Formation of lipofuscin-like autofluorescent materials in NG108-15 cells: involvement of lysosomal protein degradation

We found that neuroblastoma x glioma hybrid NG108-15 cells accumulated lipofuscin-like autofluorescent materials during neuronal differentiation in culture in a medium containing 1% fetal calf serum, 1 mM dibutyryl cyclic AMP and 1 mM theophylline. The emission maximum of the lipofuscin-like autofluorescent materials was between 500 and 550 nm. Granules positive to acid phosphatase and periodic-acid Schiff were increased, as were the autofluorescent granules in NG108-15 cells. Thiolprotease inhibitors, N-(L-3-trans-carboxyoxirane-2-carbonyl)-L-leucine-4-aminobutyla mide (E-64) and acetyl-Leu-Leu-Arg (leupeptin), markedly accelerated the accumulation of the lipofuscin-like autofluorescent materials in NG108-15 cells. On the other hand, activities of lysosomal thiolproteases, cathepsin B, C and L, were increased during neuronal differentiation. Protein content in the cells was gradually increased with the neuronal differentiation, and the rise was significantly accelerated when proteolysis was inhibited by E-64. These results suggest that the lipofuscin-like autofluorescent materials contain peptidic substances as a component, and indicate that the increase in hydrolytic activities of thiolproteases during neuronal differentiation is not enough for the hydrolysis of peptidic substrates, resulting in the accumulation of autofluorescent materials in NG108-15 cells.

Peptide mimic of phosphorylcholine, a dominant epitope found on Streptococcus pneumoniae

Even in the age of antibiotics, Streptococcus pneumoniae causes significant morbidity, especially in the young, the elderly, and the immunocompromised. While a carbohydrate-based vaccine exists, it is poorly immunogenic in the at-risk populations. In mice, antibodies directed against phosphorylcholine (PC), an epitope present on the cell wall C polysaccharide of all pneumococcal serotypes, protect against infection. However, PC itself is a poor vaccine candidate. We report here peptide mimics of PC based on the anti-idiotypic interaction of T15 anti-PC antibodies. T15 antibodies, the dominant and protective idiotype induced in mice by PC immunization, self-associate via a 24-amino-acid region in the PC binding site (ASRNKANDYTTEYSASVKGRFIVS; peptide 1). Peptide 1 has been shown to bind in the PC binding site. We demonstrated that amino acid sequences derived from peptide 1 starting at amino acid 9, 11, or 13 inhibit PC binding. Therefore, we immunized mice with bovine serum albumin (BSA) conjugates of peptide 1 or either of two selected 12-mers. The 12-mer peptides were not immunogenic. Mice immunized with peptide 1-BSA developed an anti-PC response consisting mainly immunoglobulin G1 and expressed the T15 heavy chain. Nonetheless, neither BALB/c nor CBA/N mice were protected from lethal pneumococcal infections by immunization with peptide 1-BSA. Preliminary data suggest that peptide 1-BSA is not able to elicit the canonical T15 light chain, explaining the absence of protection. This idiotype-derived mimotope of PC is a useful tool for understanding immunologic cross-reactivity and learning to design T-cell-dependent vaccines for S. pneumoniae.

Hypotonic swelling increases L-type calcium current in smooth muscle cells of the human stomach

The purpose of the present study was to characterize the Ca2+ channels in smooth muscle cells from human stomach and to examine the effects of osmotic swelling on the channel activity. Ca2+ channel current with either Ca2+ or Ba2+ as charge carrier was recorded from freshly isolated smooth muscle cells using the conventional whole-cell patch clamp technique. The degree of cell swelling as a result of hypotonic challenge was monitored using a video image analysis system. The changes in intracellular Ca2+ concentration ([Ca2+]i) were measured by microfluorimetry. The pharmacological and voltage activation profile suggests a typical dihydropyridine-sensitive L-type Ca2+ current. Cell swelling, induced by hypotonic challenge, enhanced the amplitude of currents through L-type Ca2+ channels without significant effects on steady-state voltage dependency. After treatment with the L-type Ca2+ channel agonist Bay K 8644 (0.1-2 microM), no further significant increase in calcium channel current or corresponding [Ca2+]i transients were provoked by the swelling. The above results demonstrated that the presence of L-type Ca2+ current in smooth muscle cells of the human stomach and the augmentation of the current are closely associated with the volume increase resulting from hypotonic swelling.

A latex bead-based flow cytometric immunoassay capable of simultaneous typing of multiple pneumococcal serotypes (Multibead assay)

A simple and rapid method of simultaneously determining 15 Streptococcus pneumoniae serotypes was developed. Fifteen latex beads of different sizes and different red fluorescence levels were coated with 1 of 15 serotypes (1, 3, 4, 5, 6A, 6B, 7F, 9N, 9V, 14, 18C, 19A, 19F, 22F, and 23F) of pneumococcal capsular polysaccharide (PS). The bead mixture was incubated with individual pneumococcal lysate, a pool of rabbit antisera capable of binding the 15 serotypes, and fluorescein (green fluorescence)-conjugated anti-rabbit antibody. Bead size, red fluorescence, and green fluorescence were measured in a single flow cytometer run. The green fluorescence of the beads was inhibited only when there was a serotypic match between PS on the bead and PS in the pneumococcal lysate. This method distinguished cross-reactive serotypes and correctly identified the serotypes in 100% of 86 pneumococcal isolates tested.

Muscarinic receptors controlling the carbachol-activated nonselective cationic current in guinea pig gastric smooth muscle cells

Muscarinic receptor subtypes controlling the nonselective cationic current in response to carbachol (ICCh) were studied in circular smooth muscle cells of the guinea pig gastric antrum using putative muscarinic agonists and antagonists. Both oxotremorine-M (an M2-selective agonist) and CCh dose-dependently activated the cationic current with EC50 values of 0.21 +/- 0.01 microm and 0.97 +/- 0.06 microM, respectively. In contrast, pilocarpine and McN-A 343 (an M1-selective and a putative M4 agonist) were weak partial agonists. In response to 10/microM CCh, 4-DAMP, methoctramine and pirenzepine dose-dependently inhibited ICCh and had IC50 values of 1.91 +/- 0.2 nM, 0.46 +/- 0.07 microM and 8.33 +/- 0.4 microM, respectively. 4-DAMP, methoctramine and pirenzepine shifted the concentration-response curves of ICCh to the right without significantly reducing the maximal current. Values of the apparent dissociation constant pA2 obtained from Schild plot analysis were 9.24, 7.72 and 6.62 for 4-DAMP, methoctramine and pirenzepine, respectively. Also, pertussis toxin completely blocked ICCh generation. These results suggest that the M2-subtype plays a crucial role in the activation of the ICCh, and a block of the M3-subtype reduces the sensitivity of the M2-mediated response with no significant reduction of maximum response.

The relationship between acetylcholine-evoked Ca(2+)-dependent current and the Ca2+ concentrations in the cytosol and the lumen of the endoplasmic reticulum in pancreatic acinar cells

In a study of isolated mouse pancreatic acinar cells, we used the patch-clamp whole-cell recording configuration to monitor the Ca(2+)-dependent inward ionic current and simultaneously measured the Ca2+ concentration in either the cytosol ([Ca2+]i) or the lumen of the endoplasmic reticulum ([Ca2+]Lu), using appropriate Ca(2+)-sensitive fluorescent probes. A high concentration of acetylcholine (ACh, 10 microM) evoked an increase in [Ca2+]i, which resulted in the activation of Ca(2+)-dependent inward current. Continued ACh application for several minutes led to a marked reduction in both the current and the [Ca2+]i response and after about 4-10 min of sustained ACh stimulation, the inward current response had disappeared and [Ca2+]i was back to the pre-stimulation level. Repeated stimulation with shorter pulses of ACh (10 microM) resulted in responses of declining magnitude both in terms of inward current and [Ca2+]i rises. The ACh-activated inward current was entirely dependent on the elevation of [Ca2+]i, but at a relatively high [Ca2+]i the current was saturated. ACh caused a rapid release of Ca2+ from the lumen of the endoplasmic reticulum and after discontinuation of stimulation, [Ca2+]Lu was only very slowly (10-15 min) fully restored to the pre-stimulation level. Repeated applications of ACh did not change the relationships between the Ca(2+)-dependent current and [Ca2+]i or the current and [Ca2+]Lu. When [Ca2+]Lu was greater than 100 microM, the ACh-evoked Ca2+ release from the store was so large that the current response was initially saturated. We conclude that the ACh-evoked current response essentially depends on the release of stored Ca2+. Desensitization is mainly due to the relatively slow reloading of the intracellular stores with Ca2+.

Determination of betaine in Lycium chinense fruits by liquid chromatography-electrospray ionization mass spectrometry

A rapid and sensitive high-performance liquid chromatography-electrospray mass spectrometric method has been developed for the determination of betaine in Lycium chinense fruits. Betaine was analyzed on a system consisting of a NH2 stationary phase and a mobile phase of water-acetonitrile (25:75) by isocratic elution for 40 min. Betaine was identified and quantitated by electrospray ionization mass spectrometry with selected ion monitoring of the protonated ion [Betaine+H]+ and clustered ions [nBetaines+H]+. The limit of detection for betaine by this method was ca. 0.2 ng/ml and the relative standard deviations of the assay (intra- and inter-day) were less than 8.1%.

The San Antonio Biethnic Children's Blood Pressure Study: auscultatory findings

INTRODUCTION

The purpose of this study were to: (a) examine for possible ethnicity-related and gender-related differences in blood pressure (BP) in Mexican American and non-Hispanic White schoolchildren; (b) compare auscultatory and oscillometric BP levels; and (c) establish auscultatory BP standards using the width of the BP cuff based on the circumference of the arm in schoolchildren in K-12.

METHODS

Participants were 6259 schoolchildren in kindergarten through 12th grade in the San Antonio, Texas, area. Auscultatory and oscillometric BP readings were obtained in random sequence, using BP cuff width 40% to 50% of the circumference of the upper arm. Averages of 3 readings were used for statistical analyses.

RESULTS

Auscultatory systolic pressures (SPs) in preadolescent Mexican American boys and girls were higher (1 to 3 mm Hg) auscultatory (SP) than in their White counterparts, but the difference was clinically not important. Diastolic pressures (DP) showed no important differences. Auscultatory SPs in 13- to 18-year-old boys of both ethnic groups were significantly (P < .05) higher (3 to 12 mm Hg) than they were for girls, with no ethnic differences. Oscillometric SP was higher than auscultatory SP in children of all ages studied. Oscillometric (DP) was slightly lower (0 to 5 mm Hg) than was auscultatory K4 and higher (4 to 5 mm Hg) than was auscultatory K5 DP.

DISCUSSION

No important ethnicity-related difference was found for auscultatory BP, but significant gender-related differences (boys greater than girls) were found in SP in subjects ages 13 to 18 years. Differences in BP readings by oscillometric and auscultatory methods do not allow interchange of readings. This study provides, for the first time, auscultatory BP standards using BP cuff width 40% to 50% of the arm circumference.

Overexpressed alpha3beta1 and constitutively activated extracellular signal-regulated kinase modulate the angiogenic properties of ECV304 cells

ECV304, a spontaneously transformed cell line derived from the human umbilical vein endothelial cell (HUVEC) (Takahashi et al., 1990), has been developed as an in vitro angiogenesis model. In the present study, we further characterized the angiogenic properties of this cell line. Compared to HUVEC, ECV304 cells showed distinct features including a higher activity of cellular adhesion, slower but reproducible progression of angiogenesis on Matrigel, and resistance to apoptosis. Thus, the expression of integrin and activation of extracellular-signal regulated kinase 1/2 (Erk1/2), a downstream effector of the integrin pathway, were examined. Flow cytometry revealed that alpha3beta1 integrin was markedly upregulated in ECV304 cells, while alpha(v)beta1 and alpha5beta1 integrins were slightly downregulated. Consistent with this, the binding activity to collagen type IV and laminin, major extracellular matrices of Matrigel, was increased 1.4- and 1.9-fold in ECV304 cells, respectively. This tight binding may retard the initial stage of sprouting and migration in the angiogenesis of ECV304 cells. It has been further demonstrated that Erk1/2 is constitutively active in ECV304 cells, rendering them resistent to the inhibitory effect of PD98059 on proliferation. However, migration of both HUVEC and ECV304 cells was inhibited to a similar extent by PD98059 in a dose-dependent manner. Up to 50 microM of PD98059, no significant changes in cell binding and tubulogenesis on Matrigel was observed in ECV304 cells. In contrast, the tubulogenesis of HUVEC was severely impaired by PD98059. Elevated Erk1/2 activity in ECV304 cells was suppressed by dominant negative H-Ras, but not by cytochalasin D. These results suggest that the overexpression of alpha3beta1 integrin and the constitutive activation of Erk1/2 play a key role in the alteration of the angiogenic properties of ECV304 cells.

H-Ras is a negative regulator of alpha3beta1 integrin expression in ECV304 endothelial cells

We have examined the role of Ras in integrin expression in ECV304 endothelial cells. Among the integrins examined in stable ECV304 transfectants expressing dominant active H-Ras (DAR-ECV), expression of alpha3beta1 integrin showed a prominent reduction in all the DAR-ECV clones when compared to the parental ECV304 cells. This implies that H-Ras negatively regulates the expression of alpha3beta1 integrin in ECV304 cells. When treated with inhibitors of the Ras downstream pathway (LY294002, PD98059, SB203580), the expression of alpha3beta1 integrin was up-regulated most significantly by LY294002, suggesting that among the downstream pathways of Ras, phosphatidylinositol 3-kinase is a major determinant. With the application of blocking antibody to alpha3beta1 integrin (2 - 2 x 10(4) nM), migration of ECV304 cells was enhanced to maximal (18%) at 20 nM. These results suggest that migration of endothelial cells could be modulated by H-Ras via alteration of the expression levels of alpha3beta1 integrin.

Chemokine receptor responses on T cells are achieved through regulation of both receptor expression and signaling

To address the issues of redundancy and specificity of chemokines and their receptors in lymphocyte biology, we investigated the expression of CC chemokine receptors CCR1, CCR2, CCR3, CCR5, CXCR3, and CXCR4 and responses to their ligands on memory and naive, CD4 and CD8 human T cells, both freshly isolated and after short term activation in vitro. Activation through CD3 for 3 days had the most dramatic effects on the expression of CXCR3, which was up-regulated and functional on all T cell populations including naive CD4 cells. In contrast, the effects of short term activation on expression of other chemokine receptors was modest, and expression of CCR2, CCR3, and CCR5 on CD4 cells was restricted to memory subsets. In general, patterns of chemotaxis in the resting cells and calcium responses in the activated cells corresponded to the patterns of receptor expression among T cell subsets. In contrast, the pattern of calcium signaling among subsets of freshly isolated cells did not show a simple correlation with receptor expression, so the propensity to produce a global rise in the intracellular calcium concentration differed among the various receptors within a given T cell subset and for an individual receptor depending on the cell where it was expressed. Our data suggest that individual chemokine receptors and their ligands function on T cells at different stages of T cell activation/differentiation, with CXCR3 of particular importance on newly activated cells, and demonstrate T cell subset-specific and activation state-specific responses to chemokines that are achieved by regulating receptor signaling as well as receptor expression.

Effects of ultrasound on the formation of alpha-benzoylbenzyl cyanide from benzyl cyanide and alkylphenyl ketone from alpha-alkylbenzyl cyanide by potassium superoxide in the presence of crown ether

Ultrasound accelerates the formation of alpha-benzoylbenzyl cyanide and benzoic acid in the reaction of benzyl cyanide with potassium superoxide in the presence of 18-crown-6. Similarly, 4-methylbenzyl cyanide, 4-methoxybenzyl cyanide and 4-chlorobenzyl cyanide gave the corresponding alpha-(4-methylbenzoyl)-4-methylbenzyl cyanide, alpha-(4-methoxybenzoyl)-4-methoxybenzyl cyanide and alpha-(4-chlorobenzoyl)-4-chlorobenzyl cyanide in 25-43% isolated yields under the same reaction conditions. Benzoic, p-toluic, 4-methoxybenzoic and 4-chlorobenzoic acids were also formed in these reactions. No reaction was observed when the mixture was simply stirred. Reflux instead of sonication gave lower yields of the products. However, alpha-alkylbenzyl cyanide produced a high yield of the phenylalkyl ketones when stirred. Interestingly, the corresponding benzoic acid was not formed in these reactions. Possible mechanisms for the formation of alpha-benzoylbenzyl cyanide from benzyl cyanide and phenylalkyl ketones from alpha-alkylbenzyl cyanide are also proposed.

Repertoire of human antibodies against the polysaccharide capsule of Streptococcus pneumoniae serotype 6B

We examined the repertoire of antibodies to Streptococcus pneumoniae 6B capsular polysaccharide induced with the conventional polysaccharide vaccine in adults at the molecular level two ways. In the first, we purified from the sera of seven vaccinees antipneumococcal antibodies and determined their amino acid sequences. Their VH regions are mainly the products of VH3 family genes (candidate genes, 3-23, 3-07, 3-66, and 3-74), but the product of a VH1 family gene (candidate gene, 1-03) is occasionally used. All seven individuals have small amounts of polyclonal kappa+ antibodies (Vkappa1 to Vkappa4 families), although kappa+ antibodies are occasionally dominated by antibodies formed with the product of the A27 Vkappa gene. In contrast, lambda+ anti-6B antibodies are dominated by the antibodies derived from one of 3 very similar Vlambda2 family genes (candidate genes, 2c, 2e, and 2a2) and Clambda1 gene product. The Vlambda2(+) antibodies express the 8.12 idiotype, which is expressed on anti-double-stranded-DNA antibodies. In one case, Vlambda is derived from a rarely expressed Vlambda gene, 10a. In the second approach, we studied a human hybridoma (Dob1) producing anti-6B antibody. Its VH region sequence is closely related to those of the 3-15 VH gene (88% nucleotide homology) and JH4 (92% homology). Its VL region is homologous to the 2a2 Vlambda2 gene (91%) and Jlambda1/Clambda1. Taken together, the V region of human anti-6B antibodies is commonly formed by a VH3 and a Vlambda2 family gene product.

Treatment of hydrocephalus secondary to cryptococcal meningitis by use of shunting

Hydrocephalus can be associated with increased morbidity and mortality in cryptococcal meningitis if left untreated. Both ventriculoperitoneal and ventriculoatrial shunting have been used in persons with cryptococcosis complicated by hydrocephalus, but the indications for and complications, success, and timing of these interventions are not well known. To this end, we reviewed the clinical courses of 10 non-human immunodeficiency virus-infected patients with hydrocephalus secondary to cryptococcal meningitis who underwent shunting procedures. Nine of 10 patients who underwent shunting had noticeable improvement in dementia and gait. Two patients required late revision of their shunts. Shunt placement in eight patients with acute infection did not disseminate cryptococcal infection into the peritoneum or bloodstream, nor did shunting provide a nidus from which Cryptococcus organisms proved difficult to eradicate. Shunting procedures are a safe and effective therapy for hydrocephalus in patients with cryptococcal meningitis and need not be delayed until patients are mycologically cured.

Contribution of Ca2+-activated K+ channels and non-selective cation channels to membrane potential of pulmonary arterial smooth muscle cells of the rabbit

1. Using the perforated patch-clamp or whole-cell clamp technique, we investigated the contribution of Ca2+-activated K+ current (IK(Ca)) and non-selective cation currents (INSC) to the membrane potential in small pulmonary arterial smooth muscle cells of the rabbit. 2. The resting membrane potential (Vm) was -39.2 +/- 0.9 mV (n = 72). It did not stay at a constant level, but hyperpolarized irregularly, showing spontaneous transient hyperpolarizations (STHPs). The mean frequency and amplitude of the STHPs was 5.6 +/- 1. 1 Hz and -7.7 +/- 0.7 mV (n = 12), respectively. In the voltage-clamp mode, spontaneous transient outward currents (STOCs) were recorded with similar frequency and irregularity. 3. Intracellular application of BAPTA or extracellular application of TEA or charybdotoxin suppressed both the STHPs and STOCs. The depletion of intracellular Ca2+ stores by caffeine or ryanodine, and the removal of extracellular Ca2+ also abolished STHPs and STOCs. 4. Replacement of extracellular Na+ with NMDG+ caused hyperpolarization Vm of without affecting STHPs. Removal of extracellular Ca2+ induced a marked depolarization of Vm along with the disappearance of STHPs. 5. The ionic nature of the background inward current was identified. The permeability ratio of K+ : Cs+ : Na+ : Li+ was 1.7 : 1.3 : 1 : 0. 9, indicating that it is a non-selective cation current (INSC). The reversal potential of this current in control conditions was calculated to be -13.9 mV. The current was blocked by millimolar concentrations of extracellular Ca2+ and Mg2+. 6. From these results, it was concluded that (i) hyperpolarizing currents are mainly contributed by Ca2+-activated K+ (KCa) channels, and thus STOCs result in transient membrane hyperpolarization, and (ii) depolarizing currents are carried through NSC channels.

Different contractile properties between intralobar and extralobar pulmonary arteries of the rabbit

In pulmonary circulation, small muscular resistance arteries are known to have different receptor properties and sensitivity to neurotransmitters from those of large elastic conduit arteries. It is, however, not yet certain whether the different properties are primarily due to the diameter or the location of arteries. In the present study, we compared the contractile responses to various agonists among large extralobar (ELPA, diameter: 2-3 mm), large intralobar (ILPA, diameter: 2-3 mm), and small intralobar pulmonary arteries (SPA, diameter: 300-500 microm) of the rabbit. There were no differences in normalized dose-response curves to KCl among three groups. Half maximum doses (EC50 in mM) were 38.0+/-2.0 (n=8, mean+/-SEM) in ELPA, 36.9+/-2.4 (n=10) in ILPA, and 39.0+/-0.9 (n=12) in SPA. Responses to phenylephrine, epinephrine, histamine, serotonin, and PGF2alpha were normalized and expressed as a relative contraction against maximum tension to KCl. In ELPA, the contractile responses to various agents showed the following sequence: KCl>epinephrine>phenylephrine>serotonin>PGF2alpha>histamine. In ILPA and SPA, the sequence was: KCl>histamine>PGF2alpha>serotonin. There was little response to phenylephrine and epinephrine in ILPA and SPA. These results demonstrate that the difference of contractile responses between ELPA and ILPA was more prominent than that between ILPA and SPA, suggesting that the location is more important than the diameter itself in determining the characteristic contractile responses of pulmonary arteries.

The San Antonio Biethnic Children's Blood Pressure Study: anthropometric findings

Cardiovascular diseases and diabetes are very prevalent today, and early detection of the precursors of these diseases is important. Increased weight and body mass indexes (BMIs) are known to be risk factors for these adult diseases. The objectives of this portion of the study were to obtain anthropometric measurements known to correlate with children's blood pressure levels and to compare these measurements among Mexican-American (M-A) females and males and non-Hispanic white (W) females and males. These data will allow healthcare providers to know normal weights and BMIs for different ethnic groups so that early detection of risk factors can be done. Anthropometric measurements (weight, height, BMI, subscapular and triceps skinfold thickness, and arm circumference) were obtained on 4,195 M-A and 2,039 W children in kindergarten through 12th grade in two school districts in the San Antonio, Texas, area. Data were statistically analyzed and related to age. M-A males had a tendency to be heavier than W males throughout the ages studied. M-A females had a tendency to be heavier than W females until 11 years of age, but that trend was reversed between ages 14 and 18. For all four subgroups, there was a marked skewness toward obesity based on BMI (kg/m2). Height of M-A children beginning as early as 5 years of age was slightly but significantly (P > or = .05) less than that of W children of the same gender. M-A males and females had either a tendency for or significantly higher values (P > or = .05) for BMI than W counterparts. M-A children had larger subscapular and triceps skinfold thickness than their W counterparts, with females showing greater values than males. The data indicate that there are several important differences in weight, height, BMI, and skinfold thickness between M-A and W children and between boys and girls as noted above. There are also considerable increases in weight with a relatively stable height in all four subgroups since the last published growth charts.

In vitro platelet-activating factor receptor binding inhibitory activity of pinusolide derivatives: a structure-activity study

Pinusolide, a labdane-type diterpene lactone isolated from Biota orientalis, was found to be a potent platelet-activating factor (PAF) receptor binding antagonist. To investigate the structure-activity relationship and find derivatives with improved pharmacological profiles, 17 pinusolide derivatives were prepared and tested for their ability to inhibit the PAF receptor binding. The results demonstrated that the carboxymethyl ester group at C-19, the integrity of the alpha,beta-unsaturated butenolide ring, and the exocyclic olefinic function of pinusolide are all necessary for its maximum PAF receptor binding inhibitory activity. Among the derivatives, the 17-nor-8-oxo derivative 8 was found to be as potent as pinusolide. The results also suggested that several derivatives warrant further pharmaceutical and pharmacological studies due to their improved water solubility (8 and 11) and apparent lack of susceptibility to Michael-type nucleophilic addition (13 and 18).

Modulation of voltage-dependent K+ channel by redox potential in pulmonary and ear arterial smooth muscle cells of the rabbit

It has been suggested that hypoxic pulmonary vasoconstriction (HPV) results from the depolarization that is induced by the suppression of K+ current in pulmonary arterial smooth muscle cells (PASMC). We tested the hypothesis that the effect of the cellular redox potential on voltage-sensitive K+ (Kv) current is involved in HPV as a primary sensing mechanism. Kv current in PASMC and ear arterial smooth muscle cells (EASMC) of the rabbit was recorded using the whole-cell patch-clamp technique, and the effect of redox agents [dithiothreitol, DTT and 2,2'-dithio-bis(5-nitropyridine), DTBNP] was tested. Kv current was decreased by DTT, but increased by DTBNP. DTT accelerated the inactivation kinetics, but did not affect steady-state activation and inactivation, whereas DTBNP accelerated activation kinetics. Kv current has a non-inactivating window in the range of from -40 mV to +10 mV. The resting membrane potential measured using the nystatin-perforated-patch method, however, lay between -50 mV and -30 mV and was not depolarized by 5 mM 4-aminopyridine. The membrane-impermeable oxidizing agent DTNB has no effect on Kv current, suggesting that redox modulation sites are intracellular sulphydryl groups. In EASMC, Kv current was decreased by DTT, but increased by DTBNP, indicating that the redox-potential-induced modulation of Kv current in EASMC and in PASMC is the same. It is therefore concluded that Kv current is modulated by the cellular redox potential, but that this modulation is not involved in HPV as a primary sensing mechanism.

Reduced dihydroxyacetone sensitivity and normal sensitivity to glyceraldehyde and oxidizing agent of ATP-sensitive K+ channels of pancreatic beta cells in NIDDM rats

The inhibition of ATP-sensitive K+(KATP) channels in pancreatic beta cells is a key step of insulin secretion induced by glucose. Glucose-induced insulin secretion from the beta cells is selectively impaired in patients with noninsulin-dependent diabetes mellitus (NIDDM) and in animal models of it. In order to clarify the site of this abnormal glucose response, we studied the effects of insulin secretagogues and sulfhydryl oxidizing agent, 2,2'-dithio-bis (5-nitropyridine) (DTBNP), on KATP channels in single beta cells of neonatally streptozotocin-induced NIDDM rats. We used the patch-clamp technique in cell-attached mode (Vpipette = 0 mV). The inhibitory response to glucose of KATP channels was lacking in NIDDM rats, indicating reduced sensitivity to glucose of the channels. Glyceraldehyde (2-5 mM) in the diabetic beta cells elicited the same KATP channel inhibition as that obtained in controls. In contrast, dihydroxyacetone (DHA, 2-10 mM) sensitivity of KATP channels was significantly reduced in the beta cells of NIDDM rats. KATP channels in the diabetic beta cells were rapidly inhibited by 50 microM DTBNP, just as in the normal beta cells, suggesting that KATP channel function was normal. This indicates that one of the sites responsible for impaired glucose-induced insulin secretion in the pancreatic beta cells of NIDDM rats is located in the glycerol phosphate shuttle.

Changes in P2Y1 nucleotide receptor activity during the development of rat salivary glands

Experiments that used dispersed salivary gland cells from 1-day-old rats indicated the presence of the P2Y nucleotide receptor subtype, P2Y1, based on the agonist potency profile for mobilization of intracellular free Ca2+ [2-methylthio-ATP > ADP > adenosine 5'-O-(2-thiodiphosphate) > ATP, with UTP ineffective] and sequence analysis of reverse transcription-polymerase chain reaction (RT-PCR) products obtained with P2Y1 receptor-specific primers. P2Y1 receptor activity appears to be developmentally regulated, since Ca2+ mobilization in response to the P2Y1-selective agonist, 2-methylthio-ATP, decreased as animal age increased, with the maximal response of 129 +/- 23 nM obtained in 1-day-old animals, decreasing to 30 +/- 3 nM in 4-wk-old animals. However, the abundance of P2Y1 receptor mRNA, assessed by semiquantitative RT-PCR, did not change over this time period, suggesting that receptor activity is regulated by some mechanism other than changes in steady-state levels of P2Y1 receptor mRNA. These findings indicate that functional P2Y1 nucleotide receptors are expressed in immature salivary glands and that receptor activity decreases as the glands mature, suggesting that P2Y1 receptors may have an important role during salivary gland development.

Ultrasound promoted N-alkylation of pyrrole using potassium superoxide as base in crown ether

Ultrasound accelerates the N-alkylation of pyrrole by alkylating reagents using potassium superoxide as base in the presence of 18-crown-6. A much lower yield of N-alkylated pyrrole was realized in the absence of ultrasound. N-alkylating reagents employed for pyrrole are methyl iodide, ethyl bromide, benzyl bromide, as well as acrylonitrile allyl cyanide and methyl acrylate. In an extension of this work, we have found that ultrasound was not necessary for the N-alkylation of indole and alkyl amine, such as diphenyl amine and piperidine with alkyl halides using our reagents. In all cases we observed that the 18-crown-6 catalyzed N-alkylation reaction gives higher yields of N-alkylated products than that without crown ether, when potassium superoxide was used as base. These observations are probably due to the potassium-crown complex which can be released when the reaction goes to completion.

Induction of oh8Gua glycosylase in rat kidneys by potassium bromate (KBrO3), a renal oxidative carcinogen

It has been suggested that 8-hydroxyguanine (oh8Gua), a DNA adduct formed by active oxygens, impairs the maintenance of genetic integrity, oh8Gua glycosylase removes oh8Gua residues as a free base from DNA strands. In E. coli, it has been demonstrated that oh8Gua glycosylase is induced in response to oxidative stress, but the oxidative inducibility in mammalian tissues has not yet been studied. In the present study, the inducibility of oh8Gua glycosylase was tested by comparing activity changes of this enzyme in the kidney and the liver of rats treated with potassium bromate (KBrO3). KBrO3 is known to cause oxidative damage to the kidney but not to other organs. With a single dose of KBrO3 (80 mg/kg, i.p.), activity in the kidney was found to increase significantly at 3 h compared to that at zero time. At 6 h, activity peaked, showing a 6-fold increase over that at zero time. Thereafter, it decreased and returned to its zero time level at 12 h. With increasing doses of KBrO3 (up to 160 mg/kg, i.p.), activity increased linearly with increased dosage, and over 40 mg/kg, i.p., activity increased to a level significantly higher than that in the control. In contrast to the time- and dose-dependent changes in activity in the kidney, no significant change was observed in the liver under the same conditions as above. These results show that oh8Gua glycosylase is also induced oxidatively in mammalian tissues. The induction in this tissue as well as in E. coli indicates that the adaptive response of this enzyme to oxidative stress is a general phenomenon in aerobic organisms and implies that the repair of oh8Gua residues in DNA is a process important for the survival of organisms in an aerobic environment.

Highly heterologous region in the N-terminal extracellular domain of reptilian follitropin receptors

The primary structure of the N-terminal extracellular region of the follitropin receptor (FSH-R), which is thought to be responsible for hormone binding specificity, was determined in three reptilian species (tortoise, gecko, and lizard). Remarkably low sequence homologies were detected in the C-terminal part of the extracellular domain. This region was estimated to be a part of exon 10, which is the last exon of the FSH-R gene. In this region, not only were low homologies detected among the three reptilian species, but also specific deletions and/or insertions were found. In particular, large deletions were detected in squamate (gecko and lizard) FSH-Rs. Phylogenetic analysis indicated that these large deletions occurred recently, i.e., after the Triassic period. In another region characterized, sequence homologies were high, with tortoise-rat homology 78.4%, gecko-rat 64.7%, and lizard-rat 69.1%. In this highly conserved region, however, some reptile-specific alterations were detected, such as the loss of a cysteine residue in putative exon 7 and the existence of potential N-linked glycosylation sites in putative exon 9.