Reduction of APOE accounts for neurobehavioral deficits in fetal alcohol spectrum disorders.

A hallmark of fetal alcohol spectrum disorders (FASD) is neurobehavioral deficits that still do not have effective treatment. Here, we present that reduction of Apolipoprotein E (APOE) is critically involved in neurobehavioral deficits in FASD. We show that prenatal alcohol exposure (PAE) changes chromatin accessibility of Apoe locus, and causes reduction of APOE levels in both the brain and peripheral blood in postnatal mice. Of note, postnatal administration of an APOE receptor agonist (APOE-RA) mitigates motor learning deficits and anxiety in those mice. Several molecular and electrophysiological properties essential for learning, which are altered by PAE, are restored by APOE-RA. Our human genome-wide association study further reveals that the interaction of PAE and a single nucleotide polymorphism in the APOE enhancer which chromatin is closed by PAE in mice is associated with lower scores in the delayed matching-to-sample task in children. APOE in the plasma is also reduced in PAE children, and the reduced level is associated with their lower cognitive performance. These findings suggest that controlling the APOE level can serve as an effective treatment for neurobehavioral deficits in FASD.

Reliability of Telepsychiatry Assessments Using the Attention-Deficit/Hyperactivity Disorder Rating Scale-IV for Children With Neurodevelopmental Disorders and Their Caregivers: Randomized Feasibility Study.

BACKGROUND: Given the global shortage of child psychiatrists and barriers to specialized care, remote assessment is a promising alternative for diagnosing and managing attention-deficit/hyperactivity disorder (ADHD). However, only a few studies have validated the accuracy and acceptability of these remote methods. OBJECTIVE: This study aimed to test the agreement between remote and face-to-face assessments. METHODS: Patients aged between 6 and 17 years with confirmed Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition diagnoses of ADHD or autism spectrum disorder (ASD) were recruited from multiple institutions. In a randomized order, participants underwent 2 evaluations, face-to-face and remotely, with distinct evaluators administering the ADHD Rating Scale-IV (ADHD-RS-IV). Intraclass correlation coefficient (ICC) was used to assess the reliability of face-to-face and remote assessments. RESULTS: The participants included 74 Japanese children aged between 6 and 16 years who were primarily diagnosed with ADHD (43/74, 58%) or ASD (31/74, 42%). A total of 22 (30%) children were diagnosed with both conditions. The ADHD-RS-IV ICCs between face-to-face and remote assessments showed "substantial" agreement in the total ADHD-RS-IV score (ICC=0.769, 95% CI 0.654-0.849; P<.001) according to the Landis and Koch criteria. The ICC in patients with ADHD showed "almost perfect" agreement (ICC=0.816, 95% CI 0.683-0.897; P<.001), whereas in patients with ASD, it showed "substantial" agreement (ICC=0.674, 95% CI 0.420-0.831; P<.001), indicating the high reliability of both methods across both conditions. CONCLUSIONS: Our study validated the feasibility and reliability of remote ADHD testing, which has potential benefits such as reduced hospital visits and time-saving effects. Our results highlight the potential of telemedicine in resource-limited areas, clinical trials, and treatment evaluations, necessitating further studies to explore its broader application. TRIAL REGISTRATION: UMIN Clinical Trials Registry UMIN000039860; http://tinyurl.com/yp34x6kh.

[Surgical Resection as Local Therapy for Sister Mary Joseph's Nodule Due to Pancreatic Tail Cancer].

We experienced a case of resection of a metastatic umbilical tumor(Sister Mary Joseph's nodule: SMJN)derived from a pancreatic tail carcinoma. The patient was a 70-year-old woman. She visited her previous doctor with a chief complaint of lower abdominal pain and came to our hospital due to suspicion of pancreatic tail cancer. She was found to have metastases to multiple organs which was unresectable by surgery. After chemotherapy up to the second-line of treatment, she was diagnosed to have progressive disease. The decision was made to provide the best supportive care for the patient. Thereafter, the patient developed SMJN. She had hemorrhage from the tumor accompanied by body movement, and her activity of daily living became impaired. She had difficulty controlling the bleeding despite repeated hemostatic treatment at the outpatient clinic and at her home. However, she required frequent blood transfusions for her severe anemia. Therefore, we performed a resection of the SMJN to control bleeding and to relieve her symptoms. She had a good postoperative course and was discharged on the fifth postoperative day. Due to deterioration of her general condition, she expired on the 59th day after surgery. However, the patient was able to live at home without bleeding or pain by the umbilical tumor. The local resection was considered to be useful as a palliative surgical treatment for SMJN.

Safety and effectiveness of ferric citrate hydrate in serum phosphorus management of patients with chronic kidney disease: a long-term, real-world, observational, post-marketing surveillance study.

BACKGROUND: Ferric citrate hydrate (FC) is an oral iron-based phosphate binder that is used to treat hyperphosphatemia in patients with chronic kidney disease (CKD). This post-marketing surveillance study was performed to investigate the long-term safety and effectiveness of FC. METHODS: This prospective, multicenter, observational post-marketing surveillance study was performed in a real-world setting in Japan. The study involved CKD patients with hyperphosphatemia receiving FC who were undergoing either hemodialysis or peritoneal dialysis or were non-dialysis-dependent. Adverse drug reactions, iron- and erythrocyte-related parameters (i.e., levels of serum ferritin, transferrin saturation, and hemoglobin), and serum levels of phosphorus, corrected calcium, and intact parathyroid hormone were monitored for up to 104 weeks. RESULTS: Safety was evaluated in 2723 patients. Of these patients, 20.5% discontinued FC because of adverse events, and 3.9% discontinued FC because of unsatisfactory effectiveness. Iron-related parameters gradually increased after the initiation of FC treatment but stabilized after week 36. Effectiveness was analyzed in 2367 patients. Serum phosphorus immediately decreased, and the effect persisted for 104 weeks. CONCLUSION: In this 104 week surveillance study, no new safety concerns were noted. The safety profile was not obviously different from those in pre-approval clinical trials and the 52 week interim report of this surveillance study. The serum ferritin level of most patients was below the upper limit of the target range, and iron overload risk was not evident. Long-term FC treatment effectively controlled serum phosphorus.

Predictors of a difficult Pringle maneuver in laparoscopic liver resection and evaluation of alternative procedures to assist bleeding control.

PURPOSE: To evaluate the predictors of a difficult Pringle maneuver (PM) in laparoscopic liver resection (LLR) and to assess alternative procedures to PM. METHODS: Data from patients undergoing LLR between 2013 and 2020 were reviewed retrospectively. Univariate and multivariate analyses were performed and the outcomes of patients who underwent PM or alternative procedures were compared. RESULTS: Among 106 patients who underwent LLR, PM could not be performed in 18 (17.0%) because of abdominal adhesions in 14 (77.8%) and/or collateral flow around the hepatoduodenal ligament in 5 (27.8%). Multivariate analysis revealed that Child-Pugh classification B (p = 0.034) and previous liver resection (p < 0.001) were independently associated with difficulty in performing PM in LLR. We evaluated pre-coagulation of liver tissue using microwave tissue coagulators, saline irrigation monopolar, clamping of the hepatoduodenal ligament using an intestinal clip, and hand-assisted laparoscopic surgery as alternatives procedures to PM. There were no significant differences in blood loss (p = 0.391) or transfusion (p = 0.518) between the PM and alternative procedures. CONCLUSIONS: Child-Pugh classification B and previous liver resection were identified as predictors of a difficult PM in LLR. The alternative procedures were found to be effective.

Anesthesia and surgery induce a functional decrease in excitatory synaptic transmission in prefrontal cortex neurons, and intraoperative administration of dexmedetomidine does not elicit the synaptic dysfunction.

Postoperative delirium (POD), a syndrome of confusion and inattention, frequently occurs after anesthesia and surgery. The prefrontal cortex (PFC) plays key roles in executive functions and cognitive controls. However, the neuropathogenesis of POD in the PFC remains largely unknown. We investigated whether anesthesia and surgery induced neurofunctional changes in the mouse PFC. After laparotomy was performed under isoflurane anesthesia, PFC neuronal activities were compared at the synaptic level using whole-cell patch-clamp recordings. A battery of behavioral tests measuring natural and learned behaviors, and effects of intraoperative dexmedetomidine were also examined. In the anesthesia/surgery group showing changes in natural and learned behaviors, the frequency of excitatory synaptic responses in PFC pyramidal neurons was decreased after the surgery without any changes in the response kinetics. On the other hand, neuronal intrinsic properties and inhibitory synaptic responses were not changed. In the anesthesia/surgery group administered intraoperative dexmedetomidine, the excitatory synaptic transmission and the behaviors were not altered. These results suggest that anesthesia and surgery induce a functional reduction selectively in the PFC excitatory synaptic transmission, and intraoperative dexmedetomidine inhibits the plastic change in the PFC excitatory synaptic input.

Methionine controls insulin/mammalian target of rapamycin complex 1 activity by modulating tuberous sclerosis complex 2 stability.

Tuberous sclerosis complex 2 (TSC2) is a tumor-suppressor protein that is partially regulated by insulin, energy, oxygen, and growth factors. Mutations in the TSC2 gene and loss of TSC2 promote cell growth by the mammalian target of rapamycin complex 1 (mTORC1) activation. Furthermore, S-adenosylmethionine (SAM) sensor upstream of mTORC1 indirectly inhibits mTORC1 activity via the methionine metabolite SAM. Here, we investigated the effects of methionine on insulin/TSC2/mTORC1 activity. Our results showed that methionine affected TSC2 stability and abolished TSC2 localization to the lysosome. Moreover, activation of insulin signaling contributed to TSC2 degradation in a methionine deprivation-dependent manner. Thus, methionine and insulin crosstalk occurred via TSC2.

AMP-activated protein kinase regulates ß-catenin protein synthesis by phosphorylating serine/arginine-rich splicing factor 9.

ß-catenin is a multi-functional protein with a central role in regulating embryonic development and tissue homeostasis. The abnormal accumulation of ß-catenin, due to disrupted ß-catenin degradation or unregulated ß-catenin synthesis, causes the development of cancer. A recent study showed that the overexpression of proto-oncogene serine/arginine-rich splicing factor 9 (SRSF9) promotes ß-catenin accumulation via binding ß-catenin mRNA and enhancing its translation in a manner that is dependent on the mechanistic target of rapamycin (mTOR). However, the regulation of the interaction between SRSF9 and mRNA of ß-catenin remains unclear. Here, we show that AMP-activated protein kinase (AMPK) phosphorylates SRSF9 at the RNA-interacting SWQDLKD motif that plays a major role in determining substrate specificity. The phosphorylation by AMPK inhibits the binding of SRSF9 to ß-catenin mRNA and suppresses ß-catenin protein synthesis caused by SRSF9 overexpression without changing the ß-catenin mRNA levels. Our findings suggest that AMPK activators are potential therapeutic targets for SRSF9-derived overproduction of ß-catenin in cancer cells.

MIG12 is involved in the LXR activation-mediated induction of the polymerization of mammalian acetyl-CoA carboxylase.

Liver X receptors (LXR) α and ß are a family of nuclear receptors that regulate lipogenesis by controlling the expression of the genes involved in the synthesis of fatty acids. MID1IP1, which encodes MIG12, is a target gene of LXR. MIG12 induces fatty acid synthesis by stimulating the polymerization-mediated activation of acetyl-CoA carboxylase (ACC). Here, we show that LXR's activation stimulates ACC polymerization in HepG2 cells by increasing the expression of MIG12. A knockdown of MID1IP1 abrogated the stimulation completely. The mutations of MIG12's leucine-zipper domain reduced the interaction between MIG12 and ACC, thus decreasing the MIG12's capacity to stimulate ACC polymerization. These results indicate that LXR's activation stimulates lipogenesis not only through the induction of the genes encoding lipogenic enzymes but also through MIG12's stimulation of ACC polymerization.

Vascular Bursts Act as a Versatile Tumor Vessel Permeation Route for Blood-Borne Particles and Cells.

Dynamic bursting in tumor vasculature has recently sparked interest as a novel particle transportation route for drug delivery. These bursts facilitate the transport of sub-100 nm nanoparticles into tumors, though their contribution on the access of other blood-borne particles remains unknown. To evaluate the versatility of this phenomenon, the in vivo kinetics of a variety of intravenously injected particles and their penetration in tumor xenografts and allografts are compared. Dextran, polymeric micelles, liposomes, and polymeric vesicles with diameters ranging from 32 to 302 nm are found to colocalize in virtually all vascular bursts. By mathematical modeling, the burst vent size is estimated to be 625 nm or larger, indicating the dynamic and stochastic formation of large permeation routes in tumor vasculature. Furthermore, some burst vents are found to be µm-sized, allowing the transport of 1 µm microspheres. Moreover, antibody drugs and platelets are capable of utilizing vascular burst transportation, demonstrating the application of this phenomenon to other types of therapeutics and cellular components. These findings indicate the vast potential of vascular bursts, extending the biological and therapeutic significance of this phenomenon to a wide range of blood-borne particles and cells.

Brown Rice Inhibits Development of Nonalcoholic Fatty Liver Disease in Obese Zucker (fa/fa) Rats by Increasing Lipid Oxidation Via Activation of Retinoic Acid Synthesis.

BACKGROUND: White rice and its unrefined form, brown rice, contain numerous compounds that are beneficial to human health. However, the starch content of rice can contribute to obesity, a main risk factor for nonalcoholic fatty liver disease (NAFLD). OBJECTIVES: We investigated the effect of rice consumption on NAFLD and its underlying molecular mechanism. METHODS: We randomly divided 7-week-old male obese Zucker (fa/fa) rats, an animal model of NAFLD, into 3 groups (n = 10 each) fed 1 of 3 diets for 10 weeks: a control diet (Cont; AIN-93G diet; 53% cornstarch), a white rice diet (WR; AIN-93G diet with cornstarch replaced with white rice powder), or a brown rice diet (BR; AIN-93G diet with cornstarch replaced with brown rice powder). Liver fat accumulation and gene expression related to lipid and vitamin A metabolisms, including retinoic acid (RA) signaling, were analyzed. RESULTS: Hepatic lipid values were significantly decreased in the BR group compared with the Cont group, by 0.4-fold (P < 0.05). The expression of genes related to hepatic fatty acid oxidation, such as carnitine palmitoyltransferase 2, was approximately 2.1-fold higher in the BR group than the Cont group (P < 0.05). The expression of peroxisomal acyl-coenzyme A oxidase 1 and acyl-CoA dehydrogenase medium chain was also significantly increased, by 1.6-fold, in the BR group compared with the Cont group (P < 0.05). The expression of VLDL-secretion-related genes, such as microsomal triglyceride transfer protein, was also significantly higher in the BR group (2.4-fold; P < 0.05). Furthermore, aldehyde dehydrogenase 1 family member A1, an RA synthase gene, was 2-fold higher in the BR group than the Cont group (P < 0.05). CONCLUSIONS: Brown rice prevented development of NAFLD in obese Zucker (fa/fa) rats. The beneficial effects of pregelatinized rice on NAFLD could be manifested as increased fatty acid oxidation and VLDL secretion, which are regulated by RA signaling.

AMP-activated protein kinase regulates alternative pre-mRNA splicing by phosphorylation of SRSF1.

AMP-activated protein kinase (AMPK) regulates cellular energy homeostasis by inhibiting anabolic processes and activating catabolic processes. Recent studies have demonstrated that metformin, which is an AMPK activator, modifies alternative precursor mRNA (pre-mRNA) splicing. However, no direct substrate of AMPK for alternative pre-mRNA splicing has been reported. In the present study, we identified the splicing factor serine/arginine-rich splicing factor 1 (SRSF1) as a novel AMPK substrate. AMPK directly phosphorylated SRSF1 at Ser133 in an RNA recognition motif. Ser133 phosphorylation suppressed the interaction between SRSF1 and specific RNA sequences without altering the subcellular localization of SRSF1. Moreover, AMPK regulated the SRSF1-mediated alternative pre-mRNA splicing of Ron, which is a macrophage-stimulating protein receptor, by suppressing its interaction with exon 12 of Ron pre-mRNA. The findings of this study revealed that the AMPK-dependent phosphorylation of SRSF1 at Ser133 inhibited the ability of SRSF1 to bind RNA and regulated alternative pre-mRNA splicing.

Anti-nociceptive and anxiolytic effects of systemic flupirtine and its direct inhibitory actions on in vivo neuronal mechanical sensory responses in the adult rat anterior cingulate cortex.

Flupirtine is a non-opioid centrally acting analgesic that has been in clinical use, and is reported to act on neuronal ion channels and neurotransmitter receptors. However, its action on emotional aspects of pain is still unknown. In this study, we examined whether flupirtine has anxiolytic action and assayed its direct actions on the anterior cingulate cortex (ACC) at the single neuronal and synaptic levels. Anti-nociceptive and anxiolytic effects of flupirtine were evaluated by von Frey test and elevated plus-maze (EPM) in adult rats. The effects of flupirtine on firings and synaptic currents in the rat ACC were examined using in vivo extracellular and brain slice patch-clamp recording techniques, respectively. Systemic administration of flupirtine increased paw withdrawal threshold, and reduced anxiety-like behavior in the EPM. ACC neurons fired spontaneously. Mechanical stimulation of the contralateral hind paw with the von Frey filaments increased firing from the basal spontaneous activity. Intravenous administration of flupirtine reduced both spontaneous and stimulus-evoked firing frequency in the ACC. Flupirtine microinjected into the ACC also inhibited the spontaneous and evoked-responses. In brain slices, flupirtine did not induce any detectable outward currents, but it prolonged the decay time of GABAergic inhibitory synaptic responses. These results suggest that flupirtine directly augments GABAergic synaptic currents and suppresses evoked mechanical nociceptive responses in the ACC. This direct action in the ACC may reduce emotional aspect of pain and induce anxiolytic action.

Niclosamide activates the AMP-activated protein kinase complex containing the ß2 subunit independently of AMP.

AMP-activated protein kinase (AMPK) regulates cellular energy homeostasis by suppressing anabolic processes and activating catabolic processes. AMPK activators are an important therapeutic target for metabolic syndrome due to favorable physiological effects of AMPK activation on metabolism. Recent studies show that niclosamide, an FDA-approved anthelmintic drug that exerts an uncoupling effect on the mitochondria of the parasite, improves blood glucose levels and reduces hepatic steatosis in mice via AMPK activation. Niclosamide is thought to activate AMPK by increasing AMP/ATP ratio through mitochondrial uncoupling, but details of its action remain unclear. In this study, we found that niclosamide also activates the AMPK complex, which contains the AMP-insensitive γ subunit. Further, niclosamide shows greater AMPK activation for the AMPK complex containing ß2 subunit, but not the ß1 subunit. This effect was inhibited by substituting the Ser108 residue of the ß2 subunit to alanine. Niclosamide displays a novel AMPK activation mechanism independent of the increase in AMP/ATP ratio.

PEG-OligoRNA Hybridization of mRNA for Developing Sterically Stable Lipid Nanoparticles toward In Vivo Administration.

Lipid nanoparticles (LNPs) exhibit high potential as carriers of messenger RNA (mRNA). However, the arduous preparation process of mRNA-loaded LNPs remains a huge obstacle for their widespread clinical application. Herein, we tackled this issue by mRNA PEGylation through hybridization with polyethylene glycol (PEG)-conjugated RNA oligonucleotides (PEG-OligoRNAs). Importantly, mRNA translational activity was preserved even after hybridization of 20 PEG-OligoRNAs per mRNA. The straightforward mixing of the PEGylated mRNA with lipofectamine LTX, a commercial lipid-based carrier, just by pipetting in aqueous solution, allowed the successful preparation of mRNA-loaded LNPs with a diameter below 100 nm, whereas the use of non-PEGylated mRNA provided large aggregates above 100- and 1000-nm. In vivo, LNPs prepared from PEG-OligoRNA-hybridized mRNA exhibited high structural stability in biological milieu, without forming detectable aggregates in mouse blood after intravenous injection. In contrast, LNPs from non-PEGylated mRNA formed several micrometer-sized aggregates in blood, leading to rapid clearance from blood circulation and deposition of the aggregates in lung capillaries. Our strategy of mRNA PEGylation was also versatile to prevent aggregation of another type of mRNA-loaded LNP, DOTAP/Chol liposomes. Together, our approach provides a simple and robust preparation method to LNPs for in vivo application.

The adhesion molecule cadherin 11 is essential for acquisition of normal hearing ability through middle ear development in the mouse.

Cadherin 11 (Cdh11), a member of the cadherin adhesion molecule family, is expressed in various regions of the brain as well as the head and ear. To gain further insights into the roles of Cdh11 in the development of the ear, we performed behavioral tests using Cdh11 knockout (KO) mice. KO mice showed reduced acoustic startle responses and increased thresholds for auditory brainstem responses, indicating moderate hearing loss. The auditory bulla volume and ratio of air-filled to non-air-filled space in the middle ear cavity were reduced in KO mice, potentially causing conductive hearing loss. Furthermore, residual mesenchymal and inflammatory cells were observed in the middle ear cavity of KO mice. Cdh11 was expressed in developing mesenchymal cells just before the start of cavitation, indicating that Cdh11 may be directly involved in middle ear cavitation. Since the auditory bulla is derived from the neural crest, the regulation of neural crest-derived cells by Cdh11 may be responsible for structural development. This mutant mouse may be a promising animal model for elucidating the causes of conductive hearing loss and otitis media.

Small-Cell Lung Cancer Comorbid with Pulmonary Mycobacterium avium Infection: A Case Report.

BACKGROUND: Small-cell lung cancer (SCLC) rarely coexists with pulmonary Mycobacterium avium intracellular complex (MAC) infection. The key drug for SCLC treatment is etoposide, which is metabolized by cytochrome P-450 (CYP) 3A4. Meanwhile, the key drugs for pulmonary MAC infection are clarithromycin (CAM) and rifampicin (RFP), and their metabolism influences CYP3A4. Therefore, treatment of concurrent SCLC and pulmonary MAC infection is difficult, and to the best of our knowledge, no report of treatments for concurrent SCLC and pulmonary MAC infection has been published. Patient Concerns and Diagnoses: A 65-year-old man presented to our hospital with abnormal findings of chest computed tomography: (1) a hilar region nodule in the left lung and mediastinal lymphadenopathy and (2) a thick-walled cavity lesion in the right upper lobe of the lung. After further examinations, the former lesions were diagnosed as SCLC, cT4N3M0, stage IIIC and the latter as pulmonary MAC infection, fibrocavitary disease. INTERVENTIONS AND OUTCOMES: Concurrent treatment was conducted with discontinuation of CAM and RFP before and after etoposide administration. Specifically, intravenous cisplatin and etoposide were administered on day 1 and days 1-3, respectively, and CAM, RFP, and ethambutol (EB) were administered orally on days 6-22 every 4 weeks. Concurrent radiotherapy was added to the drug administration on days 1-27 of the first cycle. The chemotherapy was continued for 4 cycles, followed by continuation of CAM and RFP administration. EB was discontinued because of optic nerve disorder. The treatments were conducted completely and safely, and both of the SCLC lesions and the MAC lesion were improved. CONCLUSIONS: Treatments for concurrent SCLC and pulmonary MAC infection may be successfully conducted with discontinuation of CAM and RFP before and after etoposide administration.

ß-Carotene prevents bone loss in hind limb unloading mice.

ß-Carotene has been reported to be useful to maintain a positive balance of bone turnover. However, the effects of ß-carotene on bone loss remain to be elucidated in mice with hind limb unloading. Therefore, we investigated whether ß-carotene prevented bone loss induced by skeletal hind limb unloading in mice. Female 8-week-old ddY mice were divided into six groups (n = 6-8 each) and subjected to: (1) normal housing, (2) sham unloading fed a control diet, (3) hind limb unloading fed a control diet, (4) hind limb unloading fed a 0.025% ß-carotene-containing diet, (5) hind limb unloading fed a 0.05% ß-carotene-containing diet, and (6) hind limb unloading fed a 0.25% ß-carotene-containing diet. After 3 weeks, bone mineral density of the tibia was markedly reduced by unloading, which was prevented by 0.025% ß-carotene. Histological analysis revealed a hind limb unloading-induced decrease in the calcified bone of the femur, which was slightly prevented by 0.025% ß-carotene. The 0.025% ß-carotene-containing diet increased the gene expression of osteoprotegerin in the bone marrow cells in unloading mice. These results suggest that a ß-carotene-containing diet may preserve bone health in subjects with disabilities as well as in astronauts.

Isolation and amino acid sequence of a dehydratase acting on d-erythro-3-hydroxyaspartate from Pseudomonas sp. N99, and its application in the production of optically active 3-hydroxyaspartate.

An enzyme catalyzing the ammonia-lyase reaction for the conversion of d-erythro-3-hydroxyaspartate to oxaloacetate was purified from the cell-free extract of a soil-isolated bacterium Pseudomonas sp. N99. The enzyme exhibited ammonia-lyase activity toward l-threo-3-hydroxyaspartate and d-erythro-3-hydroxyaspartate, but not toward other 3-hydroxyaspartate isomers. The deduced amino acid sequence of the enzyme, which belongs to the serine/threonine dehydratase family, shows similarity to the sequence of l-threo-3-hydroxyaspartate ammonia-lyase (EC 4.3.1.16) from Pseudomonas sp. T62 (74%) and Saccharomyces cerevisiae (64%) and serine racemase from Schizosaccharomyces pombe (65%). These results suggest that the enzyme is similar to l-threo-3-hydroxyaspartate ammonia-lyase from Pseudomonas sp. T62, which does not act on d-erythro-3-hydroxyaspartate. We also then used the recombinant enzyme expressed in Escherichia coli to produce optically pure l-erythro-3-hydroxyaspartate and d-threo-3-hydroxyaspartate from the corresponding dl-racemic mixtures. The enzymatic resolution reported here is one of the simplest and the first enzymatic method that can be used for obtaining optically pure l-erythro-3-hydroxyaspartate.