Effect of endotracheal tube lubrication on cuff pressure increase during nitrous oxide exposure: a laboratory and prospective randomized controlled trial

Background

We previously demonstrated that lubrication of an endotracheal tube (ETT) cuff with K-Y™ jelly strongly and significantly inhibited the increase in cuff pressure during nitrous oxide (N₂O) exposure in vitro. However, in our previous study, we identified critical differences between some influential factors, such as the amount of lubricant retained on the cuff, and studied temperature differences between laboratory and clinical conditions. Therefore, it remained unclear whether this effect holds true in clinical settings.

Methods

We first sought to study how changes in the amount of K-Y™ jelly and temperature influence the inhibitory effects of the lubricant on the increase in N₂O-induced cuff pressure in vitro. Furthermore, we aimed to determine whether the application of K-Y™ jelly inhibits the increase in ETT cuff pressure during general anesthesia using N₂O in adult patients.

Results

In the laboratory studies, we found that K-Y™ jelly inhibited the cuff pressure increase dose-dependently when the dose of K-Y™ jelly was varied (P = 0.02), and that such an inhibitory effect decreased with an increase in the studied temperature (P = 0.019). In the clinical study, lubrication with K-Y™ jelly slightly, but significantly, delayed the increase in ETT cuff pressure during general anesthesia with N₂O (P = 0.029). However, the inhibitory effect in the clinical settings was smaller than that in vitro.

Conclusions

Lubrication of the ETT cuff with K-Y™ jelly may delay the increase in cuff pressure during general anaesthesia with N₂O. However, the clinical significance of this effect may be limited.

Trial registration

UMIN Clinical Trials Registry: UMIN000031377 on March 1, 2019.

Spinal cord stimulation modulates supraspinal centers of the descending antinociceptive system in rats with unilateral spinal nerve injury

BACKGROUND

The descending antinociceptive system (DAS) is thought to play crucial roles in the antinociceptive effect of spinal cord stimulation (SCS), especially through its serotonergic pathway. The nucleus raphe magnus (NRM) in the rostral ventromedial medulla is a major source of serotonin [5-hydroxytryptamine (5-HT)] to the DAS, but the role of the dorsal raphe nucleus (DRN) in the ventral periaqueductal gray matter is still unclear. Moreover, the influence of the noradrenergic pathway is largely unknown. In this study, we evaluated the involvement of these serotonergic and noradrenergic pathways in SCS-induced antinociception by behavioral analysis of spinal nerve-ligated (SNL) rats. We also investigated immunohistochemical changes in the DRN and locus coeruleus (LC), regarded as the adrenergic center of the DAS, and expression changes of synthetic enzymes of 5-HT [tryptophan hydroxylase (TPH)] and norepinephrine [dopamine β-hydroxylase (DβH)] in the spinal dorsal horn.

RESULTS

Intrathecally administered methysergide, a 5-HT1- and 5-HT2-receptor antagonist, and idazoxan, an α2-adrenergic receptor antagonist, equally abolished the antinociceptive effect of SCS. The numbers of TPH-positive serotonergic and phosphorylated cyclic AMP response element binding protein (pCREB)-positive neurons and percentage of pCREB-positive serotonergic neurons in the DRN significantly increased after 3-h SCS. Further, the ipsilateral-to-contralateral immunoreactivity ratio of DβH increased in the LC of SNL rats and reached the level seen in naïve rats, even though the number of pCREB-positive neurons in the LC was unchanged by SNL and SCS. Moreover, 3-h SCS did not increase the expression levels of TPH and DβH in the spinal dorsal horn.

CONCLUSIONS

The serotonergic and noradrenergic pathways of the DAS are involved in the antinociceptive effect of SCS, but activation of the DRN might primarily be responsible for this effect, and the LC may have a smaller contribution. SCS does not potentiate the synthetic enzymes of 5HT and norepinephrine in the neuropathic spinal cord.

Role of nerve growth factor-tyrosine kinase receptor A signaling in paclitaxel-induced peripheral neuropathy in rats

The mechanisms underlying paclitaxel-induced peripheral neuropathy remain unknown. Nerve growth factor (NGF) is a representative neurotrophic factor that maintains neuronal function, promotes survival, and mediates neuropathic pain. We investigated expression levels of NGF and its receptors in the dorsal root ganglia (DRG) and spinal dorsal horn (DH) following paclitaxel treatment. Intraperitoneal (I.P.) administration of paclitaxel induced significant mechanical hypersensitivity and cold allodynia in rats, significantly increased the expression of NGF and its receptor tyrosine kinase receptor A (trkA) in the DRG, and increased NGF expression in the DH. In contrast, paclitaxel treatment did not alter the mRNA levels of NGF or its receptors in the DRG, DH, sciatic nerve, or hindpaw skin. Moreover, expression of NEDD4-2, a negative regulator of trkA, was significantly increased in the DRG of paclitaxel-treated rats. Intrathecal (I.T.) administration of the tyrosine kinase receptor inhibitor k252a significantly alleviated mechanical hypersensitivity in paclitaxel-treated rats. Our results suggest that NGF-trkA signaling is involved in mechanical allodynia in paclitaxel-induced neuropathy.

[A case of ruptured cerebral aneurysm associated with coarctation of the aorta]

A 15-year-old boy with subarachnoid hemorrhage was planned for emergency cerebral aneurysm clipping under general anesthesia. He had different blood pressure between the upper limbs and we found coarctation of the aorta at left subclavian artery bifurcation in the preoperative angiography. To prevent re-rupture of cerebral aneurysm and ischemia of abdominal organs, we monitored arterial blood pressure in bilateral radial arteries and non-invasive blood pressure in the left thigh, and his blood pressure was maintained within 120-150 mmHg of systolic pressure in the right radial artery and 50-70 mmHg of mean arterial pressure in the left radial artery and the left thigh during general anesthesia. The preoperative period elapsed uneventfully and the patient was planned for repair of coarctation of the aorta after discharge.

[Persistent apnea in an obese patient with myotonic dystrophy]

We report a case of a 35-year-old woman with myotonic dystrophy and severe obesity of BMI 43.3 who showed persistent apnea at emergence after ovarian resection. The patient received an iv induction with minimum dose of propofol and vecuronium 3 mg. Anesthesia was maintained with propofol, 50% nitrous oxide and 50% oxygen mixture and epidural anesthesia. Additional vecuronium 0.5 mg was administered twice. Surgery was performed uneventfully within 130 minutes and iv propofol was discontinued. The patient awoke promptly after termination of nitrous oxide but no spontaneous breathing appeared with end-tidal CO2 of 60 mmHg. Because she could obey the order to breathe, the endotracheal tube was removed 40 minutes after discontinuation of propofol. Spontaneous breathing at the rate of 17 x min(-1) started soon after extubation. We assume that this apnea was caused by breath holding. Whether this breath holding is specific to myotonic dystrophy or not, anesthesia for patients with this disease requires careful attention for perioperative respiratory management.

Regulation of the expression of human ferrochelatase by intracellular iron levels

Mammalian ferrochelatase, the terminal enzyme of the heme biosynthetic pathway, catalyzes the insertion of a ferrous ion into protoporphyrin and contains a labile [2Fe-2S] cluster center at the C-terminus. To clarify the roles of the iron-sulfur cluster in the expression of mammalian ferrochelatase, enzyme activity in human erythroleukemia K562 cells under iron-depleted conditions was examined. Treatment of cells with an iron chelator, desferrioxamine, resulted in a decrease in enzyme activity, in a dose- and time-dependent manner. Heme content decreased during desferrioxamine treatment of the cells. Addition of ferric ion-nitrilotriacetate [Fe (III)NTA] to desferrioxamine-containing cultures led to restoration of the reduction in the enzyme activity. While RNA blots showed that the amount of ferrochelatase mRNA remained unchanged during these treatments, the amount of ferrochelatase decreased with a concomitant decrease in enzyme activity. When full-length human ferrochelatase was expressed in Cos7 cells, the activity was found mainly in the mitochondria and was decreased markedly by treatment with desferrioxamine. The activity in Cos7 cells expressing human ferrochelatase in cytoplasm decreased with desferrioxamine, but to a lesser extent. When Escherichia coli ferrochelatase, which lacks the iron-sulfur cluster, was expressed in Cos7 cells, the activity did not change following any treatment. Conversely, the addition of Fe (III)NTA to the culture of K562 and Cos7 cells led to an increase in ferrochelatase activity. These results indicate that the expression of mammalian ferrochelatase is regulated by intracellular iron levels, via the iron-sulfur cluster center at the C-terminus, and this contributes to the regulation of the biosynthesis of heme at the terminal step.

Ischemia induces metallothionein III expression in neurons of rat brain

Metallothionein III (MT-III) is a brain-specific member of the metallothionein family and binds zinc in vivo. In order to confirm the precise localization of MT-III in normal rat brain and the change of MT-III expression after transient whole brain ischemia, we raised a high affinity phagemid-antibody specific for rat MT-III. Immunohistochemical analysis revealed that MT-III in normal brain is localized abundantly in neuronal cell bodies in CA1-3 regions of hippocampus, dentate gyrus, cerebral cortex, olfactory bulb and Purkinje cells in cerebellum. This expression pattern of MT-III was similar to that of MT-III mRNA observed by in situ hybridization studies. ELISA and Northern blot analysis revealed that MT-III protein as well as mRNA levels were up-regulated in cerebrum soon after ischemic stress. Immunohistochemical analysis also demonstrated intense staining in neurons in injured brain after ischemia, which distributed in the same regions as in normal brain. These results suggest that MT-III plays an important role in protecting neurons from ischemic insult by reducing neurotoxic zinc levels and inhibits uncontrolled growth of neurites after ischemia.

Induction of metallothionein isoforms in rat hepatoma cells by various anticancer drugs

The induction of metallothionein (MT) isoforms (MT-1, -2) by anticancer drugs was investigated in cultured rat hepatoma H4 II E C3 cells. The steady-state expression of MT-1 mRNAs was higher than that of MT-2 mRNAs. During incubation of the cells with various anticancer drugs, namely, adriamycin, epirubicin, cis-diamminedichloroplatinum(II) (CDDP), and cis-diammine(1, 1-cyclobutyldicarboxylato)platinum(II), both MT-1 and MT-2 mRNAs were coordinately inducible: the levels of isoMT mRNA reached a maxim of approximate by 6-fold at 3 h. Immunofluorescent studies revealed that the cytosolic fluorescence in the cells exposed to 1 microM CDDP for 48 h was more intensified than that in the untreated cells. Transfer of antisense oligonucleotides resulted in marked reduction of isoMT mRNA, and upon exposure to 5 microM CDDP for 48 h, the viabilities of these cells dropped to 25.8% of the controls. These results indicate that anticancer drugs are potent inducers of MT isoforms in hepatoma cells and that a decrease in cellular MTs enhances the susceptibility of hepatoma cells to CDDP. Thus, we conclude that endogenous MTs play a role in determining the sensitivity or resistance of cancer cells to clinically important anticancer agents.

Construction of a full-length Ca2+-sensitive adenylyl cyclase/aequorin chimera

Ca2+-sensitive adenylyl cyclases are key integrators of Ca2+ and cAMP signaling. To selectively probe dynamic changes in [Ca2+]i at the plasma membrane where adenylyl cyclases reside, a full-length, Ca2+-inhibitable type VI adenylyl cyclase/aequorin chimera has been constructed by a two-stage polymerase chain reaction method. The expressed adenylyl cyclase/aequorin chimera was appropriately localized to the plasma membrane, as judged by biochemical fractionation and functional analysis. The chimera retained full adenylyl cyclase activity and sensitivity to inhibition by physiological [Ca2+]i elevation. The aequorin portion of the chimeric construct was also capable of measuring changes in [Ca2+] both in vitro and in vivo. When the plasma membrane-tagged aequorin and cytosolic aequorin were compared in their measurement of [Ca2+]i, they showed contrasting sensitivities depending on whether the [Ca2+]i originated from internal stores or capacitative entry. This is the first full-length enzyme-aequorin chimera that retains the full biological properties of both aequorin and a Ca2+-sensitive adenylyl cyclase. This novel chimeric Ca2+ sensor provides the unique ability to directly report the dynamics of [Ca2+]i that regulates this Ca2+-sensitive enzyme under a variety of physiological conditions. Since this chimera is localized to the plasma membrane, it can also be used to assess local changes in [Ca2+]i at the plasma membrane as distinct from global changes in [Ca2+]i within the cytosol.

Effects of aminoguanidine on systemic inflammatory response syndrome induced by platelet activating factor and by lipopolysaccharide in rats

We investigated the effects of aminoguanidine, a relatively selective inhibitor of inducible nitric oxide (NO) synthase, on the systemic inflammatory response syndrome induced by platelet activating factor (PAF) and by lipopolysaccharide in rats, with emphasis on NO production in vivo. Aminoguanidine treatment improved survival rates after lipopolysaccharide challenge, whereas it aggravated the lethality caused by PAF. Lipopolysaccharide induced a marked increase in the concentrations of nitrate and nitrite in plasma compared with vehicle administration, and the increase was prevented by aminoguanidine. In contrast, PAF challenge with or without aminoguanidine did not affect the concentrations of nitrate and nitrite in plasma compared with vehicle administration. These results suggest that NO derived from inducible NO synthase is not a major participant in the systemic inflammatory response syndrome induced by PAF. Aminoguanidine is not likely to provide beneficial effects in conditions where PAF is produced and the concentrations of nitrate and nitrite in plasma are not significantly increased.

Role of superoxide and nitric oxide in platelet-activating factor-induced acute lung injury, hypotension, and mortality in rats

OBJECTIVE

To investigate the role of superoxide and nitric oxide in platelet-activating factor-induced acute lung injury, hypotension, and mortality.

DESIGN

Prospective, randomized, controlled, experimental study.

SETTING

University research laboratory.

SUBJECTS

Anesthetized male Wistar rats (180 to 220 g) were studied.

INTERVENTIONS

In the first set of experiments, animals were divided into three groups. Group 1 received platelet-activating factor (2 microg/kg i.v.). Group 2 received recombinant human superoxide dismutase (50,000 U/kg i.v.) 30 mins before platelet-activating factor injection. Group 3 received vehicle agents. In the second set of experiments, animals were divided into six groups that received N(G)-nitro-L-arginine (L-NNA), a selective inhibitor of nitric oxide synthesis, or L-arginine, the physiologic precursor of nitric oxide synthesis: a) vehicles (i.v.); b) vehicle plus L-arginine (100 mg/kg i.v.); c) vehicle plus L-NNA (10 mg/kg i.v.); d) vehicle plus platelet-activating factor (2 microg/kg i.v.); e) L-arginine plus platelet-activating factor; and f) L-NNA plus platelet-activating factor. The first intravenous administration was given 5 mins before the second intravenous injection for each group.

MEASUREMENTS AND MAIN RESULTS

In the first set of experiments, vascular labeling with Monastral blue B demonstrated diffuse microvascular injury in the alveolar capillary beds 2 hrs after platelet-activating factor challenge. Thiobarbituric acid-reactive substances in the lung significantly increased at 2 hrs after platelet-activating factor injection. Platelet-activating factor treatment also resulted in an increased concentration of total protein, albumin, and Evans blue dye in bronchoalveolar lavage fluid at 2 hrs after administration, suggesting platelet-activating factor induction of increased alveolar permeability. The platelet-activating factor-induced alveolar microvascular injury, lipid peroxidation, and increased alveolar permeability were inhibited by pretreatment with recombinant human superoxide dismutase. Although L-NNA alone did not affect alveolar permeability in the second set of experiments, L-NNA treatment before platelet-activating factor challenge significantly aggravated platelet-activating factor-induced increased alveolar permeability 2 hrs after platelet-activating factor challenge. Platelet-activating factor also produced a rapid decrease in blood pressure that was not ameliorated by treatment with L-NNA. However, L-NNA pretreatment was associated with a significant increase in platelet-activating factor-caused mortality within 6 hrs. All rats survived with L-arginine treatment before platelet-activating factor challenge. L-NNA treatment decreased nitrate/nitrite concentration, an index of total nitric oxide production, in plasma.

CONCLUSIONS

These results indicate that superoxide, the derived active oxygen species, and lipid peroxidation are implicated in the pathogenesis of platelet-activating factor-induced acute lung injury. Nitric oxide does not play a major role in platelet-activating factor-induced hypotension. Nitric oxide appears to play a protective role in the acute lung injury and mortality induced by platelet-activating factor.

Ca(2+)-inhibitable adenylyl cyclase modulates pulmonary artery endothelial cell cAMP content and barrier function

Maintenance by the endothelium of a semi-permeable barrier is critically important in the exchange of oxygen and carbon dioxide in the lung. Intracellular free Ca2+ ([Ca2+]i) and cAMP are principal determinants of endothelial cell barrier function through their mutually opposing actions on endothelial retraction. However, details of the mechanisms of this antagonism are lacking. The recent discovery that certain adenylyl cyclases (EC 4.6.1.1) could be acutely inhibited by Ca2+ in the intracellular concentration range provided one possible mechanism whereby elevated [Ca2+]i could decrease cAMP content. This possibility was explored in pulmonary artery endothelial cells. The results indicate that a type VI Ca(2+)-inhibitable adenylyl cyclase exists in pulmonary artery endothelial cells and is modulated by physiological changes in [Ca2+]i. Furthermore, the results suggest the inverse relationship between [Ca2+]i and cAMP that is established by Ca(2+)-inhibitable adenylyl cyclase plays a critical role in modulating pulmonary artery endothelial cell permeability. These data provide evidence that susceptibility to inhibition of adenylyl cyclase by Ca2+ can be exploited in modulating a central physiological process.

Bilateral internal biliary drainage of hilar cholangiocarcinoma with modified Gianturco Z stents inserted via a single percutaneous tract

PURPOSE

Modified Gianturco Z stents were used in five patients with hilar cholangiocarcinoma to permit bilobar hepatic drainage via a single percutaneous tract.

PATIENTS AND METHODS

After successful negotiation of strictures from the ipsilateral hepatic duct to the contralateral hepatic duct and the common bile duct, a modified endoprosthesis--made by connecting two double-body Z stents with two stainless steel wires in order to leave a space in between--was implanted in one stricture and a 'space' was located at the hepatic confluence. A second endoprosthesis, a two- to six-body Z stent, was introduced into the second stricture through the 'space' of the initial endoprosthesis and was implanted so that a part of the endoprosthesis should overlap the initial endoprosthesis.

RESULTS

Optimal positioning of the two endoprostheses was successful in all patients.

CONCLUSION

The technique seems simple, safe, and reliable in reconstructing the bilateral hepatic ductal systems via a single percutaneous approach in patients with hilar cholangiocarcinoma.

Molecular defect in human erythropoietic protoporphyria with fatal liver failure

We investigated the molecular basis of ferrochelatase in a Japanese patient with erythropoietic protoporphyria (EPP), complicated by fatal liver failure, and defined a novel point mutation in the ferrochelatase gene. cDNAs were synthesized using Epstein-Barr-virus-transformed lymphoblastoid cells from the proband. cDNA clones encoding ferrochelatase in the proband were isolated by amplification using the polymerase chain reaction. There were two sizes of ferrochelatase cDNAs; one was normal in size, the other being smaller. Sequence analysis of the abnormally sized cDNA clones revealed that they lacked exon 9 of the ferrochelatase gene. Genomic DNA analysis demonstrated that the proband had the abnormal allele and that it contained a G to A point mutation at the first position of the donor site of intron 9. An identical mutation was detected in the affected family members of the proband by allele-specific oligonucleotide hybridization analysis. EPP is inherited in an autosomal dominant manner in this family.

Selective IgM deficiency in a patient with Hashimoto's disease

A 70-year-old man with Hashimoto's disease had selective IgM deficiency, while other immunoglobulin levels were normal. In vitro mixing experiments were carried out in which B cells and T cells from the patient and from a healthy control donor were co-cultured in the presence of pokeweed mitogen, in order to investigate the etiology of IgM hypoproduction. The results indicated that the patient had B-cell dysfunction, involving the impairment of B-cell differentiation. In addition, both IgG of the healthy control donor and thyroid hormone may play important roles in the pathogenesis of this case.

Biliary endoprosthesis in bile duct obstruction secondary to hepatocellular carcinoma

The effect of biliary endoprosthesis was evaluated in 13 patients with major bile duct obstruction secondary to invasion by hepatocellular carcinoma. In 12 patients major portal vein branches were also invaded by the tumors. After several days' instillation of nasobiliary or percutaneous drainage tubes to flush the bile ducts, biliary endoprosthesis was performed either endoscopically (N = 9) or percutaneously (N = 4). Significant decrease (less than 50% of initial values) of alkaline phosphatase and bilirubin levels was observed in eight and two patients on day 20, respectively. Twelve patients died of hepatic failure at 27-132 days (mean 60 days). One patient without portal vein involvement is currently alive at 300 days. Biliary endoprosthesis has a limited role in the palliation of bile duct obstruction secondary to hepatocellular carcinoma, and the prognosis may be influenced mainly by the underlying hepatic function.

Structure of the human ferrochelatase gene. Exon/intron gene organization and location of the gene to chromosome 18

We have determined the structure of the human ferrochelatase gene after isolation and characterization of lambda phage clones mapping discrete regions of the cDNA. This gene was assigned to human chromosome 18 at region q21.3, by fluorescent in situ hybridization. The gene contains a total of 11 exons and has a minimum size of about 45 kb. The exon/intron boundary sequences conform to consensus acceptor (GTn) and donor (nAG) sequences, and the exons in the gene appear to encode functional protein domains. A major site of the transcription initiation, determined by S1 nuclease mapping, was assigned to an adenine base 89 bases upstream from the adenine base of the translation initiation ATG. The promoter region contains a potential binding site for Sp1, NF-E2 and erythroid-specific transcriptional factor GATA-1, but not a typical TATAA or CCAAT sequence. Analysis of primer extension showed that the transcription starts at the same position between hepatoma HepG2 and erythroleukemia K562 cell mRNA, thereby suggesting that there can be a single transcript in erythroid and non-erythroid cells.

The molecular defect of ferrochelatase in a patient with erythropoietic protoporphyria

The molecular basis of an inherited defect of ferrochelatase in a patient with erythropoietic protoporphyria (EPP) was investigated. Ferrochelatase is the terminal enzyme in the heme biosynthetic pathway and catalyzes the insertion of ferrous iron into protoporphyrin IX to form heme. In Epstein-Barr virus-transformed lymphoblastoid cells from a proband with EPP, enzyme activity, an immunochemically quantifiable protein, and mRNA content of ferrochelatase were about one-half the normal level. In contrast, the rate of transcription of ferrochelatase mRNA in the proband's cells was normal, suggesting that decreased ferrochelatase mRNA is due to an unstable transcript. cDNA clones encoding ferrochelatase in the proband, isolated by amplification using the polymerase chain reaction, were found to be classified either into those encoding the normal protein or into those encoding an abnormal protein that lacked exon 2 of the ferrochelatase gene, indicating that the proband is heterozygous for the ferrochelatase defect. Genomic DNA analysis revealed that the abnormal allele had a point mutation, C----T, near the acceptor site of intron 1. This point mutation appears to be responsible for the post-transcriptional splicing abnormality resulting in an aberrant transcript of ferrochelatase in this patient.

Molecular cloning and sequence analysis of cDNA encoding human ferrochelatase

The cDNA encoding human ferrochelatase [EC 4.99.1.1] was isolated from a human placenta cDNA library in bacteriophage lambda gt11 by screening with a radiolabeled fragment of mouse ferrochelatase cDNA. The cDNA had an open reading frame of 1269 base pairs (bp) encoding a protein of 423 amino acid residues (Mr. 47,833) with alternative putative polyadenylation signals in the 3' non-coding regions and poly (A) tails. Amino acid sequencing showed that the mature protein consists of 369 amino acid residues (Mr. 42,158) with a putative leader sequence of 54 amino acid residues. The human enzyme showed an 88% identity to mouse enzyme and 46% to yeast enzyme. Northern blot analysis showed two mRNAs of about 2500 and 1600 bp for ferrochelatase in K562 and HepG2 cells. As full-length cDNA for human ferrochelatase is now available, molecular lesions related to erythropoietic protoporphyria can be characterized.

Molecular cloning, sequencing, and expression of mouse ferrochelatase

The cDNA encoding mouse ferrochelatase (protoheme ferrolyase, EC 4.99.1.1) was isolated from a mouse erythroleukemia (MEL) cell cDNA library in lambda gt11 expression vector, by immunoscreening with a polyclonal antibody. Two full-length clones containing cDNA inserts of 2.2 and 2.90 kilobases were obtained. These clones have the same entire enzyme coding region, but alternative putative polyadenylation sites in the 3'-noncoding regions. From the deduced primary structure, a putative leader sequence of 53 amino acid residues resulted in a precursor protein of 420 amino acid residues (Mr 47,130) and a mature protein of 367 residues (Mr 41,692). The cDNA allows for the expression of active ferrochelatase by transfected culture cells. RNA blot analysis showed two species of ferrochelatase mRNA consistent with findings of two polyadenylation sites. Both the mRNAs increased by treatment of the MEL cells with dimethyl sulfoxide. The band pattern of the RNA of the mouse liver was the same as that of the MEL cells. Based on these results, we deduce that ferrochelatase in erythroid and hepatic cells can be only of one type.

Characterization of ferrochelatase in kidney and erythroleukemia cells

Ferrochelatase from bovine kidney mitochondria has been purified 1600-fold with a 6.5% yield, exhibiting a specific activity of 490 nmol mesoheme formed/mg of protein per min. The Km values for mesoporphyrin IX and protoporphyrin IX with iron were 12.5 and 12.7 microM, respectively. The Km values for iron and zinc with mesoporphyrin IX were 3.51 and 3.17 microM, respectively. The purified enzyme showed a single band with an apparent molecular mass of 42,000 daltons (42 kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The rabbit antibody against the purified enzyme markedly inhibited activities of the enzyme from both the kidney and liver. Immunoblot analysis showed that the antibody reacted with the renal as well as the hepatic enzymes showing the same molecular weight. Peptide mapping with trypsin or alpha-chymotrypsin showed that digested peptides of renal enzyme were similar to those of hepatic enzyme. Ferrochelatase activity in mouse erythroleukemia (MEL) cells increased in parallel with an increase of heme synthesis by treatment with dimethylsulfoxide. Using immunoblotting techniques, the amount of the enzyme in the MEL cells has been shown to increase by the induction, showing a molecular mass of 41 kDa which was the same as that of the mouse hepatic enzyme. Comparative structural analysis of the enzyme of MEL cells and that of mouse liver by peptide mapping showed that the partial digestive peptides of both enzymes exhibited a similar pattern. These results strongly suggest that ferrochelatase in kidney, liver and erythroid cells can be of one type.

Highly sensitive spectrophotometric determination of human serum albumin with 3',4',5',6'-tetrachlorogallein-molybdenum(VI) complex

A highly sensitive spectrophotometric determination of human serum albumin (HSA) with 3',4',5',6'-tetrachlorogallein (T.Cl.Gall)-Mo(VI) complex in a Triton X-100 + polyvinyl alcohol micellar medium is proposed. This method can be used to determine up to ca. 150 micrograms/10 ml of HSA from the optical absorbance at 640 nm, and is superior in sensitivity to the other extremely sensitive spectrophotometric methods. The great sensitivity of this method results from the use of third-derivative spectrophotometry. The binding parameters of T.Cl.Gall-Mo(VI) complex to HSA are n = 77.3 and K = 1.05 x 10(4) M-1 as determined from dual double-reciprocal plots. It is suggested that the colored complex in this system may be the association complex between [HSA]m+ and [MoVI(T.Cl.Gall)2]n- involving hydrophobic interaction between HSA and T.Cl.Gall. The proposed method should also be useful for the detection and determination of some peptides (e.g. low molecular weight peptides containing basic amino acids), as well as proteins.

Determination of beta-lactam antibiotics in water by fluorescence quenching of mercurochrome, and application for simple investigation of potency

The fluorescence quenching reaction between fluorescein mercury or halogeno-fluorescein mercury compounds (fl. Hg, 2,7- or 2,4-dichloro-fl.Hg, 3',4',5',6'-tetrachloro-fl.Hg, mercurochrome) and beta-lactam antibiotics (ampicillin (AB-PC) and cephalexin (CEX] was investigated, and mercurochrome was selected for the detection of beta-lactam antibiotics; the detection limit was about 0.8 micrograms/ml. A fluorimetric assay of beta-lactam antibiotics was established by measuring the fluorescence of mercurochrome and mercurochrome-beta-lactam antibiotics solutions in weakly basic media to determine the degree of fluorescence quenching. The maximum emission wavelength of mercurochrome solution was at 544 nm with excitation at 470 nm. The calibration graphs were linear over the ranges of about 0-6 micrograms/ml beta-lactam antibiotics penicillins (AB-PC, penicillin G, sulbenicillin, amoxicillin, cyclacillin, oxacillin, hetacillin and piperacillin) and cepham antibiotics (CEX, cefazolin, cephaloglycin, cephaloridine and cefpyramide), and the relative standard deviation was 2.7% for 1.4 micrograms/ml of AB-PC (n = 5). This fluorescence quenching reaction between mercurochrome and beta-lactam antibiotics was applied in a survey of decomposition and remaining potency of beta-lactam antibiotics.

Role of renin-angiotensin and kallikrein-kinin systems on the mechanism of the hypotensive effects of converting enzyme inhibitor, alacepril

In four patients with essential hypertension and one patient with renovascular hypertension, decreases in blood pressure and plasma angiotensin II levels, and increases in plasma renin activity and plasma kinin levels were observed during eight days of alacepril treatment. Significant correlations between the changes in mean arterial pressure and those in plasma angiotensin II or kinin levels were observed positively or negatively, respectively, in the essential hypertensives. These findings suggest that the hypotensive effect of alacepril might be caused mainly by a decrease in plasma angiotensin II levels and, at least in part, by an increase in plasma kinin levels.

Comprehensive studies on the renal kallikrein-kinin system in essential hypertension

In order to investigate the role of the renal kallikrein-kinin (K-K) system in normal (NRH) and low renin (LRH) subgroups of essential hypertension (EHT), daily urinary excretions of renal K-K system components including kallikrein (KAL), total KAL, pre-KAL, kinin (KIN) and kininase (total, I and II), were measured in 21 normotensives (NT) and 45 patients with EHT (NRH: 29, LRH: 16). Urinary KAL and KIN quantities, KAL activity, total and pre-KAL, and kininase (total, I and II) were measured by direct RIA, kininogenase assay, direct RIA of KAL after trypsin treatment, and KIN destroying capacity, respectively. The daily excretions of KAL quantity and activity, total and pre-KAL, and KIN were significantly lower in EHT than in NT. That of total kininase and kininase I were significantly higher in EHT than in NT while no significant difference was found in kininase I between EHT and NT. In comparing NRH and LRH, the urinary KAL activity and KIN were lower in LRH than in NRH, and kininase I was higher in LRH than in NRH. No significant difference, however, was found in total and pre-KAL, KAL quantity and kininase II between NRH and LRH. The ratio of KAL quantity/total KAL which reflects the conversion rate from pre-KAL in the kidney, did not show any significant difference among NT, NRH and LRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Interrelation between the renin-angiotensin system and kallikrein-kinin system in patients with essential hypertension

In order to investigate the relationship between the kallikrein-kinin (K-K) system and renin-angiotensin (R-A) system, plasma kinin (pKIN), plasma angiotensin II (pAII), plasma renin activity (PRA) and angiotensin converting enzyme activity (ACEA) were determined in 19 essential hypertensives (EHT). pKIN and pATII measurements were performed by highly sensitive radioimmunoassay (RIA), both of which were established in our laboratory. The assay sensitivity of pKIN and pAII were 0.5 pg/tube and 0.1 pg/tube, respectively. In pKIN RIA, pKIN was extracted by ethanol from 0.8 ml of plasma obtained with a syringe containing kinin generating and destroying enzyme inhibitors. In pAII RIA, pAII was measured directly in small amounts of 50-100 microliter, unextracted plasma samples. The level in pAII was significantly higher (p less than 0.05) in the normal renin group (NRH: n = 13) as compared with low renin group of EHT (LRH: n = 6). However, no significant difference was found in pKIN and ACEA between these two groups. Although a significantly positive correlation was observed between pAII and PRA (p less than 0.001) in EHT, the ratio of pAII/PRA tended to be higher in LHR than in NRH. ACEA correlated positively with pAII (p less than 0.01) or PRA (p less than 0.02), respectively. On the other hand, a significant negative correlation was also found between pKIN and pAII (p less than 0.05). From these findings, it was assumed that there was a closed relationship between R-A and K-K systems, and that angiotensin converting enzyme (kininase II) might play some role in the interrelation between both systems.

Plasma prolactin levels in patients with essential hypertension, malignant hypertension and secondary hypertension

Plasma prolactin level and plasma renin activity were determined in normal subjects and patients with low and normal renin essential hypertension, renal hypertension, renovascular hypertension, primary aldosteronism, Cushing syndrome, pheochromocytoma and malignant hypertension. In both normal subjects and the normal renin essential hypertensives, plasma prolactin was significantly higher in females than in males. Plasma prolactin was also significantly higher in the normal renin essential hypertensives than in normal subjects of both sexes, while no significant difference was found between the low renin group and normal subjects of either sex. A significantly positive correlation was observed between plasma renin activity and the plasma prolactin level in male essential hypertensives, but not in females. Although no significant difference in plasma prolactin level could be detected between patients with secondary hypertension and normal subjects, this level was significantly higher in malignant hypertensives than in normotensives. From these results, it was shown that significant differences of plasma prolactin levels exist between normal renin essential hypertensives, and low renin essential hypertensives or normal subjects, and that these differences may partly depend on renin status which might be related to the central dopaminergic activity. In malignant hypertensives, the high level of plasma prolactin may be caused by diminished renal function, but the suppression of central dopaminergic activity cannot be excluded in the mechanism of plasma prolactin increment.

A very sensitive direct radioimmunoassay system for plasma angiotensin II and its clinical application in various hypertensive diseases

A very sensitive and simplified direct radioimmunoassay system for plasma angiotensin II was developed using the antiserum against synthetic angiotensin II (final dilution = 1: 1,500,000) in combination with 125I-labeled angiotensin II (specific activity = 1,600 microCi/micrograms). In this assay system, it was possible to carry out a direct assay using 100 microliter of plasma without any extraction procedure. This conclusion was supported by 100% recovery, parallelism of plasma samples against the standard curve, and no difference in hormone levels, there was also a high positive correlation between the plasma angiotensin II levels measured by this direct assay and the dowex column extraction method. The sensitivity of this assay system was 0.1 pg/tube, which is the highest sensitivity in studies reported to date. The cross-reactivities of angiotensin III and I against this antiserum were 100% and less than 0.1%, respectively, suggesting that the antiserum was very specific for the C-terminal of angiotensin II. Plasma angiotensin II levels in normal subjects after overnight fasting ranged from 3.0 to 21.3 pg/ml (12.0 +/- 2.1 pg/ml, mean +/- SE). By comparison, plasma angiotensin II levels of patients with essential hypertension were similar to those in the normal renin group, lower than those in low renin group and higher than those in high renin group. In patients with secondary hypertension, levels were lower in those with primary aldosteronism and higher in those with renovascular hypertension when compared to normal subjects.

Plasma antidiuretic hormone levels in patients with normal and low renin essential hypertension, and secondary hypertension

In order to investigate the antidiuretic hormone (ADH) in essential hypertension and secondary hypertension, plasma ADH levels were measured in normal subjects, in patients with normal and low essential hypertension, and in other patients with various forms of secondary hypertension. Plasma ADH levels were significantly lower in low renin essential hypertension and higher in malignant hypertension than in normal subjects. The plasma ADH levels tended to be lower in renal hypertension and primary aldosteronism, and higher in renovascular hypertension, but these differences were not statistically significant. From these results, it appeared that ADH might play a role in malignant hypertension, but not in the other hypertensive diseases.

An improved method for the determination of human blood kinin levels by sensitive kinin radioimmunoassay

A highly sensitive and specific radioimmunoassay for kinin (minimal detectable amount, 0.5 pg/tube) was applied to measure the blood kinin level. A five ml blood sample was collected with a siliconized needle and plastic syringe which contained 2.5 ml of 0.8 N-HCl. The blood kinin was extracted with butanol, following reextraction with water. According to this procedure, the mean recovery (mean +/- SE) calculated from added 125I-bradykinin (500 CPM) and the known amounts of cold bradykinin were 50.4 +/- 0.8% and 51.1 +/- 2.2%, respectively. In comparison with other sampling methods in 6 normal subjects, the blood samples taken without HCl in syringes showed a higher level (24.4 +/- 10.1 pg/ml) than the samples with HCl (5.3 +/- 1.3 pg/ml). And very high levels were obtained in the plasma samples collected by the method of Talamo or Vinci (0.53 +/- 0.24 ng/ml and 3.5 +/- 1.3 ng/ml, respectively). The kinin content in blood samples taken with HCl was stable at -20 degrees C for at least one month, but increased significantly at room temperature or 4 degrees C for 48 hours. Blood samples were obtained from 17 normal subjects, and 3 patients with acute myocardial infarction. Blood kinin levels in the patient with acute myocardial infarction, 121 +/- 20.9 pg/ml, were significantly higher than those in normal subjects (3.8 +/- 0.5 pg/ml). From these results, it was concluded that high levels of blood kinin reported previously may have resulted from inadequate sampling procedures. Thus, in order to measure blood kinin accurately, inactivation of the kinin generating and destroying enzymes must be done immediately after the sampling. In addition, this radioimmunoassay method should be very useful in investigating the pathophysiological role of blood kinin in various diseases.

Excretion of human urinary kallikrein quantity measured by a direct radioimmunoassay of human urinary kallikrein in patients with essential hypertension and secondary hypertensive diseases

Recently, we established a very sensitive, specific and simple direct radioimmunoassay method for human urinary kallikrein. In this study, in order to clarify whether or not the low or high excretion rate of urinary kallikrein activity in patients with essential hypertension, primary aldosteronism, pheochromocytoma and Bartter's syndrome is caused by changes in enzyme quantity, urinary kallikrein excretion was measured with this direct radioimmunoassay method in normal subjects and in patients with these diseases. Urinary kallikrein excretion measured as enzyme quantity was significantly lower in patients with essential hypertension, and higher in patients with primary aldosteronism and Bartter's syndrome. These results are consistent with other previously reported data and our data measured by means of esterase assay or kininogenase assay. The results also suggest that lowered or elevated excretion of urinary kallikrein activity in these diseases is caused, in part at least, by the lowered or elevated excretion of enzyme quantity.

Role of endocrinological factors in the pathogenesis of idiopathic edema

In order to investigate the etiology of idiopathic edema, clinical findings and endocrinological abnormalities were analyzed in twenty-seven patients, and the following results were obtained. An easy occurrence of subcutaneous bleeding and positive Rumpel-Leede phenomenon were observed in the majority of the patients. ADH, plasma renin activity and plasma aldosterone concentration in the patients did not show abnormalities following water loading in the supine position when compared with normal controls. But the results obtained in the present study suggested that they might contribute to water and sodium retention in the upright position. In the patients, plasma prolactin levels were not decreased, but rather increased and urinary excretion of kallikrein and kinin was reduced significantly after water loading in the upright position. Thus, prolactin and urinary kallikrein-kinin system might also contribute to water and sodium retention in idiopathic edema, directly or indirectly through the augmentation of the action of ADH and of aldosterone. It was concluded that the increased vascular permeability and endocrinological polyfactors play a role, in a cooperative fashion, in the mechanism of this disease.

Measurement of urinary kallikrein acitvity by kinin radioimmunoassay

We have established a simplified assay system for the measurement of urinary kallikrein activity by utilizing the sensitive and specific radioimmunoassay system of kinins previously reported from our laboratory. Kinins were generated by incubating urine samples (50 microliter) with kininogen (1500 ng) in the presence of kininase inhibitors, and the generated kinins were measured by radioimmunoassay. Since the cross reactivity of kininogen in the kinin radioimmunoassay system was not recognized at dose up to 1.0 microgram, the amount of untreated kininogen in the radioimmunoassay samples did not interfere with the measurement of kinins. This eliminated the necessity for a kininogen extraction procedure. A good linear correlation (r = 0.939, p less than 0.001) was observed between the urinary kallikrein activity determined by this assay system (kininogenase activity) and that by esterolytic acitvity. Urinary kallikrein activity was 3.3 +/- 0.9 microgram/min/24 hour urine (mean +/- SEM), 1.4 +/- 0.4 microgram/min/24 hour urine and 0.25 +/- 0.06 microgram/min/24 hour urine in 6 normal subjects, 7 patients with non-complicated essential hypertension and 4 patients with chronic renal failure, respectively. Thus, urinary kallikrein activity was significantly lower in the patients with essential hypertension (p less than 0.05) and the patients with chronic renal failure (p less than 0.01) than in the normal subjects.