Glutathione regulates nitric oxide synthase in cultured hepatocytes

OBJECTIVE

The authors determine the relationship between glutathione and nitric oxide (NO) synthesis in cultured hepatocytes.

SUMMARY BACKGROUND DATA

Glutathione is a cofactor for a number of enzymes, and its presence is essential for maximal enzyme activity by the inducible macrophage nitric oxide synthase (iNOS), which produces the reactive nitric oxide radical. Hepatocytes contain substantial quantities of glutathione, and this important tripeptide is decreased in hepatocytes stressed by ischemia/reperfusion or endotoxemia. Endotoxemia also induces the synthesis of inflammatory cytokines that result in the production of nitric oxide from hepatocytes by iNOS, suggesting that hepatocytes may be attempting to synthesize nitric oxide at times when intracellular glutathione is reduced.

METHODS

Hepatocytes were cultured with buthionine sulfoximine and 1,3-bis(chloroethyl)-1-nitrosourea (BCNU) to inhibit glutathione. After exposure to cytokines, NO synthesis was assessed by supernatant nitrite levels, cytosolic iNOS enzyme activity, and iNOS mRNA levels.

RESULTS

Inhibition of glutathione synthesis with buthionine sulfoximine or inhibition of glutathione reductase activity with BCNU inhibited nitrite synthesis. Both buthionine sulfoximine and BCNU inhibited the induction of iNOS mRNA, as detected by Northern blot analysis. Exogenous glutathione increased cytokine-stimulated iNOS induction, overcame the inhibitory effects of BCNU, and increased nitrite production by intact hepatocytes, induced hepatocyte cytosol, and partially purified hepatocyte iNOS.

CONCLUSIONS

In cultured hepatocytes, adequate glutathione levels are required for optimal nitric oxide synthesis. This finding is predominantly due to an effect on iNOS mRNA levels, although glutathione also participates in the regulation of iNOS enzyme activity.

Proteolytic cleavage of soybean Bowman-Birk inhibitor monitored by means of high-performance capillary electrophoresis. Implications for the mechanism of proteinase inhibitors

The hydrolysis of the soybean Bowman-Birk inhibitor in the presence of catalytic amounts of bovine trypsin and the formation of the non-covalent enzyme-inhibitor complex with an equimolar amount of enzyme are monitored by means of high-performance capillary electrophoresis (HPCE). The inhibitor is cleaved in the trypsin-reactive and more slowly in the chymotrypsin-reactive subdomain. HPCE proves itself as the only reliable analytical tool to monitor these reactions in clear contrast to classical electrophoretic, chromatographic and enzymatic methods. The most efficient separation of the intact and the two active site cleaved forms of the inhibitor was achieved in borate buffer at pH 10.0. The pH dependence of the rate constant and the final extent of hydrolysis reveal the stability of the enzyme inhibitor complex as a central aspect of the mechanism of proteinase inhibitors.

IL-1 beta stimulates superoxide and delayed peroxynitrite production by pulmonary vascular smooth muscle cells

Our previous studies have shown that rat pulmonary microvascular smooth muscle cells (RPMSMC) upregulate inducible nitric oxide synthase (iNOS) and produce nitric oxide (NO) when treated with interleukin-1 beta (IL-1 beta). We now report that an additional effect of IL-1 beta stimulation in RPMSMC is an increase in production of superoxide (O2-) that results in the formation of peroxynitrite (ONOO-). IL-1 beta produced a rapid (within 1 h) concentration-dependent increase in O2-, as detected by ferricytochrome c reduction and lucigenin-enhanced chemiluminescence. O2- production was sensitive to quinacrine and diphenyliodinium, suggesting that NADH and NADPH oxidoreductases were responsible. After induction of iNOS and production of iNOS-derived NO, ONOO- was detected by luminol-enhanced chemiluminescence and was found to cause lipid peroxidation and to form nitrotyrosine in the cytoskeleton, detected by immunostaining. Cell viability, however, appeared to be unaffected. IL-1 beta-mediated induction of RPMSMC-derived ONOO- may have significant effects on pulmonary vascular function in sepsis and inflammatory states.

Glucagon inhibits hepatocyte nitric oxide synthesis

OBJECTIVE

To investigate the effects of glucagon on nitric oxide (NO) synthesis in cultured rat hepatocytes.

SETTING

Laboratory.

MATERIALS

Male Sprague-Dawley rats (weight, 200-250 g).

INTERVENTIONS

Isolated rat hepatocytes were cultured with interleukin-1 to stimulate NO synthesis. Glucagon was added at increasing concentrations (from 10(-9) to 2 x 10(-5) mol/L) at the time of interleukin-1 stimulation. Selected cultures were treated with the adenylate cyclase inhibitor, SQ 22536 (from 10(-5) to 10(-3) mol/L).

MAIN OUTCOME MEASURES

Nitric oxide synthesis was assessed by measuring the concentrations of culture supernatant nitrite and nitrite plus nitrate, hepatocyte nitric oxide synthase-2 (NOS-2) messenger RNA (mRNA), and NOS-2 protein.

RESULTS

Interleukin-1 stimulated hepatocyte NO synthesis, and this synthesis was inhibited by glucagon in a dose-dependent manner. Glucagon inhibited the accumulation of supernatant nitrite and the expression of NOS-2 mRNA and NOS-2 protein. SQ 22536 restored glucagon-induced decreases in NO synthesis.

CONCLUSIONS

Glucagon inhibits NO synthesis in interleukin-1-stimulated hepatocytes in vitro. This inhibition seems to be mediated by glucagon-induced changes in cyclic adenosine monophosphate.

Crystal structure of the bifunctional soybean Bowman-Birk inhibitor at 0.28-nm resolution. Structural peculiarities in a folded protein conformation

The Bowman-Birk inhibitor from soybean is a small protein that contains a binary arrangement of trypsin-reactive and chymotrypsin-reactive subdomains. In this report, the crystal structure of this anticarcinogenic protein has been determined to 0.28-nm resolution by molecular replacement from crystals grown at neutral pH. The crystal structure differs from a previously determined NMR structure [Werner, M. H. & Wemmer, D. E. (1992) Biochemistry 31, 999-1010] in the relative orientation of the two enzyme-insertion loops, in some details of the main chain trace, in the presence of favourable contacts in the trypsin-insertion loop, and in the orientation of several amino acid side chains. The proximity of Met27 and Gln48 in the X-ray structure contradicts the solution structure, in which these two side chains point away from each other. The significant effect of a Met27-->Ile replacement on the inhibitory activity of the chymotrypsin-reactive subdomain agrees with the X-ray structure. Exposed hydrophobic patches, the presence of charged amino acid residues, and the presence of water molecules in the protein interior are in contrast to standard proteins that comprise a hydrophobic core and exposed polar amino acids.

A nitric oxide production bioassay for interferon-gamma

Interferon-gamma (IFN-gamma), produced by stimulated T lymphocytes and natural killer cells, has an antitumor and antiviral activity by inhibition of cell growth, immunomodulation, and/or activation of macrophages. Although several IFN-gamma assays have been used, there are no simple, inexpensive, and specific assays. We have developed a new bioassay for IFN-gamma which measures the concentration of nitric oxide (NO) generated by a macrophage cell line RAW264.7 stimulated with IFN-gamma. NO production, determined by nitrite (NO2-) accumulation in culture medium, was linear at IFN-gamma concentrations between 0 and 10 U/ml and logarithmically linear between 2 and 100 U/ml, when RAW cells (1 x 10(5) cells/200 microliters/well in 96 well plate) were incubated with murine recombinant IFN-gamma for 24 h. The new assay has a high sensitivity with the detection limit of 0.1-0.2 ng/ml IFN-gamma, which is similar to that of the enzyme-linked immunosorbent assay (ELISA) and antiviral assays. Other cytokines such as IFN-alpha, IFN-beta, tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, IL-2, and IL-6, either alone or in combination did not produce NO from RAW264.7. Exogenous NO2-, NO3- or NO2- plus NO3- did not interfere with the IFN-gamma-induced NO formation as well as NO2- measurement. The IFN-gamma bioactivity, measured by the RAW264.7 bioassay, expressed from the transfected human ovarian tumor cells was closely correlated with the levels of IFN-gamma protein concentration measured by the ELISA. Therefore, our new method can be applicable for monitoring IFN-gamma gene expression and accumulation in culture medium for IFN-gamma therapy.

Heat shock response inhibits cytokine-inducible nitric oxide synthase expression in rat hepatocytes

During sepsis or inflammation, the liver expresses various protective phenotypes such as the acute phase response or the heat shock response (HSR). Inducible nitric oxide synthase (NOS2) is also expressed in the liver in these conditions and may protect the liver under some circumstances and promote injury in others. We have previously reported that the acute phase response and NOS2 expression are differentially regulated, though both can be expressed simultaneously. The HSR is known to prevent expression of other genes, but its effects on NOS2 expression in the liver is unknown. Therefore, we examined how the HSR influences NOS2 expression in primary rat hepatocytes. Sodium arsenite (Ars) or hyperthermia (43 degrees C) induced the synthesis of hsp72 messenger RNA (mRNA) and protein in hepatocytes, indicating activation of the HSR. In the absence of the HSR, combinations of interleukin-1beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma) stimulated high levels of NOS2 mRNA and nitric oxide (NO) synthesis. However, treatment with Ars or heat shock significantly attenuated cytokine-induced NOS2 mRNA and NO production. The addition of the nuclear factor kappaB (NF-kappaB) inhibitor pyrrolidine dithiocarbamate also inhibited NOS2 expression, suggesting a role for NF-kappaB in the cytokine induction of NOS2 in hepatocytes. Cytokines induced the appearance of an NF-kappaB complex as shown in gel retardation assays; however, induction of the HSR by Ars partially prevented cytokine-induced formation of this band while hyperthermia had a more complete inhibition. Furthermore, preinduction of the HSR prevented the activation of the NOS2 promoter construct in hepatocytes transfected with a 1.6 kilobase NOS2 promoter linked to luciferase. These findings show that NO production in stressed cells can be modulated by the HSR, possibly through repression of NOS2 gene transcription via the inhibition of NF-kappaB.

Effect of nitric oxide on heme metabolism in pulmonary artery endothelial cells

Primary intracellular targets for nitric oxide (NO) include nonheme iron-containing enzymes and protein-bound iron. Because NO is an important effector molecule in lung inflammation and endothelial cell-associated iron is critical to numerous forms of oxidant-mediated lung injury, we studied the effects of the NO donor S-nitrosoacetylpenicillamine (SNAP) on heme and iron metabolism in cultured sheep pulmonary artery endothelial cells. SNAP (300 microM) caused a transient increase in heme oxygenase-1 (HO-1) mRNA associated with a fivefold increase in HO activity that was completely blocked by the competitive HO inhibitor, tin protoporphyrin IX (SnPP). SNAP-induced activation of HO caused SnPP-sensitive reduction of activity of the hemoprotein catalase and decrease in heme iron. SNAP caused increases in iron-responsive gene products, ferritin and mitochondrial aconitase, secondary to the release of iron from heme stores via HO induction, since these changes were also sensitive to SNPP. The NO-induced increase in nonheme iron was apparent via electron paramagnetic resonance, where an enhanced SNAP-induced (300 microM for 4 h) g = 2.04 signal (e.g., dinitrosyl-iron-sulfur complex) was noted after exposure to a dose of SNAP (200 microM for 14 h) that in itself did not produce a detectable signal. These data show that exposure of pulmonary endothelial cells to NO results in profound changes in intracellular heme- and nonheme-iron homeostasis and that HO plays a central role in affecting this balance.

Excessive NO production dose not account for the inhibition of hepatic gluconeogenesis in endotoxemia

The pattern of inhibition of gluconeogenesis in hepatocytes was compared between endotoxemia in vivo and nitric oxide (NO) exposure in vitro. Fasted rats were injected with lipopolysaccharide (LPS; 12 mg/kg) or with vehicle alone. After 2-24 h, hepatocytes were isolated, placed in suspension, and incubated for 1 h with various gluconeogenic substrates that enter at different sites of the gluconeogenic pathway. Hepatocytes from LPS-treated rats exhibited up to a 50% decrease in gluconeogenesis for substrates that enter proximal to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) beginning at 6 h, followed by a nadir at 12 h after LPS. Although hepatocytes exposed to exogenous NO (S-nitroso-N-acetylpenicillamine) also exhibited a depressed gluconeogenesis, the pattern was not the same with inhibition in gluconeogenesis for substrates that enter the pathway both before and after GAPDH. Furthermore, when rats injected with LPS were subjected to a constant portal infusion (Alzet pump) of the NO synthase (NOS) inhibitors, NG-monomethyl-L-arginine or aminoguanidine, no changes in the LPS-induced gluconeogenesis suppression were seen. In addition, no difference in LPS-induced inhibition of gluconeogenesis was detected when hepatocytes from inducible NO synthase (NOS-2) knockout mice were compared with cells obtained from wild-type mice. Minimal decreases in GAPDH activity were measured in hepatocytes from the LPS-treated rats, whereas the activity of phosphoenol pyruvate carboxykinase (PEPCK) declined up to 40%, independent of NO synthesis. These data indicate that NO does not account for the inhibition of gluconeogenesis in endotoxemia, and they provide support for NO-independent reduction in PEPCK activity as a more plausible explanation.

PGE2 and LTB4 inhibit cytokine-stimulated nitric oxide synthase type 2 expression in isolated rat hepatocytes

Prostaglandins have been shown to have a wide range of effects on nitric oxide synthesis when studied in different cell populations. The proximity of hepatocytes to eicosanoid-producing endothelial cells and Kupffer cells prompted us to determine the effects of PGE2 and LTB4 on hepatocyte NO production by the inducible nitric oxide synthase (iNOS, NOS-2) in vitro. PGE2 decreased hepatocyte NO synthesis in a concentration-dependent manner when the cells were stimulated with a combination of cytokines or IL-1 alone. LTB4 had a similar effect. PGE2 had to be present at the time of cytokine exposure to produce maximal inhibition of NO synthesis. Reduced synthesis of NO2- was associated with reduced NOS-2 mRNA levels suggesting that the induction of NOS-2 was inhibited. These findings demonstrate that eicosanoids can regulate hepatocyte NO synthesis in vitro.

Counterprotective effect of erythrocytes in experimental bacterial peritonitis is due to scavenging of nitric oxide and reactive oxygen intermediates

Erythrocytes (RBC) in the peritoneal cavity significantly increase the lethality of bacterial peritonitis. The lethality is known to be associated with, and perhaps due to, increased bacterial counts in the peritoneal cavity. The mechanism is unknown. In this study, we investigated the hypothesis that RBC scavenge reactive oxygen intermediates (ROI) and nitric oxide (NO), so that the counterprotective effect is due to a loss of the microbiostatic activity of both ROI and NO. To study this effect, rats were subjected to a peritoneal inoculation of live Escherichia coli without RBC (nonlethal dose) or with RBC (lethal dose). The adjuvant effect of RBC was not modified by NG-monomethyl-L-arginine (NMA, an NO synthase inhibitor), superoxide dismutase, catalase, mannitol, or a combination of these agents. Furthermore, the increased number of bacteria in the peritoneal cavity in the presence of RBC was unaffected by these treatments. The administration of NMA with bacteria alone (no RBC) converted a nonlethal model into a lethal one associated with higher intraperitoneal bacterial counts. A similar effect was seen with superoxide dismutase and catalase but not with mannitol. During bacterial peritonitis in the absence of RBC, superoxide and NO formation (determined by the total nitrite plus nitrate formed) was detected in the ascites and inducible NO synthase mRNA expression was present in the peritoneal cells. In the absence of RBC, superoxide was detected and oxidation of dihydrorhodamine to rhodamine was observed, indicating that peroxynitrite was produced. Both were blocked by the inclusion of RBC. Preinjection with a low inoculum of killed bacteria protected the rats from a subsequent lethal peritoneal bacterial challenge; this effect was reversed by scavenging ROI and NO. The protective effect of killed bacterial pretreatment was lost when RBC were placed in the peritoneal cavity. In vitro bactericidal activity of NO- and ROI-generating macrophages was also inhibited by RBC or by inhibiting ROI and NO formation. Taken together, these data are consistent with the hypothesis that RBC can impair bacterial clearance by removing both NO and ROI, suggesting that NO in combination with superoxide may be important to the antimicrobial defenses of the peritoneal cavity.

Nitric oxide mediates hepatic cytochrome P450 dysfunction induced by endotoxin

BACKGROUND

Animals subjected to immunostimulatory conditions (sepsis) exhibit decreased total cytochrome P450 content and decreased P450-dependent drug metabolism. Cytochrome P450 function is of clinical significance because it mediates the metabolism of some opioid and hypnotic drugs. The authors tested the hypothesis that reduced P450 function and decreased drug metabolism in sepsis are mediated by endotoxin-enhanced synthesis of nitric oxide.

METHODS

Hepatic microsomes were prepared from male Sprague-Dawley rats in nontreated rats, rats pretreated with phenobarbital and rats receiving aminoguanidine or NG-L-monomethyl-arginine alone. Nitric oxide synthesis was augmented for 12 h with a single injection of bacterial lipopolysaccharides. Nitric oxide synthase was inhibited with aminoguanidine or N(G)-L-monomethyl-arginine during the 12 h of endotoxemia in some animals. Plasma nitrite and nitrate concentrations were measured in vivo, and total microsomal P450 content, and metabolism of ethylmorphine and midazolam in vitro.

RESULTS

Administration of endotoxin increased plasma nitrite and nitrate concentrations, decreased total cytochrome P450 content, and decreased metabolism of ethylmorphine and midazolam. Inhibition of nitric oxide formation by aminoguanidine or N(G)-L-monomethyl-arginine partially prevented the endotoxin-induced effects in the nontreated and phenobarbital-treated groups. Aminoguanidine or N(G)-L-monomethyl-arginine alone did not have an effect on either total cytochrome P450 content or P450-dependent drug metabolism. Plasma nitrite and nitrate concentrations correlated significantly negatively with P450 content (nontreated r = -0.88, phenobarbital r = -0.91), concentrations of formed formaldehyde (nontreated r = -0.87, phenobarbital r = -0.95), and concentrations of midazolam metabolites (4-OH midazolam nontreated r = -0.88, phenobarbital r = -0.93, and 1'-OH midazolam nontreated r = -0.88, phenobarbital r = -0.97).

CONCLUSIONS

Altered hepatic microsomal ethylmorphine and midazolam metabolism during sepsis is mediated in large part by nitric oxide.

MR imaging of cardiomyopathy

Spin echo and cine MR imaging provides reliable and reproducible quantitative information about the hearts of patients with cardiomyopathy. In particular, these techniques are useful in demonstrating the severity and distribution of left and right ventricular myocardial thickness, changes in myocardial thickness during ventricular contraction, ventricular chamber volume, and change in volume through the cardiac cycle. Furthermore, direct examination of the ventricular myocardium by spin echo MR imaging is beginning to demonstrate its utility in characterizing abnormal myocardium and in providing inferential information concerning the nature of the myocardial abnormality itself. MR examination is also useful in excluding other causes of myocardial dysfunction that mimic cardiomyopathy as well as in helping define the type of cardiomyopathy, both of which allow better clinical management of these patients.

Autocrine regulation of membrane transforming growth factor-alpha cleavage

Transforming growth factor alpha (TGF-alpha) is biosynthesized as a membrane-bound precursor protein, pro-TGF-alpha, that undergoes sequential endoproteolytic cleavages to release a soluble form of the factor. In the present study, we have analyzed the biosynthesis and regulation of TGF-alpha production in human tumor-derived cell lines that endogenously express pro-TGF-alpha and the epidermal growth factor (EGF) receptor. These cells biosynthesized membrane-anchored forms of the TGF-alpha that accumulated on the cell surface. Membrane-bound pro-TGF-alpha interacted with the EGF receptor, and complexes of receptor and pro-TGF-alpha contained tyrosine-phosphorylated receptor. Activation of the EGF receptor by soluble EGF or TGF-alpha had a dual effect on TGF-alpha production: an increase in pro-TGF-alpha mRNA levels and an increase in pro-TGF-alpha cleavage. These effects were largely prevented by preincubation with an anti-EGF receptor monoclonal antibody that blocked ligand binding. Growth factor autoinduction of cleavage could be stimulated by several second messenger pathways that are activated by the EGF receptor, including protein kinase C and intracellular calcium, and by other alternative mechanisms. EGF-stimulated cleavage of pro-TGF-alpha could be partially blocked by inhibition of these second messenger pathways. These results suggest that juxtacrine stimulation takes place in human tumor cells that coexpress both the EGF receptor and membrane-anchored TGF-alpha and that TGF-alpha is able to induce its own endoproteolytic cleavage by activating the EGF receptor.

H1, H2, and H3 receptors contribute to drinking elicited by exogenous histamine and eating in rats

Roles for H1, H2, and H3 receptor subtypes for drinking elicited by exogenous histamine and drinking elicited by eating was examined in adult male Sprague-Dawley rats. Drinking elicited by SC 5 mg/kg histamine was: (a) inhibited approximately 30% by H1 antagonism using IP 1 mg/kg dexbrompheniramine (DXB); (b) inhibited approximately 30% by H2 antagonism using IP 16 mg/kg cimetidine (C); (c) inhibited approximately 40% by H3 antagonism using SC 10 mg/kg thioperamide (Th); (d) inhibited approximately 80% by combined H1 and H2 antagonism using IP DXB plus IP C; (e) inhibited approximately 85% by combined H1 and H3 antagonism using IP DXB plus SC Th; (f) inhibited approximately 70% by combined H2 and H3 antagonism using IP C plus SC Th; and (g) abolished by combined H1, H2, and H3 antagonism using IP DXB plus IP C plus SC Th. For rats eating pellets and drinking after 24-h food deprivation: (a) systemic injections of DXB, C, and Th, sufficient to abolish drinking elicited by SC histamine, inhibited water/food ratio (W/F) by approximately 20%; (b) ICV injections (through a chronic cannula in a lateral ventricle) of 50 micrograms DXB plus 100 micrograms C plus 60 micrograms Th inhibited W/F by approximately 20%. For rats drinking after IG infusion (through a chronic gastric catheter) of 2 ml 1,800 mOsm/kg NaCl: (a) systemic injections of DXB, C, and Th, sufficient to abolish drinking elicited by SC histamine, inhibited water intake by approximately 70%; (b) IP DXB alone and IP C alone failed to inhibit water intake; (c) IP Th alone inhibited water intake by approximately 20%; (d) IP DXB combined with IP C inhibited water intake by approximately 55%. The results demonstrate the involvement of H1, H2, and H3 receptors for drinking elicited by exogenous histamine, and our findings extend the evidence for a role for endogenous histamine and H1, H2, and H3 receptor subtypes for drinking elicited by eating, including drinking elicited by gastrointestinal osmotic consequences of eating that can increase systemic plasma osmolality.

Identification and nucleotide sequences of mxaA, mxaC, mxaK, mxaL, and mxaD genes from Methylobacterium extorquens AM1

The DNA sequence for a 4.4-kb HindIII-XhoI Methylobacterium extorquens AM1 DNA fragment that is known to contain three genes (mxaAKL) involved in incorporation of calcium into methanol dehydrogenase (I. W. Richardson and C. Anthony, Biochem. J. 287:709-7115, 1992) was determined. Five complete open reading frames and two partial open reading frames were found, suggesting that this region contains previously unidentified genes. A combination of sequence analysis, mutant complementation data, and gene expression studies showed that these genes correspond to mxaSACKLDorf1. Of the three previously unidentified genes (mxaC, mxaD, and orf1), mutant complementation studies showed that mxaC is required for methanol oxidation, while the function of the other two genes is still unknown.

Angiotensin AT1 and AT2 receptors contribute to drinking elicited by eating in rats

A role for endogenous angiotensin II and its AT1 and AT2 receptor subtypes for mediating drinking elicited by eating was examined in adult male Sprague-Dawley rats. The ability of pharmacological antagonism of AT1 and/or AT2 receptors to abolish drinking elicited by exogenous angiotensin II was established first. The s.c. injection of the AT1 antagonist losartan (DuP 753) was sufficient to abolish drinking elicited by s.c. angiotensin II. The ICV injection (through a surgically implanted chronic cannula) of losartan inhibited drinking elicited by ICV angiotensin II; the combined ICV injection of losartan plus the AT2 antagonist PD123319 was sufficient to abolish drinking elicited by ICV angiotensin II. For rats drinking and eating after 24-h food deprivation, s.c. losartan plus PD123319 inhibited water to food ratio, but ICV losartan and/or PD123319 failed to inhibit food-related drinking. For nondeprived rats eating a small cracker, s.c. losartan and/or PD123319 attenuated water intake, but only ICV losartan produced statistically significant inhibition of drinking elicited by ingestion of cracker. The IG infusion (through a surgically implanted gastric catheter) of 2 ml 600 or 900 mOsm/kg NaCl, a treatment that is subthreshold for increase in systemic plasma osmolality at the initiation of drinking, elicited drinking that was attenuated by s.c. losartan and/or PD123319 and attenuated by ICV losartan only. The IG infusion of 2 ml 1800 mOsm/kg NaCl, a treatment that is above threshold for increase in systemic plasma osmolality at the initiation of drinking, elicited drinking that was not inhibited by S or ICV losartan and/or PD123319. These results demonstrate that peripheral AT1 and AT2 and central AT1 receptors for angiotensin II contribute to drinking elicited by eating and the gastrointestinal osmotic consequences of eating. These findings extend the evidence demonstrating a renal renin-angiotensin contribution to food-related drinking in rats.

In vivo cisplatin-exposed macrophages increase immunostimulant-induced nitric oxide synthesis for tumor cell killing

Mice pre-exposed to cisplatin increased their production of nitric oxide (NO) when treated with lipopolysaccharide (LPS). Peritoneal macrophages, isolated from mice 11 days after cisplatin treatment and cultured with LPS plus IFN-gamma, increased NO production, whereas the macrophages isolated 2 days after cisplatin treatment decreased it. In both cases, NO was not produced without immunostimulant(s). Northern and Western Blot analysis showed that macrophages exposed to cisplatin for 11 days increased production of mRNA and protein expression of inducible nitric oxide synthase (iNOS). THis result indicated that macrophages became more sensitive to LPS and IFN-gamma when they were exposed to cisplatin in vivo. Peritoneal macrophages, when activated with LPS plus IFN-gamma and then cocultured with several tumor cells, exhibited cytotoxic activity against both cisplatin-sensitive and cisplatin-resistant tumor cells. There was no difference in cytotoxicity between the paired cells. Under the same experimental condition, macrophages that were exposed to cisplatin for 11 days had significantly increased their cytotoxicity to the tumor cells. This cytotoxic activity was inhibited by the NOS inhibitor NG-monomethyl-L-arginine, indicating that NO is a major effector for macrophage-mediated tumor cell killing. Treatment of tumor cells with S-nitroso-N-acetylpenicillamine, a NO-generating compound, showed the similar tumoricidal effect. These data demonstrated that injection of cisplatin into the mice can enhance the sensitivity of macrophages to the subsequent treatment of immunostimulant(s) for effective tumor cell killing through enhanced NO production.

Histamine H3 receptors contribute to drinking elicited by eating in rats

A role for endogenous histamine and its H3 receptor subtype for mediating drinking elicited by eating was examined in adult male Sprague-Dawley rats. The i.p. injection of the H3 agonist R-alpha-methylhistamine (Ramh, 2.5 mg/kg) shortened the latency to initiate drinking and increased 1-h water intake in nondeprived rats freely eating pellets and drinking water. The ICV injection (through a surgically implanted chronic cannula) of 10 micrograms Ramh increased water intake; this Ramh-induced drinking was abolished by previous ICV injection of the H3 antagonist thioperamide (Th, 60 micrograms). For rats drinking and eating after 24-h food deprivation, s.c. Th inhibited drinking behavior: for example, 10 mg/kg Th s.c. delayed the latency to initiate drinking and inhibited 1-h water intake without inhibition of food intake. In contrast, 60 micrograms Th ICV failed to inhibit food-related drinking in rats eating after food deprivation. For nondeprived rats eating a small cracker, 10 mg/kg Th s.c. delayed the latency to initiate drinking and abolished water intake without effect of eating, and 60 micrograms Th ICV had similar effects upon drinking elicited by ingestion of cracker. The IG infusion (through a surgically implanted gastric catheter) of 2 ml 600 or 900 mOsm/kg NaCl, a treatment that is subthreshold for increase in systemic plasma osmolality at the initiation of drinking, elicited drinking that was abolished by 10 mg/kg Th s.c. and attenuated by 60 micrograms Th ICV. The IG infusion of 2 ml 1800 mOsm/kg NaCl, a treatment that is above threshold for increase in systemic plasma osmolality, elicited drinking that was attenuated by 10 mg/kg s.c. or 60 micrograms Th ICV. These results demonstrate that peripheral and central H3 receptors for histamine have a role in drinking elicited by eating and the postprandial gastrointestinal osmotic consequences of eating. These findings extend the evidence demonstrating a histaminergic contribution to food-related drinking in rats.

Endogenous histamine contributes to drinking initiated without postprandial challenges to fluid homeostasis in rats

A role for endogenous histamine and its receptor subtypes for mediating drinking elicited by eating was examined in adult male Sprague-Dawley rats in two experimental paradigms in which drinking was initiated without accompanying change in systemic fluid balance: (a) nondeprived rats eating a small (0.57 g) salted cracker; (b) nondeprived rats receiving IG infusion (through a chronic gastric catheter) of 2 ml 900 mOsm/kg NaCl. The ability of i.p., s.c., or ICV (through a surgically implanted chronic cannula in a lateral ventricle) injections of antagonists to H1, H2, or H3 receptors for histamine to inhibit drinking was examined. For rats ingesting a small cracker: systemic injection of H1 antagonists dexbrompheniramine (DXB) or pyrilamine (PYR) delayed the latency to initiate drinking. Systemic injection of H1 antagonists DXB, PYR, or terfenadine (TER; which fails to penetrate the blood-brain barrier) and ICV injection of DXB or PYR inhibited water intake. The H2 antagonist cimetidine (C) given i.p. or ICV failed to affect drinking. The H3 antagonist thioperamide (Th) given s.c. or ICV delayed the latency to drink and inhibited water intake. For rats receiving IG NaCl: systemic injection of H1 antagonists DXB or PYR or the H3 antagonist Th inhibited water intake, but the H2 antagonist C failed to inhibit drinking. Our findings extend the evidence for the involvement of endogenous histamine in drinking elicited by eating in rats by suggesting roles for peripheral and brain H1 and H3 receptors for drinking initiated by postprandial gastrointestinal osmotic consequences that are subthreshold for changes in systemic fluid balance.

Renal nerve transection inhibits drinking elicited by eating and by intragastric osmotic loads in rats

Adult Sprague-Dawley male rats surgically equipped with a chronic gastric catheter were tested for drinking after 2 ml intragastric infusions of 290, 600, 900, 1200, or 1800 mOsm/kg Nacl. Rats with bilateral transection of renal nerves (RD) drank less than neurologically intact rats (S) after 600 and 900 mOsm/kg NaCl infusions. The RD rats were capable of a rapid and robust drinking response to relatively mild experimental challenges, because they drank appropriately in response to s.c. angiotensin II and to dose of histamine that is a threshold dose for increasing water intake. The RD rats ate less than S rats, but RD rats drank appropriate amounts of water when eating and drinking after 24-h food deprivation. When nondeprived and ingesting one, two, or four small (0.57 g) salted crackers, the RD rats drank significantly less water than S rats. At the time drinking was initiated after ingestion of one salted cracker, plasma osmolality, sodium, protein, and packed cell volume were not changed from baseline conditions (i.e., no eating) in neurologically intact rats; plasma renin activity was significantly elevated at the time drinking was initiated following the ingestion of one or two small crackers. These findings (a) demonstrate a role for renal nerves in drinking behavior in rats, and (b) suggest the working hypothesis that the ingestion of a small meal, and the subsequent delivery of a relatively small osmotic load to the gastrointestinal tract and/or hepatic-portal vein, activates mechanisms for drinking that include a change in activity of renal nerves to increase plasma renin activity without cellular dehydration or hypovolemia. Such mechanisms may be activated to mobilize drinking behavior in advance of postprandial fluid deficit.

The mxaAKL genes of Methylobacter albus BG8

The facultative methanol utilizer Methylobacterium extorquens AM1 contains at least three genes (mxaA, K and L) that encode functions involved in providing calcium to the holoenzyme of methanol dehydrogenase, the enzyme that oxidizes methanol to formaldehyde in this strain. Methane-utilizing bacteria (methanotrophs) also contain methanol dehydrogenase, and evidence suggests that similar methanol oxidation (Mox) functions may be present in some of these strains. DNA fragments from Methylobacterium extorquens AM1 specific to mxaA, mxaK and mxaL were isolated for use as hybridization probes against genomic digests of a variety of methanotrophic bacteria. Only the mxaL probe showed substantial hybridization, and it was used to identify and isolate an 8.5 kb HindIII fragment from Methylobacter albus BG8 (a Type I methanotroph). Hybridization of restriction digests of this fragment to individual probes for Methylobacterium extorquens AM1 mxaA, K and L indicated that the relative mxa gene order in Methylobacter albus BG8 is A-K-L. A T7 dual promoter/polymerase protein expression system indicated that five polypeptides are expressed from a 4.5 kb region of Methylobacter albus BG8 DNA in Escherichia coli, all transcribed in the same direction, and they apparently correspond to mxaACKDL. The functions of mxaC and mxaD are currently not known, but the order of mxaDL is reversed in Methylobacter albus BG8 compared to Methylobacterium extorquens AM1. When subclones of the Methylobacter albus BG8 fragment containing these genes were used as hybridization probes to genomic digests of methanotrophic bacteria, specific bands were detected that suggested a similar gene order in most cases. These data indicate that the mxaAKL region is relatively highly conserved in methanotrophs, and that in most cases the mxaAKL genes are grouped together in the same order as in the facultative methanol utilizer Methylobacterium extorquens AM1.

Drinking after intragastric NaCl without increase in systemic plasma osmolality in rats

Drinking after intragastric hypertonic solutions was examined to determine whether increased plasma osmolality always accompanied initiation of drinking. A 2-ml infusion through a gastric catheter was the beginning of tests in Sprague-Dawley male rats. Latency to drink was shorter and 1-h water intake was greater for increasing concentrations of NaCl (600, 1,200, and 1,800 mosmol/kg) compared with baseline (290 mosmol/kg). Although 600, 900, or 1,200 mosmol/kg NaCl elicited drinking, such infusions failed to change systemic plasma osmolality, and 900 mosmol/kg also failed to change plasma sodium, protein, renin activity, or packed cell volume at the initiation of drinking. Intragastric 900 mosmol/kg sodium bicarbonate, sodium isethionate, potassium chloride, lithium chloride, and mannitol differentially increased water intake. Total subdiaphragmatic vagotomy abolished drinking elicited by intragastric NaCl; selective gastric or hepatic vagotomy attenuated intake under some conditions. These results support the hypothesis of a vagally mediated, gastrointestinal and/or hepatic-portal, osmosensitive mechanism for initiation of drinking in advance of postprandial increases in systemic osmolality.

Nitrogen oxide-induced autoprotection in isolated rat hepatocytes

Pretreatment of rat hepatocytes with low-dose nitrogen oxide (addition of SNAP in vitro or induction of nitric oxide synthase in vitro or in vivo) imparts resistance to killing and decrease in aconitase and mitochondrial electron transfer from a second exposure to a higher dose of SNAP. Induction of this resistance is prevented by cycloheximide, indicating upregulation of protective protein(s). Ferritin levels are increased as are non-heme iron-NO EPR signals. Tin-protoporphyrin (SnPP) prevents protection, suggesting involvement of hsp32 (heme oxygenase) and/or guanylyl cyclase (GC). Cross-resistance to H2O2 killing is also observed, which is also prevented by cycloheximide and SnPP. Thus, hepatocytes possess inducible protective mechanisms against nitrogen oxide and reactive oxygen toxicity.

Brazilin stimulates the glucose transport in 3T3-L1 cells

Brazilin (7,11b-dihydrobenz[b]indeno-[1,2-d]pyran-3,6a,9,10(6H)- tetrol) was found to have hypoglycemic action and increase glucose metabolism in experimental diabetic animals. In order to investigate the mechanism of hypoglycemic action of brazilin, the effects of brazilin on glucose transport, insulin receptor autophosphorylation, and protein kinase C(PKC) activity in 3T3-L1 cells were studied. Brazilin increased basal glucose transport in 3T3-L1 fibroblasts and adipocytes. However, insulin-stimulated glucose transport was not influenced. Autophosphorylation of the partially purified insulin receptor was not affected by brazilin treatment in 3T3-L1 fibroblasts. However, brazilin decreased the PKC activity in 3T3-L1 fibroblasts and adipocytes.

Loss and degradation of enzyme-bound heme induced by cellular nitric oxide synthesis

We report here that, like nonheme iron, protein-bound intracellular heme iron is also a target for destruction by endogenously produced nitric oxide (NO). In isolated rat hepatocytes NO synthesis results in substantial (approximately 60%) and comparable loss of catalase and cytochrome P450 as well as total microsomal heme, and decreased heme synthetic (delta-aminolevulinate synthetase and ferrochelatase) and increased degradative (heme oxygenase) enzymatic activities. The effect is reversible, and intact cytochrome P450 apoproteins are still present, as judged by heme reconstitution of isolated microsomes. The effects on delta-aminolevulinate synthetase and heme oxygenase are likely to be secondary to heme liberation, while the effects on ferrochelatase appear to be a direct effect of NO, perhaps destruction of its nonheme iron-sulfur center.

Decay studies of DMPO-spin adducts of free radicals produced by reactions of metmyoglobin and methemoglobin with hydrogen peroxide

The 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin adduct of myoglobin (Mb) or hemoglobin (Hb) was formed when metmyoglobin (MetMb) or methemoglobin (MetHb) reacted with H2O2 in the presence of DMPO, and both decayed with half-life of a few minutes. The DMPO spin adduct of Mb decayed with biphasic kinetics with k1 = 0.645 min-1 and k2 = 0.012 min-1, indicating that the spin adduct consisted of two kinetically heterogeneous species, stable and unstable ones. The DPMO spin adduct of Hb, however, was homogeneous. Decay of both spin adducts was accelerated in the presence of tyrosine, tryptophan or cysteine, but not phenylalanine, methionine or histidine. The decay obeyed the first order kinetics at varying concentrations of the spin adducts. The decay was accelerated by denaturation and proteolysis of protein moiety. The decay rate was not affected by the extra addition of MetMb or MetHb to each spin adduct. The decay rate of the spin adduct of Mb was increased by hematin in the presence of H2O2 and decreased by catalase. Decay of stable spin adduct of Mb, however, was not significantly changed under any experimental conditions used. These results led us to conclude that instability of the DMPO-spin adducts of Mb and Hb is due to intramolecular redox reactions between the spin adducts and amino acid residues and/or products of the reaction between heme and H2O2.

Nitric oxide and intracellular heme

Figure 2 depicts a working hypothesis for these results. Activation of .NO synthesis results in nitrogen oxide-induced loss of protein-bound heme from CYP proteins, which remain relatively intact. This heme liberation results in a decrease in heme synthesis (decreased ALAS) and an increase in heme degradation (increased HO). In addition, .NO synthesis results in direct inhibition of ferrochelatase, which further contributes to inhibition of heme synthesis. There also appears to be a mechanism to repair or resynthesize CYP after .NO synthesis is inhibited. Finally, a result of this effect may be protection against cellular injury, since increased HO is an important response against cellular injury from a variety of insults.

Endodermal sinus tumor arising from a dysgenetic gonad in a 46,XX female combined with müllerian agenesis

The occurrence of neoplastic transformation in a dysgenetic gonad of a female with 46,XX karyotype is very rare. Moreover, to our knowledge, a case of endodermal sinus tumor arising from that setting combined with Müllerian agenesis has not been reported. This case suggests the possibility of development of cancer in a dysgenetic ovary of a female even with 46,XX or Müllerian agenesis.

Cytoplasmic metallothionein overexpression protects NIH 3T3 cells from tert-butyl hydroperoxide toxicity

Metallothioneins (MT) are ubiquitous low molecular weight metal-binding proteins that may act as antioxidants. We examined the sensitivity of NIH 3T3 cells transfected with a plasmid containing mouse metallothionein-I gene (NIH3T3/MT) to the membrane permeant oxidant, tert-butyl hydroperoxide (tBH). NIH3T3/MT cells had a 4-fold increase in intracellular metallothionein as compared to cells transfected with a plasmid containing an inverted gene (NIH3T3/TM). Newly expressed metallothionein appeared to be localized to the cytoplasm as determined by immunofluorescence and confocal microscopy. NIH3T3/MT cells were 6 times more resistant than NIH3T3/TM cells to the cytotoxic effects of tBH. The antioxidant activity of NIH3T3/MT cells was greater than NIH3T3/TM cells, since exposure to tBH resulted in significantly less: (a) thiobarbituric acid-reactive substances and (b) fluorescence after loading cells with the oxidant-sensitive dye, 2'7'-dichlorodihydrofluorescein diacetate. Furthermore, homogenates of NIH3T3/MT cells were more capable of scavenging in vitro generated phenoxyl radicals as quantified by electron spin resonance detection. In contrast, overexpression of cytoplasmic MT did not protect against tBH-induced DNA damage, suggesting that subcellular location of MT is important for its function and that DNA damage is not a key determinant of cytotoxicity. These data provide direct support for an antioxidant role for MT, since physiologically relevant elevations in cytoplasmic MT interfere with tBH-induced cytotoxic peroxidation.

The effect of hemoglobin, hematin, and iron on neutrophil inactivation in superoxide generating systems

When Escherichia coli was incubated with xanthine oxidase and acetaldehyde, the killing of E. coli was accelerated by iron-EDTA but inhibited by hematin or hemoglobin. On the other hand, when E. coli was incubated with human neutrophils in the presence of phorbol myristate acetate (PMA), all of these iron species at concentrations of a few micromolar accelerated the inactivation of neutrophils and in so doing protected the E. coli from being killed by the neutrophils. The inactivation of the neutrophils was accompanied by an increase in lipid peroxidation and by a decrease in viability measured with trypan blue. This inactivation was inhibited by scavengers such as deoxyribose, mannitol, or thiourea. Desferrioxamine B and 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) both inhibited the inactivation mediated by iron-EDTA, but had no effect on the hematin- or hemoglobin-mediated inactivation. Vanadium (vanadyl ion), an effective Fenton reagent, behaved in the same way as iron-EDTA relative to the effects of DMPO on neutrophil inactivation. These results led us to conclude that neutrophils were inactivated during PMA stimulation by OH radicals in the presence of iron-EDTA and by some other oxidizing species when hematin or Hb is present. Ascorbate enhanced the inactivation of neutrophils mediated by these iron species. Catalase was very effective in inhibiting neutrophil inactivation. Superoxide dismutase was not as effective but the combination with catalase was most effective.

Tetrahydrobiopterin-dependent nitrite oxidation to nitrate in isolated rat hepatocytes

We have found that isolated rat hepatocytes and cell extracts catalyze the stoichiometric conversion of nitrite (either as a product of the oxidation of endogenously synthesized nitric oxide or added as sodium nitrite) to nitrate, which in extracts requires the presence of tetrahydrobiopterin and is inhibited by cyanide but apparently not by carbon monoxide. The reaction is sensitive to heat denaturation and does not involve oxidation of NO2- by a peroxidative or radical oxygen mechanism. These results indicate the presence of a hitherto undescribed mammalian mechanism of inorganic nitrogen oxide oxidation that may be a protective mechanism against one potentially damaging effect of endogenous .NO production (NO2- formation), and also that assays of .NO formation based on NO2- determination alone may be an inaccurate measurement of this activity.

MR imaging of hypertrophic cardiomyopathy

To assess the capability of magnetic resonance (MR) imaging to define the presence, distribution, and severity of the hypertrophic process, MR imaging was performed in 20 patients with hypertrophic cardiomyopathy and in five healthy volunteers. Among the 20 patients, 13 were classified as having asymmetric septal hypertrophy and seven as having apical hypertrophy. The mean myocardial thickness in the four-chamber view obtained in end diastole in asymmetric septal hypertrophy was 23.5 mm +/- 6.8 (mean +/- standard deviation) in the basal septum; the ratio of septal to posterolateral wall thickness was 2.05 +/- 0.44 (P < .05); those values were 10.4 mm +/- 2.7 and 1.01 +/- 0.19, respectively, in five healthy volunteers. The mean myocardial thickness in apical hypertrophy was 25.3 mm +/- 4.1 in the apex, and the ratio was 2.21 +/- 0.51 (P < .05); these values were 9.6 mm +/- 1.5 and 0.95 +/- 0.17, respectively, in five healthy volunteers. Three different subtypes of hypertrophic cardiomyopathy - resting obstructive (n = 5), latent obstructive (n = 3), and nonobstructive (n = 5) - were classified according to findings at catheterization in the 13 patients with asymmetric septal hypertrophy.

Comparison of speech recognition ability with different speech processing strategies by Korean cochlear implantees

Many variables affect the audiologic performance of cochlear implantees. With current methods of evaluation, it is difficult to directly compare auditory function with different speech coding strategies. We compared the audiologic performance directly with F0F1F2 and multipeak speech coding strategies in the same implanted ear of eight Korean cochlear implantees. We tested word and phoneme recognition abilities using Korean word lists for speech audiometry and two-syllable nonsense words, respectively. With the multipeak coding strategy, a significant difference in discrimination ability was found in the initial fricative consonant phonemes (/s/,/ss/,/h/). Our results suggest that the improvement of speech recognition ability with the multipeak coding strategy comes primarily from the better understanding of the initial fricative consonants.

Fibrosing alveolitis: prognostic implication of ground-glass attenuation at high-resolution CT

To evaluate the prognostic implication of ground-glass attenuation at high-resolution computed tomography (HRCT) in assessing response to treatment in fibrosing alveolitis, the authors correlated HRCT findings with the improvement in pulmonary function, as represented by the increase in percentage predicted values on pulmonary function tests after corticosteroid therapy. Nineteen patients underwent HRCT before treatment and pulmonary function testing before and after treatment. The HRCT scans were reviewed by two independent observers. Areas of ground-glass attenuation were quantified subjectively by using a 0%-100% scale with 10% increments. The extent of ground-glass attenuation at HRCT was significantly correlated with improvement in diffusing capacity for carbon monoxide (r = .67, P = .0019), forced vital capacity (r = .71, P = .0007), and forced expiratory volume in 1 second (r = .64, P = .0034) after steroid treatment. These results suggest that ground-glass attenuation at HRCT is a good predictor of response to treatment in fibrosing alveolitis.

Improving the quality of service delivery in Nigeria

This study evaluates the effect of a nurse training program in family planning counseling skills on the quality of service delivery at the clinic level, as well as its impact on client compliance with prearranged appointments. The study used a quasi-experimental design to compare certified nurses who received six weeks of family planning technical training with certified nurses who, in addition to the technical training course, received a three-day course in counseling skills. Data were collected through client exit interviews, expert observation, and inspection of medical record abstracts. Trained nurses performed better than their untrained counterparts in the quality-of-care areas investigated--interpersonal relations, information giving, counseling, and mechanisms for encouraging continuity. The likelihood that clients will attend follow-up visits was also found to improve when they were attended by trained professionals. Short-term counseling training can significantly improve the quality of care provided by family planning workers, as well as client compliance with follow-up appointments.

Lateral flagella of vibrios: serological classification and genetical similarity

Lateral (L-) flagella-having vibrios were classified into 13 H-serogroups (flagellar antigen serogroups) by means of H-agglutination test. Vibrio parahaemolyticus was classified into 3 serogroups, HL1 to 3. V. alginolyticus and V. harveyi were classified into 5 and 3 serogroups, respectively, but 2 of those were serogroups common to the both species. V. fluvialis and V. furnissii constituted a same serogroup, HL8. Cross-reactivity between each serogroup was not observed in H-agglutination test, although some cross-reactivity was observed in gel diffusion test. Furthermore, similarity of DNA sequence of L-flagellar structure gene was demonstrated by dot blot hybridization test with a DNA probe of HL2 L-flagellar gene fragment. These results suggest conservation of DNA sequence of the L-flagellar gene of vibrios.

Morphologic and biomechanical study of avascular necrosis of the femoral head

Radiologic review and uniaxial compression tests of 1 cm3 cubes of avascular and subjacent portions of 64 femoral heads of 51 patients with idiopathic avascular necrosis of the femoral head were performed to determine the morphologic and biomechanical changes with progression of the disease. Cases were divided into three groups according to the simple radiographic findings: group I (precollapse), group II (collapse), and group III (advanced collapse with secondary degenerative arthritis). Fourteen group I, 36 group II, and 14 group III specimens were identified. In addition to the simple radiographs, 16 magnetic resonance images were reviewed. In group I, there was no significant difference of yield and maximum stress, and modulus of elasticity between avascular and subjacent portions below the reactive rim. In group II, the above parameters showed lower values in the avascular portion than in the subjacent portion (P less than .05). In group III, maximum stress of the avascular portion showed significantly higher value than that of the subjacent region (P less than .05). In groups II and III, a major crack was observed in the subchondral area in 14 specimens and in the deep avascular and reactive junction in 36 specimens. Bone densitometry data suggested higher mineral content indicative of more sclerosis in the deep crack group. These findings might suggest that different biomechanical properties in the subchondral crack group and interface crack group might contribute to varieties in clinical manifestations. Later sclerotic changes and aspherical collapse of the femoral head might play a large role in the development of secondary degenerative arthritis of the hip joint.

Percutaneous absorption-enhancing activity of urea derivatives

The effect of urea and urea derivatives on the percutaneous absorption of salicylic acid and sodium salicylate through the skin of rabbit from petrolatum ointment was investigated. It was found that addition of urea or urea derivatives to the ointment base significantly increased the percutaneous absorption of the drugs in proportion to the concentration of the additive. The percutaneous absorption-enhancing activities of these compounds were that urea derivatives with the more and longer alkyl substituents showed the stronger activities. These activities of urea and urea derivatives were ascribed to the binding of these compounds with the lipids and proteins of the stratum corneum of the skin and the swelling of the tissues, which leads to the reduction of the barrier property of the layer. The preliminary skin irritation test showed that urea and urea derivatives were quite non-irritating to the skin. These results suggest that urea derivatives have a strong possibility to be developed as a percutaneous absorption enhancer.

Intracranial hemorrhage in hypothermic low-birth-weight neonates

We studied periventricular/intraventricular type intracranial hemorrhage (ICH) by cranial ultrasonography in 82 low-birth-weight (LBW) newborn infants with admission hypothermia against the gestational-age-matched 82 normothermic neonates. The incidence of ICH was higher in the hypothermic infants during the 1st week of life (34/82 vs 20/82, P less than 0.02). Although the distribution of individual grades of ICH was not significantly different between the groups, the first ultrasound scan showed higher incidence of major ICH (grades 3 and 4) in the hypothermic infants. Most of the minor ICH (grades 1 and 2) after the first ultrasound appeared in infants who were small for their gestational age. Our data do not support the contention that admission hypothermia can precipitate the development of IVH in LBW infants. However, the detection of admission hypothermia in a LBW neonate should make one suspect the possibility of ICH and regard it as a manifestation of the severity of ICH rather than the cause. Most likely, this close relationship between hypothermia and neonatal ICH originates from perinatal asphyxia and the cumulative adverse effects of asphyxia-related events.

Carbon monoxide dehydrogenase inhibitor in cell extracts of Pseudomonas carboxydovorans

Extracts of heterotrophically grown cells of Pseudomonas carboxydovorans were found to contain an inhibitor of carbon monoxide dehydrogenase (CO-DH). The inhibitor activity was not detected in CO-autotrophically grown cells. The inhibitor was extremely stable to heat treatment based on the extent of inhibition of CO-DH activity. The extent of inhibition was proportional to the amount of cell extract added to the reaction mixture. The inhibition was independent of a prior incubation period of the extracts with CO-DH. The inhibitor was precipitable with ammonium sulfate, phenol, and trichloroacetic acid. It was passed through benzoylated dialysis tubing and Amicon ultrafiltration membrane YM2. Denaturing and nondenturing polyacrylamide gel electrophoresis of CO-DH inactivated by inhibitor revealed that the mobilities of native enzyme and subunits were identical to those of active CO-DH. The inhibitor-treated CO-DH retained its original antigenic sites and exhibited enzyme activity upon activity staining. The CO-DH inhibitor of P. carboxydovorans was also active on CO-DHs from Pseudomonas carboxydohydrogena, Acinetobacter sp. strain JC1, and Pseudomonas carboxydoflava.

Plasmid analysis in pink facultative methylotrophic bacteria using a modified acetone-alkaline hydrolysis method

Routine screening of indigenous and recombinant plasmids in pink facultative methylotrophic bacteria has been difficult, time-consuming, and yields variable results. We report a modified alkaline hydrolysis method for rapid plasmid isolation from these organisms that reproducibly results in good yields of closed circular plasmid DNA which can be readily digested with restriction enzymes. This method greatly facilitates direct screening of indigenous and introduced recombinant plasmids in the methylotrophic host strain. We have confirmed earlier findings that the original NCIB wild-type strain of Methylobacterium sp. strain AM1 (NCIB 9133) contains three cryptic plasmids. However, sizing of these plasmids by comparison to standards and by restriction fragment analysis suggests that they are larger than previously reported. We have designated these plasmids pAM1-1 (65 kb), pAM1-2 (40 kb) and pAM1-3 (33 kb). We have also shown that a rifamycin-resistant strain of Methylobacterium sp. strain AM1 used routinely in our laboratory lacks pAM1-2, although no phenotype has been associated with its loss. Finally, we have shown that another pink facultative methylotroph, Methylobacterium isolate (#YK1), contains three cryptic plasmids of approximately 43, 37 and 22 kb, respectively.

Purification and some properties of carbon monoxide dehydrogenase from Acinetobacter sp. strain JC1 DSM 3803

A brown carbon monoxide dehydrogenase from CO-autotrophically grown cells of Acinetobacter sp. strain JC1, which is unstable outside the cells, was purified 80-fold in seven steps to better than 95% homogeneity, with a yield of 44% in the presence of the stabilizing agents iodoacetamide (1 mM) and ammonium sulfate (100 mM). The final specific activity was 474 mumol of acceptor reduced per min per mg of protein as determined by an assay based on the CO-dependent reduction of thionin. Methyl viologen, NAD(P), flavin mononucleotide, flavin adenine dinucleotide, and ferricyanide were not reduced by the enzyme, but methylene blue, thionin, and dichlorophenolindophenol were reduced. The molecular weight of the native enzyme was determined to be 380,000. Sodium dodecyl sulfate-gel electrophoresis revealed at least three nonidentical subunits of molecular weights 16,000 (alpha), 34,000 (beta), and 85,000 (gamma). The purified enzyme contained particulate hydrogenase-like activity. Selenium did not stimulate carbon monoxide dehydrogenase activity. The isoelectic point of the native enzyme was found to be 5.8; the Km of CO was 150 microM. The enzyme was rapidly inactivated by methanol. One mole of native enzyme was found to contain 2 mol of each of flavin adenine dinucleotide and molybdenum and 8 mol each of nonheme iron and labile sulfide, which indicated that the enzyme was a molybdenum-containing iron-sulfur flavoprotein. The ratio of densities of each subunit after electrophoresis (alpha:beta:gamma = 1:2:6) and the number of each cofactor in the native enzyme suggest a alpha 2 beta 2 gamma 2 structure of the enzyme. The carbon monoxide dehydrogenase of Acinetobacter sp. strain JC1 was found to have no immunological relationship with enzymes of Pseudomonas carboxydohydrogena and Pseudomonas carboxydovorans.

Results of 317 contraction stress tests with controlled nipple stimulation using an electric breast pump

Nipple stimulation is widely used for producing uterine contractions. High rates of hyperstimulation have been reported with various manual methods of stimulation. A study was undertaken in an effort to standardize the mode and amount of stimulation. Three hundred seventeen contraction stress tests were done using an automatic electric breast pump with precise pressure control. This method was successful in achieving adequate contractions in 84.2%. Hyperstimulation of the uterus was encountered in 4.1% of all tests performed. Side effects and complications were minimal.