Bioavailability and diuretic effect of furosemide during long-term treatment of chronic respiratory failure

The bioavailability and diuretic effect of furosemide 40 mg administered orally for at least 6 months have been compared in patients with chronic respiratory failure and in healthy controls. The mean urinary recovery of unchanged drug was 11.5 mg and 9.41 mg in 24 h after pre- and postprandial administration to 10 patients, whereas the recovery was 14.4 mg in 10 healthy subjects. The diuretic effect, in terms of urine flow and sodium ion excretion in the 6 h after administration, was also less in patients than in healthy subjects. This was ascribed to the lower bioavailability of furosemide in patients, based on the urinary recovery of unchanged drug, and not to a lower level of response to furosemide than in healthy subjects. The mean absolute bioavailability of furosemide in 6 patients was 41.3% and 63.4%, respectively, calculated from unchanged drug and total drug (unchanged plus glucuronide conjugate). Approximately 53.9% of the dose of furosemide was excreted as the glucuronide conjugate after oral administration, and 34.2% after i.v. injection in the 6 patients. In 3 of the 6 patients studied, a distinct first-pass effect for glucuronidation of furosemide was observed after oral administration. In another study, the mean glucuronide fraction recovered in 24-h urine was 20.7% and 7.3% (p less than 0.01) in 38 patients and 12 healthy subjects, respectively. The fraction in urine was not affected by changing the dose of furosemide from 20 to 120 mg. The lower bioavailability in patients as compared to healthy subjects is ascribed to enhanced glucuronidation and incomplete drug absorption.

Hydrodynamic properties of muscarinic acetylcholine receptors solubilized from rat forebrain

Muscarinic receptors from rat forebrain have been solubilized by Lubrol PX, lysophosphatidylcholine (LPC), digitonin and cholate/1 M sodium chloride. The overall level of solubilization was characterized using receptors prelabelled with an irreversible antagonist. The recovery of nondenatured soluble binding activity was estimated using reversible tritiated antagonists. All these detergents solubilized 60-85% of the total binding sites. In Lubrol PX most of the receptors were recovered in a denatured form. In the other detergents 30-90% of the solubilized receptors were stable and capable of binding reversible [3H]-antagonists with high affinity. The hydrodynamic properties of the soluble receptors have been examined by gel filtration and sucrose gradient centrifugation in H2O and D2O. The soluble receptors in Lubrol PX, lysophosphatidylcholine and cholate were, in general, heterogeneous as regards their molecular size. Estimates of the molecular weight after correction for bound detergent, varied from 82,000 to 134,000. Conditions were identified under which the receptor was largely monodisperse, and the estimates of molecular weight agreed with values (ca. 83,000) from sodium dodecylsulphate (SDS) polyacrylamide gel electrophoresis. The amount of bound detergent could not be calculated for the digitonin-muscarinic receptor complex which had an estimated overall median molecular weight of about 290,000. It is concluded that a subpopulation of muscarinic receptors from the rat forebrain is capable of existing in a monomeric soluble form and binding ligands. There is also evidence that complexes with other proteins can exist, but their specificity and functional relevance are not known.

Affinity chromatography of the muscarinic acetylcholine receptor

A novel compound, 3-(2'-aminobenzhydryloxy)-tropane (ABT), and an ABT-agarose gel were synthesized and used for the purification of solubilized muscarinic receptors. ABT had a high affinity with an apparent dissociation constant (Kd) of 7 nM for the muscarinic receptors solubilized from the porcine brain by digitonin. An ABT-agarose gel was prepared by coupling ABT with epoxy-activated Sepharose 6B, and the degree of substitution to the gel was determined to be 4-5 mumol/ml of the gel by UV absorption spectrum. During affinity chromatography using 10 ml of the ABT-agarose gel and 100 ml of the digitonin-solubilized preparation, 70% of muscarinic receptors were adsorbed to the gel, in marked contrast with the adsorption of only 2% of proteins. Approximately 25% of muscarinic receptors applied to the gel were eluted biospecifically with 1 mM muscarinic ligands. The purified fraction showed a high affinity for [3H]quinuclidinyl benzylate with a Kd of 0.4 nM and similar specificity for muscarinic ligands to that of unpurified soluble receptors. The protein concentration of the purified fraction was too low to be determined accurately, but very approximately a purification of 10(3)-fold was indicated.

Muscarinic receptors in porcine caudate nucleus. II. Different effects of N-ethylmaleimide on [3H]cis-methyldioxolane binding to heat-labile (guanyl nucleotide-sensitive) sites and heat-stable (guanyl nucleotide-insensitive) sites

Heat treatment of membranes from porcine caudate nucleus (50 degrees for 7 min) caused a marked decrease in [3H]cis-methyldioxolane [( 3H]CD) binding without affecting seriously the binding of [3H]3-quinuclidinyl benzilate [( 3H]QNB). Approximately 20% of the [3H]CD binding at 5 nM [3H]CD remained after the heat treatment. The remaining binding was not affected by 0.1 mM guanylyl-5'-imidodiphosphate (GppNHp) or by nickel or other cations at concentrations below 10 mM. Treatment of the membranes with trypsin (30 micrograms/mg of protein) at 20 degrees for 20 min also caused a marked decrease in [3H]CD binding without affecting seriously the binding of [3H]QNB. About 20% of the original [3H]CD binding remained in the presence of trypsin at a high concentration of protein (90 micrograms/mg). N-Ethylmaleimide (NEM) affected [3H]CD binding in two different ways: (a) preincubation of the membranes with NEM caused a marked reduction in heat- and GppNHp-sensitive [3H]CD binding, and (b) treatment with NEM caused an enhancement of heat-, GppNHp-, and trypsin-insensitive [3H]CD binding. Neither of the NEM effects required the coexistence of agonists. The concentration of NEM required for the first effect was 10 times lower than that for the second effect, indicating the existence of two NEM-binding sites with different affinities for NEM. The equilibrium dissociation constant (Kd) for [3H]CD after NEM treatment was 33 nM and was not affected by GppNHp, Ni2+, or heat treatment; the Kd was only 4 times higher than that (8 nM) without NEM treatment. These findings indicated the existence of two kinds of [3H]CD binding sites with high affinities for agonists: one is sensitive to guanyl nucleotide and is abolished by NEM and the other is induced by NEM and insensitive to guanyl nucleotide.

Muscarinic receptors in porcine caudate nucleus. I. Enhancement by nickel and other cations of [3H]cis-methyldioxolane binding to guanyl nucleotide-sensitive sites

Muscarinic acetylcholine receptors in the synaptic membrane fraction of porcine caudate nucleus were characterized by using a radiolabeled agonist, [3H]cis-methyldioxolane [( 3H]CD) and an antagonist, [3H]quinuclidinyl benzilate [( 3H]QNB). Scatchard analysis of the specific binding of [3H]CD gave a single equilibrium dissociation constant of 8.1 nM when a concentration of less than 80 nM [3H]CD was used. The binding capacity was 390 fmoles/mg of protein and corresponded to about 10% of the binding sites of [3H]QNB. Agonist/[3H]CD competition binding experiments indicated that [3H]CD was selectively bound to the sites with a high affinity for agonists. [3H]CD binding was inhibited by Na+, K+, Mg2+, and Ca2+ with the half-maximal effect at 10-50 mM. Nickel ion showed biphasic effects on [3H]CD binding: a 2- to 3-fold enhancement of binding at 0.1-10 mM and inhibition above 10 mM. Other cations, including Co2+, Mn2+, and Zn2+, at 1 mM also increased [3H]CD binding by a factor of 1.5-1.8. Among 18 cations examined, only Cd2+, Hg2+, and Cu2+ caused significant inhibition of [3H]CD binding at 1 mM. [3H]CD binding was decreased to about 20% of the control value in the presence of guanylyl-5'-imidodiphosphate (GppNHp), GTP, and GDP with the half-maximal effect at 1.3, 32, and 45 microM, respectively. [3H]CD binding in the presence of Ni2+ was decreased by GppNHp to a level obtained in the presence of GppNHp alone. The increase caused by Ni2+ in [3H]CD binding was due to the increase in the maximal binding capacity (Bmax) without changes in the affinity for [3H]CD. We conclude that Ni2+ increases the proportion of a muscarinic receptor subclass (or state) that is sensitive to guanyl nucleotide.

A study of long-term oxygen therapy in Japan and other Asian countries

In order to investigate the use of long-term oxygen therapy in Japan, I sent questionnaires to the national chronic disease hospitals and general hospitals that are known to frequently treat respiratory diseases. I found that 61% of the chronic disease hospitals that responded had patients receiving long-term oxygen therapy in the hospital, and 12% had patients receiving it at home. Of the general hospitals answering the questionnaire, 77% had inpatients on long-term oxygen and 39% had home patients receiving oxygen therapy. The majority of patients were on oxygen for treatment of tuberculosis, its sequelae, or obstructive lung diseases. The mean PaO2 for inpatients and outpatients on oxygen was 69 mm Hg and 65 mm Hg, respectively. The cannula is the most frequently used oxygen delivery appliance. Hospital piping systems are used for inpatients, and cylinders and concentrators are used by outpatients. Health insurance covers the cost of oxygen and equipment for hospitalized patients. Home oxygen and equipment are paid for by the patient himself, or at public expense. According to the results of my questionnaire, in Hong Kong long-term oxygen is administered in the hospital only. In Korea it is administered in the hospital and on rare occasion in the home. In Taiwan oxygen is not administered on a long-term basis.

Solubilisation and molecular characterisation of muscarinic acetylcholine receptors

Stable, soluble preparations of rat brain muscarinic receptors can be prepared by extracting membranes with digitonin, or with combinations of sodium cholate and sodium chloride. The stability of the cholate/NaCl extract is enhanced by the addition of egg phosphatidylcholine, which, at the same time, suppresses the considerable dispersity apparent in the hydrodynamic behaviour of the solubilised receptor. The Stokes radius of the brain muscarinic receptor in cholate/NaCl/lecithin extracts is 6.7 nm, with very similar values in other detergents, including digitonin and sodium dodecyl sulphate. Its sedimentation coefficient is 3.78s, and its molecular weight approximately 110,000 after correction for detergent binding. The isoelectric point of the digitonin - solubilised receptor is approximately 4.5.

Characterization by [3H]dihydroergocryptine binding of alpha-adrenergic receptors in neuroblastoma X glioma hybrid cells

[3H]Dihydroergocryptine ([3H]DHE) was shown to bind to sites in membranes from neuroblastoma X glioma hybrid cells (NG 108-15) that had the characteristics expected of alpha-adrenergic receptors. The binding was saturable with 0.3 pmol [3H]DHE bound per mg of protein and of high affinity, with an apparent dissociation constant (KD) of 1.8 nM. The specificity of the binding site for various ligands was more similar to that of alpha 2 receptors than to that of alpha 1. No specific binding of [3H]WB-4101 was found in the membranes derived from NG 108 cells. This finding also indicated that the [3H]DHE binding site in the cell is the alpha 2 receptor. GTP lowered the affinity of agonists for the [3H]DHE binding site, although the nucleotide hardly affected the affinity of antagonists including [3H]DHE.

Radioreceptor assay of methionine-enkephalin-like substance in human cerebrospinal fluid

A sensitive and simple radioreceptor assay system for measuring methionine(met)-enkephalin-like substance in human cerebrospinal fluid (CSF) was developed using a particulate fraction of rat brain as a receptor preparation and [3H]dihydromorphine as a radiolabeled ligand in the presence of 1 mM ethylenediamine tetracetate (EDTA) and 2 mM magnesium acetate. Metenkephalin-like substance was purified from CSF by the combination of Sephadex G-10 and SP-Sephadex (H+) column chromatographies to be free of sodium and large molecular weight substance such as beta-endorphin. The assays were carried out on samples obtained from normal subjects and patients with the disease of the brain or pituitary by lumbar or ventricular puncture. Mean level in samples obtained from normal subjects by lumbar puncture was 2.6 +/- 1.0 pmoles/ml.

Application of magnification radiography to the biliary system

Magnification radiography was applied for the diagnosis of the biliary tract diseases including cancer. Our X-ray unit was consisting of HITACHI DR-155-23 U-6M-55P and 0.1 mm focal-spot tube, FFD 80 cm giving a magnification of x2 with the conditions of 60 kVp, 20 mA, 0.8 sec. Intensifying screens such as Kyokko LH II (for a standard sized subject) or DuPont Q II (for an obese subject) were used in combination with Fuji RX films. We confirmed a high diagnostic value in revealing early lesions of this sytem. The skin dose test indicated that this technique was routinely applicable with safety for clinical use.

Adenylate cyclase permanently uncoupled from hormone receptors in a novel variant of S49 mouse lymphoma cells

A novel variant of the S49 mouse lymphoma has been selected from wild-type cells by growth in medium containing the beta-adrenergic agonist terbutaline and inhibitors of cyclic nucleotide phosphodiesterase. In contrast to the situation in the wild-type clone, synthesis of adenosine 3':5'-monophosphate (cyclic AMP) is not stimulated by beta-adrenergic agonists or by prostaglandin E1 either in intact variant cells or in membrane preparations of such clones. However, basal and NaF-stimulated activities of adenylate cyclase [ATP pyrophosphate-lyase (cyclizine), EC 4.6.1.1] are normal, enzyme activity is stimulated by guanyl-5'-yl imidodiphosphate [Gpp(NH)p], and intact cells accumulate cyclic AMP when exposed to cholera toxin. Furthermore, variant cell membranes possess ligand-binding activity consistent with the conclusion that a normal or an excessive number of beta-adrenergic receptors is present. Thus, interaction between the hormone-binding and the catalytic moieties of the adenylate cyclase system is lost. This variant phenotype, designated as uncoupled (UNC), has been stable for more than 100 generations without exposure to the drugs used for selection. Such cells should be useful for the elucidation of methanisms of transmission of information from hormone receptors to adenylate cyclase.

Microtubule formation from two components separated by gel filtration of a tubulin preparation

(1) A tubulin preparation, purified by two cycles of polymerisation in 4 M glycerol, was further fractionated into two components by chromatography on a column of 6% agarose. One was a fraction of pure tubulin dimer devoid of any combination of high molecular weight ingredients (component T). The other was an aggregate of tubulin containing several minor ingredients (component N). (2) Microtubule formation from these two components was followed in a quantitative way by measuring flow birefringence (deltan). When component N was incubated at 37 degrees C, an instantaneous increase of delta n was observed even at a low concentration of protein, and the extent of polymerisation was roughly proportional to the protein concentration. With component T, the polymerisation occurred after a lag period, and only at a protein concentration higher than at least 0.5 mg/ml. Polymerisation of component T was greatly accelerated when a small amount of component N was added to the reaction medium. (3) Component N was dissociated into a tubulin dimer when the ionic strength of the medium was increased. On reducing the ionic strength, the dimer was reassociated to form the aggregate, which was again capable of accelerating polymerisation of component T. Minor ingredients contained in the component N were not completely removed during the course of its dissociation and reassociation. The dynein-like protein that was present in the component N, however, was no longer detectable in the reassociated aggregate.

Assessment of surgery of the rheumatoid wrist

A series of 314 wrist operations performed on 227 patients with rheumatoid arthritis is presented. In 266 hands various wrist operations were undertaken with the object of synovial debridement and in 48 hands the wrist was also arthrodesed. The mean age at the time of surgical treatment was 51 years and the mean period of observation 4.2 years. This study shows that the main benefits of synovectomy are related to a constant and marked pain relief and prevention of tendon ruptures. The hope that synovectomy might arrest or prevent skeletal destruction was not realized and progression of X-ray changes was found in 74%. The very low recurrence rate in the present series as judged by clinical signs is probably not very significant and it is concluded that the X-ray findings are the most reliable criteria reflecting the real activity in a rheumatoid joint. In several wrists where prophylactic ulnar head resection had been performed through a small ulnar incision, an active dorsal tenosynovitis with tendon invasion developed later. These and other findings at the operation indicate that the erosive effect of the distal end of the ulna is certainly not the sole cause of tendon rupture in this area and that a complete exposure and decompression of the tendons should regularly be performed. Finally, arthrodesis of the wrist was so successful that it can be highly recommended.

Rapid transport of phosphatidylcholine occurring simultaneously with protein transport in the frog sciatic nerve

1. Either l-[4,5-(3)H]leucine or [Me-(3)H]choline, or both l-[U-(14)C]leucine and [Me-(3)H]-choline, were injected into the ninth dorsal root ganglion of the frog, and peripheral transport of labelled proteins and/or phospholipids, mostly phosphatidylcholine, was studied by analysis of consecutive segments of the sciatic nerve. 2. At 25 degrees C, approx. 5% of the (3)H-labelled protein was transported at the rate of 152mm/day. The rate was temperature-dependent with the Q(10) value of 2.6. The flow was completely blocked by the local application of colchicine, but was unaffected by cytochalasin D. 3. [Me-(3)H]-Choline was incorporated into phosphatidylcholine at a comparatively slow rate, but was transported in the nerve at a rate equivalent to that for (3)H-labelled proteins. 4. The simultaneous transport of phosphatidylcholine and the protein was further supported in the double-labelling experiments by an identical transport rate of (3)H-labelled phosphatidylcholine and (14)C-labelled proteins, by their identical temperature dependence, by simultaneous blockade with colchicine, and also by the parallel distribution of the two labels in subcellular fractions. Specific radioactivities on a protein basis of both (3)H and (14)C labels were highest in microsomal subfractions enriched with Na(+)-plus-K(+)-stimulated adenosine triphosphatase and acetylcholinesterase. It is suggested that (3)H-labelled phosphatidylcholine and (14)C-labelled proteins transported in the nerve reside in the same structural entity, most probably a membrane component.