dissecans of the humeral capitellum. MATERIALS AND METHODS: Among 95 patients with osteochondritis dissecans of the humeral capitellum, 16 (mean age, 12.5 years) were selected for this retrospective study because they seemed to have early osteochondritis dissecans and had been followed up without any surgical treatment for 6 months or more (mean, 3.5 years). RESULTS: The initial imaging appearances of the 16 patients' lesions were divided into two types: localized subchondral bone flattening without fragments in seven, and nondisplaced fragments in nine. Patients with lesion flattening had younger ages and significantly shorter durations of symptoms, and most had open growth plates. In five of the seven with flattening, new bone formed over the flattened bone, and the fragments united after arm motion reduction. In contrast, patients with nondisplaced fragments at clinical presentation had longer durations of symptoms with continued arm motion, and their nondisplaced fragments failed to unite. CONCLUSION: The earliest feature of osteochondritis dissecans is subchondral bone flattening, over which new bone subsequently forms. The new bone then can unite with the underlying bone. However, if subjected to repetitive forces over a given time, unstable fragments develop. These fragments, even if not yet displaced, are unable to unite.

[Endogenous D-serine in mammalian brains].

It is well established that, like glycine and D-alanine, D-serine potentiates glutamate neurotransmission via the N-methyl-D-aspartate (NMDA) receptor by selective stimulation of its strychnine-insensitive glycine site and acts as a co-agonist of the glutamate receptor. D-Serine has been found to modify behavioral changes associated with higher brain functions such as memory, convulsion, anxiety, psychotomimetic-induced abnormal behavior and cerebellar ataxia. Interestingly, a substantial amount of free D-serine has been demonstrated in mammalian brains, although it has long been presumed that D-amino acids are uncommon in mammals. Free D-serine is predominantly concentrated in the brain with a persistent high content throughout life. The patterns of the regional variations and the postnatal changes in brain D-serine are closely correlated with those of the R2B subunit of the N-methyl-D-aspartate (NMDA) type excitatory amino acid receptor. Moreover, D-serine is released to the extracellular space and taken up into the brain homogenates, C6 glioma cells and primary culture of astrocytes of the rat cerebral cortex. Recently, the conversion of L-serine to its D-form by serine racemase has been suggested by in vivo and in vitro experiments. These data are consistent with the view that D-serine might be an intrinsic positive modulator of the brain NMDA receptor containing the R2B subunit and play a pivotal role in controlling behavioral expression in mammals.