Microstructural and chemical features of impact melts on Ryugu particle surfaces: Records of interplanetary dust hit on asteroid Ryugu

The Hayabusa2 spacecraft delivered samples of the carbonaceous asteroid Ryugu to Earth. Some of the sample particles show evidence of micrometeoroid impacts, which occurred on the asteroid surface. Among those, particles A0067 and A0094 have flat surfaces on which a large number of microcraters and impact melt splashes are observed. Two impact melt splashes and one microcrater were analyzed to unveil the nature of the objects that impacted the asteroid surface. The melt splashes consist mainly of Mg-Fe-rich glassy silicates and Fe-Ni sulfides. The microcrater trapped an impact melt consisting mainly of Mg-Fe-rich glassy silicate, Fe-Ni sulfides, and minor silica-rich glass. These impact melts show a single compositional trend indicating mixing of Ryugu surface materials and impactors having chondritic chemical compositions. The relict impactor in one of the melt splashes shows mineralogical similarity with anhydrous chondritic interplanetary dust particles having a probable cometary origin. The chondritic micrometeoroids probably impacted the Ryugu surface during its residence in a near-Earth orbit.

Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples

Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate that Ryugu's parent body formed ~2 million years after the beginning of Solar System formation.

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe³⁺ to Fe²⁺ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (-OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.

Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth

The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu's boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.

Discovery of primitive CO2-bearing fluid in an aqueously altered carbonaceous chondrite

Water is abundant as solid ice in the solar system and plays important roles in its evolution. Water is preserved in carbonaceous chondrites as hydroxyl and/or H₂O molecules in hydrous minerals, but has not been found as liquid. To uncover such liquid, we performed synchrotron-based x-ray computed nanotomography and transmission electron microscopy with a cryo-stage of the aqueously altered carbonaceous chondrite Sutter's Mill. We discovered CO₂-bearing fluid (CO₂/H₂O > ~0.15) in a nanosized inclusion incorporated into a calcite crystal, appearing as CO₂ ice and/or CO₂ hydrate at 173 K. This is direct evidence of dynamic evolution of the solar system, requiring the Sutter's Mill's parent body to have formed outside the CO₂ snow line and later transportation to the inner solar system because of Jupiter's orbital instability.

Discovery of fossil asteroidal ice in primitive meteorite Acfer 094

Carbonaceous chondrites are meteorites believed to preserve our planet's source materials, but the precise nature of these materials still remains uncertain. To uncover pristine planetary materials, we performed synchrotron radiation-based x-ray computed nanotomography of a primitive carbonaceous chondrite, Acfer 094, and found ultraporous lithology (UPL) widely distributed in a fine-grained matrix. UPLs are porous aggregates of amorphous and crystalline silicates, Fe─Ni sulfides, and organics. The porous texture must have been formed by removal of ice previously filling pore spaces, suggesting that UPLs represent fossils of primordial ice. The ice-bearing UPLs formed through sintering of fluffy icy dust aggregates around the H₂O snow line in the solar nebula and were incorporated into the Acfer 094 parent body, providing new insight into asteroid formation by dust agglomeration.

Clinical effectiveness of four neuraminidase inhibitors (oseltamivir, zanamivir, laninamivir, and peramivir) for children with influenza A and B in the 2014-2015 to 2016-2017 influenza seasons in Japan

The clinical effectiveness of four neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, laninamivir, and peramivir) for children aged 0 months to 18 years with influenza A and B were investigated in the 2014-2015 to 2016-2017 influenza seasons in Japan. A total of 1207 patients (747 with influenza A and 460 with influenza B) were enrolled. The Cox proportional-hazards model using all of the patients showed that the duration of fever after administration of the first dose of the NAI was shorter in older patients (hazard ratio = 1.06 per 1 year of age, p < 0.001) and that the duration of fever after administration of the first dose of the NAI was shorter in patients with influenza A infection than in patients with influenza B infection (hazard ratio = 2.21, p < 0.001). A logistic regression model showed that the number of biphasic fever episodes was 2.99-times greater for influenza B-infected patients than for influenza A-infected patients (p < 0.001). The number of biphasic fever episodes in influenza A- or B-infected patients aged 0-4 years was 2.89-times greater than that in patients aged 10-18 years (p = 0.010), and the number of episodes in influenza A- or B-infected patients aged 5-9 years was 2.13-times greater than that in patients aged 10-18 years (p = 0.012).

The search for and analysis of direct samples of early Solar System aqueous fluids

We describe the current state of the search for direct, surviving samples of early, inner Solar System fluids-fluid inclusions in meteorites. Meteoritic aqueous fluid inclusions are not rare, but they are very tiny and their characterization is at the state of the art for most analytical techniques. Meteoritic fluid inclusions offer us a unique opportunity to study early Solar System brines in the laboratory. Inclusion-by-inclusion analyses of the trapped fluids in carefully selected samples will, in the immediate future, provide us detailed information on the evolution of fluids as they interacted with anhydrous solid materials. Thus, real data can replace calculated fluid compositions in thermochemical calculations of the evolution of water and aqueous reactions in comets, asteroids, moons and the terrestrial planets.This article is part of the themed issue 'The origin, history and role of water in the evolution of the inner Solar System'.

Luminescence Spectroscopical Properties of Plagioclase Particles from the Hayabusa Sample Return Mission: An Implication for Study of Space Weathering Processes in the Asteroid Itokawa

We report a systematic spectroscopical investigation of three plagioclase particles (RB-QD04-0022, RA-QD02-0025-01, and RA-QD02-0025-02) returned by the Hayabusa spacecraft from the asteroid Itokawa, by means of scanning electron microscopy, cathodoluminescence microscopy/spectroscopy, and micro-Raman spectroscopy. The cathodoluminescence properties are used to evaluate the crystallization effects and the degree of space weathering processes, especially the shock-wave history of Itokawa. They provide new insights regarding spectral changes of asteroidal bodies due to space weathering processes. The cathodoluminescence spectra of the plagioclase particles from Itokawa show a defect-related broad band centered at around 450 nm, with a shoulder peak at 425 nm in the blue region, but there are no Mn- or Fe-related emission peaks. The absence of these crystal field-related activators indicates that the plagioclase was formed during thermal metamorphism at subsolidus temperature and extreme low oxygen fugacity. Luminescence characteristics of the selected samples do not show any signatures of the shock-induced microstructures or amorphization, indicating that these plagioclase samples suffered no (or low-shock pressure regime) shock metamorphism. Cathodoluminescence can play a key role as a powerful tool to determine mineralogy of fine-grained astromaterials.

Low core-mantle boundary temperature inferred from the solidus of pyrolite

The melting temperature of Earth's mantle provides key constraints on the thermal structures of both the mantle and the core. Through high-pressure experiments and three-dimensional x-ray microtomographic imaging, we showed that the solidus temperature of a primitive (pyrolitic) mantle is as low as 3570 ± 200 kelvin at pressures expected near the boundary between the mantle and the outer core. Because the lowermost mantle is not globally molten, this provides an upper bound of the temperature at the core-mantle boundary (T(CMB)). Such remarkably low T(CMB) implies that the post-perovskite phase is present in wide areas of the lowermost mantle. The low T(CMB) also requires that the melting temperature of the outer core is depressed largely by impurities such as hydrogen.

Cathodoluminescence microscopy and spectroscopy of micro- and nanodiamonds: an implication for laboratory astrophysics

Color centers in selected micro- and nanodiamond samples were investigated by cathodoluminescence (CL) microscopy and spectroscopy at 298 K [room temperature (RT)] and 77 K [liquid-nitrogen temperature (LNT)] to assess the value of the technique for astrophysics. Nanodiamonds from meteorites were compared with synthetic diamonds made with different processes involving distinct synthesis mechanisms (chemical vapor deposition, static high pressure high temperature, detonation). A CL emission peak centered at around 540 nm at 77 K was observed in almost all of the selected diamond samples and is assigned to the dislocation defect with nitrogen atoms. Additional peaks were identified at 387 and 452 nm, which are related to the vacancy defect. In general, peak intensity at LNT at the samples was increased in comparison to RT. The results indicate a clear temperature-dependence of the spectroscopic properties of diamond. This suggests the method is a useful tool in laboratory astrophysics.

Oxygen isotopic compositions of asteroidal materials returned from Itokawa by the Hayabusa mission

Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 Itokawa returned by the Hayabusa spacecraft. Compositions of the particles are depleted in (16)O relative to terrestrial materials and indicate that Itokawa, an S-type asteroid, is one of the sources of the LL or L group of equilibrated ordinary chondrites. This is a direct oxygen-isotope link between chondrites and their parent asteroid.

Itokawa dust particles: a direct link between S-type asteroids and ordinary chondrites

The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid.

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced (21)Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.

Chondrulelike objects in short-period comet 81P/Wild 2

The Stardust spacecraft returned cometary samples that contain crystalline material, but the origin of the material is not yet well understood. We found four crystalline particles from comet 81P/Wild 2 that were apparently formed by flash-melting at a high temperature and are texturally, mineralogically, and compositionally similar to chondrules. Chondrules are submillimeter particles that dominate chondrites and are believed to have formed in the inner solar nebula. The comet particles show oxygen isotope compositions similar to chondrules in carbonaceous chondrites that compose the middle-to-outer asteroid belt. The presence of the chondrulelike objects in the comet suggests that chondrules have been transported out to the cold outer solar nebula and spread widely over the early solar system.

Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.

Mineralogy and petrology of comet 81P/Wild 2 nucleus samples

The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.

Comet 81P/Wild 2 Under a Microscope

The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

Three-dimensional diffusion of non-sorbing species in porous sandstone: computer simulation based on X-ray microtomography using synchrotron radiation

The diffusion pathways of porous sandstone were examined by a three-dimensional (3-D) imaging technique based on X-ray computed tomography (CT) using the SPring-8 (Super Photon ring-8 GeV, Hyogo, Japan) synchrotron radiation facility. The analysis was undertaken to develop better understanding of the diffusion pathways in natural rock as a key factor in clarifying the detailed mechanism of the diffusion of radionuclides and water molecules through the pore spaces of natural barriers in underground nuclear waste disposal facilities. A cylindrical sample (diameter 4 mm, length 6 mm) of sandstone (porosity 0.14) was imaged to obtain a 3-D image set of 450(3) voxels=2.62(3) mm(3). Through cluster-labeling analysis of the 3-D image set, it was revealed that 89% of the pore space forms a single large pore-cluster responsible for macroscopic diffusive transport, while only 11% of the pore space is made up of isolated pores that are not involved in long-range diffusive transport. Computer simulations of the 3-D diffusion of non-sorbing random walkers in the largest pore cluster were performed to calculate the surface-to-volume ratio of the pore, tortuosity (diffusion coefficient in free space divided by that in porous rock). The results showed that (i) the simulated surface-to-volume ratio is about 60% of the results obtained by conventional pulsed-field-gradient proton nuclear magnetic resonance (NMR) laboratory experiments and (ii) the simulated tortuosity is five to seven times larger than the results of laboratory diffusion experiments using non-sorbing I(-) and Br(-). These discrepancies are probably attributed to the intrinsic sample heterogeneity and limited spatial resolution of the CT system. The permeability was also estimated based on the NMR diffusometry theory using the results of the random walk simulations via the Kozeny-Carman equation. The estimated permeability involved an error of about 20% compared with the permeability measured by the conventional method, suggesting that the diffusometry-based NMR well logging with gradient coils is applicable to the in-situ permeability measurement of strata. The present study demonstrated that X-ray CT using synchrotron radiation is a powerful tool for obtaining 3-D pore structure images without the beam-hardening artifacts inevitable in conventional CT using X-ray tubes.

[Meteoritics and mineralogy on possible ancient Martian life]

Possible relic biogenic activity in martian meteorite ALH84001 was proposed by McKay et al. (Science, 273, 924-930, 1996). This ancient meteorite of 4.5 billion years old contains abundant carbonates as secondary minerals precipitated from a fluid on the martian surface. They showed the following lines of evidence for the ancient life; (1) unique mineral compositions and biominerals, (2) polycyclic aromatic hydrocarbons (PAHs) in association with the carbonates, and (3) unique structures and morphologies typical of nanobacteria or microfossils. This review is divided into two parts; one is on the martian meteorites in general and ALH84001, which has many features unlike other martian meteorites, and the other is on mineralogical (biomineralogical) and geochemical features of the carbonates and microfossil-like structures. There is little doubt that ALH84001 is from Mars as well as eleven other SNC meteorites. However, the mineralogical and biomineralogical evidence for martian bacteria given by McKay et al. (1996) is controversial, and could be formed by non-biogenic processes. Thus, further study of ALH84001 and other martian meteorites is required. We also need to consider the future Mars mission especially sample return mission.

A case of carbamylphosphate synthetase-I deficiency associated with secondary carnitine deficiency--L-carnitine treatment of CPS-I deficiency

We describe a male infant with congenital hyperammonaemia due to partial carbamylphosphate synthetase-I (CPS-I) deficiency. At 21 days of age, he had convulsions and at 53 days of age hyperammonaemic coma. Therapy with sodium benzoate, L-arginine, essential amino acids, L-carnitine and peritoneal dialysis lowered the blood ammonia levels, and his clinical manifestations improved. The CPS-I activity in liver tissue obtained by open biopsy was about 25.6% of normal values. The serum and urine free carnitine levels in the patient decreased during the hyperammonaemic crisis and were low at 7 months of age. After oral administration of L-carnitine (10 mg/kg per day) at 7 months of age, the mean blood ammonia levels decreased significantly, accompanied by an increase in serum and urine free carnitine levels. We propose the use of L-carnitine therapy to prevent secondary carnitine deficiency in patients with CPS-I deficiency as well as ornithine transcarbamylase (OTC) deficiency.

Neonatal hyperammonemia associated with carnitine deficiency

We report a case of neonatal hyperammonemia associated with secondary carnitine deficiency. She suffered from hyperammonemia soon after the birth, and then presented severe metabolic acidosis at 2 months of age. She was successfully treated for acidosis with oral administration of L-carnitine (100 mg/kg/day). Since hyperammonemia recurred with the increase of protein intake, it was necessary to increase the dose of carnitine to 150 mg/kg/day. Urea cycle enzymopathies were excluded from the laboratory data. The urinary organic acid profiled by gas chromatography mass spectrometry revealed no abnormalities. It was found that the carnitine contents in serum urine and muscle were decreased. After we investigated the carnitine status in other members of the family, the brother of this patient, who had died of metabolic acidosis and hyperammonemia of unknown etiology in the neonatal period, was also revealed to have carnitine deficiency. Since specific enzyme defects which caused secondary carnitine deficiency could not be detected in our patients, further biochemical characterization would be necessary to clarify the cause of hyperammonemia.

The role of amino acids and their transport systems in the regulation of ureogenesis in the primary culture of adult rat hepatocytes

The biosynthesis of urea, the metabolism of ammonia and the transport of amino acids were studied using the primary culture of hepatocytes from adult rats. The urea synthesis and ammonia detoxication were affected by the amino acids of urea cycle intermediates, such as ornithine, arginine and aspartate. When the hepatocytes were incubated in the medium containing 1 mM ammonium chloride, the transport activity of system-A, which was determined by the uptake of specific substrate methyl-2-amino isobutyric acid (MeAIB), did not change compared with the control level. However, the transport activity of ornithine was increased to a maximum after 4 hr of incubation with ammonia, and then decreased gradually to twice the control level. The activity of ornithine transcarbamylase (OTC) increased to twice the control. These results indicated that the amino acids of urea cycle intermediates, especially ornithine, can be the important regulators of ureogenesis.

Control of growth and amino acid transport of mature rat hepatocytes by human newborn serum

DNA synthesis and system A-mediated amino acid transport were studied in primary culture of adult rat hepatocytes maintained as a monolayer. Potent growth promoting activity and inducibility of system A-mediated amino acid transport could be found in human newborn sera but not in human adult sera. The maximal activity to promote DNA synthesis was about the same level as insulin (10(-7) M) plus epidermal growth factor (EGF, 20 ng/ml). These results suggest the presence of a hepatocyte-specific growth factor in human newborn sera controlling the amino acid metabolism during the newborn period.

Studies on the expression of liver-specific functions of human fetal hepatocytes in primary culture

Biochemical functions of human livers were studied using fetal hepatocytes in primary culture. Immunocytochemical staining showed that albumin was not expressed in any fetal hepatocytes, whereas alpha-fetoprotein was detected in almost all the cells. Tryptophan 2,3-dioxygenase (TO, EC 1.13.11.11.) activity was not induced in the presence of 10(-7) M dexamethasone and 10(-7) M glucagon, but the activity of tyrosine aminotransferase (TAT, EC 2.6.1.5.) was elevated about 35 fold under the same conditions. These results suggest that the TAT and alpha-fetoprotein genes are activated in human fetal liver at 14 to 20 weeks of gestation.

Cytotoxicities of sodium benzoate in primary culture of hepatocytes from adult rat liver

The cytotoxicities of sodium benzoate was studied using primary culture of hepatocytes established from adult rat liver by a collagenase perfusion technique and maintained as a monolayer in serum-free culture medium. The activities of ornithine transcarbamylase (as a marker of mitochondria) and tyrosine aminotransferase (as a marker of cytosol) were clearly suppressed by sodium benzoate at concentration in excess of 500 micrograms/ml. Intracellular protein synthesis and DNA synthesis were also suppressed, and the suppression of DNA synthesis was observed even with a lower concentration of benzoate (100 micrograms/ml).

Immunoenzymatic studies of ornithine transcarbamylase (OTC) in liver of patients with OTC deficiency by enzyme linked immunosorbent assay (ELISA)

Antigen contents of ornithine transcarbamylase (OTC) protein in the liver of 5 patients with OTC deficiency and mutant mice were studied by ELISA. OTC activities in the liver tissues of 2 patients were 13.1% and 5.2% of the controls, respectively. The 2 patients' antigen contents of OTC protein were decreased in parallel with the enzyme activities. OTC antigen contents were not detected in the liver tissues of remaining 3 patients who had the complete type of OTC deficiency. Enzyme activities, kinetic properties and antigen contents of the OTC deficient mutant mice were the same as the results reported previously (Briand et al. 1982). The ELISA method for the assay of OTC antigen contents used in this study is more sensitive as compared with the radial immunodiffusion technique.

Clinical, biochemical and enzymatic studies in type I hyperprolinemia associated with chromosomal abnormality

A severe mentally retarded infant with type I hyperprolinemia associated with chromosomal abnormality is reported. The patient had a characteristic facial appearance of hyperprolinemia and suffered from convulsions after the age of 10 months. The child developed severe mental and motor retardation. The karyotype of the patient revealed partial duplication of the short arm in chromosome 10 using G banding techniques. The patient and her mother showed a fasting hyperprolinemia and an abnormal clearance curve after the proline load in the serum. The proline oxidase activities of the liver tissues obtained by biopsy in the patient was about 9% of those of controls. Kinetic studies and mixed experiments of the enzyme were with normal limits. Restriction of dietary proline at the age of 12 months revealed a prompt fall of the plasma levels of proline to the normal range, and a low proline diet was continued until the present time. During the period of dietary treatment, growth was satisfactory, but her mental development did not improve. From the developmental patterns of proline oxidase activities postnataldy, we speculated that restriction of dietary proline intake should be relieved with age.

Citrullinemia: quantitative deficiency of argininosuccinate synthetase in the liver

Two cases of citrullinemia were reported. Case 1 was an one month old female. Her clinical course and findings were different from the fulminant type of neonatal citrullinemia reported in predominantly Caucasian countries. Our patient was well controlled under a low protein diet and essential amino acids till 9 months of age, but unfortunately she died of Reye's like syndrome. Case 2 was 31 year old male (at the time of death). He was admitted to our hospital because of hyperammonemia and mental retardation. By subsequent laboratory investigations he was diagnosed as having adult type of citrullinemia and died of hepatoma. Enzymological analysis revealed that argininosuccinate synthetase (ASS) activities in the liver tissues of the patients decreased to 40% (Case 1), 20% (Case 2) compared with those in control liver tissues. The other urea cycle enzyme activities were all within normal range. ASS activities in the kidney and brains of the two cases were within normal range. The kinetic constant values of ASS for three substrates in the tissues of liver and kidney were all normal. Results of immunochemical analyses indicated that citrullinemia in our patients was caused by a quantitative deficiency of ASS associated proteins of the liver and kidney tissues as to the molecular weight.

A case of pyruvate carboxylase deficiency with later prenatal diagnosis of an unaffected sibling

A severely mentally retarded infant with congenital lactic acidosis due to pyruvate carboxylase deficiency is reported. The patient suffered from vomiting and convulsions soon after birth and developed severe mental and motor retardation at 3 months of age. The persistent elevation of pyruvate and lactate in both blood and cerebrospinal fluid and hyperalanaemia suggested an impairment of pyruvate oxidation. The enzyme activities of pyruvate carboxylase in both liver tissues and cultured skin fibroblasts of the patient revealed values of about 5% of controls. However, pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase activities in liver tissues were within normal limits. The patient had no response to administration of large doses of thiamine, lipoic acid and biotin, clinically and biochemically. A prenatal diagnosis was performed in the second pregnancy and the pyruvate carboxylase activities of the cultured amniotic fluid cells obtained by amniocentesis were within normal limits.

Normal activities of hepatic pyruvate dehydrogenase and pyruvate carboxylase in Leigh's syndrome

A case of Leigh's syndrome (subacute necrotizing encephalomyelopathy, SNE), proven by autopsy, was reported. The persistent elevation of pyruvate and lactate in blood and hyperalanemia suggested an impairment of pyruvate oxidation, but the enzyme activities of pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) in liver tissues of the patient revealed normal. It is postulated that Leigh's syndrome and both enzyme deficiencies are distinct entities.

A new type of hypermethioninemia in neonates

Eleven hypermethioninemic patients were found by mass screening tests of neonates. Three of these had persistent hypermethioninemia while in the others it was transient. Serum concentrations of methionine were constantly higher than those of controls, especially in the persistent group. The enzyme activities of methionine adenosyltransferase in the liver tissues of both groups of patients were within normal limits. Serum concentrations of total folate in the persistent group were strikingly elevated and fatty degeneration of the liver tissues was a constant feature. It improved after several months under a low-methionine diet. The hypermethioninemia reported here is not associated with any clinical or biochemical finding reported previously.