Induced nitric oxide synthesis is dependent on induced alternatively spliced CAT-2 encoding L-arginine transport in brain astrocytes

The inducible isoform II of nitric-oxide synthase (iNOS) was recently cloned from brain and identified in astroglial cells. Induced nitric oxide biosynthesis occurs in brain cells only if extracellular cerebrospinal fluid contains -arginine. This study demonstrates for the first time that induced iNOS activity is strictly dependent on concomitant induction of an alternatively spliced transcript of the cat-2 gene encoding high affinity -arginine transporter System y+ in cultured rat astrocytes. Inhibition profiles of radiolabeled -arginine and -leucine uptake identified the dominance of Na+-independent transport System y+ serving cationic amino acids, with insignificant activities of Systems y+L, bo,+, or Bo,+. A reverse transcription-polymerase chain reaction/sequencing/cloning strategy was used to identify a single 123-base nucleotide sequence coding the high affinity domain of alternatively spliced CAT-2 (not CAT-2a) in astrocytes activated by lipopolysaccharide/interferon-gamma. Using this sequence as a cDNA probe, it was determined that CAT-2 mRNA, iNOS mRNA, and System y+ activity were concomitantly and strongly induced in astrocytes. Constitutive CAT-1 mRNA was weakly present in neurons and astrocytes, was not inducible in either cell type, and contributed <3% to total System y+ activity. Although astroglial iNOS Km approximately 10 microM L-arginine for intracellular substrate, hyperbolic kinetics of inducible iNOS activity measured as a function of extracellular L-arginine concentration gave Km approximately 50 microM L-arginine with intact cells. The same Km approximately 50 microM was obtained for induced membrane transport System y+ activity. iNOS activity was reduced to zero in the absence of extracellular L-arginine uptake via System y+. These findings expand the current understanding of NO biosynthesis modulation and implicate a coordinated regulation of intracellular iNOS enzyme activity with membrane L-arginine transport in brain.

Degradation of chylomicron remnants by macrophages occurs via phagocytosis

Chylomicron remnants bound to rabbit alveolar macrophages with high-affinity (Kd = 3.3 +/- 0.71 microgram of protein/mL). The binding of chylomicron remnants was competitively inhibited in the presence of unlabeled remnants and to a lesser extent by unlabeled low-density lipoproteins. Pretreatment of cells with either trypsin or pronase inhibited degradation in a dose and time dependent manner, suggesting involvement of a cell surface protein. Chylomicron remnants were degraded by alveolar macrophages from Watanabe heritable hyperlipidemic (WHHL) rabbits, which are devoid of LDL receptor activity. Moreover, colchicine and monensin which are endocytotic and lysozomal inhibitors, respectively, did not have any effect on the degradation of chylomicron remnants by macrophages from normal rabbits. The absence of divalent cations was found to enhance chylomicron remnant degradation by macrophages. Activated alpha 2-macroglobulin and lactoferrin had no effect on chylomicron remnant degradation, indicating that the low-density lipoprotein receptor-related protein was not involved. In addition, the scavenger receptor inhibitors polyinosinic acid and fucoidan increased degradation of chylomicron remnant-ruling out uptake as a consequence of lipoprotein modification. Rather, the phagocytotic inhibitor cytochalasan D was found to significantly decrease chylomicron remnant degradation. Collectively, our data show that chylomicron remnants are metabolized by phagocytotic pathways initiated after binding to a cell surface protein which is distinct from the LDL receptor, LRP, or scavenger receptors.

Angiotensin II regulation of tyrosine hydroxylase gene expression in the neuronal cultures of normotensive and spontaneously hypertensive rats

In the present study we investigated the regulation of tyrosine hydroxylase (TH) by angiotensin II (Ang II) in an attempt to provide cellular and molecular evidence that this hormone has increased neuromodulatory actions in the spontaneously hypertensive (SH) rat brain. Neuronal cells in primary culture from the hypothalamus-brain stem of both normotensive [Wistar-Kyoto (WKY)] and SH rats have been used. These cultures mimic in vivo situations. Ang II caused a time-dependent increase in TH activity in WKY rat brain neurons. A maximal increase of 2.5-fold was observed with 100 nM Ang II in an actinomycin- and cycloheximide-dependent process. In addition, Ang II caused a parallel increase in TH messenger RNA (mRNA) levels, with a maximal stimulation of 5-fold in 4 h by 100 nM Ang II in WKY rat brain neurons. The stimulation of TH mRNA was mediated by the AT1 receptor subtype, resulted from an increase in its transcription, and involved activation of phospholipase C and protein kinase C. Antisense oligonucleotide for c-fos attenuated Ang II stimulation of TH mRNA in a time- and dose-dependent fashion, indicating an involvement of c-fos as a putative third messenger in Ang II stimulation of TH. Ang II also caused stimulation of TH activity and its mRNA levels in neuronal cultures of SH rat brain by a mechanism similar to that observed for neuronal cultures of WKY rat brain, involving AT1 receptors, protein kinase C, and c-fos. However, the stimulation of TH activity and that of TH mRNA were approximately 30% and 80% higher, respectively, in the SH rat brain neurons than those in the WKY rat brain neurons. In vivo experiments have been carried out to validate the elevated response of TH gene expression to Ang II in SH rat brain neuronal cultures. Ang II stimulated both TH activity and TH mRNA levels in the hypothalami and brain stems of adult WKY and SH rats. The level of stimulation in the brain of the SH rat was significantly higher than that in the WKY rat. These observations are consistent with an increase in AT1, receptor gene expression and suggest that increased TH gene expression could be the cellular/molecular basis for the greater neuromodulatory action of Ang II in the SH rat brain.

Regulation of neuromodulatory actions of angiotensin II in the brain neurons by the Ras-dependent mitogen-activated protein kinase pathway

Angiotensin II (Ang II) stimulates norepinephrine transporter (NET) and tyrosine hydroxylase (TH) in the neurons, but the signal transduction mechanism of this neuromodulation is not understood. Treatment of neuronal cultures of hypothalamus-brainstem with Ang II resulted in a time- and dose-dependent activation of Ras, Raf-1, and mitogen-activated protein kinase. This activation was mediated by the interaction of Ang II with the AT1, receptor subtype and was associated with the redistribution of AT1 receptor with Ras and Raf-1 on the neuronal membrane. Treatment with antisense oligonucleotide (AON) to mitogen-activated protein kinase decreased mitogen-activated protein kinase immunoreactivity by 70% and attenuated Ang II stimulation of c-fos, NET, and TH mRNA levels. This demonstrates that induction of these genes requires mitogen-activated protein kinase activation by Ang II. In contrast, AON to mitogen-activated protein kinase failed to inhibit Ang II stimulation of plasminogen activator inhibitor-1 mRNA levels. These results suggest that AT1 receptors are coupled to a Ras-Raf-1 mitogen-activated protein kinase signal transduction pathway that is responsible for stimulation of NET and TH, two neuro-modulatory actions of Ang II in the brain.

Ion-Induced Morphological Changes in "Crew-Cut" Aggregates of Amphiphilic Block Copolymers

The addition of ions in micromolar (CaCl2 or HCl) or millimolar (NaCl) concentrations can change the morphology of "crew-cut" aggregates of amphiphilic block copolymers in dilute solutions. In addition to spherical, rodlike, and univesicular or lamellar aggregates, an unusual large compound vesicle morphology can be obtained from a single block copolymer. Some features of the spontaneously formed large compound vesicles may make them especially useful as vehicles for delivering drugs and as models of biological cells. Gelation of a dilute spherical micelle solution can also be induced by ions as the result of the formation of a cross-linked "pearl necklace" morphology.

Angiotensin II regulation of plasminogen activator inhibitor-1 gene expression in neurons of normotensive and spontaneously hypertensive rat brains

Neuronal cells in primary culture from the hypothalamus-brain stem areas of normotensive [Wistar-Kyoto (WKY)] and spontaneously hypertensive (SH) rat brains have been used in the present study to investigate an interaction between the brain renin-angiotensin II system and the plasminogen activator system. This is an attempt to further our understanding of the role of brain Ang II in the control of neuronal development and differentiation through its regulation of the extracellular matrix. Ang II caused a 10-fold stimulation of plasminogen activator inhibitor-1 (PAI-1) messenger RNA (mRNA) in WKY rat brain neuronal cultures. The stimulation was mediated by the AT1 receptor subtype and was accompanied by an increase in PAI-1 gene transcription and the synthesis of cellular PAI-1 protein. The stimulation involved activation of protein kinase C, and alterations in the intracellular Ca2+ pool caused a significant inhibition of Ang II stimulation of PAI mRNA. Ang II stimulation of PAI-1 mRNA succeeded its action on c-fos mRNA and was attenuated by c-fos antisense oligonucleotide. Although PAI-1 gene expression was also stimulated by Ang II in neuronal cultures of SH rat brain, two differences between WKY and SH rat brain neurons were observed: 1) the level of Ang II stimulation in SH rat neurons was 50% of that in WKY rat neurons; and 2) Ang II stimulation of c-fos was 2.4-fold higher in SH neurons than in WKY neurons, but c-fos antisense oligonucleotide did not attenuate the stimulatory action of Ang II on PAI-1 mRNA in SH neurons. These observations suggest that the changes in the Ang II-mediated signaling pathways and/or the regulatory region(s) of the PAI-1 gene may contribute to the differential actions of Ang II in WKY and SH rat brain neurons.

Nonsteroidal anti-inflammatory drugs alter chloride and fluid transport in bovine retinal pigment epithelium

Nonsteroidal anti-inflammatory drugs (NSAIDs) were added to the solutions bathing the apical membrane of bovine retinal pigment epithelium (RPE)-choroid explants. For example, niflumic acid (100 microM) depolarized the basolateral membrane voltage (VB) by approximately 12 mV, increased transepithelial potential by 4.5 mV, decreased intracellular Cl activity by 13 mM, decreased transepithelial resistance by 17 omega.cm2, and increased the ratio of apical to basolateral membrane resistance nearly threefold. All of these changes are consistent with an increase in basolateral membrane Cl conductance. In addition, niflumic acid caused intracellular Ca concentration to decrease by 16 nM and fluid transport rate to increase by 1.5 microliters.cm-2.h-1. Flufenamic acid, which is structurally very similar to niflumic acid, had the opposite effects on membrane voltage and resistance. Basal application of the Cl channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid or current clamping VB to the reversal potential for Cl practically abolished the niflumic acid response. The niflumic acid results suggest that certain NSAIDs can directly alter Cl conductance in the bovine RPE, apparently independently of cyclooxygenase inhibition.

[Isolation and structure flucidation of alkaloids from the bulb of Fritillaria Wabuensis S.Y. Tang et S.C. Yueh]

Eight alkaloids were isolated from the bulb of Fritillaria Wabuensis S.Y. Tang et S.C. Yueh the best "Chuan Bei" cultivated in Sichuan province, which is efficacious against cough. Five of them are known, identified as imperialine (I), peimisine (II), ebeinone (III), isoverticine (IV), and imperialine-beta-N-oxide (V). All the signals for both 1H and 12C-NMR spectra of base (V) were assigned by 2D NMR experiments, and an X-ray structural data of alkaloid (V) was obtained for the first time.

Immobilized chymotrypsin on reversibly precipitable polymerized liposome

A polymerized liposome (PLS) was prepared using a synthesized phosphatidylethanolamine with a diacetylene moiety that showed a reversibly precipitable property on addition and removal of salt. To prepare a soluble-insoluble immobilized enzyme, chymotrypsin was covalently immobilized on the outer surface of the PLS. The carbodiimide method was employed for the enzyme immobilization. Coupling was rapid and nearly complete at a weight ratio of enzyme to the PLS of < 0.12. The immobilized enzyme showed favorable activity yields for both low- and high-mol-wt substrates, i.e., 90 +/- 9% for N-benzoyl-L-tyrosine ethyl ester and 59 +/- 5% for casein up to an enzyme coupling density of 0.38 g/g-PLS. The immobilized enzyme was reusable and more stable at high temperature and long-term incubation than the native enzyme.

Regulation of norepinephrine transport system by angiotensin II in neuronal cultures of normotensive and spontaneously hypertensive rat brains

Brain angiotensin II (Ang II) plays a key role in blood pressure control in part by interacting with catecholamines (CA) and by stimulation of sympathetic pathways. The significance of Ang-CA interaction is further heightened by the presence of a hyperactive brain Ang II system in spontaneously hypertensive (SH) rat, a genetic model for essential hypertension. Neuronal cells in primary culture from the hypothalamus-brainstem that mimic in vivo situations in so far as many cellular actions of Ang II are concerned, have been used in the present study to elucidate Ang II regulation of CA by determining its cellular action on the norepinephrine transporter (NET) system. Ang II causes both acute and chronic stimulation of [3H]-norepinephrine (NE) uptake in neuronal cultures of Wistar Kyoto (WKY) rat brain. Acute stimulation begins as early as 5 min, reaches maximal levels in about 30 min in the presence of 100 nM Ang II, and is blocked by losartan, a specific antagonist for AT1 receptor subtype. In addition, this acute stimulation appears to be a posttranscriptional event and does not involve protein kinase C (PKC) or NET gene transcription. Chronic stimulation of [3H]-NE uptake by Ang II persists throughout the duration of Ang II incubation (24 h), is dose dependent, and is also mediated by AT1 receptor subtype. However, chronic stimulation of [3H]-NE uptake involves PKC, cfos, and NET gene transcription. Ang II also stimulates [3H]-NE uptake in neuronal cultures of SH rat brain, both acutely and chronically, by mechanisms similar to those observed in neuronal cultures of WKY rat brain. The stimulation of NET by Ang II is 2-fold higher than that seen in WKY and is consistent with increased AT1 receptor gene transcription and increased functional AT1 receptors in SH rat brain neurons compared with WKY rat brain neurons. The Ang II stimulation of the NET system is also higher in adult SH compared with WKY rats in vivo. These observations show that 1) Ang II stimulates the NET system both acutely and chronically, the former involving activation of preexisting transporters and the latter involving NET gene transcription and translation; and 2) Ang II stimulation of the NET system is elevated in SH rat brain neurons.

AT1-receptors and cellular actions of angiotensin II in neuronal cultures of stroke prone-spontaneously hypertensive rat brain

AT1-receptors, its mRNA and cellular actions of angiotensin II (Ang II) have been compared between neuronal cultures of Wistar Kyoto (WKY) and stroke-prone spontaneously hypertensive (SP-SH) rat brains. Bmax for AT1-receptor binding is 2-fold higher and is associated with a parallel increase in the levels of AT1-receptor mRNA in SP-SH rat brain neurons compared with WKY rat brain neurons. Ang II causes stimulation of both c-fos and norepinephrine transporter (NET) mRNAs in both strains of neurons and this stimulation is also 2-3-fold higher in SP-SH rat brain neurons compared with WKY rat brain neurons. In contrast, Ang II stimulation of PAI-1 mRNA in SP-SH neurons is only 50% that of in WKY rat brain neurons suggesting that SP-SH neurons express a decrease in AT1-receptor coupling with PAI-1 response. These observations demonstrate that SP-SH neurons express AT1-receptor-functions similar to those described for SHR neurons.

Differential activation of peroxisome proliferator-activated receptors by eicosanoids

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that regulate gene transcription in response to peroxisome proliferators and fatty acids. PPARs also play an important role in the regulation of adipocyte differentiation. It is unclear, however, what naturally occurring compounds activate each of the PPAR subtypes. To address this issue, a screening assay was established using heterologous fusions of the bacterial tetracycline repressor to several members of the peroxisome proliferator-activated receptor (PPAR) family. This assay was employed to compare the activation of PPAR family members by known PPAR activators including peroxisome proliferators and fatty acids. Interestingly, the activation of PPARs by fatty acids was partially inhibited by the cyclooxygenase inhibitor indomethacin, which prevents prostaglandin synthesis. Indeed, prostaglandins PGA1 and 2, PGD1 and 2, and PGJ2-activated PPARs, while a number of other prostaglandins had no effect. We also screened a variety of hydroxyeicosatetraenoic acids (HETEs) for the ability to activate PPARs. 8(S)-HETE, but not other (S)-HETEs, was a strong activator of PPAR alpha. Remarkably, PPAR activation by 8(S)-HETE was stereoselective. In addition, 8(S)-HETE was able to induce differentiation of 3T3-L1 preadipocytes. These results indicate that PPARs are differentially activated by naturally occurring eicosanoids and related molecules.

[An experimental study on homoharringtonine and glaucoma surgery]

PURPOSE

To test the inhibiting effect of a Chinese herbal drug. Homoharringtonine (HH) on the wound healing process at the filtering site in an experimental model.

METHODS

Posterior sclerectomies were performed in 20 rabbits. Postoperatively one eye of each rabbit received subconjunctival injections of HH and fellow eye received saline injections in a randomized masked fashion.

RESULTS

14 days after operation, intraocular pressure decreased significantly compared with that of control (P < 0.05). The number of filtration blebs was greater than that of control (14/6). On pathological examination, the number of fibroblasts per square measure of cross section of tissue cut from filtration region that was diminished significantly compared with that of control (P < 0.01). There were no serious and permanent ocular toxic and side effects.

CONCLUSIONS

The study suggests that the HH can inhibit cicatrization at the glaucoma filtering site, promote the formation of filtering blebs and provide a sufficient evidence for the further clinical use of HH.

Retrovirus-mediated transfer of an angiotensin type I receptor (AT1-R) antisense sequence decreases AT1-Rs and angiotensin II action in astroglial and neuronal cells in primary cultures from the brain

The AT1-R has been implicated in many cellular and physiological actions of angiotensin II (AII) in the brain. A retrovirus vector (LNSV) containing an AT1B-R antisense sequence (AT1B-AS) (termed LNSV-AT1B-AS) was constructed and used to determine the feasibility of using viral-mediated gene transfer to control AT1-Rs and AII actions in astroglial and neuronal cells in primary cultures from rat brain. Briefly, a 1.26-kb antisense sequence corresponding to nt -132 to +1128 of AT1-R cDNA was cloned into the LNSV vector, the vector was transfected into PA317 cells, and transfected cells were selected in G418. Incubation of brain cells with culture medium containing LNSV-AT1B-AS viral particles showed that AT1B-AS was integrated into the genome and transcribed in brain cells. This was associated with a significant decrease in AT1-Rs and in the AII-stimulated increase of c-fos mRNA, a measure of AT1-R function. These observations show that the AT1B-AS gene can be transferred into astroglial cells in culture by LNSV and that such a transfer inhibits AT1-Rs and the AII stimulation of cellular activities. In addition, the usefulness of this approach to study AII-dependent pathophysiology in primary neuronal cultures from brain, in particular, is established.

Expression of a dominant negative inhibitor of intercellular communication in the early Xenopus embryo causes delamination and extrusion of cells

A chimeric construct, termed 3243H7, composed of fused portions of the rat gap junction proteins connexin32 (Cx32) and connexin43 (Cx43) has been shown to have selective dominant inhibitory activity when tested in the Xenopus oocyte pair system. Co-injection of mRNA coding for 3243H7 together with mRNAs coding for Cx32 or Cx43 completely blocked the development of channel conductances, while the construct was ineffective at blocking intercellular channel assembly when coinjected with rat connexin37 (Cx37). Injection of 3243H7 into the right anterodorsal blastomere of 8-cell-stage Xenopus embryos resulted in disadhesion and delamination of the resultant clone of cells evident by embryonic stage 8; a substantial number, although not all, of the progeny of the injected cell were eliminated from the embryo by stage 12. A second construct, 3243H8, differing from 3243H7 in the relative position of the middle splice, had no dominant negative activity in the oocyte pair assay, nor any detectable effects on Xenopus development, even when injected at four-fold higher concentrations. The 3243H7-induced embryonic defects could be rescued by coinjection of Cx37 with 3243H7. A blastomere reaggregation assay was used to demonstrate that a depression of dye-transfer could be detected in 3243H7-injected cells as early as stage 7; Lucifer yellow injections into single cells also demonstrated that injection of 3243H7 resulted in a block of intercellular communication. These experiments indicate that maintenance of embryonic cell adhesion with concomitant positional information requires gap junction-mediated intercellular communication.

Lactate transport mechanisms at apical and basolateral membranes of bovine retinal pigment epithelium

The isolated bovine retinal pigment epithelium actively transports lactate from the apical to the basal bath. Net short-circuit [14C]lactate flux in 20 mM lactate was 0.46 +/- 0.09 mu eq.cm-2.h-1 (n = 8). In open circuit, with a physiological lactate gradient, net [14C]lactate flux was 0.66-1.31 mu eq.cm-2.h-1 (n = 3). Lactate in the apical bath caused intracellular acidifications that were saturable, apparently stereospecific, and reduced in magnitude by several H-lactate cotransport inhibitors. In the basal bath, lactate caused intracellular alkalinizations that were dependent on the presence of Na. In short circuit, 20 mM lactate in both baths reversed the direction of net transepithelial 22Na transport from secretion to absorption, suggesting the presence of basolateral Na-lactate cotransport moving lactate out of the cells. Outwardly directed Na-lactate cotransport requires a lactate:Na stoichiometry > 1.4:1, consistent with the coupled movement of Na, lactate, and net negative charge across the basolateral membrane. Intracellular microelectrode recordings showed that basal lactate hyperpolarized and apical lactate depolarized the basolateral membrane. For lactate absorption, this is a novel arrangement of membrane proteins:luminal H-lactate cotransport and serosal electrogenic Na:(n)lactate cotransport. Lactate transport across the retinal pigment epithelium may play an important role in regulating retinal metabolism and subretinal space volume and composition.

Comparison of heated water-filled mattress and space-heated room with infant incubator in providing warmth to low birthweight newborns

BACKGROUND

Prevention of excessive heat loss is fundamental to survival of low birthweight (LBW) newborns. The use of infant incubators (INC) is beyond the resources of developing countries, and the space-heated room (SHR) has been the only feasible means of providing thermal protection to LBW newborns. Recently a thermostatically controlled, heated, water-filled mattress (HWM) has been developed as a potentially simpler and affordable alternative.

METHODS

In a neonatal care ward of a referral hospital in Addis Ababa, 62 < 1 week old newborns, weighing 1000-1999 g, who were well enough to breathe comfortably in room air and tolerate oral feeds, were randomly allocated to INC, HWM or SHR and followed for 3 weeks. The level of cold stress as assessed by core-to-skin temperature gradient and the rate of weight gain were the main outcome measures.

RESULTS

The level of cold stress was lowest in the INC, intermediate in the HWM and highest in the SHR. Relative to the INC group, the HWM group exhibited a modest increase in the occurrence of clinically important hyperthermic or hypothermic deviations in core temperature (rate ratio (RR) = 2.3; 95% CI: 0.9, 5.6), and the SHR displayed a definite increase (RR = 4.0; 95% CI: 1.7, 9.3). During the first week, the rate of weight gain was highest in the INC group (3.6 g/kg/day), lowest in the SHR group (-2.3 g/kg/day, P < 0.05 versus INC) and intermediate in the HWM group (1.6 g/kg/day, P > 0.1 versus INC).

CONCLUSION

Care in the SHR produced clinically significant thermal stresses and was associated with deficient early neonatal growth, but the use of HWM may constitute a feasible and clinically acceptable alternative in providing warmth to LBW newborns during the neonatal period.

Signalling the molecular stress response to nephrotoxic and mutagenic cysteine conjugates: differential roles for protein synthesis and calcium in the induction of c-fos and c-myc mRNA in LLC-PK1 cells

Nephrotoxic and mutagenic cysteine conjugates (NCC) are activated by the enzyme cysteine conjugate, beta-lyase, to reactive acylating species which bind covalently to cellular macromolecules. We now show that an early event after treatment of LLC-PK1 cells with NCC is the induction of mRNA for both c-fos and c-myc. Treatment with S-(1,2-dichlorovinyl)-L-cysteine (DCVC) induced c-fos (53-fold) and c-myc mRNA (20-fold) and increased transcription about 3-fold for both genes. Covalent binding was required for induction of both mRNAs. Dithiothreitol partially prevented induction of both c-fos and c-myc RNA. Buffering the DCVC-induced increase in cytosolic free calcium had no effect on c-fos mRNA, but partially blocked c-myc mRNA induction. Cycloheximide blocked the induction of c-myc mRNA in the absence of an effect on c-fos induction. The data suggest that the increase in c-fos mRNA is a primary response to DCVC toxicity and occurs without a requirement for protein synthesis or an increase in intracellular free calcium. In contrast, c-myc induction requires protein synthesis, suggesting that the presence of another primary response factor may regulate induction either transcriptionally or posttranscriptionally. The data suggest that different signalling pathways regulate induction of c-fos and c-myc mRNA in response to stress caused by reactive acylating species.

Establishment of three rat soft tissue tumor cell lines with different degrees of myogenic differentiation

Soft tissue malignancies often show divergent differentiation, including myogenic lineage. Five rat tumors induced with 20-hydroxymethylcholanthrene (20-OH-MCA), were cultured in vitro, and three cell lines (YMC-1, YMC-2, YMC-3) were established from them. YMC-2 and -3 cells were spindle-shaped, and YMS-1 cells round and epithelioid. In confluency, YMC-3 cells formed myotubes. The nude mouse xenotransplants showed morphological features consistent with their myogenic phenotypes. Muscle-specific enzyme activities were highest in YMC-3 cells. These lines may be useful in the investigation of the myogenic differentiation of undifferentiated mesenchymal cells.

[A comparative study of homoharringtonine with 5-fluorouracil in filtering surgery]

With a prospective, randomized and double-masked control method, homoharringtonine(H.H) and 5-Fluorouracil (5-FU) were used in filtering surgery. We compared the effect and side effect of H.H with those of 5-FU. 24 eyes were in H.H group and 23 eyes in 5-FU group. An average follow-up of 18 months revealed: (1) the cumulative percentage of functioning bleb in H.H group (84.9%) was significantly higher than that in 5-FU group (62.2%) (P < 0.05); (2) the cumulative surgical success rate in H.H group (85.7%) was significantly higher than that in 5-FU group (61.1%) (P < 0.05); (3) the rate of corneal erosion in H.H group (20.8%) was significantly lower than that in 5-FU group (52.2%) (P < 0.05), the difference of other complications between H.H group and 5-FU group was not significant.

Micellar bolaform and omega-carboxylate phosphatidylcholines as substrates for phospholipases

A series of mixed-chain diacyl-PCs which contain an omega-COOH on the sn-2 chain [1-Cx-2-Cy-(COOH)-PC] and bolaform (1-Cx-2,2'-Cy-1'-Cx-PC) phosphatidylcholines were synthesized and examined as substrates for phospholipase A2 (Naja naja naja) and C (Bacillus cereus). There is very little detectable phospholipase A2 activity toward pure micellar 1-acyl-2-acyl-(omega-COOH) species. In addition, when these same omega-COOH species are present at concentrations above their CMCs, they are potent inhibitors of phospholipase A2 hydrolysis of other micellar lipids. In contrast, phospholipase C hydrolysis of the same 1-acyl-2-acyl-omega-COOH)-PC species proceeds with rates comparable to that of diheptanoyl-PC. The bolaform lipids, which are tethered through a common sn-2 acyl chain, (e.g., 1-C8-2,2'-C12-1'-C8-PC) display quite different kinetic results. Under limiting Ca2+ conditions (100 microM) all the available sn-2 acyl bonds of the dimer are hydrolyzed. However, at high Ca2+ concentrations (1-10 mM) the reaction curves have a biphasic nature, characterized by an initial burst of activity followed by much slower rate. This is consistent with only the micellar 1-acyl-2-acyl-(omega-COOH)-PC produced in situ from phospholipase A2 hydrolysis of the dimer acting as an inhibitor of subsequent phospholipase A2 activity. Phospholipase C hydrolysis of the PC dimer and the sn-2 omega-COOH PC is rapid, with both available glycerophosphate groups cleaved at presumably the same rate. These results are discussed in terms of the unique physical properties (as measured by NMR and fluorescence experiments) of these phospholipids.

Chromophobe renal cell carcinoma: a report of two cases

Chromophobe renal cell carcinoma (RCC) is a recently established subtype of RCC, which has rarely been reported in Japan. In this communication, the authors report two Japanese cases of chromophobe RCC together with the immunohistochemical findings. The tumors were composed of sheets and cribriform glands formed by tumor cells with cloudy and reticular cytoplasm. Ultrastructurally, the cytoplasm was filled with numerous microvesicles. The tumor cells were positive for cytokeratin, epithelial membrane antigen, and Tamm-Horsfall protein. Occasionally, LeuM1-positive cells were also noted. Vimentin was negative, unlike the usual RCC. Reactivity for peanut agglutinin was more frequent than that to Lotus tetragonolobus agglutinin. The results of this study suggest that the tumor cells possessed phenotypes similar to the distal nephron rather than to the proximal tubular cells.

Visually guided attention is neutralized when informative cues are visible but unperceived

The ability to voluntarily shift the focus of visual attention away from the focus of gaze was investigated in a novel paradigm designed to elaborate the stages of processing underlying this ability. A basic experimental method used to investigate guided visual attention involves measuring response times to targets presented at positions of which the observer has been informed by an orienting cue. Binocular rivalry was utilized to dissociate presentation of the orienting cue from visual awareness of that cue. The findings indicated that when an informative cue was presented to an eye during the dominance phase, thus reaching visual awareness, manual response times were significantly affected by cue validity. In contrast, when the same cue was presented to an eye during suppression, and thus was not seen by observers, response times were not influenced by cue validity. We conclude that to guide attention, neural signals registering informative visual cues must be processed at stages lying beyond the site of rivalry suppression. Implications for investigating the neural basis of visual attention are discussed.

Rapid estimation of genetic relatedness among heterogeneous populations of alfalfa by random amplification of bulked genomic DNA samples

A procedure which involves the use of RAPD markers, obtained from bulked genomic DNA samples, to estimate genetic relatedness among heterogeneous populations is demonstrated in this study. Bulked samples of genomic DNA from several alfalfa plants per population were used as templates in polymerase chain reactions with different random primers to produce RAPD patterns. The results show that the RAPD patterns can be used to determine genetic distances among heterogeneous populations and cultivars which correspond to their known relatedness. The results also indicate that, by using ten primers with bulked DNA samples from ten individuals, 18-72 populations or cultivars can be distinguished from each other on the basis of at least one unique RAPD marker. We anticipate that DNA bulking and methods for comparing RAPD patterns will be very useful for identifying cultivars, for studying phylogenetic relationships among heterogeneous populations and for selecting parents to maximize heterosis in crosses.

Identification of a RAPD marker associated with somatic embryogenesis in alfalfa

The current study was conducted to identify random amplified polymorphic DNA (RAPD) markers linked to genes controlling somatic embryogenesis in alfalfa. Segregation analyses of the somatic embryogenesis trait and the RAPD markers in an F1 population of 83 plants, derived from a cross between embryogenic A70-34 and non-embryogenic Arrow36 alfalfa plants, identified a polymorphic band that is associated with somatic embryogenesis. Based on the assumptions that somatic embryogenesis in alfalfa is controlled by two dominant genes with complementary effects and that the genotypes of A70-34 and Arrow36 are AAaaBbbb and aaaabbbb, respectively, the segregation data for the marker and the somatic embryogenesis trait in the F1s indicate that the marker is linked to the A locus. The maximum recombination fraction estimated for the linkage between the marker and the gene is 36.3%.

Effect of administration route and estrogen manipulation on endometrial uptake of Photofrin porfimer sodium

OBJECTIVE

Our purpose was to evaluate the influence of the route of drug administration and target tissue vascularity on the distribution of a photosensitizer, Photofrin porfimer sodium, in the uterus.

STUDY DESIGN

The study was divided in two phases. In phase I 80 mature female rats were hormonally suppressed and then stimulated with estrogen. They were randomized to receive intravenous, intraperitoneal, or intrauterine Photofrin and killed 3, 6, 24, or 48 hours later. Drug distribution and levels were then determined. In phase II 40 female rats were randomized to receive hormonal stimulation, suppression, both, or neither. All received intrauterine Photofrin and were killed 24 hours later. Statistical analysis was performed with the unpaired t test and the two-way analysis of variance.

RESULTS

Intrauterine administration was determined to be the simplest and most effective method of delivery because it provided for optimal uptake and distribution (p = 0.05) within the uterus, at lower doses.

CONCLUSIONS

Selective localization of photosensitizer within the target tissue suggests that highly selective photodynamic destruction of endometrial tissue can be achieved. Furthermore, the combination of intrauterine administration of photosensitizer with estrogen adjuvant may minimize the most debilitating side effect of Photofrin, cutaneous phototoxicity.

Contrast media for cardiothoracic MR imaging

Contrast media have been used for the study of disease of the thorax. Most experience has consisted of the use of MR contrast media for improving the delineation of acute myocardial infarction, for demarcating the area of acute myocardial ischemia, and for demonstrating the area of potentially jeopardized myocardium after acute coronary occlusion. Contrast agents demonstrate the ischemic or jeopardized area as a zone of decreased signal intensity to normal myocardium. On the other hand, the magnetic susceptibility agents demonstrate the ischemic or jeopardized area as a zone of increased signal intensity to normal myocardium. Little experience exists concerning the use of MR contrast media for enhancing mediastinal and lung masses. The few reports to date demonstrate that contrast media can improve the conspicuity of thoracic masses. A new nonionic contrast medium, gadodiamide injection, has been shown to considerably increase S/N and C/N of thoracic masses. Further studies are necessary to define the role of MR contrast media in the evaluation of myocardial ischemia and thoracic masses in clinical practice.

The effect of cholesterol-lowering agents on hepatic and plasma cholesterol in Niemann-Pick disease type C

Niemann-Pick disease type C (NP-C) is a neurovisceral lipidosis characterized by defective intracellular trafficking of cholesterol and lysosomal accumulation of unesterified cholesterol, believed to be an offending metabolite. We studied the effect of cholesterol-lowering agents on hepatic and plasma cholesterol levels in NP-C by randomly assigning 25 patients with NP-C to one of five treatment regimens containing different combinations of cholestyramine, lovastatin, nicotinic acid, or dimethyl sulfoxide (DMSO). Unesterified cholesterol content was measured in liver biopsies before and after 4 months' treatment. All drug regimens except DMSO alone reduced hepatic and plasma cholesterol levels. Toxicity was limited and did not prevent any patient from completing the study. The combination of cholestyramine, lovastatin, and nicotinic acid lowered cholesterol levels in liver and blood with minimal side effects. A controlled clinical study will be necessary to determine if this regimen influences the rate of neurologic progression.

Regulation of the cellular stress response by reactive electrophiles. The role of covalent binding and cellular thiols in transcriptional activation of the 70-kilodalton heat shock protein gene by nephrotoxic cysteine conjugates

The cytotoxicity of nephrotoxic cysteine conjugates (NCC) in the renal epithelial cell line, LLC-PK1, is due to the covalent binding of a reactive electrophilic metabolite produced from NCC metabolism by cysteine conjugate beta-lyase. Covalent binding of NCC-derived reactive metabolites leads to a cascade of events including depletion of cellular non-protein sulfhydryls, increased cytosolic free calcium, and lipid peroxidation, which is ultimately responsible for cell death. We have used this model to investigate the signalling mechanism(s) through which reactive electrophiles increase synthesis of the 70-kD heat shock protein (HSP70). NCC treatment resulted in increased HSP70 synthesis as well as time- and dose-dependent increases in hsp70 mRNA in LLC-PK1 cells. The induction of hsp70 mRNA was blocked by actinomycin D, and nuclear run-on experiments showed that the hsp70 gene was transcriptionally activated. Inhibition of protein synthesis did not block the increase in hsp70 mRNA or transcriptional activation of the hsp70 gene suggesting that induction occurs due to activation of existing transcription factors. Inhibiting the covalent binding with a beta-lyase inhibitor, aminooxyacetic acid, blocked the increase in hsp70 mRNA. Agents which do not alter binding but do prevent toxicity by blocking the rise in cytosolic free calcium and lipid peroxidation were not effective inhibitors of hsp70 mRNA accumulation. However, the thiol reducing agent, dithiothreitol, inhibited induction of hsp70 mRNA by NCC. The data suggest that covalent binding and alterations in cellular non-protein thiols serve as signals for activation of pre-existing transcription factors which increase hsp70 gene expression. It is proposed that reactive electrophiles may have a primary effect on protein conformation resulting in activation of the hsp70 gene.

Transcriptional regulation of the thrombomodulin gene

The transcriptional start sites of the endogenous human thrombomodulin (TM) gene and transiently expressed TM promoter/CAT gene constructs were defined by nuclease S1 mapping which showed two closely spaced sites at +1 and +6, respectively. Transient expression and in vitro transcription assays of 5' and internal deletion mutants of the TM promoter/CAT gene constructs reveal that the region from -72 to -29 exhibits a positive acting domain which is essential for transcriptional activity, whereas the region from -373 to -225 possesses two positive acting subdomains, -343 to -277 and -245 to -225, which together augment transcriptional activity by about 40%. Electrophoretic mobility shift assays with a duplex oligonucleotide corresponding to -72 to -29 and DNase I footprinting experiments show two specific interaction products which individually or cooperatively protect the DNA sequence from about -60 to -30. These components are essential for TM gene transcription since affinity fractionation of nuclear extracts with a duplex oligonucleotide corresponding to -72 to -29 depletes the above interaction products and specifically inhibits in vitro transcription activity of the promoter, whereas addition of the eluted components specifically restores in vitro transcription activity of the promoter. Electrophoretic mobility shift assays with duplex oligonucleotides corresponding to -294 to -215, as well as -373 to -295 and DNase I footprinting experiments show two specific interaction products which individually bind to the two subdomains but not -72 to -29 and protect the coding and noncoding strands from -245 to -225, and the noncoding strand from -337 to -314, respectively. Transient expression studies reveal that the TM promoter construct starting at -51 and including the TATA box is responsive to TNF only in cell lines exhibiting sensitivity of the endogenous receptor gene to cytokine, whereas other promoter constructs possessing a TATA box sequence are insensitive to TNF in all cell types. Based upon the above data, the regulatory events involved in TNF-dependent transcriptional regulation of the TM gene can be defined with the experimental tools and conceptual framework developed by the present investigation.

Do recognizable figures enjoy an advantage in binocular rivalry?

Five experiments examined whether recognizable stimuli predominate in binocular rivalry. It was found that a face predominated more than did a pattern equated for spatial frequency, luminance, and contrast; an objective reaction time procedure confirmed predominance of the face. The face was still liable to fragmentation as stimulus size increased. Observers tracked exclusive dominance of a picture of a camouflaged figure (a Dalmatian dog) prior to and then following discovery of the figure's presence; control observers received the same protocol with a scrambled version of the dog stimulus. Compared with control results, predominance of the dog picture was higher even before observers knew of the camouflaged figure. Inversion of the dog figure reduced its predominance. Binocular rivalry is sensitive to object-related, configural properties of a stimulus.

[Umbilical and maternal amino acid concentrations in appropriate and small for gestational age infants]

Serum amino acid concentrations were determined in 63 pregnant women and their infants at delivery. Samples were obtained from 47 appropriate for gestational age infants (AGA) and 16 small for gestational age infants (SGA). The SGA group had significantly lower concentrations of total amino acid, compared with those of AGA, in both the umbilical and maternal blood. The essential amino acids of the cord, such as isoleucine and threonine, and maternal essential amino acids like threonine and arginine in the SGA group were lower than those in the AGA group. In contrast, nonessential amino acid concentrations, such as alanine, proline and aspartic acid were significantly higher in the umbilical blood of the SGA infants, while there were no differences in the maternal blood of both AGA and SGA groups. There was a positive relationship between maternal and umbilical total amino acid concentrations in the AGA group, but no relationship exists in the SGA group.

Optimization of the PCR program for RAPD analysis

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Activation of the growth arrest and DNA damage-inducible gene gadd 153 by nephrotoxic cysteine conjugates and dithiothreitol

The cellular and biochemical events which transduce chemical insults into signals for increased expression of the stress-responsive gene gadd 153 were investigated using nephrotoxic cysteine conjugates. In LLC-PK1 cells, cysteine conjugate toxicity is initiated by covalent binding, but depletion of cellular thiols, an increase in cytosolic free calcium, and lipid peroxidation couple the binding to cell death (Chen, Q., Jones, T. W., Brown, P. C., and Stevens, J. L. (1990) J. Biol. Chem. 265, 21603-21611; Chen, Q., Jones, T. W., and Stevens, J. L. (1991) Toxicologist 11, 101, 1991). Three different toxic cysteine conjugates induced gadd 153 mRNA. With S-(1,2-dichlorovinyl)-L-cysteine (DCVC), the induction was both concentration and time-dependent. Preventing the metabolism of DCVC and covalent binding of DCVC-derived reactive metabolites to cellular macromolecules with the beta-lyase inhibitor (aminooxy)acetic acid blocked the induction. However, buffering free calcium with a cell permeable calcium chelator or blocking lipid peroxidation with an antioxidant did not affect the induction of gadd 153 mRNA by DCVC even though these treatments inhibit toxicity. These data suggest that covalent binding of reactive metabolites to cellular macromolecules may serve as a primary signal for the induction of gadd 153 mRNA by nephrotoxic cysteine conjugates. Interestingly, the sulfhydryl agent dithiothreitol, which was nontoxic and prevented the toxicity of DCVC, also induced an increase in gadd 153 mRNA. When both dithiothreitol and DCVC were added to cells, there were no inhibitory or additive effects on expression. Therefore, cellular thiol-disulfide status may also play a role in gadd 153 induction.

Thrombomodulin gene regulation by cAMP and retinoic acid in F9 embryonal carcinoma cells

Thrombomodulin (TM) expression was investigated during differentiation of F9 embryonal carcinoma cells into primitive or parietal endoderm. Exposure of F9 cells to retinoic acid (RA) triggers differentiation into primitive endoderm and induces the appearance of barely detectable amounts of TM mRNA, whereas treatment with dibutyryl cAMP plus theophylline (CT) augments the levels of TM mRNA to a 4-fold greater extent than RA. Exposure of F9 cells to RA plus CT initiates differentiation into parietal endoderm and synergistically increases the levels of TM mRNA by 10- to 12-fold compared with CT. The time-dependent establishment of cooperativity between RA and CT appears to be secondary to RA-induced differentiation to primitive endoderm. The above alterations in TM mRNA levels occur by a transcriptional mechanism as judged by nuclear run-on experiments. Transient gene expression experiments show that the human TM promoter is transactivated by coexpression of the human RA receptor beta. Thus, the mechanism of induction of TM expression in F9 cells undergoing differentiation to parietal endoderm appears to be similar, but not identical, to that noted for other late response genes.

Do recognizable figures enjoy an advantage in binocular rivalry?

Five experiments examined whether recognizable stimuli predominate in binocular rivalry. It was found that a face predominated more than did a pattern equated for spatial frequency, luminance, and contrast; an objective reaction time procedure confirmed predominance of the face. The face was still liable to fragmentation as stimulus size increased. Observers tracked exclusive dominance of a picture of a camouflaged figure (a Dalmatian dog) prior to and then following discovery of the figure's presence; control observers received the same protocol with a scrambled version of the dog stimulus. Compared with control results, predominance of the dog picture was higher even before observers knew of the camouflaged figure. Inversion of the dog figure reduced its predominance. Binocular rivalry is sensitive to object-related, configural properties of a stimulus.

Altered expression of HLA antigens and CD16 Fc receptors on leukocytes of alcoholic subjects and uremic patients

The possible influences of ethanol and its metabolic product acetate on the surface expression of HLA class I and class II antigens and CD16 Fc receptors were examined. Fluorescent-labeled monoclonal antibodies and flow cytometry were used to measure these antigens on leukocytes from reference controls, subjects admitted for alcohol detoxification, uremic patients undergoing hemodialysis using Cu-prophan dialyzers and fluids containing 4 to 37 mM acetate, and uremic patients that were not hemodialyzed. In comparison to the controls, the mean intensity of staining for class I antigens was not changed significantly on lymphocytes or monocytes from alcoholics but was depressed on cells from eight of 12 uremic patients. Interferon-gamma above 5 units/ml was detected in less than 15% of plasma samples from controls, uremic patients or alcoholics on admission but was detected in four of eight samples from alcoholics at discharge (2-4 days after admission). The intensity of staining for class II antigens was depressed by more than 50% on lymphocytes from alcoholics and uremic patients. The expression of HLA class I and class II antigens was depressed whether uremic patients were hemodialyzed or not. The percentage of lymphocytes expressing CD16 was depressed in three of seven alcoholics and five of seven hemodialyzed patients. In contrast, the percentage of monocytes expressing CD16 was increased in six of seven hemodialyzed patients and three of five uremic patients not undergoing hemodialysis suggesting activation of monocytes in these patients. Plasma levels of beta 2-microglobulin were elevated by 61% in alcoholics, 50-fold in hemodialyzed patients, and 26-fold in nonhemodialyzed uremic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of sarcoid granulomatous interstitial nephritis improved by steroid therapy]

We report a case of sarcoid granulomatous tubulointerstitial nephritis diagnosed by renal biopsy. A 60-year-old man presented with productive cough, and exertional dyspnea of 3 months duration. A chest X-ray film revealed diffuse reticulonodular infiltrates in both lung fields. A transbronchial lung biopsy specimen showed inflammation of the alveolar septum associated with non-caseating granulomas. The patient also had tubular proteinuria and glucosuria. Ga-scintigraphy demonstrated an abnormal accumulation of gallium in both lungs and kidneys. Renal function tests revealed tubular dysfunction. Tubulointerstitial nephropathy was suspected. A renal biopsy specimen exhibited tubulointerstitial nephritis associated with numerous non-caseating granulomas, similar to the findings of the lung biopsy specimen. No glomerular abnormalities were evident. Later, a scalene node biopsy confirmed the diagnosis of sarcoidosis. Prednisolone therapy yielded a favorable outcome for both the renal and pulmonary involvement. During the corticosteroid therapy, measurement of the urinary beta-2-microglobulin concentration proved a valuable monitoring tool for assessing the recovery of the tubular impairment.

Genetics of 51D-52A, a region containing several maternal-effect genes and two maternal-specific transcripts in Drosophila

Two genomic clones exhibiting a maternal-specific pattern of expression map to cytological region 52A. To elucidate the function of these clones we have undertaken a mutagenesis of the cytological region 51D-52A. This paper presents the results of this screen and the preliminary analysis of female-sterile and lethal mutations isolated. A total of twelve complementation groups have been identified, four of which are defined exclusively by female-sterile alleles. Only one visible mutation was isolated, a recessive temperature-sensitive allele of Thickened-arista (Tarts). Several of the seven lethal loci display an embryonic lethal phase. Three of the four female-sterile loci affect chorion structure with one resulting in underamplification of the chorion genes, and two (possibly three) of the four female-steriles affect nuclear division/DNA replication. Thus it appears that this is a "developmentally important" region, possibly representing a clustering of genes involved in either DNA replication or nuclear division.