New saponins from Mangifera indica

Two new terpenoidal saponins, indicoside A [1] and indicoside B [2], were isolated from Mangifera indica. Their structures were determined as 28-hydroxylupa-12,20(29)-diene-3-O-[beta-glucopyranosyl-(1-->2)] [-beta-glucopyranosyl-(1-->3)]-alpha-L-arabinopyranoside [1] and 28-hydroxylupa-12,20(29)-diene-3-O-[beta-glucopyranosyl-(1-->3)-al pha-L-rhamnopyranosyl-(1-->2)][beta-glucopyranosyl(1-->3)]-alpha-L- arabinopyranoside [2] on the basis of chemical and spectroscopic studies.

Endothelin activation of phospholipase D: dual modulation by protein kinase C and Ca2+

Previous work from this laboratory has identified an endothelin (ET) type A (ETA) receptor on cultured rat renal medullary interstitial cells (RMIC), coupled to phosphatidylinositol-specific phospholipase C (PI-PLC), dihydropyridine-insensitive receptor-operated Ca2+ channels, and phospholipase A2. The current studies explored a role for ET stimulation of phosphatidylcholine-specific phospholipase D (PC-PLD) in intracellular signaling of this cell type. ET stimulated PLD activation, as measured by phosphatidic acid (PA) or phosphatidylethanol (PEt) accumulation, in a time- and concentration-dependent manner. Inhibition of diacylglycerol (DAG) kinase by ethylene glycol dioctanoate or 6-(2)4-[(4-fluorophenyl)-phenylmethylene]-1-piperadinyl]ethy l-7-methyl-5H - thiaxolo-[3,2-alpyrimidin]-5-one (R 59022) failed to blunt PA accumulation, indicating that PLD, and not DAG, was the source of PA. Inhibition of PA phosphohydrolase (PAP) by propranolol increased late accumulation of PA, suggesting that the prevailing metabolic flow was in the direction of PA to DAG. Phorbol 12-myristate 13-acetate (PMA) augmented ET-evoked PEt accumulation, whereas downregulation of protein kinase C (PKC) obviated agonist-induced PEt production. PMA augmentation of PLD activity proceeded independent of cytosolic free Ca2+ concentration. Ca2+ derived from either intracellular or extracellular sources enhanced ET-related PEt accumulation but was without effect in PKC-downregulated cells. Collectively, these observations indicate that ET stimulates PLD production in RMIC. PKC is the major regulator of this process, with Ca2+ playing a secondary, modulatory role. In addition, these data suggest that PC-PLD is coupled to the ETA receptor.

Alterations of plasma membrane fatty acid composition modify the kinetics of Na+ current in cultured rat diencephalic neurons

Properties of inward Na+ currents (INa) were examined in dissociated diencephalic neurons whose plasma membrane fatty acid composition had been altered. These neurons were grown in a defined medium supplemented with essential fatty acids (EFA) of either the w3 class (linolenic acid, 18:3w3) or the w6 class (linoleic acid, 18:2w6), which resulted in a two-fold increase in the plasma membrane phospholipid polyunsaturated fatty acid (PUFA) concentration. The properties of the inward INa of these neurons were compared with those of control neurons grown in the absence of any supplemented fatty acids. The INa of neurons supplemented with a non-essential fatty acid (NFA) of w9 class (oleic acid, 18:1w9) was also examined. Several properties have been modified to different degrees. The ratio of the amplitudes between the fast and the slow decay components as well as the time constant of the fast decay component changed consistently and reversibly with the membrane phospholipid PUFA composition. The current-voltage relationships, channel selectivity, rates of inactivation and recovery from inactivation did not change. Other parameters, such as time-to-peak and steady-state inactivation curves, have changed in EFA- and NFA-supplemented cultures and did not reverse completely. These findings demonstrate that the kinetics of INa can be modified by fatty acid supplementation. These effects can be correlated, in part, with alterations in plasma membrane phospholipid fatty acid composition.

A characterization of glycinergic receptors present in cultured rat medullary neurons

1. Whole-cell current responses to bath application of glycine, beta-alanine, and taurine were studied in medullary neurons cultured from embryonic rats. 2. Two current components were seen in the responses to bath application of agonist, one component that desensitized and another that did not. 3. The two current components have different dose-response characteristics, with the nondesensitizing component being activated more effectively at lower concentrations than the desensitizing component and also reaching its peak at lower concentrations. The agonist concentrations producing half-maximal responses are 26 +/- 4 (SE, n = 6) and 69 +/- 17 (n = 7) microM for the nondesensitizing and desensitizing components, respectively, for glycine; 54 +/- 7 (n = 9) and 127 +/- 37 (n = 7) microM for beta-alanine; and 153 +/- 24 (n = 9) 443 +/- 99 (n = 3) microM for taurine. Thus, for each component, the order of potency is glycine greater than beta-alanine greater than taurine. 4. When total responses to glycine, beta-alanine, and taurine are compared in the same cells, taurine and beta-alanine are less potent agonists than glycine, with relative potencies of 1:0.4:0.1 for glycine-beta-alanine-taurine. 5. The desensitizing component is more sensitive to strychnine than the nondesensitizing one. The strychnine concentrations that block 50% of the response to a control dose of agonist are 15 and 500 nM for the desensitizing and nondesensitizing components, respectively, for glycine; 60 nM and 1 microM for beta-alanine; and 18 and 500 nM for taurine. 6. The complete occlusion between the responses to glycine and beta-alanine or glycine and taurine suggests that these agonists activate the same receptors. 7. The two current components may be manifestations of one receptor population with complicated kinetics or two independent receptor populations.

Characterization of sodium current in developing rat diencephalic neurons in serum-free culture

1. Dissociated, synchronized (G1 phase of cell cycle), and birth-dated fetal rat diencephalic neurons were grown in a serum-free defined medium. The gigaseal whole-cell voltage-clamp technique was used to measure the inward Na+ currents (INa) from morphologically identified bipolar neurons. The earliest expressed somatic INa has been characterized and compared with that present at a later date. 2. The identity of the INa was established on the basis of its reversal potential and reversible blockade by tetrodotoxin (TTX). Close agreement between the measured reversal potentials (68.5 +/- 1.3 and 38.3 +/- 2.4 mV, mean +/- SE) and calculated Nernst equilibrium potentials (64.6 and 34.7 mV) at two different bath Na+ concentrations (120 and 35 mM, respectively) suggests that the channels are highly selective for Na+. 3. The peak INa density increased from 47.7 +/- 2.9 pA/pF in younger neurons (5-6 days in culture) to 93.9 +/- 6.4 pA/pF in older neurons (12-13 days in culture). The activation voltage and the voltage for peak current were also shifted by 10 mV in the hyperpolarizing direction, from -30 and +10 mV in younger neurons to -40 and 0 mV in older neurons, respectively. However, the reversal potential did not change (69.2 +/- 2.3 and 68.5 +/- 1.3 mV in younger and older neurons, respectively). 4. In older neurons the steady-state inactivation parameters (V1/2, the voltage at which inactivation was 50% of maximum, and kh, the voltage at which there is an e-fold change in inactivation) were significantly altered. V1/2 was shifted from -41.5 +/- 2.3 to -48.8 +/- 1.8 mV, and kh was increased from 6.2 +/- 0.5 to 8.9 +/- 0.4 mV. However, the time course of activation and the rates of inactivation and recovery from inactivation were unchanged. 5. In both groups, the INa decays were best described by a sum of two exponentials. The corresponding time constants were voltage dependent. Also, the amplitudes of the two components were differentially affected by membrane potential and niflumic acid. 6. The extrapolated amplitudes of both the fast and the slow components of INa were larger in older neurons, but the ratio of the amplitudes of the two components did not change with age. The voltage dependencies of the time constants of both components were altered. 7. We conclude that INa in fetal rat diencephalic neurons grown in a defined medium with only essential nutrients undergoes in vitro changes in current density and in some, but not all, kinetic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholinergic stimulation produces oscillations of cytosolic Ca2+ in a secretory epithelial cell line, T84

The effects of carbamylcholine (carbachol) on intracellular Ca2+ concentration ([Ca2+]c) of T84 cells were examined using the fluorescent Ca2+ indicator fura-2 and microfluorometric techniques. In single isolated cells, carbachol (100 microM) caused a rapid increase in [Ca2+]c of 184 +/- 15 nM (SE, n = 44) from a resting value of 56 +/- 7 nM. This initial transient was followed by a series of oscillations in 68% of the cells. Atropine (10 microM) blocked this response. Removal of bath Ca2+ did not inhibit the rise in [Ca2+]c or oscillations, but the response duration was shortened in 47% of the cells. The amplitude and latency of the initial Ca2+ rise, frequency of oscillations, and number of responding cells varied with the agonist concentration. We have previously shown that carbachol induces an oscillating K+ conductance in T84 cells [D. Devor, S. Simasko, and M. Duffey. Am. J. Physiol. 258 (Cell Physiol. 27): C318-C326, 1990]. Simultaneous measurement of membrane K+ current and fura-2 fluorescence in the same cell demonstrated a correlation between the rise in [Ca2+]c and increase in K+ current. These results show that a rise in [Ca2+]c and oscillations is likely to underlie the membrane K+ current responses to carbachol in T84 cells. Responses from a single cell within a subconfluent monolayer were different from those of isolated cells. In cells of a monolayer the initial [Ca2+]c rise (111 +/- 8 nM; n = 41) was followed by a decline to a stable plateau, and oscillations were not seen. Removal of bath Ca2+ both reduced the initial transient and eliminated the plateau phase of the response. These results suggest that cell-to-cell contact or differentiation during monolayer formation influences the Ca2+ handling mechanisms of T84 cells.

Manipulation of plasma membrane fatty acid composition of fetal rat brain cells grown in a serum-free defined medium

Modifications of plasma membrane acyl-linked phospholipid fatty acid composition were produced by supplementing the culture medium with essential fatty acids. The plasma membrane fraction was purified by Percoll gradient centrifugation from dissociated fetal rat brain cells grown in a serum-free culture medium. Both the concentration dependence and the time course of the modifications were examined. Supplementation of the medium with essential polyunsaturated fatty acid, linolenic acid (18:3 omega 3) or linoleic acid (18:2 omega 6), produced incorporation of the elongated and desaturated products of omega 3 or omega 6 class, respectively, i.e., the incorporation was class specific. Within each class, the most unsaturated and elongated members, i.e., terminal members, were preferentially incorporated until they reached a maximum concentration within 6-7 days. At higher concentrations of supplemented fatty acids, additional class specific incorporation in plasma membrane was produced by an increase in the concentration of intermediate members. At the same time, the concentration of monounsaturated fatty acids declined and that of saturated fatty acids remained unchanged. The modifications in fatty acid composition were reversible, with the time course similar to that of incorporation. The total plasma membrane phospholipid and sterol contents did not change with alterations of fatty acid composition, but did change with time in culture. This preparation should prove useful for investigating the role of polyunsaturated fatty acids in brain cell functions, including neuronal excitability.

Health sciences libraries and information services in Bangladesh

Basic problems relating to the status of health sciences libraries and information centers in Bangladesh are highlighted and discussed; strategies for improving the country's health sciences information services are suggested. A survey of libraries is reported, the country's national science and technology information policy is defined, and recommendations for action are proposed.

Introduction of percutaneous arteriovenous femoral shunt: a new access for continuous arteriovenous hemofiltration

In most critically ill unstable patients, continuous arteriovenous hemofiltration (CAVH) and continuous arteriovenous hemofiltration with dialysis (CAVHD) offer significant advantages over dialysis and ultrafiltration. Improvements in CAVH methodology have occurred since its introduction, but an ideal vascular access has yet to be designed. Scribner shunts may result in loss of a future access site, while femoral artery and vein catheterization render the patient immobilized. We have developed a percutaneous external arteriovenous femoral shunt to overcome this difficulty. The catheter consists of two single-lumen flexible polyurethane catheters with a subcutaneous Dacron cuff. A percutaneous Seldinger technique is used with a peel-away sheath to insert one catheter in the artery and one in the vein. To minimize infection and ensure durability, a 10-cm tunnel is created so that the exit of the catheters on the upper thigh is away from the groin. Like the Scribner shunt, a connecting tube is used between the catheters to maintain the patency when the shunt is not in use. Our experience with this technique is limited to seven treatments in seven patients (five CAVH, two CAVHD). Good blood flow (average, 80 mL/min), ultrafiltration rate (7 mL/min), and biochemical studies demonstrated the efficiency of the access. The average treatment was 10 days and patients were allowed to do moderate movement without resulting thrombosis or infection of the access. The major advantages of this new and efficient access for CAVH and CAVHD include simple introduction by a nephrologist, lack of potential serious complications, avoidance of sacrifice of major vessels, early ambulation and movement without compromising function, and a design for prolonged usage.

Glutamate stimulates release of Ca2+ from internal stores in astroglia

We report here that, in the absence of external Ca2+, glutamate produces a transient increase in intracellular Ca2+ [( Ca2+]i) in cultured spinal cord astrocytes, by mobilizing internal Ca2+ stores. [Ca2+]i was measured with Fura-2 using the ratiometric method. Astrocytes were identified by immunostaining for glial fibrillary acidic protein. Glutamate and quisqualate consistently caused a transient increase in [Ca2+]i, with both the response amplitude and latency being graded functions of agonist concentration. Some cells produced multiple transients. N-Methyl-D-aspartate, kainate and aspartate were ineffective. We conclude that the quisqualate subtype of glutamate receptors mediates release of Ca2+ from internal stores in mammalian astrocytes.

[The incidence of atypical pulmonary mycobacterium infections in Reunion before the era of acquired immunodeficiency syndrome (AIDS)]

The authors analyzed cases of pulmonary non-tuberculous mycobacterial infection observed in the Reunion Island between 1979 and 1986, before any reported case of AIDS in the Island. Isolation of non tuberculous mycobacteria from bronchopulmonary specimens was estimated at 21.4% among all positive cultures (n = 971). The analysis of clinical and biological data from 791 different patients with a positive culture concluded to the responsibility of a non tuberculous mycobacteria in 117 (14.8%); among these 117, only 10 (8.5%) were considered as pathogen. Species repartition, antituberculous drug sensitivity and clinical out come are discussed.

Total and coronary heart disease mortality in relation to major risk factors--Quebec cardiovascular study

The relationships of blood pressure, smoking, serum cholesterol and education levels on total and coronary artery disease (CAD) mortality were evaluated in 4576 Quebec men aged 35 to 64 years, free from overt CAD at entry and followed for 12 years. From January 1974 to January 1986, there were 417 deaths, 131 due to CAD. A progressive increase in total and CAD mortality was observed from quintile 3 to 5 for both systolic and diastolic blood pressure. In comparison to quintile 1, the adjusted relative risks of quintiles 4 and 5 for systolic blood pressure were significantly elevated (2 P less than 0.01), being 1.5 and 2.0 for total mortality, and 2.6 and 3.5 for CAD mortality, respectively. The relative risks of quintiles 4 and 5 for diastolic blood pressure were also significantly elevated (2 P less than 0.04), being 1.5 and 1.6 for total mortality and 1.9 and 2.7 for CAD mortality, respectively. In comparison to those who never smoked, the relative risks of smoking one to 20, and 21 and more cigarettes per day, were 2.1 (2 P less than 0.003) and 3.1 (2 P less than 0.0001) for overall mortality, and 2.2 (2 P less than 0.08) and 3.5 (2 P less than 0.002) for CAD mortality. Men who had discontinued smoking at least one year before the study, had a relative risk not different from those who had never smoked. Serum cholesterol and education levels were not significantly associated with total or CAD mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental changes in the regulation of glycine-activated Cl- channels of cultured rat medullary neurons

Glycine-activated currents in 1- to 11-day-old rat medullary neurons were studied using patch clamp techniques. Glycine produced neither repeatable whole-cell current responses nor single-channel activity in the cell-attached mode until cells were in culture for a week or more. However, Cl- channels were present at the early stages because glycine-activated channels were seen in excised, inside-out patches. Furthermore, for cells less than a week in culture, 10 patches which did not exhibit glycine-activated Cl- channels in the cell-attached mode did upon excision. Consequently, the activation properties of these Cl- channels undergo a developmental change in that some cellular factor(s) presumably prevents the Cl- channels from opening in the intact cell during the initial stages in culture.

Euphorcinol: A New Pentacyclic Triterpene from Euphorbia tirucalli

Euphorcinol, a new triterpene of the friedelane group, has been isolated from the fresh and un-dried stem bark of EUPHORBIA TIRUCALLI. The structure 1 is assigned to it on the basis of chemical and spectroscopic studies including 2D-NMR.

Characteristics of glycine-activated conductances in cultured medullary neurons from embryonic rat

Characteristics of glycine-activated currents in 10- to 20-day-old neurons were studied using the gigaseal whole-cell technique. Glycine activated a Cl- conductance that was blocked by strychnine acting as a mixed inhibitor, effecting both Imax and Kd. Glycine receptors with at least two different sensitivities to strychnine were found, based on the apparent inhibition constants (Ki). These two Ki values were associated with different Hill coefficients for the glycine responses. Cs+ activated the same receptor and also activated a relatively nonselective cation conductance.

Expression of membrane currents in rat neocortical neurons in serum-free culture. I. Inward currents

The gigaseal whole-cell voltage clamp technique has been used to investigate the timing of expression and properties of voltage-dependent inward currents in cultured neocortical pyramidal-shaped neurons. The dissociated primary cultures of synchronized (same cell cycle), growth arrested (G1-phase) and birth-dated neurons from fetal rat (E18) were maintained in a serum-free medium. The earliest inward current is expressed within 24 h. This current is carried by Na+ and the channels are located in distal neurites at discrete sites. The Na+ channels near the cell body are expressed after 5 days in culture, at which time the neuritic Na+ current persists. The magnitude of the current near the soma increases with age of the neuron. The Na+ current is blocked by both tetrodotoxin (TTX) and nitrendipine. The sensitivity to nitrendipine changes with age of the culture. The results suggest that Na channels expressed early during neuronal development have some structural component common also to Ca2+ channels.

Expression of membrane currents in rat neocortical neurons in serum-free culture. II. Outward currents

The timing of expression and properties of outward membrane currents in cultured neocortical pyramidal-shaped neurons have been investigated using the gigaseal whole-cell voltage clamp and single-channel recording techniques. Dissociated primary cultures of synchronized (same cell cycle), growth arrested (G1 phase) and birth-dated cells from fetal rat (E18) were maintained in a serum-free medium. The earliest appearing membrane current in the soma is a voltage-dependent outward current carried by K+. The current consists of two components, one rapidly rising component, resembling those associated with the transient outward current (IA) and the other similar to the delayed rectifier current (IK). The ratio between the peak IA and IK was about 0.3 at all membrane voltages. The magnitude of both IA and IK increased with time in culture but the ratio remained unchanged. Direct measurements of unitary currents showed the presence of two voltage-activated outward conductances, 32 pS and 120 pS. The small conductance channel was sparse. The large conductance channel is K+-selective and was sensitive to both voltage and internal Ca2+.

Calcium regulation by and buffer capacity of molluscan neurons during calcium transients

The properties of Ca-regulation and -buffering of physiological levels of Ca-transients were examined in the soma of Archidoris monteryensis neurons. The rate of recovery from a Ca-transient was examined with two experimental protocols; in one the pulse duration was kept constant and its amplitude was varied, and in the other the duration was varied while the amplitude was kept constant. These experiments revealed that the recovery from a Ca-transient was approximately a first order process and the apparent first order rate constant was dependent on the duration of Ca-influx. The calcium buffer capacity of the cytoplasm was determined by an indirect method which utilised measured amounts of intracellular EGTA to reduce transient changes in free calcium. An equation for the cytoplasmic buffer capacity was derived on the assumption that the capacities of exogenous and endogenous Ca buffers summate linearly. The resting cytoplasmic Ca buffer capacity was 45.2 microM/delta pCa, when it was assumed that the incoming Ca diffuses a distance of 10 microns into the cytoplasm. For a diffusion distance of 5 microns it was 34.5 microM/delta pCa. In both cases, the buffer capacity increased with an increase in the size of Ca transient.

Determination of the birth date and proliferative state of dissociated cells from fetal rat brain

The proliferative status and time of origin of dissociated cells from cerebral cortex, basal ganglia, diencephalon, mesencephalon and rhombencephalon of the fetal rat brain have been analyzed. The distributions of cells in different phases of the cell cycle after dissociation and after 7 days in culture have been determined with flow cytofluorometry. Two separate DNA indicators, propidium iodide and Hoechst 33258, have been used. Almost all of the dissociated cells recovered from the 5 brain regions, between embryonic days 15 and 20, are in G1, or growth arrest phase of the cell cycle. In contrast, only about 55% of the liver cells (same fetal age) are in G1, or growth arrest phase. The times of the last in vivo mitoses of the dissociated cells have been determined by maternal injection of [3H]thymidine and autoradiography of cultures. The majority of the cells recovered on embryonic days 16 and 17 from the 5 brain regions appeared to have undergone DNA synthesis within a period of 24 h prior to dissociation. When the fetuses were sacrificed 96 h after the injection, less than 20% of the cells were labelled, and grain density was drastically reduced. Most labelled cells survive in the serum-free culture medium for more than 7 days. Dissociated cultures of synchronized and birth-dated cells from different brain regions of fetal rat should prove particularly useful for the study of cellular development and function.

DNA glycosylase enzymes induced during chemical adaptation of M. luteus

Five peaks of DNA glycosylase activity showing a preference for MNNG alkylated DNA have been identified from extracts of adapted M. luteus. They are numerically designated as GI to GV in order of their decreasing molecular weights. The first two of these peaks have been highly purified. GI, is a constitutive heat labile protein, 35% stimulated by the presence of 50 mM NaCl, acts exclusively on 3 MeA residues in alkylated DNA, 60-70% inhibited by the presence of 2 mM free 3MeA and has been designated as 3MeA DNA glycosylase enzyme. GII, which is an inducible protein, is heat stable, 28% inhibited by the presence of 50 mM NaCl, removes 3MeA, 3MeG, 7MeA & 7MeG with different efficiency, and has been designated as 3,7 methylpurine DNA glycosylase enzyme. The rate of release of 3 methylpurines is 30 times that of 7MeG. There is no activity of either enzyme on O2-MeC, O2-MeT, O4-MeT or O6-MeG. The apparent molecular weights of GI and GII proteins are 28 Kd and 22 Kd respectively.

Expression of membrane currents in rat diencephalic neurons in serum-free culture

The whole-cell gigaseal voltage clamp technique has been used to investigate the timing of expression and type of voltage-dependent ionic currents in dissociated primary cultures of fetal rat (E17) diencephalic neurons grown in a serum-free defined medium. The expression of membrane currents varied among cells at any particular time in culture. Despite this variability, certain characteristics of the appearance of ionic currents emerge from this study. These are: (i) the earliest appearing membrane current is a voltage-dependent outward current carried by K+. In some cells, it is the classical delayed rectifier current, whereas in others it is the transient outward current (IA). (ii) The earliest appearing inward current is carried by Na+. In some cells the channels are first expressed in the neurites and then in or near the cell body. The early neuritic Na+ channels are blocked by cobalt or cadmium as well as by tetrodotoxin (TTX). In others, the early Na+ channels appear in or near the cell body and are only blocked by TTX. (iii) With additional time in culture, a majority of cells exhibit a Ca2+ current at the time of Na+ channel appearance in or near the cell body as well as a transient Ca2+-dependent outward current. The Ca2+ current is only a small fraction of the total inward current. These inward currents show the classical pharmacologic profile. The complex pattern of expression of ionic current may reflect multiple populations of neurons with different developmental sequences resulting from differences in cell age and lineage.

Isolation and characterization of Streptomyces venezuelae mutants blocked in chloramphenicol biosynthesis

Twelve Streptomyces venezuelae mutants blocked in chloramphenicol biosynthesis were isolated. Two of these (Cm1-1 and Cm1-12) were apparently blocked in the conversion of chorismic acid to p-aminophenylalanine and three (Cm1-4, Cm1-5 and Cm1-8) accumulated p-aminophenylalanine and may have been blocked in the hydroxylation reaction that converted this intermediate to p-aminophenylserine. One mutant (Cm1-2) accumulated D-threo-1-p-nitrophenyl-2-propionamido-1,3-propanediol and D-threo-1-p-nitrophenyl-2-isobutyramido-1,3-propanediol, indicating that chlorination of the alpha-N-acyl group of chloramphenicol was blocked. The remaining six strains did not excrete any detectable chloramphenicol pathway intermediates.

Diffusion of ions and indicator dyes in neural cytoplasm

The dispersion of dye molecules and small cations injected from a point source in the cytoplasm of molluscan neurons has been measured photometrically and compared with dispersion in aqueous solution. The diffusion of phenol red and arsenazo III was at least a factor of five slower in the cytoplasm than in saline. Movement of both dyes was slowed by about the same factor in a given cell. The dispersion rate of arsenazo III was not significantly affected by preloading the cytoplasm to dye concentrations up to 0.5 mM. Calcium and barium dispersion was measured in neurons and saline droplets preloaded with arsenazo III, while phenol red absorbance changes were used to follow the dispersion of injected protons. Ba2+ and H+ moved very slowly in the cytoplasm compared to aqueous solution. Ca2+ movement in all probability underwent a similar retardation in the neurons but high-affinity buffering of the cytoplasm severely restricted the spread of detectable amounts of this ion away from the injection site.

Adaptive response of Micrococcus luteus to alkylating chemicals

Wild type M. luteus cells have been adapted by a step-wise treatment with sub-lethal concentrations of MNNG. The adapted cells exhibit 5.7 fold increased resistance to the killing effects of the mutagen and a simultaneous efficient removal of various base modifications present in cellular DNA. A protein extract prepared from adapted cells contains inducible repair functions which can reduce 80-90% of the alkylated DNA content of 06-MeG is effected by a transmethylase and there is no concomitant release of the modified base. However, N-3 MeG is released as a free modified base through the action of a DNA glycosylase. The release of N-3 MeA is unaffected by the induction treatment whereas that of N-7 methylpurine is slightly improved in the adapted cells.

Properties of neurons from dissociated fetal rat brain in serum-free culture

Because of the unknown constituents and varying composition of serum, its presence in media used in cell culture unavoidably compromises attempts to study cellular mechanisms of growth and differentiation. To overcome this, we have devised a serum-free, chemically defined medium which maintains primary cultures of fetal rat brain cells for more than 6 weeks. This medium allows expression of characteristic properties of neurons and prevents overgrowth of non-neuronal elements without use of antimitotic agents. Cells prepared and plated without exposure to serum attach in less than 20 min to poly-D-lysine substratum and begin to extend processes within 1 hr. After 2 days in culture, process-bearing cells can be divided into those with characteristic neuronal morphology, including long processes which generally branch at a distance from the perikaryon, and those having the appearance of glial cells with many short, thin processes which branch frequently near the cell body. The remaining non-neuronal cells are large and flat with few or no processes. The presence of neurons and astroglia was demonstrated by immunofluorescence detection of bound tetanus toxin as a neuron-specific surface marker, and glial fibrillary acidic protein as an astroglial marker. By the 3rd day in culture, many cells of neuronal morphology were able to generate action potentials in response to electrical stimulation. The ionic composition of the inward current changes from Ca2+ to predominantly Na+ by about 10 days in culture. The presence of synaptic vesicles and myelin was demonstrated by electron microscopy. The ability of dissociated cells from mammalian brain to grow in defined medium without serum and acquire selected properties of mature cells in vivo demonstrates the potential of this culture system for neurobiological studies at the cellular level.

Cryptogenic cirrhosis in relapsing polychondritis

A case of relapsing polychondritis with histologically proven cirrhosis is reported. This association has not been described before.

Cirrhosis of liver

Clinical analysis of 293 cases of cirrhosis from two moderate sized hospitals in the city of Dacca has been presented. Maximum number of cases were in the age group over 40 with 150 (51.2%) males and 19 (5.8%) females. Significant past history included viral hepatitis (21.5%), kala-azar (11.6%) and malaria (10.24%). History of alcoholism was present only in 16 (5.5%) cases. Weakness (84.3%), weight loss (72%) and anorexia (39.3%) constituted the most common symptoms. Ascites (45%), haematemesis (11.6%) and melaena (28.7%) were the next common symptoms. Hepatosplenomegaly was found in about one-third of the cases. Testicular atrophy was recorded in 41.63% cases whereas gynaecomastia was relatively less common (5.5%). Scanty body hair and white nails were present in almost equal number of cases (14.7% and 18%). The cases presented here are those with overt manifestation. Nevertheless, the clinical features are not materially different from those reported by other authors. In the absence of alcoholism, viral hepatitis is presumably the most important aetiological factor in our cases and the clinical features compare favourably with non-alcoholic cirrhosis of the western writers. Cryptogenic cirrhosis has been considered to be most common type constituting 43.7% of our cases.

Stoichiometry and apparent dissociation constant of the calcium-arsenazo III reaction under physiological conditions

In vitro and in situ tests have been run to characterize the reaction of the mettalochromic indicator, arsenazo III, with calcium. Job plots as well as plots of indicator absorbance vs. [Ca2+] at different indicator concentrations show a 1:1 reaction stoichiometry. Equilibrium analysis and analysis using Adair's equation are also consistent with 1:1 complexes being formed and give estimates of 34 and 45 muM for the apparent dissociation constant. In situ tests were carried out using giant neurons from Archidoris monteryensis, a marine gastropod mollusc. Dye absorbance changes were measured during voltage clamp pulses which produced a fixed calcium influx. The dependence of absorbance change on total dye concentration is consistent with the formation of a 1:1 complex of Ca with ArIII if measurements are made during the initial period of the loading pulse, less than 300 ms, although the apparent dependency changes with longer delay in measurements from the onset of the pulse.

Intracellular pH changes induced by calcium influx during electrical activity in molluscan neurons

Simultaneous measurements of electrical activity and light absorbance have been made on nerve cell bodies from Archidoris monteryensis injected with indicator dyes. pH indicators, phenol red and bromocresol purple, and arsenazo III, which under normal conditions is primarily a calcium indicator have been employed. Voltage clamp pulses which induced calcium influx caused an absorbance decrease of the pH dyes indicating an internal acidification. The onset of the pH drop lagged the onset of Ca2+ influx by 200-400 ms, and pH continued to decrease for several seconds after pulse termination which shut off Ca2+ influx. Trains of action potentials also produced an internal pH decrease. Recovery of the pH change required periods greater than 10 min. The magnitude of the pH change was largely unaffected by external pH in the range 6.8-8.4. The voltage dependence of the internal p/ change was similar to the voltage dependence of calcium influx determined by arsenazo III, and removal of calcium from the bathing saline eliminated the pH signal. In neurons injected with EGTA (1-5 mM), the activity-induced internal Ca2+ changes were reduced or eliminated, but the internal pH drop was increased severalfold in magnitude. After the injection of EGTA, voltage clamp pulses produced a decrease in arsenazo III absorbance instead of the normal increase. Under these conditions the dye was responding primarily to changes in internal pH. Injection of H+ caused a rise in internal free calcium. The pH buffering capacity of the neurons was measured using three different techniques: H+ injection, depressing intrinsic pH changes with a pH buffer, and a method employing the EGTA-calcium reaction. The first two methods gave similar measurements: 4-9 meq/unit pH per liter for pleural ganglion cells and 13-26 meq/unit pH per liter for pedal ganglion cells. The EGTA method gave significantly higher values (20-60 meq/unit pH per liter) and showed no difference between pleural and pedal neurons.

Hypertension in Secretariate population of Bangladesh

A total of 8,172 persons constituting 98.6% of the total Secretariate Population of Bangladesh were screened for elevated blood pressure. One thousand and ninety cases (13.3%) showed diastolic blood pressure of 90 mmHg or above. Those with diastolic blood pressure of 95 or above constituted 3.7% of the population. More than two-thirds of the latter group (71.6%) remained undetected indicating that vast majority of our hypertensive population remains undiagnosed and untreated. It is recommended that the misconception regarding symptomatic hypertenson should be removed by adequate emphasis on the preventive value of the control of hypertension on cardiovascular and cerebrovascular complication. A plea has also been made for a large-scale survey to determine the extent of the problem in Bangladesh.

Measurement of calcium influx under voltage clamp in molluscan neurones using the metallochromic dye arsenazo III

1. The metallochromic indicator dye, arsenazo III, was injected into somata of molluscan neurones from Archidoris monteryensis. Membrane current and dye absorbance change were simultaneously monitored under voltage clamp. 2. Absorbance measured at 660 nm increased during positive-going voltage steps large enough to activate membrane conductances. In situ idifference spectra were qualitatively similar to dye, dye-calcium difference spectra recorded in vitro. The absorbance change was abolished by either a thorough removal of external calcium or internal chelation of calcium by EGTA. It was concluded that the absorbance increase primarily reflected changing internal calcium concentration and that the calcium entered from the outside. 3. Dye absorbance increased in a nearly linear fashion during voltage clamp pulses of 100--300 msec duration. This is in qualitative agreement with electrical stuidies which demonstrated only fractional inactivation of calcium conductance during such periods. Plots of absorbance change vs. Vm peaked at +30 to +40 mV and fell off sharply until approximately +70 mV where the slope became less steep. A null or reversal of the absorbance change was generally observed aroung +110 mV. Evidence is presented that calcium influx was in some cases sufficient to cause sizeable changes in its equilibrium potential. 4. During multisecond voltage clamps the slope of the absorbance change showed a large decline. Where barium substituted for calcium as the influx species in identical clamps, the absorbance at 660 nm also increased but in a much more linear fashion. Except for a slight effect on the initial few pulses, the absorbance signal did not recover after a period of barium influx. These results suggest that part of the slope decline might result from processes related to calcium uptake and not to membrane conductance decrease. 5. Dye absorbance changes during normal and TEA action potentials were measured. Comparison of these changes with voltage clamp records indicated that calcium influx during a spike was capable of raising concentration by roughly 2 X 10(-7) M if the cell were considered to be a uniform sphere with no buffering capacity. Calcium influx during action potentials was increased dramatically by TEA, primarily as a result of a prolonged plateau phase. The existence and duration of the plateau was controlled mainly by potassium conductance systems, however. There was no evidence found for facilitation of the calcium conductance. 6. Following a moderate influx of calcium it required 20--60 sec, depending on the neurone, for the dye absorbance to return to base line (at 9 degrees C). The recovery time course showed a marked difference when examined at different wavelengths. For lambda = 660 nm there was an initial period in which the absorbance decreased rapidly, followed by a slower phase which generally carried the absorbance below the initial (prepulse) value...

Combined effects of diphenyliodonium chloride, pine oils, and mustard oil soaps on certain microorganisms

Bactericidal and bacteriostatic activities of an emulsion containing 10.0% (v/v) terpineol, 0.5% (w/v) diphenyliodonium chloride, 11.0% (v/v) ethyl alcohol, and 5.62% saponified mustard oil were tested against a number of different types of organisms. The bactericidal concentration for Salmonella typhosa was 1:400. In the presence of 5.0% horse serum, it increased to 1:250. The bacteriostatic concentration varied from organism to organism; Escherichia coli and Staphylococcus aureus required 4,000 mug/ml for complete bacteriostasis, whereas Corynebacterium diphtheriae, Salmonella paratyphi-A, and Shigella required only 2,000 mug/ml for complete inhibition. A 4.0% concentration of the emulsion killed the spores of Bacillus subtilis within 6 hr.