X-ray diffraction studies of as-cast high-palladium alloys

OBJECTIVES

The purpose of this study was to use x-ray diffraction (XRD) to investigate four representative high-palladium alloys in the as-cast condition and obtain new information about the metallurgical phases.

METHODS

Two Pd-Cu-Ga alloys and two Pd-Ga alloys were cast into plate-shaped specimens (20 mm x 1.5 mm) which were bench-cooled. Polished and etched specimens were analyzed using two different x-ray diffractometers and CuKa radiation.

RESULTS

All four alloys exhibited strong XRD peaks for the face-centered cubic (fcc) palladium solid solution matrix, and variations in the lattice parameter were consistent with alloy compositions. Comparison of the relative peak intensities for the alloys and the pure palladium powder standard indicated that the as-cast microstructures had preferred crystallographic orientation. Because the two Pd-Cu-Ga alloys contained appreciable amounts of near-surface lamellar interdendritic or eutectic constituents, it was possible to determine previously unreported XRD peaks for the Pd2Ga phase in these alloys. Low-intensity peaks in the Pd-Ga alloys were attributed to small amounts of secondary phases observed in the microstructures.

SIGNIFICANCE

Knowledge of the metallurgical structures of these high-palladium alloys can be important for interpretation of microstructural observations, mechanical properties, corrosion behavior and clinical performance.

[An observation on pathological changes in retinal ultrastructure of rat with hypertension and after its life-long treatment with captopril]

The fundus and retinal ultrastructural changes of rats with hypertension and such rats having taken life-long captopril treatment were examined by funduscope, light and transmission electron microscopes. The normal rats were the controls. The results showed that in the hypertension group, the ratio of the diameter of the retinal artery to that of the vein was 1:2, the arteries were spastic and narrowed, their light reflexes were widened and their calibers of the lumens were uneven, the fundus appearances being consistent with grade I and II retinal changes of systemic hypertension. Under the light microscope, it was discovered that the basement membranes of the retinal capillaries were thickened and their lumens narrowed, resulting in retinal ischemia and anoxia. Under the transmission electron microscope, the main pathological changes involved the external segments of photoreceptors and ganglionic cells. The pathological changes were hazy renewed membranous discs at the basal portions of the external segments of photoreceptors, edematous ganglionic cells being the majority, their cytoplasm stained pale, mitochondrial vacuolization, enlargement of smooth endoplasmic reticula and degranulation of rough endoplasmic reticula. In the group of rats with hypertension having taken life-long captopril treatment, the fundi and blood pressure remained normal and no significant ultrastructural changes had taken place in their retinae.

The refined crystal structure of hexon, the major coat protein of adenovirus type 2, at 2.9 A resolution

The crystal structure of hexon, the major coat protein from adenovirus type 2, has been refined at 2.9 A resolution. Hexon is a homo-trimer (molecular mass 3 x 109,077 Da) and crystallizes in the cubic space group P2(1)3, with a cell edge of 150.5 A. There are four molecules in the unit cell so that the crystallographic asymmetric unit contains one subunit of the trimer. The electron density in most regions is well-defined and 880 amino acid residues, of the 967 in this unusually long polypeptide chain, have been located and fitted. The N terminus (1 to 43) and three internal stretches (192 to 203, 270 to 291 and 444 to 453) are not defined, and a stretch (168 to 207) with unclear side-chain density is modelled as poly(Ala/Gly). The current refined model, consisting of 6943 non-hydrogen protein atoms and 85 water molecules, yields an R-factor of 19.9% for 18,176 reflections in the resolution range 5.0 to 2.9 A. The model has reasonable geometry with root-mean-square deviations from ideal bond lengths of 0.022 A and angle-related 1-3 distances of 0.056 A. The overall shape of the trimeric hexon molecule is unusual and may be divided into a pseudo-hexagonal base rich in beta-structure, and a triangular top formed from three long loops containing some secondary structure. The base contains two similar pedestal domains, P1 and P2, each of which is a flattened eight-stranded beta-barrel with the "jelly-roll greek key" topology characteristic of other viral coat proteins. P1 and P2 are related by an approximate 6-fold operation about the molecular 3-fold axis so that six barrels form the walls of the tubular hexon base. The hexon bases form close-packed p3 arrays on each facet of the icosahedral adenovirus virion. Unlike other viral capsids, the barrel axes are almost perpendicular to rather than parallel with the capsid surface. The hexon top, which consists of intimately interacting loops emerging from P1 and P2 in the base, has a triangular outline and so does not exhibit the pseudo-symmetry of the base. The structure of the hexon trimer shows how economically it meets the demands of its function as a stable protective viral coat, reveals the significance of the special features in its unusual amino acid sequence, and explains its biochemical and immunological properties. The molecule is hollow, with a large central cavity, and so has a high effective volume for its mass.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of intestinal intraepithelial T lymphocytes is independent of Peyer's patches and lymph nodes in aly mutant mice

We have previously reported a new spontaneous recessive mutation that induces a generalized lack of lymph nodes (LNs) and Peyer's patches (PPs) accompanied by immunodeficiency in mice (gene symbol, aly). In this study, we have analyzed gut-associated lymphatic tissues of the mutant aly/aly mice and have compared the intestinal intraepithelial T lymphocytes (IEL) in aly/aly and normal aly/+ littermate mice. Immunohistochemical studies revealed that colonization of IEL and lamina propria T cells takes place in the absence of PPs and IgA-producing B cells in the lamina propria. Absolute numbers of Thy-1- IEL-alpha beta and -gamma delta are not altered in aly/aly mutant mice, whereas absolute numbers of Thy-1+ IEL-alpha beta and -gamma delta in aly/aly mice are about half of those in aly/+ mice. In IEL-alpha beta from aly/aly mice, the major CD8 alpha alpha+ and CD8 alpha beta+ subsets are maintained, whereas CD4+ and CD4+, CD8+ subsets are reduced. Although the population size of major CD8 alpha alpha+ and CD4-, CD8- IEL-gamma delta subsets is slightly reduced, the use of TCR-gamma- and -delta-chain variable gene segments by IEL-gamma delta remains almost the same in aly/aly mice. The constitutive cytolytic activity of IEL-alpha beta and -gamma delta is attenuated sharply in the aly/aly condition. This activity is, however, augmented significantly after in vitro stimulation with anti-CD3 mAb. These results indicate that most of the IEL subpopulations develop independently of passage through PPs and mesenteric LNs and that the aly mutation interrupts cytotoxic IEL development during relatively late differentiation steps that convert cytotoxic precursors to the constitutively cytolytic state.

Development of intestinal intraepithelial T lymphocytes is independent of Peyer's patches and lymph nodes in aly mutant mice

We have previously reported a new spontaneous recessive mutation that induces a generalized lack of lymph nodes (LNs) and Peyer's patches (PPs) accompanied by immunodeficiency in mice (gene symbol, aly). In this study, we have analyzed gut-associated lymphatic tissues of the mutant aly/aly mice and have compared the intestinal intraepithelial T lymphocytes (IEL) in aly/aly and normal aly/+ littermate mice. Immunohistochemical studies revealed that colonization of IEL and lamina propria T cells takes place in the absence of PPs and IgA-producing B cells in the lamina propria. Absolute numbers of Thy-1- IEL-alpha beta and -gamma delta are not altered in aly/aly mutant mice, whereas absolute numbers of Thy-1+ IEL-alpha beta and -gamma delta in aly/aly mice are about half of those in aly/+ mice. In IEL-alpha beta from aly/aly mice, the major CD8 alpha alpha+ and CD8 alpha beta+ subsets are maintained, whereas CD4+ and CD4+, CD8+ subsets are reduced. Although the population size of major CD8 alpha alpha+ and CD4-, CD8- IEL-gamma delta subsets is slightly reduced, the use of TCR-gamma- and -delta-chain variable gene segments by IEL-gamma delta remains almost the same in aly/aly mice. The constitutive cytolytic activity of IEL-alpha beta and -gamma delta is attenuated sharply in the aly/aly condition. This activity is, however, augmented significantly after in vitro stimulation with anti-CD3 mAb. These results indicate that most of the IEL subpopulations develop independently of passage through PPs and mesenteric LNs and that the aly mutation interrupts cytotoxic IEL development during relatively late differentiation steps that convert cytotoxic precursors to the constitutively cytolytic state.

Prenatal ethanol exposure reduces phosphoinositide hydrolysis stimulated by quisqualate in rat cerebellar granule cell cultures

Prenatal ethanol exposure-induced alteration in poly-phosphoinositide (PPI) hydrolysis stimulated by excitatory amino acids (EAA) was studied in rat cerebellar granule cells previously labeled with [3H]myoinositol. The prenatal exposure to ethanol was achieved via maternal consumption of a Sustacal (chocolate flavored) liquid diet containing either 5% ethanol (w/v, 35% of calories) or isocaloric sucrose (pair-fed) substituted for ethanol from gestation d 11 until the day of parturition. The ionotropic glutamate receptor agonists, N-methyl-D-aspartate, kainate or (+/-)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) (100 microM each) induced a two- to four-fold increase in PPI hydrolysis over the basal level, regardless of the liquid dietary treatment. Stimulation with quisqualate (QA), an agonist activating both metabotropic and ionotropic glutamate receptors, resulted in a much stronger and dose-dependent response in PPI hydrolysis and exposure in utero to ethanol significantly reduced this response. Tetrodotoxin, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), or (+/-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP) had no effect on QA-stimulated PPI hydrolysis nor on the suppression of this hydrolysis by ethanol. Exposure in utero to ethanol did not affect PPI hydrolysis stimulated by a selective metabotropic glutamate receptor agonist, trans-(+/-)-l-amino-1,3-cyclopentanedicarboxylic acid (t-ACPD). Although the PPI hydrolysis stimulated by t-ACPD could be blocked by (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG), an antagonist of the metabotropic glutamate receptor, MCPG was incapable of affecting QA-induced PPI hydrolysis and the suppressive effects of prenatal ethanol exposure on this hydrolysis. Taken together, the data suggest that the long-lasting suppressive effects of prenatal ethanol exposure on QA-stimulated PPI hydrolysis in cerebellar granule cell cultures is through a metabotropic QA receptor pathway that may be different from the one activated by t-ACPD.

[Orthognathic surgery of dentofacial deformities post surgerical repairing of cleft palate and lip.]

10 cases with maxillary development limited post surgical repairing of cleft palate and lip were undergone modified Le Fort I segmental osteotomy,that is,put the maxilla forward without velopharyngeal function change and oro-nasal fistula.By Computer Aided Simulation System for orthognathic surgery(CASSOS),analysis of dental pulp,evaluation of velopharyngeal function,compacting profile pre-to-post operation, authors described that surgical procedure has the satisfactory effectiveness.

Mast cells display natural suppressor activity partially by releasing transforming growth factor-beta

We have previously reported a method for inducing natural suppressor (NS) cells by long-term culture of normal adult mouse spleen cells. The NS cells were further identified as mucosal or immature mast cells by morphology, cytochemistry, histochemistry and function. A cloned immature mast cell line was also confirmed to have NS activity. As NS cells, the cell line suppressed non-specifically the plaque-forming cell (PFC) response. The NS cell-free supernatant was partially enriched by chromatography and some fractions suppressed the PFC response and thymocyte proliferation. Heat treatment of the fractions failed to deplete the suppressive activity. The fractions were confirmed, by immunoblotting analysis, to contain transforming growth factor (TGF)-beta. Recombinant human TGF-beta was also able to suppress the PFC response and thymocyte proliferation. Neutralizing anti-TGF-beta reversed the suppression by both human TGF-beta and the fraction. From the above results, it is clear that mast cells displayed NS activity, at least partially, through the release of TGF-beta.

Resting and activated T cells display different requirements for CD8 molecules

Clonotype-positive (1B2+) T cells from 2C T cell receptor (TCR) transgenic mice were used to define the role of CD8 molecules in the induction phase vs. the effector phase of the primary response to class I alloantigens. Three main findings are reported. First, in the presence of exogenous lymphokines, resting CD8+ 2C cells gave strong proliferative responses to two alloantigens, Ld and Kbm11. In the absence of added lymphokines, however, CD8+ 2C cells responded only to Ld and not to Kbm11; Ld stimulated both interleukin 2 (IL-2) and IL-2 receptor (R) synthesis, whereas Kbm11 elicited only IL-2R synthesis. The primary response of CD8+ 2C cells was thus helper-independent (HI) to Ld but helper-dependent (HD) to Kbm11, presumably reflecting that Ld is a stronger antigen than Kbm11. Second, in contrast to CD8+ cells, CD8- 2C cells mounted only an HD and not an HI response to the strong Ld antigen; conversely, selecting for a minor subset of CD8hi cells enabled 2C cells to mount an HI response to the weak Kbm11 antigen. These findings, together with experiments with heterozygous vs. homozygous stimulator cells, suggest that HI and HD responses reflect differences in the overall avidity of T antigen presenting cell (APC) interaction: high-avidity interaction leads to strong intracellular signaling and an HI response, whereas low-avidity interaction causes weak signaling and an HD response; high-avidity T/APC interaction is heavily dependent on CD8 expression. Third, CD8 expression was found to be less important for CTL activity than for primary proliferative responses. Thus, in contrast to HI proliferative responses, CTL responses of 2C cells to Ld were CD8 independent. However, 2C lysis of Ld targets became strongly CD8 dependent in the presence of limiting doses of anti-TCR (1B2) antibody. Collectively, the data suggest that, both for T cell induction and the expression of effector function, CD8 molecules play a decisive role in augmenting TCR-mediated signaling, either by promoting TCR contact with antigen or delivering kinases (p56lck) to the TCR/CD3 complex, or both.

[An analysis of the cephalometric investigation of the Chinese craniofacical pattern in neolithic]

Craniofacial morphology provides valuable data for determining races and ethnic groups and evolutionary adaptedness of prehistoric human population.Craniofacial investiation yield reliable clues to the ethnic of skeletal series,because craniofacial traits can be evaluated in different ethnic groups.The neolithic human skull of Chinese in this study are about 6000 years ago (B.C.4750-3700).Authors studied the neolithic human skull of Chinese with cephalometric radiography.

Cytolytic activity of intestinal intraepithelial lymphocytes in germ-free mice is strain dependent and determined by T cells expressing gamma delta T-cell antigen receptors

We have compared the cytolytic activities and the cellular compositions of the intestinal intraepithelial lymphocyte (i-IEL) populations in three different combinations of conventional (CV) and germ-free (GF) mice. Cytolytic activity of i-IELs expressing gamma delta T-cell antigen receptors (TCRs) is strain dependent in CV mice (high vs. low), and this strain-dependent variability is unaltered in the GF condition. Although absolute numbers of gamma delta i-IELs are slightly decreased, the composition of CD8 alpha alpha+ and CD4-CD8- subsets and the usage of TCR gamma- and delta-chain variable gene segments by gamma delta i-IELs remain the same in GF mice. By contrast, cytolytic activity of alpha beta TCR-expressing i-IELs is uniformly high in CV mice but attenuated sharply in the GF condition. A conspicuous decrease in the total numbers of alpha beta i-IELs is also noted, and CD8 alpha beta+ and CD4+CD8+ subsets are reduced, whereas the CD8 alpha alpha+ subset is expanded in GF mice. These results indicate that microbial deprivation preferentially influences the alpha beta i-IEL population to decrease and become noncytolytic but has little effect on the pool size or characteristics of gamma delta i-IELs. Consequently, cytolytic activity of freshly isolated i-IELs from GF mice is determined by T cells expressing gamma delta TCRs and is found to be strain dependent.

Differential expression of H-2K and H-2D in the central nervous system of mice infected with Theiler's virus

A model of demyelination induced by Theiler's murine encephalomyelitis virus (TMEV) was used to study differential regulation of class I MHC gene products in the brain and spinal cord of resistant (B10) and susceptible (B10.Q and B10.RBQ) mice. Allelic polymorphisms in the H-2D region, but not the H-2K region, play a primary role in determining susceptibility to late demyelinating disease. However, even though significant structural diversity distinguishes class I alleles, there are no discernible K or D-specific patterns of structural diversity within the peptide binding domains of these glycoproteins. Our hypothesis was that D region association of susceptibility to demyelination was related to differences in the expression of the K and D Ag in the central nervous system (CNS) after TMEV infection. Using allele-specific mAb and an immunoperoxidase technique, we demonstrated transient but equivalent increases in K and D Ag expression in the brain and spinal cord of resistant mice beginning 7 days after TMEV infection, which returned to baseline by 90 days. However, when genetically susceptible animals were examined, a significantly greater increase in D expression relative to K expression was seen in the brain and spinal cord at all post-infection observation periods. Immunosuppression of genetically resistant animals before TMEV infection, which results in viral persistence, was accompanied by equivalent increases in both the K and D Ag. Depletion of CD8+ T cells, but not CD4+ T cells, in susceptible mice ablated class I expression in the CNS in response to TMEV infection, implying that CD8+ cells contribute to the differential regulation of K and D Ag in the CNS. These findings are consistent with the hypothesis that differences in gene regulation may account for different roles of the K and D loci play in determining resistance and susceptibility to TMEV-induced demyelinating disease.

Differential expression of H-2K and H-2D in the central nervous system of mice infected with Theiler's virus

A model of demyelination induced by Theiler's murine encephalomyelitis virus (TMEV) was used to study differential regulation of class I MHC gene products in the brain and spinal cord of resistant (B10) and susceptible (B10.Q and B10.RBQ) mice. Allelic polymorphisms in the H-2D region, but not the H-2K region, play a primary role in determining susceptibility to late demyelinating disease. However, even though significant structural diversity distinguishes class I alleles, there are no discernible K or D-specific patterns of structural diversity within the peptide binding domains of these glycoproteins. Our hypothesis was that D region association of susceptibility to demyelination was related to differences in the expression of the K and D Ag in the central nervous system (CNS) after TMEV infection. Using allele-specific mAb and an immunoperoxidase technique, we demonstrated transient but equivalent increases in K and D Ag expression in the brain and spinal cord of resistant mice beginning 7 days after TMEV infection, which returned to baseline by 90 days. However, when genetically susceptible animals were examined, a significantly greater increase in D expression relative to K expression was seen in the brain and spinal cord at all post-infection observation periods. Immunosuppression of genetically resistant animals before TMEV infection, which results in viral persistence, was accompanied by equivalent increases in both the K and D Ag. Depletion of CD8+ T cells, but not CD4+ T cells, in susceptible mice ablated class I expression in the CNS in response to TMEV infection, implying that CD8+ cells contribute to the differential regulation of K and D Ag in the CNS. These findings are consistent with the hypothesis that differences in gene regulation may account for different roles of the K and D loci play in determining resistance and susceptibility to TMEV-induced demyelinating disease.

Acute, chronic and differential effects of several anesthetic barbiturates on glutamate receptor activation in neuronal culture

The acute and chronic effects of several anesthetic barbiturates, in therapeutic concentrations, on the excitatory amino acid (EAA)-induced elevation of intracellular calcium levels ([Ca2+]i) were examined in neuronal tissue culture. The ultrashort-acting barbiturate, thiamylal, was effective in blocking elevations of [Ca2+]i induced by kainate, N-methyl-D-aspartate (NMDA), and quisqualate or by membrane depolarization with 40 mM KCl. The structurally similar barbiturate, secobarbital which differs from thiamylal only by having an oxygen in place of a sulfur, was able to block elevations induced by the above EAAs but was less effective than thiamylal and did not significantly reduce [Ca2+]i that resulted from membrane depolarization with KCl. Pentobarbital, while differing from secobarbital by only a methyl group, was without effect on either the NMDA- or 40 mM KCl-induced elevations of [Ca2+]i. By contrast, cyproheptadine, a compound that has been shown to block Ca2+ channels, has a different profile from the above barbiturates in that cyproheptadine is more effective in blocking elevation of [Ca2+]i induced by membrane depolarization with KCl while the barbiturates are more effective in reducing [Ca2+]i induced by EAAs. An anticonvulsant barbiturate, phenobarbital, did not reduced elevations of [Ca2+]i induced by any EAA tested or by membrane depolarization with KCl. When cells were treated chronically with thiamylal for 4 days, 2-6 h after the abrupt drug withdrawal there was a hyperresponsiveness to the elevations of [Ca2+]i induced by both kainate and NMDA but not by quisqualate. A similar hyperresponsiveness was not seen after the chronic treatment with phenobarbital.(ABSTRACT TRUNCATED AT 250 WORDS)

New high-palladium casting alloys: Part 2. Effects of heat treatment and burnout temperature

Castings simulating a maxillary central incisor coping were fabricated from five representative high-palladium alloys, using burnout temperatures of 1,400 degrees F and 1,500 degrees F, with a carbon-free phosphate-bonded investment. Three castings of each alloy were individually prepared at each burnout temperature. Each casting was sectioned into two specimens, and one specimen was subjected to simulated porcelain firing heat treatment. Polished and etched specimens in as-cast and heat-treated conditions were examined with optical and scanning electron microscopes. Mean values of Vickers hardness (1-kg load) were determined for each alloy and condition. It was observed that the simulated porcelain firing cycles caused major changes in as-cast bulk microstructures for the three first-generation alloys, while only subtle alterations were observed for the two second-generation alloys. In addition, complex regions associated with oxidation processes were found near the surfaces of all the heat-treated alloys. While the as-cast microstructure and the hardness of each alloy did not vary appreciably for the two burnout temperatures, the incidence of hot tearing in one first-generation alloy was substantially reduced at the lower burnout temperature. Statistically significant decreases in hardness generally occurred in the high-palladium alloys after the simulated porcelain firing cycles, but the relatively small changes (usually 10% or less) should not have any clinical significance. Other clinically relevant applications are also discussed.

Resiliency to amplification of carbon tetrachloride hepatotoxicity by chlordecone during postnatal development in rats

The interactive hepatotoxicity of CCl4 and chlordecone, at an individually nontoxic dosage, was studied in neonatal and young developing rats. The well-documented amplification of CCl4 (100 microL/kg) hepatotoxicity and lethality by prior dietary exposure to chlordecone (10 ppm, for 15 d) was absent in neonatal and developing rats through 35 d of age. The chlordecone-potentiated hepatotoxicity and lethality of CCl4 was partially expressed in 45-d-old rats and fully expressed in 60-d-old rats. Although hepatic microsomal cytochrome P-450 content in 2- or 5-d-old rats was significantly lower than that in older age groups, the cytochrome P-450 content was not significantly different between 35-, 45-, and 60-d-old chlordecone-treated rats. During postnatal development, the ongoing hepatocellular proliferation declined in a biphasic manner, more rapidly up to 20 d and slowly thereafter, as indicated by 3H-thymidine incorporation in hepatic nuclear DNA. This pattern of postnatal liver proliferation and growth was not altered by exposure to chlordecone. In vivo metabolism of CCl4, in terms of 14CO2 production derived from 14CCl4 and 14CCl4 metabolites bound to hepatic tissue, was not significantly different between 35-, 45-, and 60-d-old chlordecone-treated rats, whereas CCl4-stimulated hepatocellular regeneration in 35-d-old chlordecone-treated rats was significantly higher than in 45- or 60-d-old chlordecone-treated rats, as indicated by 3H-thymidine incorporation into hepatic DNA and histomorphometric analysis. These data suggest that the absence of potentiation of CCl4 toxicity by chlordecone in postnatally developing rats is well correlated with the presence of ongoing and stimulatable hepatocellular regenerative activity.

[The Chinese demographic challenge]

Recent official vital statistics data from China are used to emphasize the seriousness of the demographic situation in China, and to highlight the continued pressure on limited resources exerted by a growing population that is struggling to achieve socioeconomic development. The authors conclude that "the pessimistic scenarios of evolution of Chinese vital factors justify the pursuit, or even the intensification, of the birth control programme. New educational programmes should focus on the necessity to develop new solidarities, to achieve a [reasonable] vital growth at least during the next five decades, which could lead to a better balanced...development of the economy." (SUMMARY IN ENG)

Amitriptyline, desipramine, cyproheptadine and carbamazepine, in concentrations used therapeutically, reduce kainate- and N-methyl-D-aspartate-induced intracellular Ca2+ levels in neuronal culture

The glutamate receptor agonists, kainate and N-methyl-D-aspartate (NMDA) result in the elevation of intracellular calcium levels ([Ca2+]i) in primary cultures of cerebellar granule neurons. Several tricyclic antidepressants (TCAs), amitriptyline (0.5-1 microM), desipramine (1 microM) and doxepine (1 microM) partially prevent this elevation induced by both of these excitatory amino acids (EAAs), but not elevations of [Ca2+]i induced by another EAA, quisqualate. Evidence suggests that this EAA-tricyclic interaction may involve voltage-dependent Ca2+ channels since amitriptyline also partially blocks the elevation of [Ca2+]i induced by membrane depolarization with 40 mM KCl. However, the blockade is not reversed in high concentrations of extracellular Ca2+ ([Ca2+]o) as would be predicted by a direct interaction with Ca2+ channels. Cyproheptadine (0.5-1 microM), a serotonin antagonist that is structurally similar to amitriptyline, causes similar effects as reported above for the TCAs; however, ketanserine (10 microM), also a serotonin antagonist but without the tricyclic nucleus, is less effective in this regard. Carbamazepine, an anticonvulsant with a tricyclic nucleus, produces similar effects as the above three compounds only in higher, yet therapeutic, concentrations (50 microM). Neither 5-hydroxytryptamine nor norepinephrine (100 microM, each) had effects on the EAA-induced elevation of [Ca2+]i. This is the first report to show an interaction of tricyclic antidepressants with the function of glutamate receptors in concentrations which are consistent with therapeutic dosages.

Selective effects of cyanide (100 μM) on the excitatory amino acid-induced elevation of intracellular calcium levels in neuronal culture

The effect of low concentrations of cyanide on the excitatory amino acid-induced elevations of intracellular calcium levels ([Ca2+]i) was studied in cerebellar granule cells using ratio fluorometry with fura-2. Glutamate, kainate, N-methyl-D-aspartate (NMDA), quisqualate (50 microM, each) and membrane depolarization by 40 mM KCl caused elevations of [Ca2+]i which were 10-, 10-, 3-, 2.3-, 10-fold over baseline levels, respectively. Cyanide, 100 microM, greatly augmented the increases in [Ca2+]i induced by glutamate, kainate and NMDA but not those induced by quisqualate or KCl. In the absence of these excitatory amino acids, cyanide had no significant effect in concentrations up to 400 microM. Elevations of [Ca2+]i induced by quisqualate and KCl were not significantly augmented by higher concentrations of cyanide (400 microM). Selective antagonists could block the effect of cyanide+the respective agonist; however, the calcium channel blockers, lanthanum and diltiazem lowered both NMDA- and kainate-induced elevations of [Ca2+]i, yet neither blocked increases in calcium when 100 microM cyanide was added. Collectively, these data support an interaction of cyanide with the excitatory amino acid receptor.

Structural and functional analysis of three D/L-like class I molecules from H-2v: indications of an ancestral family of D/L genes

Three cDNA with D region gene features have been identified from the H- 2v haplotype. Provisionally, the sequences have been designated as D/Lv1, D/Lv2, and D/Lv3. The coding segments for the antigen binding domain (ABD) of all three D/Lv genes were engineered into a class I genomic expression vector and expressed in L cells. FACS analysis of the three D/Lv-Ld gene transfectants revealed that the D/Lv1 molecules were recognized by both monoclonal antibodies (mAbs) 141 and 142, and the D/Lv2 molecules were recognized by mAb 143. In addition to the D/Lv1 molecules, the mAb 141 also recognized the D/Lv3 molecules. Both the D/Lv1-Ld and D/Lv2-Ld transfectants were killed efficiently by H- 2Dv region-specific alloreactive CTL. The D/Lv3 gene is the first identified D region gene other than D and L that is transcribed abundantly in spleen and the D/Lv3 RNA is present as two alternatively spliced forms. Structural analysis of the D/Lv3 hybrid molecules showed that it was susceptible to proteolysis and thermolabile at 37 degrees C, suggesting D/Lv3 is a transcribed pseudogene. A parsimony tree analysis of three D/Lv sequences with a set of class I gene sequences revealed that the H-2v sequences clustered with D region genes. The presence of a third gene with D/L-like features in H-2v, yet structurally different from the known D/L alleles, raises the possibility that the current D/L genes evolved from a family of D/L- like genes, some of which are no longer represented among many of the mouse major histocompatibility complex haplotypes. The observation that D region alleles cluster into subgroups suggests that the alleles are not all related to each other by linear descent through a single locus. We propose that current alleles are derived from more than one ancestral locus in a manner similar to the origin of the gamma 2 a immunoglobulin constant region alleles.

Hepatotoxicity and lethality of halomethanes in Mongolian gerbils pretreated with chlordecone, phenobarbital or mirex

The hepatotoxic and lethal effects of CBrCl3, CCl4 and CHCl3 were investigated in gerbils with or without prior exposure to dietary chlordecone (CD), phenobarbital (PB) and mirex (MX) at 10, 225 and 10 ppm, respectively, for 15 days. Gerbils were quite sensitive to these halomethanes (48 h LD50: 20, 80 and 400 microliters/kg, respectively). CD, known to potentiate hepatotoxic and lethal effects of halomethanes in rats, failed to potentiate the toxic effects of any of these three halomethanes in gerbils. PB and MX were also ineffective. Since stimulation of early hepatocellular regeneration has been shown to be responsible for the recovery from the toxicity of a low dose of CCl4, liver cell regeneration and tissue repair were studied in gerbils after CCl4 administration. The objectives of these studies were to investigate the possible reasons for the high sensitivity of gerbils to halomethane toxicity and to investigate the mechanism for their refractoriness to CD-potentiated halomethane toxicity. A low and a high dose of CCl4 (15 and 80 microliters/kg, i.p. respectively) were used to study the time-course of liver injury in gerbils pretreated with or without CD. The low dose of CCl4 stimulated cellular regeneration as indicated by the increase of 3H-thymidine (3H-T) incorporation in hepatic nuclear DNA. The cellular regeneration and tissue repair activities resulted in complete recovery from the limited liver injury in both CD-pretreated and control gerbils. In contrast to rats, however, the process of cell division in gerbils occurred much later, 2 days after CCl4 administration. Evidence from histomorphometric studies was consistent with serum enzyme and 3H-T incorporation data.(ABSTRACT TRUNCATED AT 250 WORDS)

[Determination of eucalyptole in eucalyptus oil by gas chromatography]

This paper reports the determination of eucalyptole in eucalyptus oil by gas chromatography. The results were similar to the specifications in the Chinese Pharmacopoeia. The method is simple, rapid, accurate and sensitive and requires only small amount of samples. The coefficient of variation is less than or equal to 0.52%.

Scanning electron microscopic observation on the surface ultrastructure of leucocytes in CSF

Using scanning electron microscope (SEM), The CSF leucocytes from 3 healthy subjects and 12 patients with various NS diseases were observed. The findings were used to compare with those by optical microscope (OM) and those of human peripheral blood cells by SEM. Five types of CSF cells with particular surface structures, are emphasized in relation to both optical microscopic findings and the involved diseases.

Microencapsulated hepatocytes: an in vitro and in vivo study

Using a modified alginate-polylysine membrane, we have successfully encapsulated rat hepatocytes with little loss of viability. Urea and albumin release from encapsulated liver cells was comparable to that from non-encapsulated cells during the first 4 days in culture. Histological studies also showed that more than 50% of the encapsulated hepatocytes remained viable 35 days after implantation in the peritoneal cavity of both normal rats and rats with galactosamine induced fulminant hepatic failure. Transplantation of microencapsulated hepatocytes provides a potential clinical treatment for liver failure.