Transient and persistent tetrodotoxin-sensitive sodium currents in squid olfactory receptor neurons

Squid olfactory receptor neurons are primary bipolar sensory neurons capable of transducing water-born odorant signals into electrical impulses that are transmitted to the brain. In this study, we have identified and characterized the macroscopic properties of voltage-gated Na+ channels in olfactory receptor neurons from the squid Lolliguncula brevis. Using whole-cell voltage-clamp techniques, we found that the voltage-gated Na+ channels were tetrodotoxin sensitive and had current densities ranging from 5 to 169 pA pF-1. Analyses of the voltage dependence and kinetics revealed interesting differences from voltage-gated Na+ channels in olfactory receptor neurons from other species; the voltage of half-inactivation was shifted to the right and the voltage of half-activation was shifted to the left such that a "window-current" occurred, where 10-18% of the Na+ channels activated and did not inactivate at potentials near action potential threshold. Our findings suggest that in squid olfactory neurons, a subset of voltage-gated Na+ channels may play a role in generating a pacemaker-type current for setting the tonic levels of electrical activity required for transmission of hyperpolarizing odor responses to the brain.

Human immunodeficiency virus type 1 Vif-derived peptides inhibit the viral protease and arrest virus production

Human immunodeficiency virus type 1 (HIV-1) Vif protein is required for productive HIV-1 infection of peripheral blood lymphocytes and macrophages in cell culture and for pathogenesis in the SCID-hu mouse model of HIV-1 infection. Vif inhibits the viral protease (PR)-dependent autoprocessing of truncated HIV-1 Gag-Pol precursors expressed in bacterial cells and efficiently inhibits the PR-mediated hydrolysis of peptides in cell-free systems. The obstructive activity of Vif has been assigned to the 92 amino acids residing at its N'-terminus (N-Vif). To determine the minimal Vif sequence required to inhibit PR, we synthesized overlapping peptides derived from N-Vif. These peptides were then assessed, using two in vitro and two in vivo systems: (i) inhibition of purified PR, (ii) binding of PR, (iii) inhibition of the autoprocessing of the Gag-Pol polyprotein expressed by a vaccinia virus vector, and (iv) inhibition of mature virus production in human cells. The peptides derived from two regions of N-Vif encompassing residues Tyr-30-Val-65 and Asp-78-Val-98, inhibited PR activity in both the in vitro and the in vivo assays. Thus, these peptides can be used as lead compounds to design new PR inhibitors.

Cocaine acts as an apparent competitive inhibitor at the outward-facing conformation of the human norepinephrine transporter: kinetic analysis of inward and outward transport

The inhibition by cocaine of inward and outward transport of dopamine (DA) at the cloned human norepinephrine transporter (hNET) and the relationship of the inhibitory patterns of cocaine to the conformational requirements of the transporter were investigated. This was done using rotating disk electrode voltammetry in transfected cells. The uphill uptake of external DA, the lack of inhibition by internal substrates on DA uptake, and the accelerated exchange of internal DA by external m-tyramine support a carrier model in which the hNET alternates between outward-facing and inward-facing conformations. Cocaine exhibited competitive inhibition of DA uptake, which was insensitive to intracellular substrates. In contrast, the inhibition by cocaine of the m-tyramine-induced DA efflux appeared noncompetitive relative to intracellular DA, but competitive relative to extracellular m-tyramine. Simultaneous measurement of m-tyramine uptake and accompanying DA efflux at various concentrations of intracellular DA showed that cocaine did not alter the ratio of DA efflux to m-tyramine uptake. Moreover, cocaine displayed similar potency for inhibiting DA uptake and efflux. Additionally, the inhibition profile of cocaine was unrelated to the addition time of cocaine, simultaneously with or earlier than a substrate. All of the findings are consonant with a competitive interaction between cocaine and substrates at the outward-facing conformation of the hNET. This action directly prevents the inward transport of external substrates, thereby inhibiting the outward transport of internal substrates by reducing the availability of the inward-facing conformation. Consequently, the experimental inhibition pattern of cocaine depends on the conformation of the hNET to which the transported substrate is exposed.

Preparative application of commercial automated gel electrophoresis apparatus to subcellular-sized particles: sequential isolations, fractions re-run, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, yield and purity

The analytical and preparative potential of automated gel electrophoresis apparatus with intermittent fluorescence scanning of the migration path, the HPGE-1000 apparatus (LabIntelligence, Belmont, CA) was further developed in application to subcellular-sized particles. Resolution between two rat liver microsome components in agarose (MetaPhor) gel electrophoresis was found to increase with decreasing agarose concentration to 0.04%. It was less, even in an agarose solution at that low concentration, than that in laterally aggregated 4% polyacrylamide gel. The three components of the microsomal preparation were sequentially isolated from 0.6 and 0.8% agarose gel electropherograms. One fraction when re-electrophoresed was found to exhibit the original mobility and did not give rise to the other components. Yields of each component were near-quantitative after one or two electroelution steps. Based on protein content, no impurities could be detected in two of the microsome fractions; the third fraction contained 2% of nonmicrosome impurity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of all three microsome fractions were indistinguishable from one another and from that of the unfractionated microsome preparation.

Rpe65 is necessary for production of 11-cis-vitamin A in the retinal visual cycle

Mutation of RPE65 can cause severe blindness from birth or early childhood, and RPE65 protein is associated with retinal pigment epithelium (RPE) vitamin A metabolism. Here, we show that Rpe65-deficient mice exhibit changes in retinal physiology and biochemistry. Outer segment discs of rod photoreceptors in Rpe65-/- mice are disorganized compared with those of Rpe65+/+ and Rpe65+/- mice. Rod function, as measured by electroretinography, is abolished in Rpe65-/- mice, although cone function remains. Rpe65-/- mice lack rhodopsin, but not opsin apoprotein. Furthermore, all-trans-retinyl esters over-accumulate in the RPE of Rpe65-/- mice, whereas 11-cis-retinyl esters are absent. Disruption of the RPE-based metabolism of all-trans-retinyl esters to 11-cis-retinal thus appears to underlie the Rpe65-/- phenotype, although cone pigment regeneration may be dependent on a separate pathway.

Vanadium induces AP-1- and NFkappB-dependent transcription activity

Vanadate has been reported to be involved in the causation of cancer. In this study, we found that both AP-1 and NFkappaB activities were increased after treatment with sodium vanadate in JB6 cells. Maximum induction of AP-1 and NFkappaB appeared at 48 to 72 h. Phosphorylations of Erks and p38 kinases were markedly increased at 100 microM of vanadate, while phosphorylation of JNKs was not affected. Vanadate also enhances the phosphorylation of IkappaBalpha. These results suggest that the activation of AP-1 and NFkappaB by vanadate may be mediated through enhancement of phosphorylation of Erk/p38 kinases and IkappaBalpha, respectively.

A clinicopathological study of Alport syndrome and detection of type IV collagen chains in Alport patients

OBJECTIVE

To summarize the clinical and pathological findings of Alport syndrome (AS), detect the distribution of type IV collagen within basement membrane of patients with AS and evaluate the diagnostic value of indirect immunofluorescence (iIF) study of type IV collagen in AS.

METHODS

Fourteen patients belonging to 12 families were collected from January 1990 to June 1996. The clinical examinations include biochemical examination, audiometry and ocular examination. IIF technique was used to detect the location of chains of type IV collagen in 6 renal and 5 skin specimens from 8 Alport patients.

RESULTS

Among fourteen patients, 11 were male and 3 female (mean age 29.4 years). Microscopic hematuria was found in 13 patients, and recurrent gross hematuria in 7. All had proteinuria. Three patients presented nephrotic syndrome. Slowly progressive renal failure occurred in 10 of 11 males (11-39 years) and 1 female (40 years). Sensorineural deafness was observed in 9 patients particularly high frequency sound. Anterior lenticonus were presented in 2. Five families transmitted as X-linked dominant (XD) trait and 3 autosomal dominant, 3 autosomal recessive inheritance. In 7 renal biopsies, the findings by light microscopy mostly revealed focal and segmental sclerosis glomerulonephritis (4/7). The results of IF were negative in 4. Ultrastructural studies showed variable thickening, thinning of glomerular basement membrane (GBM) in 7 specimens with lamellation and basket wearing of GBM in 1. Using the iIF technique, the alpha 3, 4, 5 (IV) chains were observed to be absent within both GBM and EBM of 4 male XD-AS patients. Six patients were treated with hemodialysis, 2/6 with transplantation.

CONCLUSION

Alport syndrome (AS) is a heterogeneous hereditary disease characterized by progressive hematuric nephritis with or without sensorineural hearing loss and ocular defects. Ultrastructural alterations of GBM are helpful to the diagnosis of AS. IIF study suggests that type IV collagen in basement membrane of AS was abnormal and iIF study of type IV collagen chains distribution is useful for confirming the diagnosis of AS.

Objective evaluation of oral and maxillofacial sensory nerves

OBJECTIVE

The purpose of this article is to recommend a set of methods for the clinical objective evaluation of neurosensory nerves and to establish criteria for the clinical objective evaluation of oral and maxillofacial regions in a Chinese population.

METHODS

Sensations in the oral and maxillofacial regions of 35 healthy subjects were objectively and quantitatively evaluated by means of two-point discrimination, static light touch, brush directional stroke, and thermal discrimination.

RESULTS

Criteria for the clinical neurosensory evaluation were established for the sensations of the oral and maxillofacial regions of healthy Chinese.

CONCLUSIONS

Two-point discrimination, static light touch, brush directional discrimination, and thermal discrimination can provide objective, quantitative information for the evaluation of sensory nerve impairment. These convenient methods represent the important tools in the diagnosis and treatment of sensory nerve impairment in oral and maxillofacial regions.

Unilateral cricothyroid contraction and glottic configuration

It is frequently stated that unilateral cricothyroid muscle (CT) paralysis can be diagnosed by physical examination, noting rotation of the glottis, and shortening and vertical displacement of the ipsilateral vocal fold. These signs, however, are inconsistently observed, and there is considerable controversy regarding the direction of glottic rotation. To determine the effects of CT contraction on three-dimensional glottic configuration, we performed computerized tomography on cadaver larynges before and after simulated CT contraction. Radiopaque makers were used to compute distances. Unilateral CT contraction equally increased the length of both membranous vocal folds, and rotated the posterior glottis less than 1 mm. CT contraction neither adducted the vocal processes, nor significantly their altered vertical level. These results suggest that unilateral CT paralysis cannot be diagnosed on the basis of any clinically apparent change in glottal configuration.

Voltammetric studies on mechanisms of dopamine efflux in the presence of substrates and cocaine from cells expressing human norepinephrine transporter

The effects of substrates m-tyramine and beta-phenethylamine, as well as cocaine, on the DA efflux from a cell line stably expressing the human norepinephrine transporter (hNET) were investigated by using rotating disk electrode voltammetry. Both the substrates and cocaine induced apparent DA efflux in a concentration-dependent manner. Their EC50 values for inducing DA efflux were similar to their IC50 values for inhibiting DA uptake. The substrate-induced DA efflux was inhibited by various NET blockers, enhanced by raising the internal [Na+] with Na+,K+-ATPase inhibition, but was insensitive to membrane potential-altering agents valinomycin, veratridine, and high [K+]. The initial rate of m-tyramine-induced DA efflux was related to preloaded [DA] in a manner defined by a Michaelis-Menten expression. In contrast, DA efflux in the presence of cocaine displayed a much slower efflux rate, lower efficacy, was not stimulated by elevated internal [Na+], and was nonsaturable with preloaded [DA]. Single exponential kinetic analysis of the entire time course of the DA efflux showed that the apparent first-order rate constant for m-tyramine-induced DA efflux declined with increased preloaded [DA], whereas that for the DA efflux in the presence of cocaine was unchanged with varying preloaded [DA]. These results suggest that the substrates stimulate the NET-dependent DA efflux by increasing the accessibility of the NET to internal DA, whereas cocaine "uncovers" NET-independent DA efflux by reducing the accessibility of diffused/leaked external DA to the NET.

[Experimental study of dahuang zhechong pills in the treatment of immunological liver fibrosis in rats]

OBJECTIVE

To study the effect of DHZC on liver fibrosis.

METHOD

Immuno-injured fibrosis in rats was induced by bovine serum albumin and DHZC was given during and after the model production respectively. Hepatic collagen contents, pathology of liver and serum hyaluronic acid were measured. Colchicine was used as control.

RESULT

It shows that the liver fibrosis rates of the DHZC treated group during and after the model production were 72.7% and 71.2% respectively, while those of the untreated and colchicine group were 92.3%-100%. Compared with the untreated group, there was a remarkable decrease of hepatic collagen contents in the DHZC-treated rats.

CONCLUSION

DHZC have thus been proved helpful in reversing liver fibrosis to some extent.

Preparative electrophoresis in "sieving media" of subcellular-sized particles

The commercial gel electrophoresis apparatus with intermittent scanning of the migration path and preparative capacity (HPGE-1000, LabIntelligence) is applicable to polymer solutions as well as gels. Unresolved rat liver microsomes can be isolated from 11-15% polyvinylpyrrolidone (PVP) solution by means of a syringe. The automated band isolation technique applied under resolving conditions in dilute polymer solutions allowed for the sequential isolation of three microsome components with 85, 76 and 75% recovery, respectively, under strict control of the dimensions of the volumetric collection module of the HPGE-1000 apparatus. Separations of unlabeled microsomes and sea urchin egg components in dilute polymer solutions have been performed, using detection by "fluorescence reduction". The unlabeled major component of a sea urchin egg homogenate has been isolated from electrophoresis in 1.5% PVP (Mr = 10(6)) solution in 25-50% yield (0.24-4 microg/8 lanes of the HPGE-1000 apparatus). However, since separations of both microsomes and sea urchin egg granules in dilute polymer solutions are restricted to a narrow range of polymer concentrations, their retardation coefficients, KR = d(log mobility)/d(polymer concentration), are not ascertained.

Separation and microgram-scale isolation of sea urchin egg granules by electrophoresis in polyvinylpyrrolidone solution, using horizontal gel electrophoresis apparatus with fluorescence detector

A homogenate of sea urchin (Lytechinus pictus) eggs rich in exocytotic membrane vesicles (granules) was subjected to analytical and preparative electrophoresis in the commercial automated horizontal gel electrophoresis apparatus (HPGE-1000, LabIntelligence, Belmont, CA) capable of intermittent scanning of the migration path, using buffered solutions of polyvinylpyrrolidone (PVP). The nonfluorescent granules were detected by "fluorescence reduction", i.e., a decrease of fluorescence intensity due to the absorbance and/or light scattering properties of the particle. Granules migrated at linear migration rates in buffers ranging from 0 to 2.5% PVP. Two bands were observed and optimally separated in 1.5% PVP solution. As shown by sodium dodecyl sulfate (SDS)-polypeptide patterns, the material recovered from the bands was qualitatively indistinguishable from the two major fractions A and C of granules previously separated by free-flow electrophoresis in the absence of polymer. Ferguson plot analysis failed to provide the sizes of the granules in view of the narrow PVP concentration range available for mobility measurement and the unavailability of chemically homogeneous size standards.

Differentiation-specific increase in ALA-induced protoporphyrin IX accumulation in primary mouse keratinocytes

A treatment regimen that takes advantage of the induction of intracellular porphyrins such as protoporphyrin IX (PPIX) by exposure to exogenous 5-amino-laevulinic acid (ALA) followed by localized exposure to visible light represents a promising new approach to photodynamic therapy (PDT). Acting upon the suggestion that the effectiveness of ALA-dependent PDT may depend upon the state of cellular differentiation, we investigated the effect of terminal differentiation upon ALA-induced synthesis of and the subsequent phototoxicity attributable to PPIX in primary mouse keratinocytes. Induction of keratinocyte differentiation augmented intracellular PPIX accumulation in cells treated with ALA. These elevated PPIX levels resulted in an enhanced lethal photodynamic sensitization of differentiated cells. The differentiation-dependent increase in cellular PPIX levels resulted from several factors including: (a) increased ALA uptake, (b) enhanced PPIX production and (c) decreased PPIX export into the culture media. Simultaneously, steady-state levels of coproporphyrinogen oxidase mRNA increased but aminolaevulinic acid dehydratase mRNA levels remained unchanged. From experiments using 12-o-tetradecanoylphorbol-13-acetate, transforming growth factor beta 1 and calcimycin we demonstrated that the increase in PPIX concentration in terminally differentiating keratinocytes is calcium- and differentiation specific. Stimulation of the haem synthetic capacity is seen in primary keratinocytes, but not in PAM 212 cells that fail to undergo differentiation. Interestingly, increased PPIX formation and elevated coproporphyrinogen oxidase mRNA levels are not limited to differentiating keratinocytes; these were also elevated in the C2C12 myoblast and the PC12 adrenal cell lines upon induction of differentiation. Overall, the therapeutic implications of these results are that the effectiveness of ALA-dependent PDT depends on the differentiation status of the cell and that this may enable selective targeting of several tissue types.

[Quantitative studies of taste and fungiform papillae on the anterior human tongue]

OBJECTIVE

To study qantitatively in the taste and fungiform papillae on the anterior human tongue.

METHODS

Sixty normal adults were evaluated the spatial taste and the fungiform papilla density at spatially-matched sides on the right and left sides of the anterior tongue. The taste stimulative solutions were delivered to a spatially-matched flow chamber attached to the surface of the right or left anterior tongue.

RESULTS

(1) There is no statistical difference in number of the fungiform papillae, taste threshold and magnitude matching between right/left, male/female and races; (2) There is a significant difference in fungiform papilla density and taste functions in different individuals; (3) The fungiform papilla density is the key to taste function on 2/3 anterior of tongue, and is positively correlated to it; (4) The use of a spatially-matched flow chamber is a valid test system for overall, objective and accurate evaluating taste on the 2/3 anterior of tongue, and can be used to study quantitatively the fungiform papilla density.

CONCLUSION

It is of clinical significance for the diagnosis of taste diseases and the dynamic studies of the taste and the fungiform papillae after lingual nerve injury and repair.

Mass spectrometric analysis of integral membrane proteins: application to complete mapping of bacteriorhodopsins and rhodopsin

Integral membrane proteins have not been readily amenable to the general methods developed for mass spectrometric (or internal Edman degradation) analysis of soluble proteins. We present here a sample preparation method and high performance liquid chromatography (HPLC) separation system which permits online HPLC-electrospray ionization mass spectrometry (ESI-MS) and -tandem mass spectrometry (MS/MS) analysis of cyanogen bromide cleavage fragments of integral membrane proteins. This method has been applied to wild type (WT) bacteriorhodopsin (bR), cysteine containing mutants of bR, and the prototypical G-protein coupled receptor, rhodopsin (Rh). In the described method, the protein is reduced and the cysteine residues pyridylethylated prior to separating the protein from the membrane. Following delipidation, the pyridylethylated protein is cleaved with cyanogen bromide. The cleavage fragments are separated by reversed phase HPLC using an isopropanol/acetonitrile/aqueous TFA solvent system and the effluent peptides analyzed online with a Finnigan LCQ Ion Trap Mass Spectrometer. With the exception of single amino acid fragments and the glycosylated fragment of Rh, which is observable by matrix assisted laser desorption ionization (MALDI)-MS, this system permits analysis of the entire protein in a single HPLC run. This methodology will enable pursuit of chemical modification and crosslinking studies designed to probe the three dimensional structures and functional conformational changes in these proteins. The approach should also be generally applicable to analysis of other integral membrane proteins.

A dynein heavy chain homologue gene in Hexamita inflata

A gene encoding an unusually small dynein heavy chain homologue, hDYHH, was cloned from the genome of a free-living diplomonad, Hexamita inflata (Hi). The open reading frame (ORF) of hDYHH is 867bp and encodes a polypeptide of 289 amino acids (aa), hDYHH. hDYHH is homologous to the region around the third P-loop ATP-binding site of several dynein heavy chain polypeptides that are around 4000aa. Northern blot analysis showed that hDYHH is expressed in vivo and that the mRNA length (approximately 1.8kb) is consistent with the gene length (1.67kb). Southern blot analysis indicated that there are hDYHH homologues within the Hi genome, possibly including a longer dynein heavy chain gene. An hDYHH homologue was also identified in Hexamita pusilla (Hp). hDYHH is the first full-length protein-encoding gene cloned from Hexamita.

Enhanced detection sensitivity of "fluorescence reduction" by shifting the analyte absorbance spectrum and use of a fluorescent paper with higher signal/noise ratio

Nonfluorescing protein bands can be detected by the fluorescence optics of the commercial gel electrophoresis apparatus with automated scanning of the migration path (HPGE-1000, LabIntelligence, Belmont CA), taking advantage of the decrease of emission from a fluorescent paper placed below the gel by the absorbance of proteins ("fluorescence reduction"). That decrease of fluorescence gives rise to an inverted protein peak. Nonfluorescent colorless proteins appear to reduce the intensity of light emitted from the fluorescent paper due to absorbance of incident and emitted light. When the absorbance spectrum only slightly overlaps with the excitation and emission spectra of the fluorescent paper, that reduction is weak, and detection sensitivity in that application is consequently only 1/30 of that of fluorescent proteins. By contrast, when the protein is colored so that its absorbance spectrum overlaps widely with the excitation and emission spectra of the fluorescent paper, the sensitivity of "fluorescence reduction" equals 1/4 to 1/5 of that obtained for fluorescent proteins. Bands detected by "fluorescence reduction" provide a quantitative measure of protein load and mobility. The area of the inverted bands is proportional to protein loads up to 16 microg/lane of the gel tray. A theory of "fluorescence reduction" is presented which accounts for the existence of a linear relationship between band area and load.

Integrin-mediated adhesion and signalling in ovarian cancer cells

The integrins are a family of cell surface receptors which mediate cellular adhesion and signalling events. Our goal was to evaluate integrin function and signalling pathways in ovarian cancer cells. Ovarian cancer cell lines, NIH:OVCAR-3 and NIH:OVCAR-5, exhibited distinct extracellular matrix (ECM) binding preferences which were mediated primarily through beta1 integrin interactions. Western blot analysis was used to identify changes in cellular phosphotyrosine, focal adhesion kinase (FAK) and mitogen activated protein (MAP) kinase. Tyrosine phosphorylation of integrin-associated phosphoproteins was not enhanced in either cell type in response to adhesion onto ECM components or receptor crosslinking. FAK expression was greater in NIH:OVCAR-5 cells while MAP kinase activity was higher in NIH:OVCAR-3 cells. The data suggest that these two ovarian cancer cell lines exhibit specific ECM binding preferences and distinct differences in phosphotyrosine, focal adhesion and MAP kinase expression profiles.

Capillary electrophoresis of DNA fragments in 9 to 20% uncrosslinked polyacrylamide gels: unique separating capacity hypothetically related to maintenance of random-coil DNA conformation independently of gel concentration

DNA fragments (0.1 to 2 kb) were separated by capillary electrophoresis (CE) in 9 to 20% uncrosslinked polyacrylamide gels with a resolving power ranging from 3 to o.1 million theoretical plates/meter across that DNA size range. The unique feature of electrophoresis in 18 to 20% uncrosslinked polyacrylamide is that it provides a method capable of resolving charge isomeric species of DNA fragments (0.4 to 2 kb), confirming a previous report by Heiger et al. [Heiger DN, Cohen AS, Karger BL. J Chromatogr 516 (1990) 33-48]. A similarly unique resolving capacity of uncrosslinked polyacrylamide gels for DNA previously reported is that for heteroduplex DNA [Pulyaeva H, Zakharov SF, Garner MM, Chrambach A. Electrophoresis 15 (1994) 1095-1100] matched by crosslinked gels only in the presence of denaturants [Peeters AV, Kotze MJ. PCR Methods Appl 4 (1994) 188-190; Ganguly A, Rock MJ, Prockop DJ. Proc Natl Acad Sci USA 90 (1993) 10 325-10 329]. A clue as to the cause of that unique resolving capacity of crosslinked polyacrylamide is provided by the finding in the present study of a single, gel concentration independent KR [retardation coefficient, d(log mobility)/d(gel concentration)] for the DNA fragments, which contrasts with the decrease of KR with gel concentration observed for crosslinked polyacrylamide across a wide concentration range [Orban L, Chrambach A. Electrophoresis 12 (1991) 241-246; Tietz D, Chrambach A. Electrophoresis 14 (1993) 185-190]. Since the decrease of KR with gel concentration correlates with a decrease in equivalent molecular radius [Tietz D, Chrambach A. Electrophoresis 14 (1993) 185-190], it has been interpreted as being due to the transition from a random-coiled to a stretched DNA conformation upon passage through gels of increasing concentration. Since in uncrosslinked gels the decrease of KR does not occur, it is correspondingly assumed that the random-coil conformation of DNA is maintained in those gels in the investigated concentration range up to 20%. The maintenance of random-coil conformation [Tietz D, Chrambach A. Electrophoresis 14 (1993) 185-190]. The effect of denaturants in allowing for resolution of heteroduplex DNA in crosslinked gels [Peeters AV, Kotze MJ. PCR Methods Appl 4 (1994) 188-190; Ganguly A, Rock MJ, Prockop DJ, Proc Natl Acad Sci USA 90 (1993) 10 325-10 329] supports that hypothesis of the enhanced resolving power of electrophoresis in gels that maintain random-coiled DNA within the gel concentration range used.

A novel poxvirus gene and its human homolog are similar to an E. coli lysophospholipase

A novel poxvirus gene has been characterized within the genome of ectromelia virus. It has significant similarity to a family of lysophospholipases suggesting that it may function in the degradation of lysophospholipids. Since these molecules are active in the stimulation of inflammation, we hypothesize that this gene may play a role in virus virulence. This gene is expressed early in the ectromelia virus replication cycle, before DNA replication. We have also characterized a human cDNA that encodes a protein which is 49.5% identical to the ectromelia virus protein. By its presence in multiple cDNA libraries, this human gene is known to be expressed in a variety of body tissues and is likely to function in the normal regulation of lysophospholipid levels. This family of proteins have conserved blocks of amino acids that are indicative of a serine-aspartic acid-histidine catalytic triad, similar to those used by true lipases and a number of esterases.

[Immunohistochemical study of type IV collagen chain distribution within basement membrane in patients with Alport syndrome]

To observe the distribution of type IV collagen chains within basement membrane in patients with Alport syndrome (AS), discuss the pathogenesis of AS and assess the diagnostic value of indirect immunofluorescent study of type IV collagen chains. By using indirect immunofluorescence technique, the distribution of different chains of type IV collagen in specimen of renal (6 specimens) and skin (5 specimens) basement membrane of 8 AS patients belonging to 7 kindreds were investigated. In 4 male patients with X-linked dominant (XD) AS, the specific monoclonal antibodies against NC1 domains of the alpha 3, alpha 4 and alpha 5 chains of type IV collagen failed to localize on glomerular basement membrane (GBM) and the alpha 5 chain of type IV collagen were also absent in the epidermal basement membrane (EBM). The results of immunofluorescent study were positive in 3 autosomal dominant and 1 autosomal recessive AS patients as same as that in control. AS presents a biochemical abnormality of type IV collagen. The pathogenesis of XD-AS may associate with the abnormal products of alpha 5 chain. The immunofluorescent study of type IV collagen chains distribution within GBM and EBM by using monoclonal antibodies is useful in confirming the diagnosis of AS, especially XD-AS.

Mutation of arginine 134 to lysine alters the pK(a)s of key groups involved in proton pumping by bacteriorhodopsin

Arginine 134 is located near the extracellular surface of bacteriorhodopsin (bR) and may interact with one or more nearby glutamate residues. In the bR mutant R134K, light-induced Schiff-base deprotonation (formation of the M intermediate) exhibits several kinetic components and has a complex pH dependence. The kinetics and pH dependence of M formation were analyzed using the following general guidelines for interpreting M formation: (1) The fastest component of M formation reflects the redistribution of the Schiff-base proton to D85, the usual proton acceptor, in response to the change in the proton affinities of the Schiff base and D85 early in the photocycle; (2) Two additional components of M formation reflect transitions between spectroscopically similar substates of M. By applying these guidelines, supplemented by information about the pK(a)s of D85 and the proton release group from acid (purple-to-blue) and alkaline titrations of the absorption spectra of the unphotolyzed R134K pigment, we explain the pH dependence of M formation as being due to titration of the counterion, D85, and of the proton release group. We calculate, in R134K, that the pKa of D85 is 4.6 in the unphotolyzed state, while the pKa of the proton release group is 8.0 in the unphotolyzed state but drops to approximately 5.8 in the M intermediate. The same value for the pKa of the proton release group in the M intermediate is obtained when we use photocurrent measurements to monitor proton release. The altered values of these pK(a)s relative to the corresponding values in wild-type bR suggest that D85 and the proton release group are coupled more weakly in R134K than in the wild type.

[Evaluating methods and effects of repairing injured lingual nerves on human]

We evaluated the regenerations of sense and taste on the anterior 2/3 of the tongue following repairing injured lingual nerve. Injured lingual nerves in 14 patients were repaired with anastomosis of the nerve epineurium. On the anterior 2/3 of the ipsilateral tongue, most of the fungiform papillae atrophied and disappeared, the sense and taste degenerated after severe injury to lingual nerve. Following repair of the injured lingual nerve with anastomosis of nerve epineurium, the papillae and their taste pores can regenerated, 50% of the patients recovered their tongue sense and 35.71% of the patients recovered their tongue taste 1 year after the repair. It is objective, accurate and reliable to evaluate the regenerations of sense and taste on the anterior 2/3 of the tongue after repair of injured lingual nerve by sensory test, taste evaluation, quantitative observation of fungiform papillae, and their taste pores.

p27Kip1 induces an accumulation of the repressor complexes of E2F and inhibits expression of the E2F-regulated genes

p27Kip1 is an inhibitor of the cyclin-dependent kinases and it plays an inhibitory role in the progression of cell cycle through G1 phase. To investigate the mechanism of cell cycle inhibition by p27Kip1, we constructed a cell line that inducibly expresses p27Kip1 upon addition of isopropyl-1-thio-beta-D-galactopyranoside in the culture medium. Isopropyl-1-thio-beta-D-galactopyranoside-induced expression of p27Kip1 in these cells causes a specific reduction in the expression of the E2F-regulated genes such as cyclin E, cyclin A, and dihydrofolate reductase. The reduction in the expression of these genes correlates with the p27Kip1-induced accumulation of the repressor complexes of the E2F family of factors (E2Fs). Our previous studies indicated that p21WAF1 could disrupt the interaction between cyclin/cyclin-dependent kinase 2 (cdk2) and the E2F repressor complexes E2F-p130 and E2F-p107. We show that p27Kip1, like p21WAF1, disrupts cyclin/cdk2-containing complexes of E2F-p130 leading to the accumulation of the E2F-p130 complexes, which is found in growth-arrested cells. In transient transfection assays, expression of p27Kip1 specifically inhibits transcription of a promoter containing E2F-binding sites. Mutants of p27Kip1 harboring changes in the cyclin- and cdk2-binding motifs are deficient in inhibiting transcription from the E2F sites containing reporter gene. Moreover, these mutants of p27Kip1 are also impaired in disrupting the interaction between cyclin/cdk2 and the repressor complexes of E2Fs. Taken together, these observations suggest that p27Kip1 reduces expression of the E2F-regulated genes by generating repressor complexes of E2Fs. Furthermore, the results also demonstrate that p27Kip1 inhibits expression of cyclin A and cyclin E, which are critical for progression through the G1-S phases.