A human chorionic gonadotropin-specific antiserum against synthetic peptide analogs to the carboxyl-terminal peptide of its beta-subunit

A chemically synthesized Na-acetyl-triacontapeptide analogous to the carboxyl-terminal region (residues 116--145) of hCG beta-subunit was conjugated to bovine thyroglobulin. This synthetic antigen was used to immunize five rabbits; one of these rabbits (H-114) generated a useable antiserum. The binding properties of this antiserum were compared extensively to a well characterized antiserum (H-93) against the natural tricosaglycopeptide (residues 123--145) of desialylated hCG beta-subunit conjugated to bovine serum albumin. The two antisera showed nearly identical immunological specificities and sensitivities when examined in a conventional RIA system. These similarities included: 1) antibody recognition sites residing at the carboxyl-terminal pentadecapeptide region; 2) binding neither [125I]iodo-hLH nor [125I]iodo-oLH; and 3) lack of neutralizing capability against the biological activity of hCG in vivo. However, synthetic pentadeca or longer peptides are twice as potent in inhibiting 125I]iodo-hCG binding to H-114 than to H-93. Synthetic peptides may provide a superior means of generating antisera capable of distinguishing hCG from human LH, since they can be obtained more easily in large quantities than analogous purified natural fragments and because peptides of synthetic origin avoid the risk of contamination from strongly antigenic regions of the native molecules. Such hCG-specific antisera may have extensive application in RIA systems and fertility control, where selective binding to hCG but not human LH is desired.

Effects of kanamycin on the auditory evoked responses during postnatal development of the hearing of the rat

The ototoxic effects of kanamycin were studied in rats during the early postnatal period and at an adult age. Brain stem potentials as well as auditory cortical potentials were used for the estimating of ototoxic damage. The auditory potentials decreased promptly and markedly in the animals which were treated daily with 400 mg/kg body weight of kanamycin starting from the 11th day after birth. In these animals, the auditory potentials were almost completely abolished within 10 days after the beginning of the kanamycin treatment. However, when the same amount of kanamycin was applied earlier or later than that, i.e., avoiding the period of the initial appearance and the greatest development of auditory functions (from the 11th to the 15th day after birth in the rat), the auditory potentials were not apparently damaged. In light and scanning electronmicroscopy, marked ototoxic changes were observed which underlay the functional damage. The meaning of these findings is discussed.

Immunoelectron microscope localization of cytochrome P-450 on microsomes and other membrane structures of rat hepatocytes

Localization of cytochrome P-450 on various membrane fractions of rat liver cells was studied by direct immunoelectron microscopy using ferritin-conjugated antibody to the cytochrome. The outer surfaces of almost all the microsomal vesicles were labeled with ferritin particles. The distribution of the particles on each microsomal vesicle was usually heterogeneous, indicating clustering of the cytochrome, and phenobarbital treatment markedly increased the labeled regions of the microsomal membranes. The outer nuclear envelopes were also labeled with ferritin particles, while on the surface of other membrane structures such as Golgi complexes, outer mitochondrial membranes and plasma membranes the labeling was scanty and at the control level. The present observation indicates that cytochrome P-450 molecules are localized exclusively on endoplasmic reticulum membranes and outer nuclear envelopes where they are probably distributed not uniformly but heterogeneously, forming clusters or patches. The physiological significance of such microheterogeneity in the distribution of the cytochrome on endoplasmic reticulum membranes is discussed.

Isolation of tridecaptins A, B and C (studies on antibiotics from the genus Bacillus. XXIII)

Three new antibiotics, tridecaptins A, B and C, were isolated from culture broths of strains of Bacillus polymyxa AR-110, B-2 and E-23, respectively. All are acyl tridecapeptides differing from each other in the fatty acid components and amino acid residues. They are weakly active against Gram-negative and Gram-positive bacteria in vitro and in vivo.

Adaptive rundown of excitatory post-synaptic potentials at synapses between hair cells and eight nerve fibres in the goldfish

1. The excitatory post-synaptic potentials (e.p.s.p.s.) evoked by sound stimuli were recorded intracellularly from large afferent eight nerve fibres in the sacculus of the goldfish (S1 fibres). The fish were anaesthetized with MS-222 and spike potentials were suppressed with locally applied tetrodotoxin. 2. The e.p.s.p.s. successively evoked in response to each wound wave showed a marked rundown in size, while no reduction was observed in the microphonic potentials. The amplitude of successive e.p.s.p.s was reduced keeping approximately a fixed ratio to the preceding ones, suggesting that the rundown is attributable to a depletion of transmitter quanta from the release sites. 3. The rate of rundown of successive e.p.s.p.s, however, remained almost unchanged when the intensity of the stimulus sound was changed. It was also observed that, even after the e.p.s.p.s had been completely adapted to a continuous sound, a vigorous discharge of new e.p.s.p.s was observed when the intensity of the sound was increased. 4. These findings seem to indicate that it is the size of the readily available store and not the release fraction that is changed by a change in the sound intensity. 5. The saccular macula was superfused with solutions different in Ca and Mg ion concentrations. High Ca ion concentration brought about an increase in the size of the readily available store as well as the release fraction. 6. Mechanisms underlying these observations were discussed in terms of the quantal release mechanism as well as the morphology of the release sites.

Quantal analysis of the size of excitatory post-synaptic potentials at synapses between hair cells and afferent nerve fibres in goldfish

1. A statistical analysis has been made of the transmitter release at the hair cell afferent fibre synapse in the sacculus of the goldfish, using the amplitude of the excitatory post-synaptic potentials (e.p.s.p.s) in response to stimulus tone as a measure of the transmitter release under application of tetrodotoxin. 2. Application of binomial statistics allowed a direct calculation of the mean probability of release (p) and the readily available store (n), and the X2-test showed that the binomial predictions fitted fairly well with the observed distribution of the responses. 3. Adaptive rundown of e.p.s.p.s during sound stimulation, i.e. the successive rundown in the size of the mean quantal content (m), was found to be associated with a reduction in the size of parameter n, but not of p. 4. A marked negative correlation was demonstrated between the amplitude of two consecutive e.p.s.p.s, supporting the depletion hypothesis of the adaptive rundown of e.p.s.p.s. 5. The increase in the e.p.s.p. amplitude and the increase in the mean quantal content, m, brought about by an increase in the tone intensity were found mostly explicable in terms of an increase in the statistical parameter n. The probability parameter p was found largely in invariable, although in certain instances the increase in m was also accompanied by a slight increase in the parameter p.

Catabolic conversion of sepiapterin to 6-(1-carboxyethoxy)pterin by Bacillus subtilis

Structural elucidation of an intensely blue fluorescent compound (A) formed from sepiapterin by Bacillus subtilis is described. The structure of the catabolite (A) was found to be 2-amino-6-(1-carboxyethoxy)-4(3H)-pteridinone (9) from both spectroscopic and degradation studies. This was confirmed by an unambiguous synthesis of 9. The stereochemical structure of the side chain at the 6-position of A was confirmed to be the L(or S) configuration, as in sepiapterin, by analysis of the lactic acid formed from A on acid hydrolysis. This suggests that the side chain is rearranged intact during the catabolic conversion of sepiapterin. A possible mechanism for the conversion is discussed.

Isolation of two new polymyxin group antibiotics. (Studies on antibiotics from the genus Bacillus. XX)

Two new members of polymyxin group antibiotics, polymyxins S1 and T1, were isolated from the culture broths of strains identified as Bacillus polymyxa Rs-6 and Bacillus polymyxa E-12, respectively. These antibiotics are strongly basic substances, their hydrochloric acid salts are soluble in water and methanol. They are primarily active against Gram-negative bacteria in vitro and in vivo though polymyxin T1 exhibits higher activities against Gram-positive bacteria than other polymyxin group antibiotics.

Effects of stereochemical structures of tetrahydrobiopterin on tyrosine hydroxylase

1. Four stereochemical isomers of tetrahydrobiopterin, i.e., 6-L-erythro-, 6-D-erythro-, 6-L-threo-, or 6-D-threo-1,2-dihydroxypropyltetrahydropterin, have been synthesized and used as cofactors for tyrosine hydroxylase (EC 1.14.18.-) purified from the soluble fraction of bovine adrenal medulla. The L-erythro- (the putative natural cofactor) and D-threo isomers showed a striking similarity in their cofactor activities for tyrosine hydroxylase; the remaining two isomeric tetrahydrobiopterins, D-erythro and L-threo isomers, also had very similar cofactor characteristics. 2. The Km values of the L-erythro and D-threo isomers as cofactor were found to be dependent on their concentrations. When their concentrations were below 100 muM, the Km values of the L-erythro and D-threo isomers were fairly low (about 20 muM). However, the Km values were markedly higher (about 150 muM) at concentrations above 100 muM. The same kinetic behavior was also observed with the tetrahydrobiopterin prepared from a natural source (bullfrog). In contrast, the Km value of the L-threo or D-erythro isomer was found to be independent of the concentration and remained constant throughout the concentration examined. 3. The Km values of tyrosine did not show much difference (from 20 muM to 30 muM) with respect to the structure of the four isomeric cofactors. At high concentrations tyrosine inhibited the enzymatic reaction with any one of the four tetrahydrobiopterin cofactors. 4. Oxygen at high concentrations was also inhibitory with any one of the four stereochemical isomers as cofactor. Approximate Km values for oxygen with the tetrahydrobiopterins as cofactor were 1-5%. 5. In contrast to the four isomers of tetrahydrobiopterin, when 6-methyltetrahydropterin or 6,7-dimethyltetrahydropterin was used as cofactor tyrosine or oxygen did no inhibit the enzymatic reaction at high concentrations, and the Km values toward the pterin cofactor, tyrosine, and oxygen were significantly higher than the Km values with the tetrahydrobiopterins as cofactor.

Evidence for a gonadotropin from nonpregnant subjects that has physical, immunological, and biological similarities to human chorionic gonadotropin

Substances from urinary extracts of normal, nonpregnant subjects and human pituitary gonadotropin preparations were found to react similarly to human chorionic gonadotropin (hCG) in a radioimmunoassay system that is highly specific for hCG and without crossreactivity to human luteinizing hormone (hLH). The antiserum was produced in a rabbit immunized with a bovine albumin conjugate of the unique carboxyl-terminal peptide (residues 123-145) isolated from a tryptic digest of the reduced, S-carboxymethylated hCGbeta subunit. The antibody recognition site on the peptide was found to reside on the last 15 amino acid residues of the carboxyl-terminal peptide, as evidenced by the competitive binding activities against 125I-labeled hCG of a series of peptides chemically synthesized according to the carboxyl-terminal sequence of HCGbeta. In order to elucidate the nature of the crossreacting substance in urinary extracts, a human postmenopausal urinary preparation (Pergonal) and a kaolin-acetone extract of urine from a patient with Klinefelter's syndrome were subjected to gel chromatography on Sephadex G-100. The results indicate that fractions showing immunocrossreactivity with the antiserum to hCGbeta-carboxyl-terminal peptide coeluted with 125I-labeled hCG which was separated distinctly from hLH. The same fractions from this postmenopausal urinary gonadotropin preparation exhibited in vitro biological activity proportional to the immunocrossreactivity of the hCG-specific antiserum. Concentration of postmenopausal women's urine by acetone precipitation retained approximately five times more immunoreactivity per unit volume than kaolin-acetone extraction, when assayed with the antiserum to hCGbeta-carboxyl-terminal peptide.

Structure of wye (Yt base) and wyosine (Yt) from Torulopsis utilis phenylalanine transfer ribonucleic acid

A fluorescent base wye (Yt base) was isolated from Torulopsis utilis tRNAPhe. The structure was established as 4,9-dihydro-4,6-dimethyl-9-oxo-1H-imidazo[1,2-alpha]purine based on ultraviolet (uv), nuclear magnetic resonance (NMR), and mass spectra, and by direct comparison with synthetic material. The nucleoside, wyosine (Yt), was isolated from purified tRNAPhe by enzymatic degradations followed by column and thin-layer chromatographies. The structure of wyosine is proposed as 3-ribofuranosyl-4,9-dihydro-4,6-dimethyl-9-oxo-1H-imidazol[1,2-alpha]purine (the ribosyl group is attached to the N-9 position of guanine nucleus) on the basis of comparison with model compounds.

Immunochemical and immunoelectron microscope studies on localization of NADPH-cytochrome c reductase on rat liver microsomes

By the use of ferritin-conjugated antibody (conjugate) indirect immunoelectron microscopy, NADPH-cytochrome c reductase was localized on rat liver microsomes. Most microsomes in the sections had from 1 to 12 conjugates on their outer surfaces. Among the conjugates, 83% was estimated to bind to NADPH-cytochrome c reductase at a molecular ratio of 1:1, 12% at the ratio of 2:1, and 5% at the ratio of 3 or 4:1. The correlation between immunochemical and morphological data confirmed that most of the NADPH-cytochrome c reducatase reacted with the conjugates. Subsequent morphological analyses have revealed that the enzyme is distributed homogeneously on the outer surfaces of microsomes but heterogeneously within microsomes in groups of three to five enzyme molecules.

Relationship between disturbances of micellar formation and steatorrhea

In order to clarify the correlation between decrease in micellar formation and degree of steatorrhea, upper intestinal content was analyzed after administering a test meal of Borgström et al. Fecal fat was also measured. It was demonstrated that micellar phase was composed chiefly of fatty acid and monoglyceride, with low concentrations of diglyceride and triglyceride. The fat composition of micellar phase was nearly constant in normal subjects and in cases of malabsorption syndrome. The correlation between the ratio of micellar fat to the whole ingested fat in the intestinal content and daily excretion of fecal fat was very marked.

Abnormal micelle formation in various malabsorption syndromes

In order to clarify the abnormal micelle formation in various malabsorption syndromes, the analysis of upper intestinal contents after administering a test meal of Borgström et al. was performed. It was demonstrated that the percentage of micellar fat to total fat and lipase concentrations decreased markedly from the normal controls despite of normal concentrations of bile salts and pH in cases of pancreatitis and pancreatectomy. In contrast, it was shown that the percentage of micellar fat was markedly low and the concentrations of conjugated bile salts were reduced in cases of ileal diseases. Unconjugated bile salts were detected although the concentrations of total bile salts were normal in blind-loop syndrome. The correlation between the percentage of micellar fat and lipase concentrations or bile salts concentrations in normal controls and various malabsorption syndromes was also reported.

Isolation of galantins I and II, water-soluble basic peptides. Studies on antibiotics from the genus Bacillus. III

Two water-soluble basic antibiotics named galantins I and II were isolated from a strain resembling Bacillus pulvifaciens. Both antibiotics are peptides containing glycine, alanine, ornithine, lysine and some unknown ninhydrin-positive components. An approximate empirical formula C50 plus and minus H98plus and minus 2O17N16 is indicated for galantin I. These are active against some gram-positive, acid-fast and gram-negative bacteria.

Ultrastructural and biochemical studies on the precursor ribosomal particles isolated from rat liver nucleoli

Sucrose density gradient analyses of pH 5.5 and pH 7.4 extracts from rat liver nucleoli revealed the presence of two broad peaks of approximately 60S and 80S, and 60S and 80-100S, respectively. Ribonucleoprotein (RNP) particles containing precursor ribosomal RNA in these peaks have been characterized by electron microscopy and RNA analyses. Spherical particles only were found in the 60S peak of the pH 5.5 extract, from which 28S RNA and smaller RNA (23S and 18S RNA) exclusively were extracted. In the broad 80S peak of the pH 5.5 extract, about 60% of the particles were spherical while 30% were rodlike. In the RNA species present there were 28S plus smaller RNA (80%) and 35S RNA (20%). The 60Speak of the pH 7.4 extract contained mainly spherical particles (84%), and the RNA species present was mostly 28S plus smaller RNA (89%). In addition to spherical particles (43%), a number of rodlike (31%) and filamentous molecules (26%) were observed in the heavier side of the 80-100S peak of the pH 7.4 extract, from which 45S (14%), 35S (26%), and 28S and smaller RNA (60%) were extracted. Thus the precursor ribosomal particles containing 45S RNA and 35S RNA appear to be filamentous and rodlike molecules, respectively. Folding of loose ribonucleoprotein filaments into compact, spherical, large subparticles may be part of the maturation process of ribosomal large subparticles, in addition to the so-called sequential cleavage of RNA.

Depolarization of sensory nerve endings and impulse initiation in common carotid baroreceptors

1. Electrical events in the peripheral nerve terminals of baroreceptors were investigated following isolation and identification of receptive fields innervated by single baroreceptor fibres. A slow potential change, that is a local depolarization which had the characteristics of a generator (receptor) potential, was recorded from the common carotid baroreceptor fibres at a point close to the sensory terminals.2. The slow potential increased in amplitude with increasing stimulus strength and its time course increased with increasing duration of the mechanical stimulus. Action potentials were initiated from the slow potential when the applied mechanical stimulus was suprathreshold.3. The slow potentials evoked by a train of subthreshold stimuli summed to evoke action potentials.4. When a high-frequency train of suprathreshold stimuli was applied to the baroreceptors, the slow potential following a preceding one from which an action potential was initiated failed to fire the nerve fibre.5. When the sodium content of the Ringer-Locke solution was decreased, the slow potential remained after blockage of the action potential.6. The slow potential remained after abolishing the spike potential by application of tetrodotoxin.

Chemoreceptor properties of glomus tissue found in the carotid region of the cat

1. ;Miniglomera' appearing as small masses of tissue with ample vascularization were found around the common carotid artery of the cat. Physiological, gross anatomical and electron microscopic studies were conducted on these tissues.2. The chemosensory function of each ;miniglomus' was evident from the behaviour of the afferent nerve fibres supplying the tissue: afferent responses became more active during asphyxia, when the blood flow through the tissue was reduced or blocked and when cyanide or ACh were applied. The afferent impulses became more infrequent during hyperventilation.3. Sensory frequency response curves constructed against percentage of inhaled O(2) showed that the impulses of single units increased in frequency with lowering of O(2) content of the inhaled gas.4. These miniglomera are innervated by afferent fibres emerging from the nodose ganglion; sometimes these fibres are contained in the aortic or common carotid baroreceptor nerves, but sometimes they emerge as independent nerves. None of the miniglomera are supplied by branches of the sinus nerve.5. The fine structure of the miniglomus is similar to that of the carotid body. The tissue contains two types of cells: glomus cells which contain dense cored granules, and sustentacular cells whose fine processes enclose the former. Membrane densifications occur where glomus cells lie adjacent to one another or where they are contacted by nerve terminals. Nerve fibres are common in the miniglomus but they contact glomus cells less frequently than in the carotid body.