[Mechanism of cytogenetic adaptive response induced by low dose radiation]

Cytogenetic observation on human lymphocytes indicated that pre-exposure of 10, 50 and 75 mGy X-rays could induced the adaptive response. Experimental results with different temperature treatment showed that the adaptive response induced by low dose radiation could be enhanced by 41 degrees C and 43 degrees C, but inhibited by 4 degrees C in addition the treatment by 41 degrees C for one hour could also cause the adaptive response as did low dose radiation. Results showed that adaptive response induced by low dose radiation (10 or 50 mGy X-rays) could be eliminated by the protein synthesis inhibitor, implying that the adaptive response is related with the metabolism of cells, especially with the production of certain protective proteins.

Simplified analysis and structural design for ridge mos optical waveguides

A simplified method is presented for analyzing the optical characteristics of ridge MOS optical waveguides. Equations are derived for calculating the effective refractive indices and the absorption loss coefficients of the E(x)(pq) modes. The computations are performed for air-Au-air/SiO(2)/GaAs/AlGaAs ridge MOS waveguides. To achieve single-mode propagation with low absorption loss, appropriate selection of the structural parameters for this kind of waveguide is discussed.

Major effects on teratogen-induced facial clefting in mice determined by a single genetic region

A major correlation has been found between the incidence of glucocorticoid-induced cleft palate and the chromosome 8 segment identified by N-acetyl transferase in mice. The resistant strain became fully susceptible while the susceptible strain became resistant when this chromosomal region, representing less than 0.7% of the genome, was transferred from one strain to the other by the construction of congenic strains. 6-Aminonicotinamide-induced cleft palate and phenytoin-induced cleft lip with or without cleft palate are also influenced by this genetic region but not as strongly. In both cases the susceptible strain became quite resistant to the teratogen-induced clefting when the N-acetyl transferase region of chromosome 8 was transferred. However, this chromosomal region does not make the resistant strain susceptible to these two teratogens.

Vitamin E supplementation enhances cell-mediated immunity in healthy elderly subjects

The effect of vitamin E supplementation on the immune response of healthy older adults was studied in a double-blind, placebo-controlled trial. Subjects (n = 32) resided in a metabolic research unit and received placebo or vitamin E (800 mg dl-alpha-tocopheryl acetate) for 30 d. Alpha-tocopherol content of plasma and peripheral blood mononuclear cells (PBMCs), delayed-type hypersensitivity skin test (DTH), mitogen-stimulated lymphocyte proliferation, as well as interleukin (IL)-1, IL-2, prostaglandin (PG) E2, and serum lipid peroxides were evaluated before and after treatment. In the vitamin E-supplemented group 1) alpha-tocopherol content was significantly higher (p less than 0.0001) in plasma and PBMCs, 2) cumulative diameter and number of positive antigen responses in DTH response were elevated (p less than 0.05), 3) IL-2 production and mitogenic response to optimal doses of concanavalin A were increased (p less than 0.05), and 4) PGE2 synthesis by PBMCs (p less than 0.005) and plasma lipid peroxides (p less than 0.001) were reduced. Short-term vitamin E supplementation improves immune responsiveness in healthy elderly individuals; this effect appears to be mediated by a decrease in PGE2 and/or other lipid-peroxidation products.

[Nutritive physiology of Psoralea corylifolia L]

Our study has shown that P. corylifolia absorbs and accumulates N2 and K2O most speedily in the periods of branching, flowering and fruiting, while P2O5 in the period of full flowering and fruiting. P2O5 is accumulated mainly in the seed and K2O in the stem. The nutriment accumulation is positively correlated with that of dry substances. To produce 100 kg of P. corylifolia an absorption of 10.59 kg of N2, 3.68 kg of P2O5 and 10.21 kg of K2O is needed.

[Effect of seed soaking in plant hormone and trace element fertilizer on the growth of Psoralea corylifolia L]

Our study shows that seed soaking in triacontanol, ammonium molybdate and gibberellin can promote the growth of P. corylifolia, reduce its premature flower and fruit drop, raise the fruit-bearing rate by 6.5-17.4%, and fruit-bearing number by 21.6-28.4%, so as to increase the yield per unit area by 31.5-34.8%. Seed soaking in naphthylacetic acid and boric acid does not give such a marked effect.

Programmable optical threshold logic implementation with an optoelectronic circuit

We demonstrate optical binary threshold logic by using an optoelectronic circuit. This threshold gate is in itself a logical complete set owing to the availability of both positive and negative weights and threshold. Furthermore, the weights and the threshold are optically addressed, thereby providing real-time operation. Experimental results demonstrate AND, OR, and MAJORITY functions and three other arbitrary logic functions for three input signals with a single gate. Applications in neural computing and two-dimensional parallel logic processing are discussed.

Deformation of the dog lung in the chest wall

Data on the shape of the chest wall at total lung capacity (TLC) and functional residual capacity (FRC) were used as boundary conditions in an analysis of the deformation of the dog lung. The lung was modeled as an elastic body, and the deformation of the lung from TLC to FRC caused by the change in chest wall shape and gravity were calculated. Parenchymal distortions, distributions of regional volume at FRC as a fraction of the volume at TLC, and distributions of surface pressure at FRC are reported. In the prone dog there are minor variations in fractional volume along the cephalocaudal axis. In transverse planes opposing deformations are caused by the change of shape of the transverse section and the gravitational force on the lung, and the resultant fractional volume and pleural pressure distributions are nearly uniform. In the supine dog, there is a small cephalocaudal gradient in fractional volume, with lower fractional volume caudally. In transverse sections the heart and abdomen extend farther dorsally at FRC, squeezing the lung beneath them. The gradients in fractional volume and pleural pressure caused by shape changes are in the same direction as the gradients caused by the direct gravitational force on the lung, and these two factors contribute about equally to the large resultant vertical gradients in fractional volume and pleural pressure. In the prone position the heart and upper abdomen rest on the rib cage. In the supine posture much of their weight is carried by the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

[Biological characteristics of Psoralea corylifolia L]

A study has been made on the biological characteristics of Psoralea corylifolia under general cultivating conditions. To search for the laws of growth and development so as to facilitate further studies on the cultivating techniques for higher production of Psoralea corylifolia.

Quantitative light- and electron-microscopic analysis of cytochrome-oxidase distribution in neurons of the lateral geniculate nucleus of the adult monkey

The distribution of cytochrome oxidase (CO) in the lateral geniculate nucleus (LGN) of normal adult macaque monkeys was analyzed in quantitative light- and electron-microscope (EM) studies. Both reactive and nonreactive neurons were found throughout laminae 1-6. Darkly reactive neurons were more numerous in laminae 1, 2, and 6. Within each lamina, there was a positive correlation between cell size and level of CO activity in neurons. The cell density was greater in laminae 1, 4, and 6, which received input from the contralateral eye, than in corresponding laminae representing the ipsilateral eye (2, 3, and 5). The cell density in each of the magnocellular laminae was less than that in each of the parvicellular laminae. Three types of neurons could be distinguished within magnocellular laminae at the EM level. Types I and II were interpreted to be relay neurons, while the small size of type III qualified them to be interneurons. Two populations were found within parvicellular laminae, corresponding to relay neurons and interneurons, respectively. EM quantitative analyses revealed that the darkly reactive neurons contained a high proportion of moderate to darkly reactive mitochondria, which comprised 44.2%, 42.5%, and 39.2% of the mitochondrial population within neurons of laminae 1, 2, and 6 respectively. In contrast, a relatively low proportion of reactive mitochondria were found in neurons within laminae 3 (22.8%), 4 (26.4%), and 5 (32.4%). Moreover, magnocellular laminae contained a higher density of synapses on cell bodies than parvicellular laminae. All laminae, except layer 5, contained predominantly symmetric synapses on cell bodies. However, the proportion of symmetrical synapses in the magnocellular laminae (65.6%) was greater than that in the parvicellular laminae (59%). Our quantitative light and EM results indicate that the level of metabolic activity in neurons of the monkey LGN is higher in magnocellular, ON-center, and contralateral than in parvicellular, OFF-center, and ipsilateral visual pathways, respectively. The metabolic activity of neurons is likely to reflect the chronic level of spontaneous and synaptically evoked discharges of these cells.

Increased canine pancreatic acinar cell damage after organophosphate and acetylcholine or cholecystokinin

Sublethal doses of organophosphate anticholinesterases cause acute pancreatitis in dogs within 2 h. In vitro studies using canine pancreatic fragments have also demonstrated that the peak of amylase release in response to acetylcholine is shifted far to the left after incubation with the organophosphates echothiophate (10(-4) M) or tetraisopropyl pyrophosphoramide (iso-OMPA) (10(-3) M), indicating an increased sensitivity of response. The present in vitro study examined whether there was also an increased susceptibility to acinar cell damage at the electron microscopic level after acetylcholine or cholecystokinin. Minced pieces of whole fresh canine pancreas 2-3 mm in size were placed in buffered Eagle's solution and gassed with 100% O2. After pretreatment 1 h with echothiophate or iso-OMPA, they were then incubated with acetylcholine (10(-5) M). Other tissues preincubated with echothiophate were stimulated with cholecystokinin (10(-9) M). These are submaximal doses for untreated canine pancreatic fragments. After acetylcholine and echothiophate or acetylcholine and iso-OMPA, there was extensive acinar damage with the appearance of large vacuoles and lakes, and interstitial edema. There was evidence of intense supramaximal stimulation and lateral exocytosis. Similar destructive changes were seen after echothiophate and cholecystokinin. In control sections from tissues stimulated with acetylcholine (10(-5) M) or cholecystokinin (10(-9) M, there were lumenal exocytotic patterns typical of submaximal stimulation. Other controls, organophosphate alone and unstimulated basal conditions, showed only minor changes. It is concluded that the increased sensitivity to acetylcholine after organophosphate incubation correlates with an increased susceptibility to acinar ultrastructural damage from acetylcholine and cholecystokinin.

Recombinant soluble CD4 therapy in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. A phase I-II escalating dosage trial

STUDY OBJECTIVE

To study the safety and pharmacokinetics and to derive preliminary evidence on surrogate indicators of efficacy of recombinant soluble CD4 (rsCD4) in patients with the acquired immunodeficiency syndrome (AIDS) and advanced AIDS-related complex.

DESIGN

Open label, escalating dosage, phase I-II tolerance trial.

SETTING

Massachusetts General Hospital, Cedars-Sinai Medical Center, and Stanford University Medical School, three tertiary care institutions and members of the National Institute of Allergy and Infectious Diseases AIDS Clinical Trials Group.

INSTRUCTIONS

Cohorts of 3 to 11 patients received rsCD4 by intravenous infusion or intramuscular injection in dosages of up to 30 mg per day for 28 days.

MEASUREMENTS AND MAIN RESULTS

Recombinant soluble CD4 was tolerated by these patients with no significant clinical or immunologic toxicities. Serum levels of rsCD4 in patients receiving doses of 9 or 30 mg per day administered intramuscularly were in the range of rsCD4 concentrations required to inhibit replication of human immunodeficiency virus 1 (HIV-1) in vitro. A decline in serum HIV-1 p24 antigen was seen in patients receiving 30 mg of rsCD4 daily, but no such changes were noted at lower dosages.

CONCLUSIONS

Recombinant soluble CD4 is well tolerated by patients with AIDS or advanced AIDS-related complex. Our study has also provided preliminary evidence of antiviral activity of rsCD4 in vivo. Our data suggest that further trials of receptor-based therapies against HIV-1 are warranted.

A model for urbanizing rural population and development measures: survey of a large specialized market in Xiliu town, Liaoning province

The authors present an urbanization model using the example of Xiliu town in Liaoning province, China. Xiliu has developed from a rural commune into a large-scale clothing market during the period since 1979. "The purpose...is to show, by means of a survey conducted in the town, the characteristics and formative factors of the model and to discuss the prospect of and measures for furthering this development."

Intracellular sodium affects ouabain interaction with the Na/K pump in cultured chick cardiac myocytes

Whether a given dose of ouabain will produce inotropic or toxic effects depends on factors that affect the apparent affinity (K0.5) of the Na/K pump for ouabain. To accurately resolve these factors, especially the effect of intracellular Na concentration (Nai), we have applied three complementary techniques for measuring the K0.5 for ouabain in cultured embryonic chick cardiac myocytes. Under control conditions with 5.4 mM Ko, the value of the K0.5 for ouabain was 20.6 +/- 1.2, 12.3 +/- 1.7, and 6.6 +/- 0.4 microM, measured by voltage-clamp, Na-selective microelectrode, and equilibrium [3H]ouabain-binding techniques, respectively. A significant difference in the three techniques was the time of exposure to ouabain (30 s-30 min). Since increased duration of exposure to ouabain would increase Nai, monensin was used to raise Nai to investigate what effect Nai might have on the apparent affinity of block by ouabain. Monensin enhanced the rise in Na content induced by 1 microM ouabain. In the presence of 1 microM [3H]ouabain, total binding was found to be a saturating function of Na content. Using the voltage-clamp method, we found that the value of the K0.5 for ouabain was lowered by nearly an order of magnitude in the presence of 3 microM monensin to 2.4 +/- 0.2 microM and the magnitude of the Na/K pump current was increased about threefold. Modeling the Na/K pump as a cyclic sequence of states with a single state having high affinity for ouabain shows that changes in Nai alone are sufficient to cause a 10-fold change in K0.5. These results suggest that Nai reduces the value of the apparent affinity of the Na/K pump for ouabain in 5.4 mM Ko by increasing its turnover rate, thus increasing the availability of the conformation of the Na/K pump that binds ouabain with high affinity.

Involvement of sulfhydryl residues in aldose reductase-inhibitor interaction

Purification and storage of aldose reductase isolated from human placenta or kidney in beta-mercaptoethanol-containing buffers causes a time-dependent decrease in its catalytic activity, as well as in its sensitivity to inhibition by aldose reductase inhibitors such as sorbinil. Dithiothreitol (DTT) slowly regenerated the enzyme activity, as well as reversed the alterations in the sensitivity of the enzyme to sorbinil. In contrast to sorbinil, the inhibition of aldose reductase by tolrestat was less affected by purification and/or storage in beta-mercaptoethanol-containing buffers. Kinetic analysis of the rate of increase in sensitivity of the enzyme to sorbinil on incubation with DTT reveals that the reaction follows two kinetically distinct rate constants. Also, sorbinil protected the enzyme from inactivation with sulfhydryl-modifying reagents 5,5'-dithiobis(2-nitrobenzoic acid) and glutathione disulfide. The enzyme stored in beta-mercaptoethanol migrates as two distinct bands, one corresponding to molecular weight 36,000 and the other to molecular weight 33,000, on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis, whereas under reducing conditions the protein migrates as a single discrete band corresponding to molecular weight 36,000. Moreover, the molecular weight 33,000 form of the enzyme could be converted to the molecular weight 36,000 form on reduction with DTT, indicating that the molecular weight 33,000 form of the enzyme is due to intramolecular disulfide bond(s) formed, which presumably cause the protein to assume a more folded conformation and migrate faster through the gel, and not due to proteolysis. These studies indicate that oxidation of sulfhydryl residues, including disulfide bond formation, during purification and storage in beta-mercaptoethanol-containing buffers alters the sensitivity of the enzyme to some inhibitors.

Relationship of Substance P-lmmunoreactive Nerve Fibers with Somatotropes of the Anterior Pituitary in the Monkey

Abstract In a previous study, substance P-immunoreactive nerve fibers were demonstrated in the pars distalis of the anterior pituitary in the monkey. The present work investigated their relationship with somatotropes. Pituitaries of Macaca mulatta monkeys were frozen, sectioned and double immunostained with antisera against substance P and human growth hormone. Substance P-immunoreactive nerve fibers, with many varicosities, were found in close proximity to somatotropes. It is suggested that a direct neural factor may be involved in the regulation of growth hormone secretion.

The effect of oxidants on biomembranes and cellular metabolism

During the reductive process in the tissues, the aerobes generate a number of oxidants. Unless these oxidants are reduced, oxidative damage and cell death would occur. Oxidation of plasma membrane lipids leads to autocatalytic chain reactions which eventually alter the permeability of the cell. The role of oxidative damage in the pathophysiology of diabetic complications and ischemic reperfusion injury of myocardium, especially the changes in the channel activity which may lead to arrhythmia have been studied. Hyperglycemia activates aldose reductase which could efficiently reduce glucose to sorbitol in the presence of NADPH. Since NADPH is also aldose required by glutathione reductase for reducing oxidants, its diversion would lead to membrane lipid oxidation and permeability changes which are probably responsible for diabetic complications such as cataractogenesis, retinopathy, neuropathy etc. Antioxidants such as butylated hydroxy toluene (BHT) and also reductase inhibitors prevent or delay some of these complications. By using patch-clamp technique in isolated frog myocytes, we have shown that hydroxy radicals generated by ferrous sulfate and ascorbate as well as lipid peroxides such as t-butyl hydroperoxide facilitate the entry of Na+ by oxidizing Na+-channels. Increased intracellular Na+ leads to an increase in Na+/Ca2+ exchange. The increased Na+ concentration by itself may produce electrical disturbance which would result in arrhythmia. Increased Ca2+ may affect proteases and may help in the conversion of xanthine dehydrogenase to xanthine oxidase, consequently increased production of super oxide radicals. Increased membrane lipid peroxidation and other oxygen free-radical associated membrane damage in myocytes has been demonstrated.

Interaction of (Na + K + 2 Cl) cotransport and the Na/K pump in cultured chick cardiac myocytes

We have recently reported the presence of an electroneutral (Na + K + 2 Cl) cotransport mechanism that is bumetanide-sensitive and maintains Cli above its electrochemical equilibrium in cultured chick heart cells. In steady state, (Na + K + 2 Cl) cotransport is inwardly directed and so contributes to the Na influx that must be counterbalanced by the activity of the Na/K pump to maintain Nai homeostasis. We now show that manipulating (Na + K + 2 Cl) cotransport by restoring Clo to a Cl-free solution indirectly influences Na/K pump activity because the bumetanide-sensitive recovery of aiNa to its control level and the accompanying hyperpolarization could be blocked by 10(-4)M ouabain. In another protocol, when the Na/K pump was reactivated by restoring Ko (from 0.5 mM to 5.4 mM) and removing ouabain, the recovery of aNa was attenuated by 10(-4)M bumetanide. The relatively slow rate of ouabain dissociation coupled with the activation of Na influx by (Na + K + 2 Cl) cotransport clearly establishes the interaction of these transport mechanisms in regulating Nai. Although (Na + K + 2 Cl) cotransport is electroneutral, secondary consequences of its activity can indirectly affect the electrophysiological properties of cardiac cells.

Quantitative measurements of hip strength in different age groups

The purpose of this study was to develop a clinically useful method of assessing the strength of the hip musculature and to develop a normal data base with this technique. The strength of 72 subjects aged 20-81 years (37 women and 35 men) was measured through the use of a modified Cybex II with an upright stabilization frame for testing sagittal and frontal plane motions; transverse plane motions of internal and external rotation were tested in the seated position. The subjects were tested at multiple isokinetic speeds and isometric angles. Regardless of age or gender, hip extensors were the strongest muscle group, following by flexors, adductors, abductors, and rotators. As the velocity of exercise increased, the magnitude of the torques produced decreased. Demographically, younger men produced the greatest torques and older women the lowest. The strength values of older men and younger women were similar. The results have clinical implications for objective assessment of strength in pathologic patient populations.

Optoelectronic multiple-valued logic implementation

A design for optoelectronic multiple-value logic circuits that uses bistable laser diodes or light-emitting diodes is reported. In this multiple-valued logic design, an optoelectronic tristable switching circuit, or light-current mirror, in which two bistable light-emitting diodes are connected in parallel serves as the basic logic element. Five ternary logic implementations: Complement. Max(x, y), Min(x, y), Cycle, and Literals, have been demonstrated experimentally. Furthermore, any ternary logic function can be generated with the light-current mirror and the logic primitives.

Antigenic differences between metastatic and nonmetastatic BSp73 rat tumor variants characterized by monoclonal antibodies

Variants AS and ASML of the BSp73 rat tumor differ markedly with respect to morphology and to the capacity for spontaneous metastasis via the lymphatics. Monoclonal antibodies (MAbs) were raised in order to identify surface molecules associated with both phenotypes. Mice were immunized with either whole cells or isolated membranes and hybridoma supernatants were screened according to the criteria of selective binding to cultured cells of the variant used for immunization. Of two MAbs reacting with the nonmetastasizing AS variant, one showed immunostaining of AS tissue. From 11 MAbs binding to the metastatic ASML variant, 6 showed specific staining of ASML tissue, while the remaining 5 MAbs showed cross-reaction with normal rat tissues. According to Western blot data, the 6 MAbs selectively binding to ASML tissue identified at least 2 different antigens, one of them showing up as a complex of 12 bands.

[Effects of elevated intraocular pressure on the morphology and function of the corneal endothelium in rabbits]

The intraocular pressure in 40 rabbits (80 eyes) was experimentally raised by injection of balanced salt solution into posterior vitreous. The corneal endothelia were studied by slit-lamp, vital staining, compound staining, electron microscopy and corneal pachymetry. The results indicated that elevation of intraocular pressure induced morphological changes and functional disorders of the corneal endothelium in rabbits. The mechanism involved was discussed.

The relationship of substance P-immunoreactive nerve fibers to thyrotropes and corticotropes in the pars distalis of the anterior pituitary in the monkey

In our previous studies substance P-immunoreactive nerve fibers have been demonstrated in the pars distalis of the anterior pituitary in macaque monkeys, and they have been found to contact somatotropes. The present study investigated the relationship of the substance P-immunoreactive fibers to thyrotropes and corticotropes. Macaca mulatta monkeys were used. Sections of the anterior pituitaries were double immunostained with antisera against either substance P and human thyrotropin or substance P and human adrenocorticotropic hormone. Substance P-immunoreactive varicosities were found to be in close proximity to thyrotropes and corticotropes. It is therefore suggested that a direct neural factor may take part in the regulation of thyrotropin and adrenocorticotropic hormone secretion.

In vitro synergy studies with ciprofloxacin and selected beta-lactam agents and aminoglycosides against multidrug-resistant Pseudomonas aeruginosa

In order to determine the effect of combining ciprofloxacin with beta-lactam and aminoglycoside agents against multidrug-resistant P. aeruginosa, ciprofloxacin was tested in vitro with the checkerboard broth microdilution technique with various current beta-lactam and aminoglycoside agents. In both inhibitory and bactericidal testing, the combination of ciprofloxacin with a beta-lactam agent (ceftazidime, piperacillin, mezlocillin, azlocillin, or imipenem) was more likely to show a synergistic effect or additive effect and lack of antagonism (96.5% of all inhibitory and cidal tests) than was a combination of ciprofloxacin with an aminoglycoside [(amikacin, tobramycin, or gentamicin), 90% of all inhibitory and cidal tests]. Finding of antagonism in some testing, especially with aminoglycosides, indicates that results are unpredictable. These results may influence selection of agents for selection in clinical situations.

Fish oil and tocopherol-induced changes in natural killer cell-mediated cytotoxicity and PGE2 synthesis in young and old mice

Natural killer cell (NK) activity decreases and prostaglandin E2 (PGE2) level increases in aged mice. Because PGE2 is involved in control of NK activity this study was conducted to investigate whether or not decreasing PGE2 level by changing the type of dietary fat or increasing the level of vitamin E (vit. E) modulates NK activity of young and old mice. Mice were fed either a corn oil (CO) or a fish oil (FO) diet supplemented with 30 or 500 mg/kg diet of vit. E for 6 wk. To study the effect of vit. E during active immune response and oxidative stress, groups of old mice fed CO and either 30 or 500 mg/kg diet of vit. E were injected with sheep red blood cells (SRBC) prior to assessment of their NK activity. As reported by others regarding mice fed a nonpurified diet, the old mice in all dietary groups had significantly less NK activity and tended to synthesize more PGE2 than young mice. FO-fed mice synthesized less PGE2 than CO-fed mice; however, their NK activity was not higher than that of CO-fed mice. By contrast young mice fed FO had a moderately lower NK activity than those fed CO. Vit. E supplementation did not change NK activity in nonimmunized mice but was effective in preventing SRBC-induced decrease in NK activity of old mice.

Genetics of susceptibility to 6-aminonicotinamide-induced cleft palate in the mouse: studies in congenic and recombinant inbred strains

In a search for genetic differences in susceptibility to cleft palate, congenic and recombinant inbred strains of mice were treated with 6-aminonicotinamide or control injections. Of six loci tested, only the chromosome segment marked by N-acetyl transferase was found to affect susceptibility to 6-aminonicotinamide-induced cleft palate. This chromosome segment is known to affect glucocorticoid-induced cleft palate and phenytoin-induced cleft lip with or without cleft palate in these strains of mice.

(Na + K + 2Cl) cotransport in cultured embryonic chick heart cells

The coupled movements of Na, K, and Cl were studied in cultured chick embryonic heart cells using ion-selective microelectrodes. Movements of K and Cl in response to changes in extracellular [K] ([K]o) showed a furosemide-sensitive coupled process. The movement of Na was then studied. Lowering extracellular [Na] ([Na]o) to 27 mM caused a decrease in intracellular Cl activity (aicl). Upon restoring [Na]o to 143 mM, Cl was taken up against its electrochemical gradient (delta mu Cl). In Cl-free solution, cells lost Na against delta mu Na and simultaneously lost Cl. Upon restoring extracellular [Cl] ([Cl]o), Cl was taken up against delta mu Cl; this was accompanied by an uptake of Na. The Cl uptake was 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS)-insensitive (0.1 mM) but inhibited by removing Nao. Both Cl and Na uptakes were potentiated by raising [K]o from 5.4 to 15 mM, and Na uptake was diminished by lowering [K]o to 1 mM. In all experiments, Cl and Na movements were furosemide (0.3 mM) or bumetanide-sensitive (0.1 mM). Removal of Nao, with resultant depletion of intracellular [Na] ([Na]i), blocked the furosemide or bumetanide-sensitive Cl loss or uptake upon exposure to zero or 133 mM [K]o + SITS (0.1 mM), respectively. These results suggest that cultured heart cells possess an electroneutral (Na + K + 2Cl) cotransport.

Disposition of levobunolol after an ophthalmic dose to rabbits

The ocular and systemic disposition of levobunolol (LBUN), an antiglaucoma agent, was studied in albino rabbits. After topical administration to eyes, LBUN was rapidly adsorbed, with 2.5% of the dose bioavailable to the intraocular tissues as intact drug and 46% to the systemic circulation. On passage across the cornea, approximately 4.7% of a topically applied LBUN dose was biotransformed to dihydrolevobunolol (DHB), and subsequently became bioavailable to intraocular tissues. The major sites of ocular metabolism were the cornea epithelium and the iris-ciliary body. Another 12% of the topical LBUN dose entered the systemic circulation as DHB after presystemic biotransformation. Our study indicated a rapid absorption of LBUN into the aqueous humor after topical dosing. The tpeak was 15 min after dosing and the Cmax was 4 micrograms/mL. Dihydrolevobunolol (DHB) was formed steadily and reached a maximum in the aqueous humor 45 min after dosing. After distribution equilibrium had been reached, the aqueous humor concentrations of both LBUN and DHB declined. Six hours after dosing, the concentration of DHB in the aqueous humor was approximately 10 times higher than that of its parent compound. Because DHB is equivalent to its parent compound in beta-blocking activity, its formation in the rabbit eye may contribute to the pharmacodynamic effects observed after topical doses of LBUN.

Relationship between the ocular and systemic disposition of flurbiprofen: the effect of altered protein dynamics at steady state

The differences in flurbiprofen disposition in the aqueous humor and the plasma were examined after systemic doses. Steady state plasma concentrations of flurbiprofen (20-60 micrograms/mL) were achieved via intravenous infusion to albino rabbits. Flurbiprofen demonstrated linear systemic kinetics throughout the dosing range, with constant body clearance and unbound fraction in plasma. At steady state, aqueous humor drug concentrations depended on the corresponding plasma drug concentration. Two clearance terms--CLS----O, the systemic clearance to ocular tissues, and CLO----S, the ocular clearance to systemic circulation--were used. After systemic doses, the drug concentration in the aqueous humor was related to that in the plasma as well as to the ratio of these two clearances. Flurbiprofen was extensively bound to plasma proteins and showed limited ocular distribution; its CLS----O to CLO----S ratio was very small. Thus, the concentration of flurbiprofen in the aqueous humor after systemic doses was lower than that obtained after ophthalmic doses. A plasmapheresis technique was utilized to lower the plasma protein concentrations to 60% of normal levels. As a consequence, flurbiprofen demonstrated reduced aqueous humor protein concentrations, increased unbound fractions in the plasma and the aqueous humor, elevated aqueous humor drug concentrations, and elevated total body clearance. The unbound body clearance stayed unchanged. Our study indicated that a drug should present a significant CLS----O/CLO----S ratio in order to achieve therapeutic concentrations in the eye via systemic doses. The drug-protein binding kinetics can be different between the plasma and the aqueous humor circulations. Because the ocular compartment is very small compared to the overall systemic distribution of flurbiprofen, it has little effect on the steady state systemic concentrations.

Electrogenic sodium-calcium exchange in cultured embryonic chick heart cells

1. The membrane potential (Em) of cultured chick embryonic heart cells depolarized to -36 mV after inhibition of the Na+-K+ pump by 0.1 mM-ouabain in a [K+]o of 24 mM: this was accompanied by a rise in Na+ content of approximately 65% in 3 min. Lowering [Na+]o to 27 mM then caused a fall in Na+ content, a rise in Ca2+ content and a small hyperpolarization of approximately 5 mV. The fall in Na+ content indicated a movement of Na+ which was in the opposite direction to the Na+ electrochemical gradient (a countergradient movement). 2. In the presence of 10 mM-Cs+ or 1 mM-Ba2+ the hyperpolarization was approximately 10 or approximately 30 mV, respectively. A 30 mV hyperpolarization took Em negative to the reversal potentials for K+, and Cl- as measured by ion-selective micro-electrodes. 3. The decay of the intracellular Na+ activity alpha iNa, in an [Na+]o of 27 mM followed a simple exponential time course (time constant, 36 s). The initial rate depended on the value to which [Na+]o was lowered in a manner suggesting a simple competitive inhibition of the exchange by external Na+. 4. The low-[Na+]o hyperpolarization was unaffected by amiloride (0.1 or 1 mM) or verapamil (20 microM). Both La3+ (1 mM) and Mn2+ (20 mM) blocked the hyperpolarization sufficiently to prevent Em hyperpolarizing negative to the reversal potentials for K+, Na+ and Cl-. 5. Re-establishing [Na+]o caused a rise in Na+ content and a countergradient drop in Ca2+ content. The effects of verapamil (20 microM), amiloride (0.1 and 1 mM), dichlorobenzamil (0.1 mM), quinidine (1 mM), Mn2+ (20 mM) and La3+ (1 mM) were tested on the movements of Na+ and Ca2+ both during exposure to an [Na+]o of 27 mM and on re-establishing [Na+]o. The only consistent and substantial effects were the attenuation by La3+ and Mn2+ and Ca2+ movements during exposure to an [Na+]o of 27 mM. However, neither La3+ nor Mn2+ affected the movements of Na+ and Ca2+ on re-establishing [Na+]o. 6. We conclude that cultured embryonic chick heart cells contain a Na+-Ca2+ exchange evidenced by the ability to cause movements of Na+ and Ca2+ which are counter to their respective electrochemical gradient and which are accompanied by downhill movements of the counter ion.(ABSTRACT TRUNCATED AT 400 WORDS)

Persistence of serum hepatitis B virus deoxyribonucleic acid in hepatitis B surface antigen-positive patients with chronic persistent hepatitis treated with prednisone

The effect of a short course of prednisone therapy was evaluated in 8 patients with liver biopsy-verified chronic persistent hepatitis B. In 6 of the 8 (75%) patients, an abrupt fall in serum alanine aminotransferase levels after the initiation of prednisone was noted, and in 4 patients, there was an increase in serum alanine aminotransferase values after prednisone was discontinued. However, the serum levels of hepatitis B virus deoxyribonucleic acid were consistently greater than or equal to 200 pg before, during, and after the course of treatment in 7 of the 8 (87.5%) patients. All patients were initially hepatitis B e antigen-positive and remained so during the study period. These findings indicate that, unlike some patients with chronic active hepatitis B, immunosuppression with prednisone had no effect in altering hepatitis B viral replication in patients with chronic persistent hepatitis.

Determination of the effect of antimicrobics in combination against Listeria monocytogenes

The in vitro activity of selected penicillins, extended spectrum cephalosporins, vancomycin, gentamicin, erythromycin, tetracycline, rifampin, and trimethoprim and sulfamethoxazole (alone and in combination) was determined by microtiter technique for 20 isolates of Listeria monocytogenes. The activity of selected combinations of antimicrobics was determined by the microtiter checkboard technique. Trimethoprim-sulfamethoxazole (1:20 ratio) was the most active agent in inhibitory tests and also showed bactericidal activity. The combinations of gentamicin with either ampicillin or vancomycin and that of erythromycin with tetracycline showed bactericidal effect in synergy studies. Combining ampicillin with an extended spectrum cephalosporin showed no antagonism, whereas, combining rifampin with trimethoprim or with trimethoprim/sulfamethoxazole led only to indifference or antagonism. These observations may have importance in selection of therapy in animal models or in selected clinical situations.