bluuebunny/crossref_metadata_2025 huggingface dataset:
GABAA Receptor Subtypes: Ligand Binding Heterogeneity Demonstrated by Photoaffinity Labeling and Autoradiography
Authors: Bureau Michel H. , Olsen Richard W.
Published: December 2006

Abstract: Heterogeneity of binding affinities for a variety of ligands was observed for γ‐aminobutyric acid type A (GABAA) receptors in the rat CNS, at both GABA and ben‐zodiazepine recognition sites. Photoaffinity labeling by [3H]flunitrazepam and [3H]muscimol to affinity column‐purified receptor proteins was examined by gel electropho‐resis in sodium dodecyl sulfate. Anesthetic barbiturates (pentobarbital) and steroids (alphaxalone) both differentially stimulated the incorporation of [3H]flunitrazepam more so into the 51‐kDa α1 subunit than into the 53‐kDa aL2 polypeptide, and incorporation of [3H]muscimol into the 55‐kDa β2 subunit more so than the 58‐kDaβ3 polypeptide. Binding to these polypeptides was also affected differentially by other allosteric modulators and competitive inhibitors, including the benzodiazepine “type 1” selective ligand CL218.872. Heterogeneity in affinity of this drug for the single 51‐kDa α1 polypeptide strongly suggests that type I receptors, like type II, are heterogeneous. In brain sections, the extent of enhancement of [3H]muscimol binding showed significant regional variation, similar for both steroids and barbiturates, and the GABA analogues THlP and taurine inhibited muscimol binding with regional variations in affinity that were almost opposites of each other. Modulation of [3H]flunitrazepam binding by steroids, barbiturates, and THlP significantly varied with regions. Taken together, ligand binding heterogeneity exhibited by photoaffinity labeling and autoradiography demonstrate the existence of multiple pharmacological‐binding subtypes resulting from the combination of multiple polypeptide gene products into several oligomeric isoreceptors. Comparison of the regional distribution of binding subtypes with that of different subunit gene products allows the following conclusions about possible subunit compositions of native pharmacological receptor subtypes present in the brain: Benzodiazepine pharmacology of the oligomeric receptor isofotms is dependent on the nature of α and subunits other than α, GABA‐benzodiazepine coupling is dependent on the nature of the α subunits, GABA site pharmacology is dependent on the nature of the β sub‐units, and several subunits including α and β contribute to the degree of sensitivity to steroids and barbiturates. Finally, the presence of discrete subunits may be necessary but is not sufficient to postulate a defined pharmacological property.
Role of Phosphoinositide Hydrolysis in Astrocyte Volume Regulation
Authors: Bender A. S. , Neary J. T. , Norenberg M. D.
Published: December 2006

Abstract: Astrocytes exposed to hypoosmotic stress swell and subsequently reduce their size to almost their original volume, a phenomenon called regulatory volume decrease (RVD). We found that during hypoosmotic swelling there was a twofold increase in phosphatidylinositol (PI) hydrolysis. This increase was inhibited by the phosphdipase C inhibitor, U‐73122 (10 μM). Inhibition of PI hydrolysis resulted in blockage of RVD. We also examined whether agents that stimulate PI hydrolysis would enhance RVD. These agents significantly accelerated RVD. The rank order of potency was endothelin (20 nM) ≥ norepinephrine (100 μM) > endothelin‐3 (7 nM) > thrombin (1 U/ml) ≥ ATP (500 μM) > bradykinin (20 μM) ≥ carbachol (500 μM), as indicated by RVD rate constants. The extent of PI hydrolysis induced by these agents at the beginning of RVD exhibited a logarithmic relationship with the magnitude of RVD enhancement. Also, there was a linear relationship between the rate of PI hydrolysis and RVD rate constants. Our results suggest that stimulated PI hydrolysis is involved in the regulation of cell volume in astrocytes.
Stimulation of Brain Pregnenolone Synthesis by Mitochondrial Diazepam Binding Inhibitor Receptor Ligands In Vivo
Authors: Korneyev A. , Pan B. S. , Polo A. , Romeo E. , Guidotti A. , Costa E.
Published: December 2006

Abstract: Evidence that neurosteroids are potent modulators of the action of GABA at GABAA receptors has prompted the investigation of the mechanism that controls brain neurosteroid synthesis by glial cell mitochondria in vivo. In vitro studies suggest that the interaction of the diazepam binding inhibitor (DBI)—a polypeptide that is abundant in steroidogenic cells—with glial mitochondrial DBI receptors (MDRs) is a crucial step in the physiological regulation of neurosteroid biosynthesis. MDRs bind 4‐chlorodiazepam (4′‐CD), N,N‐di‐n‐hexyl‐2‐(4‐fluorophenyl)‐indol‐3‐acetamide (FGIN‐1–27), and the isoquinoline carboxamide PK 11195 with high affinity, and these ligands have been used to investigate whether the stimulation of glial MDRs increases brain pregnenolone production in vivo. Adrenalectomized and castrated (A‐C) male rats (to eliminate peripheral sources of pregnenolone) were pretreated with trilostane (to prevent pregnenolone metabolism to progesterone), and the pregnenolone content in brain regions dissected after fixation with a 0.8‐s exposure to microwave irradiation focused to the head was determined by HPLC followed by specific radioimmunoassay. The forebrain and cerebellum of A‐C rats contained 4–7 ng of pregnenolone/g of tissue, and the olfactory bulb contained 10–14 ng/g. These concentrations of brain pregnenolone are only 30–40% lower than those of shamoperated rats. In contrast, the plasma pregnenolone content of sham‐operated rats was 2–3 ng/ml, but it was only 0.15–0.20 ng/ml in the plasma of A‐C rats. In A‐C rats, treatment with the MDR ligands 4‐CD and FGIN‐1–27 increased the pregnenolone content in the brain but failed to change the plasma or peripheral tissue content of this steroid. The effect of 4′‐CD on brain pregnenolone content was maximal (70–100% increase) at the dose of 18 μmol/kg, 5–10 min after intravenous injection. The effect of oral administration of FGIN‐1–27 on brain pregnenolone content was maximal (80–150% increase) at doses of 400–800 μmollkg and peaked at ∼ 1 h. That this effect of FGIN‐1–27 was mediated by the MDR was documented by pre‐treatment with the MDR partial agonist PK 11195 (100 μmol/kg, i.p.). PK 11195 did not affect basal brain pregnenolone content but prevented the accumulation of brain pregnenolone induced by FGIN‐1–27. FGIN‐1–27 and 4‐CD failed to increase the brain concentration of dehydre epiandrosterone in A‐C rats. These data suggest that glial cell MDRs play a role in neurosteroid biosynthesis in vivo.
Striatal L‐DOPA Decarboxylase Activity in Parkinson's Disease In Vivo: Implications for the Regulation of Dopamine Synthesis
Authors: Gjedde Albert , Léger Gabriel C. , Cumming Paul , Yasuhara Yoshifumi , Evans Alan C. , Guttman Mark , Kuwabara Hiroto
Published: December 2006

Abstract: L‐DOPA is a large neutral amino acid subject to transport out of, as well as into, brain tissue. Competition between dopamine synthesis and L‐DOPA egress from striatum must favor L‐DOPA egress if decarboxylation declines relatively more than transport in Parkinson's disease. To test this hypothesis, we injected patients with Parkinson's disease with a radidabeled analogue of L‐DOPA and recorded regional brain radioactivity as a function of time by means of positron emission tomography. We simultaneously estimated the activity of the decarboxylating enzyme and the amino acid transport. In the striatum of patients, we found the L‐DOPA decarboxylase activity to be reduced in the head of the caudate nucleus and the putamen. However, the rate of egress of the DOPA analogue was unaffected by the disease and thus inhibited dopamine synthesis more than predicted in the absence of L‐DOPA egress.
The Rat Central Nervous System Expresses Alzheimer's Amyloid Precursor Protein APP695, but Not APP677 (L‐APP Form)
Authors: Ohgami Tetsuya , Kitamoto Tetsuyuki , Tateishi Jun
Published: December 2006

Abstract: A novel splicing form of βA4 amyloid precursor protein (APP) lacking exon 15, corresponding to 18 residues, was first reported in leukocytes and then in ubiquitous organs. To determine which APP molecules (APP695, APP751, or APP770) either with (N‐APP) or without (L‐APP; leukocytederived APP) exon 15 were expressed in various organs, we investigated the alternative splicing at exon 15 in the rat brain, kidney, heart, and testis by a PCR analysis of reverse‐transcribed RNA and Southern blot analysis. Regarding APP695 without exons 7 and 8, L‐APP was either seldom or never expressed in the brain, whereas both N‐ and L‐APP were expressed in other organs. On the other hand, regarding APP751/770 containing exon 7, which codes for the Kunitz‐type serine protease inhibitor domain, both N‐ and L‐APP were expressed in all the organs examined, including the brain. These results suggest that a particular alternative regulation system related to exon 15 might be present in only APP695 of the brain and influence the proteolytic processing of APP.
Presence of the N‐Methyl‐D‐Aspartate‐Associated Glycine Receptor Agonist, D‐Seine, in Human Temporal Cortex: Comparison of Normal, Parkinson, and Alzheimer Tissues
Authors: Chouinard Michael L. , Gaitan Dano , Wood Paul L.
Published: December 2006

Abstract: The amino acid D‐serine (D‐Ser), previously recognized as a pharmacological tool for potentiating neuronal activity mediated by the N‐methyl‐D‐aspartate (NMDA) receptor complex. in vitro and in vivo, has been observed in several brain regions of the rat and mouse, most prominently in cortex. In addition to reconfirming the presence and distribution of D‐Ser in rat brain, we have observed, for the first time, endogenous, free D‐Ser in temporal cortex of normal human brains at a level of 2.18 ± 0.12 nmol/mg of protein, representing 15 ± 2% of the free L‐Ser pool. The D‐and L‐Ser specific content and the D/L‐Ser ratio obtained from temporal cortex of Parkinson and Alzheimer brains did not differ significantly from those of controls. However, at the levels ob served here, and considering its specificity and affinity for the NMDA‐associated glycine receptor, endogenous D‐Ser is a plausible NMDA receptor glycine site agonist.
Protection of ROC‐1 Hybrid Glial Cells by Polyethylene Glycol Following ATP Depletion
Authors: Jurkowitz‐Alexander Marianne S. , Altschuld Ruth A. , Haun Steven E. , Stephens Ralph E. , Horrocks Lloyd A.
Published: December 2006

Abstract: Oligodendroglia‐glioma hybrid cells (ROC‐1) subjected to inhibition of glycolytic and oxidative ATP synthesis undergo a sequence of changes, including ATP depletion, parallel processes of cell swelling and blebbing, and finally plasma membrane disruption and cell death. The morphological and biochemical changes that follow ATP depletion were studied in the presence and absence of polyethylene glycol (M, 8,000), a nonpermeant oncotic agent. Polyethylene glycol prevented cell swelling and membrane blebbing. It significantly delayed, but did not prevent, the release of lactate dehydrogenase into the medium; it did not affect the fall in [ATP]. These results suggest that osmotic cell swelling may be a contributing factor in the loss of cell viability when ROC‐1 cells are depleted of ATP.
Biotechnology in Aquaculture: Transgenics and Polyploidy
Authors: Rasmussen Rosalee S. , Morrissey Michael T.
Published: December 2006

ABSTRACT:  Although capture fisheries have experienced slow to stagnant growth in recent years, the world population has been increasing, with subsequent rises in demands for marine‐based foods. One possibility for alleviating potential food shortages and price increases is through aquaculture, which has experienced rapid worldwide expansion. A major focus of research in the aquaculture industry is on the use of biotechnology to increase food availability and reduce production costs, specifically through the manipulation of the genes and chromosomes of cultivated species. Examples include transgenic fish with properties such as increased growth rates, feed conversion efficiency, disease resistance, cold tolerance, and improved metabolism of land‐based plants. However, use of transgenic organisms in aquaculture is a very controversial topic due to a number of environmental and human health concerns such as escapement and introduction of genetically modified organisms into the food chain. In response, some transgenic research has also been focused on inducing sterility to reduce the risk of transgenic organisms breeding with wild species. A method of chromosome manipulation, referred to as polyploidy, provides the option of creating sterile organisms, some of which also exhibit increased growth rates. This review paper will discuss recent advances in biotechnology research, specifically in regards to the manipulation of genes and chromosomes, for enhanced cultivation of fish and invertebrates. Major environmental and human health concerns will also be addressed.
Suitability of Arabidopsis thaliana as a model for host plant–Plutella xylostella–Cotesia plutellae interactions
Authors: Barker J.E. , Poppy G.M. , Payne C.C.
Published: December 2006

Successful pest management is often hindered by the inherent complexity of the interactions of a pest with its environment. The use of genetically characterized model plants can allow investigation of chosen aspects of these interactions by limiting the number of variables during experimentation. However, it is important to study the generic nature of these model systems if the data generated are to be assessed in a wider context, for instance, with those systems of commercial significance. This study assesses the suitability of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) as a model host plant to investigate plant–herbivore–natural enemy interactions, with Plutella xylostella (L.) (Lepidoptera: Plutellidae), the diamondback moth, and Cotesia plutellae (Kurdjumov) (Hymenoptera: Braconidae), a parasitoid of P. xylostella. The growth and development of P. xylostella and C. plutellae on an A. thaliana host plant (Columbia type) were compared to that on Brassica rapa var. pekinensis (L.) (Brassicaceae), a host crop that is widely cultivated and also commonly used as a laboratory host for P. xylostella rearing. The second part of the study investigated the potential effect of the different A. thaliana background lines, Columbia and Landsberg (used in wider scientific studies), on growth and development of P. xylostella and C. plutellae. Plutella xylostella life history parameters were found generally to be similar between the host plants investigated. However, C. plutellae were more affected by the differences in host plant. Fewer adult parasitoids resulted from development on A. thaliana compared to B. rapa, and those that did emerge were significantly smaller. Adult male C. plutellae developing on Columbia were also significantly smaller than those on Landsberg A. thaliana.
Life‐table analysis of mortality factors affecting populations of Bemisia tabaci on cassava in Uganda
Authors: Asiimwe P. , Ecaat J. S. , Otim M. , Gerling D. , Kyamanywa S. , Legg J. P.
Published: December 2006

A study was set up to determine the sources and rates of mortality of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on field‐grown cassava in Uganda. Using a cohort‐based approach, daily direct observations were used to construct partial life tables for 12 generations of egg and nymph populations which were studied over a 1‐year period. Mortality was categorized as dislodgement, predation, parasitism (for nymphs only), unknown death, and inviability (for eggs only). The highest mean rate of marginal mortality across all stages was attributed to parasitism, with dislodgement and predation following, respectively. Across all factors, the highest mean rate of marginal mortality was observed in the fourth instar followed by the eggs, first‐, second‐, and third‐instars, respectively. Key factor analysis revealed that dislodgement was the major mortality factor contributing to generational mortality in eggs while for nymphs, parasitism in the fourth instar was the main driving force behind the observed generational mortality. Highest irreplaceable mortality in both the egg and nymph stages was attributed to dislodgement followed by parasitism and predation, and least was due to unknown death. Across stages, highest irreplaceable mortality rates were observed in the eggs and the fourth‐instar nymphs. The other stages had relatively low rates of irreplaceable mortality. Rain‐protection experiments revealed no significant differences in marginal mortality rates when compared to the open field situation.
Decision‐making tools for Frankliniella occidentalis management in strawberry: consideration of target markets
Authors: Coll Moshe , Shakya Sulochana , Shouster Inbar , Nenner Yaakov , Steinberg Shimon
Published: December 2006

The western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), a cosmopolitan pest of many crops, is considered a major pest of low tunnel and greenhouse strawberries. The extent of damage to strawberry is unclear because different studies have produced contradictory results. Also, economic thresholds published for WFT in strawberry vary greatly, and most fail to incorporate economic factors. This study was aimed at developing a decision‐making tool for WFT management in strawberries in Israel. Toward this end, economic injury levels (EIL) and economic thresholds were calculated, based on target markets (export vs. domestic). Results indicate that serious infestation of ripe berries may cause a dull, rough appearance, and the fruit may be soft and have a reduced shelf life, rendering it unsuitable for export. Most fruit damage occurred at green and turning‐red stages of development. Two decision‐making tools were developed, one for winter, when WFT populations increase slowly but crop value is high (export market); and the second for spring, when the pest increases rapidly but crop value is low (local markets). Economic thresholds of 10 and 24 WFT/flower were calculated for winter and spring strawberries, respectively, based on direct thrips damage to fruit. This calculation does not take into account the recorded WFT damage to flowers, or its role in facilitating Botrytis cinerea fruit infection. Western flower thrips has proved only an occasional economic pest in Israeli strawberries, and no routine control measures are warranted. Furthermore, augmentative releases of Orius laevigatus or Neoseilus cucumeris against WFT are not justified in this system, because Orius colonizes strawberry fields spontaneously in high numbers when no broad spectrum insecticides are used.
The molecular bases of plant resistance and defense responses to aphid feeding: current status
Authors: Smith C. Michael , Boyko Elena V.
Published: December 2006

Plant genes participating in the recognition of aphid herbivory in concert with plant genes involved in defense against herbivores mediate plant resistance to aphids. Several such genes involved in plant disease and nematode resistance have been characterized in detail, but their existence has only recently begun to be determined for arthropod resistance. Hundreds of different genes are typically involved and the disruption of plant cell wall tissues during aphid feeding has been shown to induce defense responses in Arabidopsis, Triticum, Sorghum, and Nicotiana species. Mi‐1.2, a tomato gene for resistance to the potato aphid, Macrosiphum euphorbiae (Thomas), is a member of the nucleotide‐binding site and leucine‐rich region Class II family of disease, nematode, and arthropod resistance genes. Recent studies into the differential expression of Pto‐ and Pti1‐like kinase genes in wheat plants resistant to the Russian wheat aphid, Diuraphis noxia (Mordvilko), provide evidence of the involvement of the Pto class of resistance genes in arthropod resistance. An analysis of available data suggests that aphid feeding may trigger multiple signaling pathways in plants. Early signaling includes gene‐for‐gene recognition and defense signaling in aphid‐resistant plants, and recognition of aphid‐inflicted cell damage in both resistant and susceptible plants. Furthermore, signaling is mediated by several compounds, including jasmonic acid, salicylic acid, ethylene, abscisic acid, giberellic acid, nitric oxide, and auxin. These signals lead to the development of direct chemical defenses against aphids and general stress‐related responses that are well characterized for a number of abiotic and biotic stresses. In spite of major plant taxonomic differences, similarities exist in the types of plant genes expressed in response to feeding by different species of aphids. However, numerous differences in plant signaling and defense responses unique to specific aphid–plant interactions have been identified and warrant further investigation.
FILARIASIS
Authors: Coggeshall L. T.
Published: December 2006

Filariasis is a disease in humans which affects many thousands of individuals in the tropical and subtropical areas of the world. There is no doubt that the economy and welfare of many lands are seriously affected by these infections in spite of the fact that they are associated with very low mortality rates. Until the present, there have been no chemotherapeutic agents which have demonstrated their ability to influence the infection in man.

The chief method of control must lie in the suppression or eradication of the vectors, a task made much easier since the discovery of more effective insecticides. In this respect, we cannot be hopeful of too much success, since all diseases of high morbidity and low mortality are usually associated with indifference on the part of the general public, and only those directly concerned with public health responsibilities can be expected to exert any considerable influence. All too frequently, their efforts are so restricted, in spite of general educational campaigns, that widespread benefits are not obtained.

As stated above, this discussion is not considered chemotherapy. However, since there is little prospect of a successful immunizing agent, and since the vectors and procedures for their control have been recognized for at least two decades without apparent diminution of the incidence of the disease, the introduction of an effective chemotherapeutic agent would be a most welcome adjunct to those charged with the responsibility of eliminating this infection.
THE ROLE OF THE SEMINIFEROUS TUBULES IN THE PRODUCTION OF HORMONES
Authors: McCullagh E. Perry , Schaffenburg C. A.
Published: December 2006

Tables 2, 3, and 4 are reprinted from the Journal of Clinical Endocrinology. 11: 1403. Nov. 1951.
SOLUBILITIES OF SALTS IN METALS*
Authors: Yosim S. J. , Luchsinger E. B.
Published: December 2006

A series of experiments to determine the solubilities of metal chlorides in their metals was carried out, using a visual technique. The systems studied were: Bi, Hg, Pb, Cd, Zn, Sn, In, Ag, and Cu, with their chlorides. The results show that BiCl3 and Hg2Cl2 are most soluble, the former being completely miscible with Bi at 778° C., while the latter is soluble to the extent of 7 mole per cent, at 600°C. PbCl2 is slightly soluble (1 mole per cent at 1000°C.), while the remaining salts are considered insoluble in their metals. There appears to be no single criterion for predicting the solubility of salts in their metals.

Experiment's were also carried out to see if nonspecificity of solubility exist's at high temperatures, that is, to determine if metals dissolve salts other than their own halides. It was found that solubility does occur. It was also found that the less stable the salt, the greater is the solubility of the salt in a given metal, until the solubility approaches that of the salt of the metal. Thermodynamic calculations indicate that the solubility of a foreign salt in a metal can be explained in terms of oxidation‐reduction reactions to form the halide of the metal, which in turn dissolves in the metal. These calculations suggest that BiCl3 dissolves in bismuth metal as BiCl.
POWER SERIES SOLUTION, BY MACHINE, OF A NONLINEAR PROBLEM IN TWO‐DIMENSIONAL FLUID FLOW*
Authors: Richtmyer R. D.
Published: December 2006

The solution of a partial differential equation, with Cauchy data given on an initial surface, can be obtained as a power series expansion in the independent variables about a point on the surface if the functions appearing in the differential equations, the equation for the initial surface, and the Cauchy data are all analytic, as has been known since the work of Cauchy and Kowalewski. This power series and its analytic continuations can be used in principle for calculating the solution. The practical application of these ideas to a certain class of problems, with the use of a modern computing machine, can be achieved by means of techniques that have been developed at New York University. Typical of the class is the problem of determining the flow of air past an axially symmetric blunt body moving at supersonic speed. This flow contains a detached shock ahead of the body and, aft of the shock, a subsonic region near the nose and a supersonic region farther downstream. Normally heat conduction and viscosity can be ignored, except in a boundary layer of negligible thickness on the surface of the body. If the problem is inverted–if the shock is assumed to lie on a given analytic surface and the Rankine‐Hugoniot jump conditions at the shock are used to provide Cauchy data from which the flow aft of the shock can be obtained, and from which, in turn, the body shape required to produce the assumed shock and resulting flow can be determined, there results a problem of the kind described, with a fourth‐order system of nonlinear partial differential equations in two independent variables. The techniques described, which yield a powerful computational procedure for problems of this kind, are (1) algorithms that enable the machine to perform the needed algebraic as well as the numerical work; (2) special floating‐point subroutines, utilizing the so‐called significance arithmetic; (3) methods for obtaining analytic extensions of the functions describing the flow. These techniques and typical results are described.
RESOLUTION OF MULTI‐COMPONENT EXPONENTIAL DECAY CURVES USING FOURIER TRANSFORMS
Authors: Gardner Donald G.
Published: December 2006

A frequently encountered problem in many branches of science involves the resolution of experimental data in a sum of exponentials of the form
image

to estimate the physically significant parameters Ni° and λ i and to determine n, the number of components. The components may be separate and unrelated, or there may be decay chains where some components are produced as the result of the disappearance of other components. In the present approach the exponential series is represented by a Laplace integral equation
image
.

This equation is inverted by a method of Fourier transforms. The results of the analysis appear in the form of a frequency spectrum. Each true peak in the spectrum indicates a component, the abscissa value at the center of the peak is the decay constant λi while the height of the peak is directly proportional to Ni°/λi.
A PROCEDURE FOR HIGH VOLTAGE ELECTROPHORESIS IN AGAR GEL, WITH A NOTE ON ITS APPLICATION TO ACRYLAMIDE AND STARCH GEL*
Authors: Wieme R. J.
Published: December 2006

Summary and Conclusions

By carefully selecting the experimental conditions it is possible to obtain highquality separations in an agar gel. The electrophoretic run can also be conducted at constant temperature. The procedure is described and several of its aspects discussed; its adaptation to acrylamide gel and to starch gel electrophoresis is considered.
SIMPLIFIED “DISC” (POLYACRYLAMIDE GEL) ELECTROPHORESIS*
Authors: Clarke John T.
Published: December 2006

Cross‐linked homogeneous 5 per cent polyacrylamide gel in rod form is a convenient medium for sharp analytical electrophoretic separation in microgram quantities of most serum proteins and of many biological ampholytes.
THE USE OF GEL ELECTROPHORESIS IN THE DIAGNOSIS OF THE PARAPROTEINEMIAS*
Authors: Hammack William J. , Moore Martel , Albert Barbara
Published: December 2006

Gel electrophoresis was utilized to study 140 sera containing “paraproteins.” No consistent differentiation into the three basic immunologic types or the idiopathic type was possible. Since normal serum and paraprotein containing serum can be resolved into many discrete proteins, this technique may be very helpful in basic protein research.
THE IMPACT OF GEL ELECTROPHORESIS UPON OUR UNDERSTANDING OF THE ESTERASES*
Authors: Hunter Robert L. , Rocha Jácia T. , Pfrender Ann R. , DeJong David C.
Published: December 2006

General Discussion and Summary

The impact of gel electrophoresis upon our understanding of the esterases has been formidable in that it has provided us with new insights and understanding concerning the number and biochemical characteristics of the many esterase‐active proteins found in biological material. The relationships between the esterases within a species and among species still remains largely to be determined. With regard to the function of esterases it is to be expected that there will be several. One promising possibility is suggested by the work of Allen and Hunter, which illustrated a dependent relationship between male sex hormone and the esterases in the mouse epididymis. Supporting this work is the observation by Shaw and Koen (1963) demonstrating the presence of an esterase in the mouse kidney, which also was dependent on male sex hormone. The change observed in the serum esterase of the pregnant rabbit reported here and in women by Friedman and Lapman (1961) may also relate to hormone changes associated with pregnancy, although this relationship remains to be demonstrated. A second area where the esterases are likely to be functioning is in relation to protein synthetic activity of the endoplasmic reticulum. The only evidence supporting this suggestion is the abundant presence of esterases found in this location. The seven experiments described and discussed here along with those included in the references may serve as illustrations of the kind of work that can be accomplished by the use of these methods.*
AN UNUSUAL ISOZYME OF LACTATE DEHYDROGENASE IN MATURE TESTES: LOCALIZATION, ONTOGENY, AND KINETIC PROPERTIES*
Authors: Zinkham William H. , Blanco Antonio , Clowry Lawrence J.
Published: December 2006

Summary

One or more electrophoretically unusual isozymes of LDH have been demonstrated in homogenates of mature testes from some species. Analyses of the isozymic composition of many other tissues, developing testes, and seminal fluid revealed that these unusual forms, or “band X” isozymes, are present only in postpubertal testes and are localized in the differentiating germ cells of the seminiferous tubules. Rates of reactivity with certain alpha‐hydroxy acids and analogs of nicotinamide adenine dinucleotide differentiated some of the “band X” isozymes from the usual LDH isozymes. Results of dissociation and recombination studies on homogenates of human and rabbit testes indicated a similarity in structure between “band X” and the other isozymes.

The ontogeny and characteristic distribution of the “band X” isozymes suggested that each fulfills a specific metabolic function. As yet the nature of this metabolic assignment has not been determined.
CARBONIC ANHYDRASE ISOZYMES OF NEONATAL AND ADULT HUMAN AND SOME ANIMAL ERYTHROCYTES*
Authors: Tappan Donald V. , Jacey Michael J. , Boyden Helen M.
Published: December 2006

Ion exchange separations utilizing DEAE‐cellulose are described that are capable of isolating carbonic anhydrases individually or in groups as they occur in bovine, guinea pig, adult human, or neonatal human erythrocytes.

Acrylamide gel electrophoresis procedures have been utilized for evaluation of purification processes as well as for demonstration of relative carbonic anhydrase activities of the various enzymes and for estimation of their esterase activities.

Guinea pig carbonic anhydrases, similar to those from human erythrocytes, have both high and low specific activity forms, while the bovine enzymes demonstrate no such difference in activity.

The pattern of the neonatal resembles that of the major adult human carbonic anhydrases; a reduction in activity, however, is apparent for the principal high activity form of the enzyme. The total recoverable enzyme as well as the measurable activity is lower in neonatal than adult erythrocytes.

The active carbonic anhydrases in the three species studied have esterase activities independent of carbonic anhydrase activity but approximately proportional to protein concentration. Inasmuch as these enzymes hydrolyze napthyl acetates but are very inactive toward α‐napthyl propionate, α‐napthyl butyrate, or higher napthyl esters, they may be identified as acetyl esterases. They are, however, not sensitive to eserine.
SPECTROPHOTOMETRIC ANALYZERS FOR DISC ELECTROPHORESIS: STUDIES OF YEAST CYTOCHROME c
Authors: Taber Harry W. , Sherman Fred
Published: December 2006

Attachments to the Beckman DU and DK‐2 spectrophotometers are described for use in recording the disc electrophoresis patterns of colored materials at various wavelengths of light. The attachment to the DK‐2 instrument allows automatic recording of the pattern and can in addition be used to obtain a full wavelength scan of a given electrophoretic component. A study of the electrophoresis of yeast cytochrome c with these instruments showed that this hemoprotein can be readily converted to derivative forms by treatment with hydroquinone and by washing the resin‐bound enzyme with dilute buffer.
THE ORIGIN OF THE MULTIPLE FORMS OF PHOSPHORYLASE IN ALGAE*
Authors: Fredrick Jerome F.
Published: December 2006

Two isozymes of phosphorylase are present in the alga Oscillatoria princeps that are similar to the animal phosphorylases in their need for adenosine‐5‐phosphate as cofactor.

The biosynthesis of the adenosine‐5‐phosphate independent isozyme can be effectively blocked by the addition of the phytotoxic compound, 3‐amino‐1,2,4‐triazole, to cultures of the alga.

Evidence is presented for the possible existence of a kinaselike enzyme that converts the AMP‐requiring isozyme in this alga to the AMP‐independent form.

The evolutionary significance of these observations is examined.
METHODS OF OXYGEN ADMINISTRATION IN RESPIRATORY FAILURE
Authors: Campbell E. J. M.
Published: December 2006

Physiological and clinical evidence suggest that the hypoxic hypoxia of respiratory failure in patients with chronic lung disease should be managed by using inspired oxygen concentrations in the range 24 to 33 per cent.

Conventional methods of oxygen administration do not permit the requisite control but it can be simply achieved using the principle of high air flow with oxygen enrichment (HAFOE).

Methods of implementing HAFOE using the Venturi principle are described and our present practice outlined.
RESPIRATOR TREATMENT FOR HYPOVENTILATION FOLLOWING THORACIC SURGERY*
Authors: Björk Viking Olov , Son Holmdahl Martin H:
Published: December 2006

Summary and Conclusion

Indications for the use of respirator treatment following thoracic surgery and crush injuries to the chest have been briefly discussed.

Prevention of a decrease in arterial oxygen tension due to development of atelectasis and reduction of the metabolic requirements of the patient due to elimination of the respiratory work are put forward as arguments for prophylactic respirator treatment before gross alveolar hypoventilation with a rise in arterial carbon dioxide tension makes such treatment mandatory. The prevention of a decrease in arterial oxygen tension is essential in patients with small cardiac reserves.
THE MANAGEMENT OF RESPIRATORY FAILURE IN CHRONIC OBSTRUCTIVE LUNG DISEASE
Authors: Cherniack Reuben M.
Published: December 2006

Summary

The management of the chronic respiratory diseases should consist of measures designed to restore as far as possible normal pulmonary function. It must be emphasized that patients with chronic respiratory disease, like patients with diabetes or heart failure, are suffering from a chronic condition which may be incurable, but progression of the disease can be prevented to a large extent. For this reason, the patients should be advised to continue all modes of therapy and to inhale the nebulized bronchodilator in a proper fashion every day, as soon as they wake up in the morning, the last thing at night before going to bed, at any time during the day or night they might feel the slightest tightness in the chest, and prior to undertaking any exertion. The morning and night therapy, maintenance of adequate hydration, and oral bronchodilators should be continued no matter how well they feel. The importance of preventative measures cannot be stressed enough in the managment of respiratory disease. Too often the patient is sent home from hospital without being advised to continue his medications in order to prevent attacks of bronchial obstruction.

When respiratory failure with hypoxia and hypercapnia develops, therapy should be directed at improving the alveolar ventilation by reduction of work of breathing through alleviation of airway obstruction and pulmonary congestion; and reducing the metabolism by treating infection or excessive weight; and provision of an adequate alveolar ventilation by assisting or controlling ventilation.

Because of our advances in knowledge of therapy of this condition, we are now being faced with patients who, despite continuation of these measures in an intensive fashion, reach a state where no improvement in clinical status and arterial blood gases can be achieved. These patients pose a great therapeutic challenge, and much can be done to prevent progression of the disease. In our hands we have observed extremely beneficial results from the use of Dichlorphenamide, a graded exercise program, and the establishment of a “Home Care” program.
Identification of Specific Chemoattractants and Genetic Complementation of a
Borrelia burgdorferi
Chemotaxis Mutant: Flow Cytometry-Based Capillary Tube Chemotaxis Assay
Authors: Bakker Richard G. , Li Chunhao , Miller Michael R. , Cunningham Cynthia , Charon Nyles W.
Published: December 2006

Measuring the chemotactic response of
Borrelia burgdorferi
, the bacterial species that causes Lyme disease, is relatively more difficult than measuring that of other bacteria. Because these spirochetes have long generation times, enumerating cells that swim up a capillary tube containing an attractant by using colony counts is impractical. Furthermore, direct counts with a Petroff-Hausser chamber is problematic, as this method has a low throughput and necessitates a high cell density; the latter can lead to misinterpretation of results when assaying for specific attractants. Only rabbit serum and tick saliva have been reported to be chemoattractants for
B. burgdorferi
. These complex biological mixtures are limited in their utility for studying chemotaxis on a molecular level. Here we present a modified capillary tube chemotaxis assay for
B. burgdorferi
that enumerates cells by flow cytometry. Initial studies identified
N
-acetylglucosamine as a chemoattractant. The assay was then optimized with respect to cell concentration, incubation time, motility buffer composition, and growth phase. Besides
N
-acetylglucosamine, glucosamine, glucosamine dimers (chitosan), glutamate, and glucose also elicited significant chemoattractant responses, although the response obtained with glucose was weak and variable. Serine and glycine were nonchemotactic. To further validate and to exploit the use of this assay, a previously described nonchemotactic
cheA2
mutant was shown to be nonchemotactic by this assay; it also regained the wild-type phenotype when complemented in
trans
. This is the first report that identifies specific chemical attractants for
B. burgdorferi
and the use of flow cytometry for spirochete enumeration. The method should also be useful for assaying chemotaxis for other slow-growing prokaryotic species and in specific environments in nature.
Analysis ofThalassiosira pseudonanaSilicon Transporters Indicates Distinct Regulatory Levels and Transport Activity through the Cell Cycle
Authors: Thamatrakoln Kimberlee , Hildebrand Mark
Published: December 2006

An analysis of the expression and activity of silicon transporters (SITs) was done on synchronously growing cultures of the diatomThalassiosira pseudonanato provide insight into the role these proteins play in cellular silicon metabolism during the cell cycle. The first SIT-specific polyclonal peptide antibody was generated and used in the immunoblot analysis of whole-cell protein lysates to monitor SIT protein levels during synchronized progression through the cell cycle. Peaks in SIT protein levels correlated with active periods of silica incorporation into cell wall substructures. Quantitative real-time PCR on each of the three distinctSITgenes (TpSIT1, TpSIT2, and TpSIT3) showed that mRNA levels for the most highly expressedSITgenes peaked during the S phase of the cell cycle, a period prior to maximal silicon uptake and during which cell wall silicification does not occur. Variations in protein and mRNA levels did not correlate, suggesting that a significant regulatory step of SITs is at the translational or posttranslational level. Surge uptake rates also did not correlate with SIT protein levels, suggesting that SIT activity is internally controlled by the rate of silica incorporation. This is the first study to characterize SIT mRNA and protein expression and cellular uptake kinetics during the course of the cell cycle and cell wall synthesis, and it provides novel insight into SIT regulation.
Pirin Regulates Pyruvate Catabolism by Interacting with the Pyruvate Dehydrogenase E1 Subunit and Modulating Pyruvate Dehydrogenase Activity
Authors: Soo Po-Chi , Horng Yu-Tze , Lai Meng-Jiun , Wei Jun-Rong , Hsieh Shang-Chen , Chang Yung-Lin , Tsai Yu-Huan , Lai Hsin-Chih
Published: December 2006

The protein pirin, which is involved in a variety of biological processes, is conserved from prokaryotic microorganisms, fungi, and plants to mammals. It acts as a transcriptional cofactor or an apoptosis-related protein in mammals and is involved in seed germination and seedling development in plants. In prokaryotes, while pirin is stress induced in cyanobacteria and may act as a quercetinase in
Escherichia coli
, the functions of pirin orthologs remain mostly uncharacterized. We show that the
Serratia marcescens
pirin (pirin

Sm

) gene encodes an ortholog of pirin protein. Protein pull-down and bacterial two-hybrid assays followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrospray ionization-tandem mass spectrometry analyses showed the pyruvate dehydrogenase (PDH) E1 subunit as a component interacting with the pirin

Sm

gene. Functional analyses showed that both PDH E1 subunit activity and PDH enzyme complex activity are inhibited by the pirin

Sm

gene in
S. marcescens
CH-1. The
S. marcescens
CH-1 pirin

Sm

gene was subsequently mutated by insertion-deletion homologous recombination. Accordingly, the PDH E1 and PDH enzyme complex activities and cellular ATP concentration increased up to 250%, 140%, and 220%, respectively, in the
S. marcescens
CH-1 pirin

Sm

mutant. Concomitantly, the cellular NADH/NAD
+
ratio increased in the pirin

Sm

mutant, indicating increased tricarboxylic acid (TCA) cycle activity. Our results show that the pirin

Sm

gene plays a regulatory role in the process of pyruvate catabolism to acetyl coenzyme A through interaction with the PDH E1 subunit and inhibiting PDH enzyme complex activity in
S. marcescens
CH-1, and they suggest that pirin

Sm

is an important protein involved in determining the direction of pyruvate metabolism towards either the TCA cycle or the fermentation pathways.
Differentiation and Distribution of Colistin- and Sodium Dodecyl Sulfate-Tolerant Cells inPseudomonas aeruginosaBiofilms
Authors: Haagensen Janus A. J. , Klausen Mikkel , Ernst Robert K. , Miller Samuel I. , Folkesson Anders , Tolker-Nielsen Tim , Molin Søren
Published: December 2006

DuringPseudomonas aeruginosaflow cell biofilm development, the cell population differentiates into a nonmotile subpopulation which forms microcolonies and a migrating subpopulation which eventually colonizes the top of the microcolonies, resulting in the development of mushroom-shaped multicellular structures. The cap-forming subpopulation was found to develop tolerance to membrane-targeting antimicrobial agents, such as the cyclic cationic peptide colistin and the detergent sodium dodecyl sulfate. The stalk-forming subpopulation, on the other hand, was sensitive to the membrane-targeting antibacterial agents. All biofilm-associated cells were sensitive to the antibacterial agents when tested in standard plate assays. A mutation eliminating the production of type IV pili, and hence surface-associated motility, prevented the formation of regular mushroom-shaped structures in the flow cell biofilms, and the development of tolerance to the antimicrobial agents was found to be affected as well. Mutations in genes interfering with lipopolysaccharide modification (pmr) eliminated the biofilm-associated colistin tolerance phenotype. Experiments with a PAO1 strain harboring apmr-gfpfusion showed that only the cap-forming subpopulation in biofilms treated with colistin expresses thepmroperon. These results suggest that increased antibiotic tolerance in biofilms may be a consequence of differentiation into distinct subpopulations with different phenotypic properties.
β-
d
-Allose Inhibits Fruiting Body Formation and Sporulation in
Myxococcus xanthus
Authors: Chavira Marielena , Cao Nga , Le Karen , Riar Tanveer , Moradshahi Navid , McBride Melinda , Lux Renate , Shi Wenyuan
Published: December 2006

Myxococcus xanthus
, a gram-negative soil bacterium, responds to amino acid starvation by entering a process of multicellular development which culminates in the assembly of spore-filled fruiting bodies. Previous studies utilizing developmental inhibitors (such as methionine, lysine, or threonine) have revealed important clues about the mechanisms involved in fruiting body formation. We used Biolog phenotype microarrays to screen 384 chemicals for complete inhibition of fruiting body development in
M. xanthus
. Here, we report the identification of a novel inhibitor of fruiting body formation and sporulation, β-
d
-allose. β-
d
-Allose, a rare sugar, is a member of the aldohexose family and a C3 epimer of glucose. Our studies show that β-
d
-allose does not affect cell growth, viability, agglutination, or motility. However, β-galactosidase reporters demonstrate that genes activated between 4 and 14 h of development show significantly lower expression levels in the presence of β-
d
-allose. Furthermore, inhibition of fruiting body formation occurs only when β-
d
-allose is added to submerged cultures before 12 h of development. In competition studies, high concentrations of galactose and xylose antagonize the nonfruiting response to β-
d
-allose, while glucose is capable of partial antagonism. Finally, a
magellan-4
transposon mutagenesis screen identified
glcK
, a putative glucokinase gene, required for β-
d
-allose-mediated inhibition of fruiting body formation. Subsequent glucokinase activity assays of the
glcK
mutant further supported the role of this protein in glucose phosphorylation.