Distribution profiles of fluoride in three different kinds of rat bones

The study was performed to reveal the detailed distribution profiles of fluoride in three different kinds of rat bone--humerus, vertebral arch, and parietal bone--and to compare this with the histological appearance of each bone type. Two groups of Wistar rats were provided water ad libitum containing 0 and 100 ppm fluoride, respectively, for 24 weeks. The fluoride distribution profiles across the bone of the three different bones from the outer to the inner surface were determined by means of an abrasive micro-sampling technique. In control animals, both humerus and parietal bones showed higher concentrations at the periosteal and endosteal surfaces, while the vertebral arch showed additional high levels in the middle (containing trabecular bone) of the tissue. In exposed animals, fluoride levels increased greatly in all three bone types. The vertebral and parietal fluoride distribution profiles were relatively unchanged, although humerus fluoride increased from periosteum to endosteum. The differences in fluoride distribution profiles were apparently related to the histological appearances of these bones. The surface area of bone available and the extent of vascularity appear to affect fluoride uptake.

Use of the hemagglutinating virus of Japan (HVJ)-liposome method for analysis of infiltrating lymphocytes induced by hepatitis B virus gene expression in liver tissue

We previously developed a method for introducing foreign genes into liver tissue using liposomes with incorporated hemagglutinating virus of Japan (HVJ, Sendai virus), and found that liver cells transfected with the E. coli beta-galactosidase gene or the gene for hepatitis B virus (HBV) surface protein (HBsAg) expressed these proteins in vivo. Here, we analyzed cellular reactions leading to hepatitis in the liver by expressing the genes of HBV in vivo. Lymphocytes were eluted directly from liver transfected with the HBsAg genes and shown to be cytotoxic only to cells expressing HBsAg in vitro. These lymphocytes were identified as cytotoxic T lymphocytes with the CD4- CD8+ phenotype. Transfer of these lymphocytes to transgenic mice with the whole HBV genome led to elevation of the serum glutamic-pyruvic transaminase (SGPT) level, indicating the induction of hepatitis due to the cytotoxic T lymphocytes in vivo. Similarly, direct transfer of the gene for the HBV secretory core protein (HBeAg) induced expression of HBeAg in hepatocytes and the appearance of antibody against HBeAg in the serum. However, using this system, we found that the lymphocytes infiltrating the transfected liver showed no cytotoxicity specific for HBeAg. These results indicate that expression of HBsAg, one of the components of virions, in animal liver induced hepatitis efficiently through generation of specific cytotoxic T lymphocytes (CTL) without any expression of the other viral components. This in vivo experimental system should be useful for evaluating how expression of a given gene induces cellular reactions and intrinsic functions in the living body.

Ambient glucose and aldose reductase-induced myo-inositol depletion modulate basal and carbachol-stimulated inositol phospholipid metabolism and diacylglycerol accumulation in human retinal pigment epithelial cells in culture

Physiological hyperglycemia has been speculated to alter phosphoinositide (PPI; inositol phospholipid) signal transduction in cells prone to diabetic complications by two separate mass-action mechanisms with antiparallel putative effects on diacylglycerol (DAG): (i) sorbitol-induced depletion of myo-inositol leads to diminished PPI synthesis and turnover and DAG release, and (ii) elevated glucose-derived DAG precursors enhance de novo DAG synthesis. Because the first mechanism is mediated by aldose reductase (AR2), which converts glucose to sorbitol, the effects of glucose on basal and stimulated PPI signaling were explored in lines of cultured human retinal pigment epithelial cells differing widely in their basal AR2 gene expression and enzymatic activity. The results suggest that the effects of glucose on PPI signaling vary inversely with the level of AR2 activity and parallel the extent of AR2-induced myo-inositol depletion.

Development and application of an enzyme immunoassay for tenascin

A sandwich enzyme immunoassay system for detecting tenascin in human serum was established using purified antibodies to tenascin. The assay system comprises polystyrene balls with immobilized polyclonal antibody F(ab')2 fragments and monoclonal antibody F(ab')2 fragments labeled with beta-D-galactosidase from Escherichia coli. The assay system has a minimum detectable sensitivity of 10 ng/ml of tenascin in human serum, with an assay range of 3 micrograms/ml. The assay system was found not to cross-react with laminin, vitronectin, human epidermal growth factor, fibrinogen, or fibronectin. Coefficients of variation within-run and between-run for the assay of human serum tenascin were less than 10%. Serum samples from healthy adults (n = 86) contained about 800 ng/ml and serum tenascin concentrations of patients with carcinoma (n = 47) were increased. These results suggest that tenascin in serum might be a marker substance for carcinoma.

An immunohistochemical study of copper/zinc superoxide dismutase and manganese superoxide dismutase in rat hippocampus after transient cerebral ischemia

We investigated the changes of copper/zinc superoxide dismutase (CuZn-SOD) and manganese superoxide dismutase (Mn-SOD) in the rat hippocampus after 10 min of cerebral ischemia induced by 4-vessel occlusion. The rats were allowed to survive for 4 h, 1 day, 3 days, and 7 days after ischemia. The distribution of SODs were determined by immunohistochemical staining with antibodies against rat CuZn-SOD and Mn-SOD. CA1 pyramidal neurons and granule cells of the dentate gyrus showed intense CuZn-SOD immunoreactivity, whereas CA3 and CA4 neurons showed weaker immunostaining than CA1 neurons in normal animals. The immunoreactivity was reduced by 4 h after ischemia in CA1, CA3, and CA4 neurons when no histological damage was observed. Mn-SOD immunostaining revealed more intense immunoreactivity in CA3 pyramidal neurons than in CA1 neurons in normal animals. Interneurons in the CA1 and CA3 regions and the dentate hilus also showed high Mn-SOD immunostaining. Although CA1 neurons lost Mn-SOD immunoreactivity by 1 day after ischemia, CA3 neurons and interneurons retained the immunoreactivity and preserved intact cell contour after ischemia. In addition, reactive glial cells, which were differentiated by immunocytochemical staining against glial fibrillary acidic protein for reactive astrocytes and histochemical staining for reactive microglial cells, were intensely stained for CuZn-SOD and Mn-SOD after ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the cell wall of Butyrivibrio species

Most Butyrivibrio strains have been isolated from the gastrointestinal tract of animals and have been classified as Butyrivibrio fibrisolvens. A few strains isolated from human feces are designated as Butyrivibrio crossatus, the other species in this genus. Butyrivibrio fibrisolvens strains are anaerobic, curved rods that produce butyrate, but numerous studies have shown that these strains display considerable variations in phenotypic properties and heterogeneity in DNA relatedness. Although over 60 strains have been characterized in these respects, the cell wall structure of only a few strains has been studied. In this study, cell wall related properties of 12 strains representative of five DNA relatedness groups were examined. All strains were very sensitive to penicillin and other antibiotics that interfere with cell wall synthesis. Although an occasional resistant strain was found, most strains were sensitive to a variety of protein synthesis antibiotics that included aminoglycosides and tetracycline. In contrast, all strains were highly resistant to nalidixic acid. Peptidoglycans were isolated from seven B. fibrisolvens strains and Lachnospira multiparus. Compositional analyses indicated molar ratios of 0.7:2:2:1:0.8 for muramic acid, glucosamine, alanine, glutamic acid, and diaminopimelic acid, respectively, in all peptidoglycans, which also showed a low degree of cross-linking. A trichloroacetic acid extractable galactosamine-containing polysaccharide copurified with the Butyrivibrio peptidoglycans. Electron microscopy of thin sections showed all strains to possess a Gram-positive type of cell wall that was atypically thin (12-18 nm). Most strains also displayed external (surface) polysaccharide layers. Cytoplasmic inclusions and granules were evident in many strains and were composed of polysaccharides, on the basis of cell composition analyses. The findings that Butyrivibrio strains have overall similarities in cell wall properties, but differences in DNA relatedness, suggest that these organisms should be classified as several more species in the same genus or family.

Cocaine and metabolite excretion in saliva under stimulated and nonstimulated conditions

The accessibility of saliva for rapid, noninvasive sampling makes it an attractive biological fluid for detecting drug use. However, little is known about salivary excretion patterns of the major cocaine metabolites, benzoylecgonine (BE) and ecgonine methyl ester (EME). Additionally, there is a general lack of information on the effects of salivary collection conditions on cocaine excretion in saliva. This study documents the profile of cocaine and metabolites in human saliva under stimulated and nonstimulated saliva flow conditions. Saliva samples were obtained periodically from six healthy volunteers who were administered three, equally spaced, single intravenous doses of 25 mg of cocaine during a 6-h test session. On different days, whole saliva was obtained either under nonstimulated or stimulated (sour candy) conditions. The samples were analyzed for cocaine and metabolites by GC/MS. Cocaine, BE, and EME were detected and quantitated in the saliva of all subjects. Cocaine was the predominant analyte identified in all samples. Nonstimulated saliva contained substantially more drug than stimulated samples. The ratio of the area under the curve (AUC) of cocaine in nonstimulated saliva to that of stimulated saliva was variable and ranged from 3.0 to 9.5. The AUC ratios of BE and EME were similar to those observed for cocaine. The lowering of cocaine concentration in saliva in the stimulated flow condition was likely due to an increase in saliva pH associated with increased saliva flow rate; it is known that an increase in saliva pH retards cocaine partitioning into this biological fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Nerve-specific marker proteins as indicators of organic solvent neurotoxicity

Effects of chronic exposure to n-hexane and toluene on some nerve-specific marker proteins in rat central nervous system (CNS) and peripheral nervous system (PNS) were assessed and compared. The rats were exposed to 2000 ppm n-hexane, 12 hr/day, 6 days/week, for 24 weeks, and to 1000 ppm toluene, 8 hr/day, 6 days/week, for 16 weeks. The level of neuron-specific enolase (NSE), creatine kinase-B (CK-B), and beta-S100 protein in cortex, cerebellum, spinal cord, and proximal and distal sciatic nerve was determined by enzyme immunoassay method. In n-hexane-exposed rats, the level of NSE, CK-B, and beta-S100 decreased significantly in the distal segment of the sciatic nerve, while the marker proteins in CNS and proximal sciatic nerve remained unchanged. In contrast, chronic exposure to toluene mostly affected these marker proteins in CNS tissues, displaying the increase of NSE, CK-B, beta-S100 in cerebellum, as well as the increase of beta-S100 in spinal cord. No quantitative changes of the three proteins in distal sciatic nerve were observed after exposure to toluene. n-Hexane-induced peripheral distal neuropathy and toluene-induced brain gliosis appeared to be responsible for this different pattern of biochemical changes. The present study suggests the usefulness of using these nerve-specific marker proteins to assess the solvent-related CNS and PNS neurotoxicity.

Toxic pustuloderma induced by ofloxacin

A patient with drug-induced toxic pustuloderma is presented. The patient, who was asthmatic and who was being treated with ofloxacin for bronchitis and pharyngitis, developed intense erythemas followed by subcorneal pustulation associated with fever and a neutrophil leukocytosis. The diagnosis was confirmed by oral readministration of ofloxacin, with the result that pustular eruptions were induced. This form of drug eruption had not previously been attributed to ofloxacin.

[Study of the localization and the concentration of superoxide dismutase in various thyroid disorders]

The localization of Cu/Zn and Mn superoxide dismutase (SOD), which catalyzes the dismutation of superoxide radicals (O2-) to O2 and H2O2, in various thyroid disorders was studied by an immunohistochemical technique in 20% formalin fixed paraffin embedded thin sections using anti-human Cu/Zn and Mn-SOD antibodies. The concentrations of both SODs in those tissues were also measured by a sandwich enzyme immunoassay technique. Cu/Zn SOD was immunocytochemically stained in most of papillary carcinoma, and some of other disorders. In the normal follicular cells it localized in the perinuclear cytoplasm, whereas in the tumor or hyperplastic cells it was in the cytoplasm homogeneously. Mn SOD was strongly stained in papillary carcinoma and papillary growing cells in adenoma and Graves' disease. The concentrations of Cu/Zn and Mn SOD in every thyroid disorder were higher than those in normal thyroid, and it was much higher in the malignant tumors. The ratio of the concentration of Mn SOD against Cu/Zn SOD in the tissues was higher only in papillary carcinoma compared with that in normal thyroid. In conclusion, SOD seems to be relating to the cell proliferation and differentiation in the thyroid since both SODs increased in tumors and hyperplastic disorders, and Cu/Zn SOD changed its localization and Mn SOD existed predominantly in papillary carcinoma or papillary growing cells.

Purification of four forms of the beta gamma subunit complex of G proteins containing different gamma subunits

To investigate the physiological significance of the diversity of gamma subunits of G proteins, we purified four forms of beta gamma of G proteins from bovine brain (beta gamma-B1, beta gamma-B2, beta gamma-B3), and spleen (beta gamma-S1) by the sequential chromatography on columns of DEAE-Sephacel, Ultrogel AcA 34, heptylamine-Sepharose, phenyl-5PW, and DEAE-5PW. Electrophoretic analyses showed that each beta gamma mainly contained the 36-kDa beta and a distinct but homogeneous gamma. These beta gamma complexes were subjected directly to proteolytic digestion and subsequent amino acid sequence analyses of their fragments. It was revealed that beta gamma-B1, -B2, and -B3 were identical to beta 1 gamma 7 (with a low level of beta 2 gamma 7), beta 1 gamma 2 and beta 1 gamma 3, respectively, while beta gamma-S1 was composed of beta 1 and an unidentified form of gamma. Then we examined the functional differences among these beta gamma complexes and the beta gamma of transducin (beta gamma-T, beta 1 gamma 1). Few differences were observed among all beta gamma complexes to enhance pertussis toxin-catalyzed ADP-ribosylation of the alpha subunits of G(o) and Gt. The four forms of beta gamma complexes purified from brain and spleen showed indistinguishable inhibitory effects on the release of GDP from G(o) alpha, but beta gamma-T was much less effective. Brain and spleen beta gamma complexes were equally effective in inhibiting calmodulin-stimulated adenylyl-cyclase activity, but beta gamma-T had a very weak inhibitory effect. Five forms of beta gamma facilitated metarhodopsin II-catalyzed binding of GTP gamma S to Gt alpha in a concentration-dependent manner with the following rank order of effectiveness: beta gamma-S1 > beta gamma-T > beta gamma-B1 > beta gamma-B2 > beta gamma-B3. Because the beta gamma complexes used in this study mostly contained the same beta subunit, the functional differences must be dependent on the gamma subunits. Thus, it seems likely that the receptor, the alpha subunits, and the effector are able to distinguish between the various gamma subunits.

Incidence of acetylcholine-induced spasm of coronary arteries subjected to balloon angioplasty

To examine the vasospastic activity of coronary arteries which have been subjected to previous balloon angioplasty, we conducted an acetylcholine provocative test at diagnostic catheterization in 147 consecutive patients. All patients underwent successful elective angioplasty and had follow-up angiography 1 to 6 months after the procedure. Sixty-two patients had a history of prior myocardial infarction and 43 patients had multivessel coronary artery disease. Angioplasty was performed on 176 vessels. Incremental doses of acetylcholine (25 micrograms, 50 micrograms, 100 micrograms) were injected into the right and left coronary arteries over a period of 1 min. The incidence of coronary spasm of arteries which had been subjected to angioplasty was 44%. Angiographic restenosis was observed in 59 patients (40%). There was no correlation between the occurrence of coronary spasm and the presence of restenosis. The maximal dose of injected acetylcholine was smaller in patients with positive evidence of spasm than in patients with negative evidence of spasm (55 +/- 27 micrograms vs 82 +/- 28 micrograms, p < 0.01). In patients with single vessel coronary artery disease, the incidence of spasm of the contralateral artery, i.e. the artery without angioplasty, was lower than that of the artery subjected to angioplasty (22% vs 46%, p < 0.01). Thus, the data suggest that coronary arteries which have been previously subjected to angioplasty have enhanced vasospastic activity in response to acetylcholine.

Construction of subtracted cDNA libraries enriched for cDNAs for genes expressed in the mesoderm of early Xenopus gastrulae

We present a new method for the construction of subtracted cDNA libraries. It makes use of two directional cDNA libraries in phagemid vectors and has two advantages over traditional protocols: it can be used when a limiting amount of driver material is available and the cDNA inserts in the subtracted libraries are long enough to encode functional proteins. Using this method, we have constructed two subtracted libraries enriched for sequences expressed in the mesoderm of early Xenopus gastrulae.

New E2A/PBX1 fusion transcript in a patient with t(1;19)(q23;p13) acute lymphoblastic leukemia

About 25% of the children with pre-B cell acute lymphoblastic leukemia (ALL) have a chromosomal translocation of t(1;19)(q23;p13). This translocation juxtaposes the E2A gene on chromosome 19 to the PBX1 gene on chromosome 1, leading to production of a fusion transcript. The fusion sites of the E2A and PBX1 coding sequence have been identical among all cases of t(1;19) ALL studied so far. Here we described a new fusion site of the E2A and PBX1 genes, which was detected in the leukemic blasts of a child with t(1;19) pre-B ALL using the reverse transcriptase polymerase chain reaction and direct sequencing. The fusion site was located just upstream of the DNA binding domain of the E2A gene, and was close to a homeodomain of the PBX1 gene.

Physiological and pathological changes in levels of the two small stress proteins, HSP27 and alpha B crystallin, in rat hindlimb muscles

The two small stress proteins, HSP27 and alpha B crystallin, are expressed widely in normal rat tissues and abundantly in skeletal muscle. In order to clarify the physiological significance of these stress proteins, the changes in their levels were determined immunochemically, in the slow-twitch soleus muscle and fast-twitch extensor digitorum longus muscle or rectus femoris muscle of growing rats, and in those of adult rats during denervation and tenotomy. HSP27 was quantitated by specific immunoassay, similar to that for alpha B crystallin, with antibodies raised in rabbits against purified rat HSP27. In adult rats, HSP27 was present at high levels in tissues composed of striated muscle, and it was present at much higher levels in the soleus muscle than in the rectus femoris or extensor digitorum longus muscle, as is alpha B crystallin. However, in rats of perinatal age (from prenatal day 2 to postnatal day 3), levels of HSP27 in the rectus femoris muscle were enhanced like those in the soleus muscle, reaching the maximum levels at postnatal day 3. Thereafter HSP27 in the fast-twitch muscle showed a steep decrease. The increase in alpha B crystallin in the hindlimb muscles was also observed in the perinatal period. However, alpha B crystallin concentrations in the soleus muscle of perinatal rats were as low as those in rectus femoris muscle. The transection of the sciatic nerve resulted in decreases in the levels of HSP27 and alpha B crystallin in the soleus muscle of adult rats, together with increases in the levels of the two proteins in the extensor digitorum longus muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term prognosis in 990 medically treated Japanese patients with coronary artery disease

We performed a retrospective analysis of the fate of 990 medically treated Japanese patients with coronary artery disease. Patients were enrolled in this study between September 1973 and February 1984. They were confirmed to have significant coronary artery disease by coronary angiography. There were 924 males and 66 females with a mean age of 54.4 years. The mean duration of follow-up was 9.4 years with a range of 6.5 to 17.0 years. The 5-year and 10-year survival rates for the entire population were 92.1% and 84.4%. The 5-year and 10-year survival rates in patients with single- (SVD), double- (DVD), and triple-vessel disease (TVD) and left main trunk (LMT) disease were as follows: 96.0% and 91.9% for SVD, 93.8% and 87.5% for DVD, 83.2% and 68.3% for TVD, and 89.3% and 84.6% for LMT disease. This was the first large follow-up study of coronary artery disease in Japan. Its results suggest that the prognosis of Japanese patients with coronary artery disease is more favorable than that of patients in Western countries. In addition, the findings should provide a control data base for future studies in Japan and the West.

Alterations in pharmacokinetics and protein binding behavior of cefazolin in endotoxemic rats

The possible alterations in the pharmacokinetics and protein binding behavior of the beta-lactam antibiotic cefazolin (CEZ) were investigated in endotoxemic rats induced by Klebsiella pneumoniae O3 lipopolysaccharide (LPS). LPS (250 micrograms/kg of body weight) was infused for 20 to 30 min 2 h before an intravenous administration of CEZ (20 mg/kg). Significant decreases in systemic clearance and renal clearance of CEZ were observed in LPS-treated rats without any changes in fraction of urinary excretion in unchanged CEZ (> 0.8). The volume of distribution at steady state showed a tendency to increase. The protein binding parameters of CEZ, the binding capacity, and number of binding sites on the albumin molecule were decreased by LPS, whereas the dissociation constant did not change. Significant decreases in systemic and renal clearances for unbound CEZ were observed in LPS-treated rats. The glomerular filtration rate estimated as inulin clearance was also decreased by LPS. The ratio of renal clearance of unbound CEZ to glomerular filtration rate (clearance ratio) dropped to 70% of that in control rats, and the net tubular secretion of CEZ was also dramatically reduced. The present study suggests that LPS has an effect on the pharmacokinetics of CEZ by changes which occur in renal handling and protein binding.

Introduction of functional groups onto the surface of polyethylene for protein immobilization

Amino and carboxyl groups could be introduced onto the surface of high-density polyethylene film by utilizing graft polymerization of acrylamide and the subsequent Hofmann degradation and alkaline hydrolysis of grafted polyacrylamide. Graft polymerization was carried out by immersing an argon-plasma treated film in an aqueous solution of the monomer, followed by heating after degassing the monomer/film mixture. The surface density of these functional groups could be increased up to 10(-7) mol/cm2. The surfaces having amino and carboxyl groups exhibited positive and negative zeta potentials, respectively, when contacted with KCl aqueous solution. Both of the functional groups introduced onto the polyethylene surface were found to be utilizable for covalent immobilization of protein using carbodiimide for the carboxylic group or mediators such as glutaraldehyde and ethylene glycol diglycidyl ether for the amino group.

The close relationship between DNA replication and the selection of differentiation lineages of human erythroleukemia cell lines K562, HEL, and TF1 into either erythroid or megakaryocytic lineages

The selection of differentiation lineages into either erythroid or megakaryocytic series was analyzed with human erythroleukemia cell lines K562, HEL, and cytokine-dependent TF1. A tumor promoter, TPA, induced a megakaryocyte marker, glycoprotein IIb/IIIa (GP IIb/IIIa) or IIIa (GP IIIa), but suppressed erythroid differentiation. On the other hand, aphidicolin, which is a potent inhibitor of DNA replication, inhibited GP IIb/IIIa or IIIa expression, but induced the expression of erythroid phenotypes. These phenomena were observed in all erythroleukemia cell lines tested. The bromodeoxyuridine labeling experiments indicated that de novo DNA synthesis was completely suppressed by aphidicolin treatment but was well preserved in TPA-treated cells. Among these three cell lines, erythropoietin (EPO) treatment induced erythroid differentiation of TF1 cells, which was dependent on GM-CSF or IL-3. In this case, EPO functioned as the survival factor and mild stimulator for cell proliferation as well as the inducer of erythroid differentiation. However, when either GM-CSF or IL-3 was depleted from the culture medium, TF1 ceased cell growth; concomitantly, hemoglobin-positive cells appeared, which is consistent with the results obtained with aphidicolin. The incubation of K562 cells for 48 h with either TPA or aphidicolin induced the irreversible commitment of cells to megakaryocytic and erythroid lineages, respectively. Our results using three different erythroleukemia cell lines suggest that a possible linkage between the DNA replication system and the selection of a differentiation lineage is the common feature of human erythroleukemia cell lines, and that these culture systems provide a suitable model for the analysis of the signal transduction system for differentiation lineage selection.

Nitric oxide inhibitors facilitate the induction of hippocampal long-term potentiation by modulating NMDA responses

1. The effects of the competitive nitric oxide (NO) synthase inhibitor, L-nitroarginine (L-NOArg), on synaptically activated N-methyl-D-aspartate (NMDA) currents and the induction of long-term potentiation (LTP) were studied in the CA1 region of rat hippocampal slices. 2. Application of 10 microM L-NOArg increased the amplitude of NMDA currents by approximately 50% in the presence of 2 mM extracellular Mg2+. This augmentation occurred within minutes of L-NOArg administration and was readily reversible on removal of the drug. L-arginine (100 microM) overcame the enhancement produced by L-NOArg. 3. At 5-100 microM, 10-25-min applications of L-NOArg facilitated the induction of LTP produced by a single 100 Hz X 300 ms tetanus. In control slices, the 100 Hz X 300 ms tetanus was insufficient to induce LTP. The development of LTP in L-NOArg-treated slices was inhibited by 50 microM D-2-amino-5-phosphonovalerate (D-APV), and the effects of L-NOArg were overcome by 10-fold higher concentrations of L-arginine but not by D-arginine. 4. Hemoglobin, an agent that binds NO extracellularly, also facilitated NMDA currents and the development of LTP when administered at 10 microM. 5. These results suggest that tonically released NO modulates the threshold for LTP in the CA1 hippocampal region and are consistent with prior studies indicating that untimely activation of NMDA receptors and release of NO inhibit LTP.

Identification of three forms of the gamma subunit of G proteins isolated from bovine spleen

We reported previously that G proteins from bovine spleen contain at least five forms of the gamma subunit (designated S1 through S5), among which S1 and S5 have been identified as novel gamma and gamma 2 subunits, respectively. In this study, we identified the other three forms of the gamma subunit, namely, S2, S3 and S4. Amino acid sequences of proteolytic fragments obtained from S2, S3 and S4 coincided exactly with internal sequences of gamma 7, gamma 5 and gamma 2, respectively. However, sequence analysis of undigested S4 revealed that S4 was an N-terminally truncated form of gamma 2, while analysis of the C-terminal fragment by fast atom bombardment mass spectrometry revealed that the C-terminus of S4 seemed to be geranylgeranylated and carboxymethylated as is that of intact gamma 2. Thus, the three types of gamma subunit obtained from bovine spleen were identified as gamma 7, gamma 5, and an N-terminally truncated gamma 2.

13C NMR study of the mode of interaction in solution of the B fragment of staphylococcal protein A and the Fc fragments of mouse immunoglobulin G

The mode of interaction of the B domain (FB) of staphylococcal protein A and the Fc fragments of mouse immunoglobulin G (IgG) has been investigated by 13C NMR spectroscopy. Mouse IgG1, IgG2a, and IgG2b proteins have been selectively labeled with 13C at the carbonyl carbon of His, Met, Trp or Tyr residue and used to prepare the corresponding Fc fragments by limited proteolysis. Site-specific resonance assignments have been made for each of these Fc analogues. FB was reported to form two contacts (contact 1 and contact 2) with human Fc in the crystal [Biochemistry 20 (1981) 2361-2370]. Comparisons of the chemical shift data of the Fc fragments observed in the absence and presence of FB have led us to conclude that in solution contact 1 is responsible for the formation of the Fc-FB complexes.