(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.

Susceptibility to phenytoin-induced cleft lip with or without cleft palate: many genes are involved

In a search for genetic differences in susceptibility to cleft lip with or without cleft palate [CL(P)], congenic and recombinant inbred strains of mice were treated with phenytoin or control injections. Of six loci tested, five were found to affect susceptibility to phenytoin-induced and/or sporadic CL(P): (1) the major histocompatibility locus,H-2; (2) the locus controlling β2-microglobulin,B2m; (3) a locus controlling β-glucuronidase,Gus; (4) the locus controllingN-acetyl transferase,Nat; and (5) the locus for brown pigmentation,b. B2mandGusonly affected the sporadic incidence of CL(P), while theblocus only affected phenytoin-induced incidence of CL(P). Three of these loci are also known to affect glucocorticoid-induced isolated cleft palate (CP), but different alleles of the loci are involved. Phenytoin did not affect levels of adenosine 3′,5′-cyclic monophosphate (cAMP) in palates and tongues of day 15 fetuses. A comparison of glucocorticoid receptor parameters with the incidence of phenytoin-induced CL(P) found no correlation.

Infant's apnea, bradycardia and tachycardia monitor based on the Z-80 microprocessor

Home monitoring has been increasingly adopted by pediatricians to help in the prevention of sudden infant death syndrome. The home monitor can be made reliable, easy to operate, inexpensive, and capable of data storage. This can be done by using a microprocessor and a minimum number of integrated circuit chips. Simple real-time algorithm's and digital hardware have been developed to achieve this goal.

Projections from the hypothalamus and its adjacent areas to the posterior pituitary in the rat

Cholera toxin conjugated horseradish peroxidase was injected into the posterior pituitary and its afferents traced in 21 albino rats. The neuronal processes as well as the perikarya were elaborately displayed. The principal and retrochiasmatic supraoptic nuclei and the magnocellular paraventricular subnuclei were densely labelled. The accessory cell groups or nuclei labelled included: the medial preoptic and anterior hypothalamic areas, the anterior and posterior fornical nuclei, the lateral hypothalamic area, the nucleus circularis and nucleus of the forebrain bundle and hitherto unknown or not fully appreciated retrochiasmatic area, the dorsal accessory groups in an area between the stria medullaris and fornix, on the one hand, and the stria terminalis and internal capsule, on the other, and a well developed subependymalperiventricular zone. The medial preoptic nucleus, subfornical organ and organ vasculosum laminae terminalis were also weakly stained. Dendrites of the magnocellular paraventricular nucleus have been said by some to be largely confined to the subnuclei in which they lie. Immunohistochemical studies have proved that they extended beyond their nuclear confinement. The present study has found much wider extension of their dendritic fields. In fact, dendrites of the magnocellular neurosecretory cells in general were long and had a certain degree of directional bias. Several sites projecting to the posterior pituitary were closely related to the cerebrospinal fluid. Namely, the subependymal neuronal plexuses along the third ventricle and beneath the interventricular foramen, and the subpial dendritic plexuses of the supraoptic and retrochiasmatic supraoptic nuclei. Neurons were seen to squeeze in-between the ependymal cells, bringing themselves very close to the cerebrospinal fluid. No direct cerebrospinal fluid-contacting elements, either cell bodies or processes, however, could be ascertained. It is proposed that these plexuses may monitor changes in the cerebrospinal fluid. Besides the principal neurohypophysial tract the posterior pituitary was found in the present study to receive its afferents via two accessory fasciculi, one coursing in the medial forebrain bundle and the other running along the lateral wall of the infundibular recess subependymally.

The orbitozygomatic infratemporal approach: a new surgical technique

Lesions in the parasellar region and the interpeduncular fossa, including medial-third sphenoid wing meningiomas, petroclival meningiomas, trigeminal neurinomas, and basilar tip aneurysms, are very difficult to approach for radical procedures. To minimize brain retraction and achieve excellent exposure in the shortest possible distance for safe manipulation within these regions, the authors have developed a new surgical technique, an orbitozygomatic infratemporal approach. Sixteen patients with parasellar tumors, nine patients with basilar tip aneurysms, and one patient with a P-1 distal aneurysm were operated on using this orbitozygomatic infratemporal approach, with excellent results. The operative technique and its results are detailed.

Normal human neutrophils are a source of a specific interleukin 1 inhibitor

In the course of our study on neutrophil production of an interleukin 1 (IL-1)-like factor, we found that the addition of polymorphonuclear neutrophils (PMN) to monocytes cultured in the presence of zymosan resulted in decreased IL 1 activity of the resultant supernatant, suggesting that PMN may contain an inhibitor of IL 1. The objective of this investigation was to study this IL 1 inhibitor which normal human PMN contain. The inhibitor is constitutively present in the PMN because 0 hr PMN lysates and unstimulated PMN supernatants also show inhibitory activity. The PMN inhibitor inhibits IL 1 (crude and partially purified) in a dose-response manner and does not affect basal [3H]thymidine incorporation in the presence or absence of PHA-P. The PMN inhibitor does not have any effect on interleukin 2 (IL 2)-induced proliferation of the IL 2-dependent CTLL cells. The inhibitor can be generated in the absence of serum and is not produced as a result of proteolytic activity from PMN enzymes. The inhibitor is heat-labile and is most stable at neutral pH. Gel filtration studies on Sephadex G-200 indicate that the inhibitor is heterogeneous in size. Two inhibitory peaks, at 45,000 to 70,000 m.w. and at greater than 160,000 m.w., were observed. When zymosan-stimulated PMN supernatant was chromatographed, there was separation of inhibitory factor from a 17,000 m.w. proliferating factor. Presence of this PMN inhibitor may be important in negative regulation of IL 1.

Normal human neutrophils are a source of a specific interleukin 1 inhibitor

In the course of our study on neutrophil production of an interleukin 1 (IL-1)-like factor, we found that the addition of polymorphonuclear neutrophils (PMN) to monocytes cultured in the presence of zymosan resulted in decreased IL 1 activity of the resultant supernatant, suggesting that PMN may contain an inhibitor of IL 1. The objective of this investigation was to study this IL 1 inhibitor which normal human PMN contain. The inhibitor is constitutively present in the PMN because 0 hr PMN lysates and unstimulated PMN supernatants also show inhibitory activity. The PMN inhibitor inhibits IL 1 (crude and partially purified) in a dose-response manner and does not affect basal [3H]thymidine incorporation in the presence or absence of PHA-P. The PMN inhibitor does not have any effect on interleukin 2 (IL 2)-induced proliferation of the IL 2-dependent CTLL cells. The inhibitor can be generated in the absence of serum and is not produced as a result of proteolytic activity from PMN enzymes. The inhibitor is heat-labile and is most stable at neutral pH. Gel filtration studies on Sephadex G-200 indicate that the inhibitor is heterogeneous in size. Two inhibitory peaks, at 45,000 to 70,000 m.w. and at greater than 160,000 m.w., were observed. When zymosan-stimulated PMN supernatant was chromatographed, there was separation of inhibitory factor from a 17,000 m.w. proliferating factor. Presence of this PMN inhibitor may be important in negative regulation of IL 1.

In vitro activity of aryl fluoroquinolones, Abbott 56619 and Abbott 56620, compared to ciprofloxacin, norfloxacin and beta-lactams versus multidrug-resistant Enterobacteriaceae and Pseudomonas aeruginosa

The new aryl fluoroquinolones, Abbott 56619 and Abbott 56620, were compared to ciprofloxacin, norfloxacin and newer beta-lactam agents in standardized microtiter testing versus multidrug-resistant gram-negative bacilli. Ciprofloxacin, followed by Abbott 56620, was generally the most active quinolone and imipenem the most active beta-lactam agent.

Isolation of feline rotaviruses and their relationship to human and simian isolates by electropherotype and serotype

Rotaviruses were detected by electron microscopy in the faecal specimens of six clinically well cats and virus was subsequently isolated from four of them. Analysis of the RNA of the isolates showed the existence of three electrophoretic types characteristic of the 'long' RNA electrophoretic pattern exhibited by rotaviruses. All feline isolates were neutralized only by antiserum to SA11 rotavirus, indicating that these isolates were serotype 3 rotaviruses. Antiserum prepared against a feline strain neutralized all the feline isolates as well as SA11 but showed no neutralizing activity against human isolates of serotype 1, 2 or 4.

Class II histocompatibility antigen-mediated immunologic function of normal articular chondrocytes

Using monoclonal antibodies, we examined the display of rabbit Ia by articular chondrocytes. We found that 29 to 46% of chondrocytes displayed Ia antigen compared with 46 to 60% of spleen cells. Ia antigen expression was not likely to be the result of enzyme treatment. To investigate antigen presenting activity of enzyme dissociated normal articular chondrocytes, adult rabbits were immunized in the front foot pads with ovalbumin (OVA) in complete Freund's adjuvant. Four to six weeks later, draining popliteal lymph node cells (LNC) were obtained. Articular chondrocytes were obtained by overnight collagenase, DNase, and hyaluronidase digestion of cartilage from both ends of femurs and proximal end of tibias. Antigen-presenting cells from spleen were used as positive controls. LNC and nylon wool-purified T cells were cultured with OVA pulsed and mitomycin C-treated chondrocytes or spleen cells, and lymphocyte proliferation was measured by 3H-TdR uptake. Both chondrocytes and spleen cells showed antigen presenting activity, and stimulation of lymphocyte proliferation was inhibited by murine monoclonal anti-rabbit Ia antibody (2C4), whereas control plasmacytoma cell supernatants had no effect. When T cells were purified first by Sephadex G-10 and later by nylon wool columns, these cells were dependent on antigen-presenting cells for immunogen (OVA)-induced lymphocyte proliferation. Again, chondrocytes under these strict experimental conditions presented antigen to T cells. Chondrocytes also stimulated autologous and allogeneic normal lymphocytes. Thus, normal chondrocytes have Ia antigens on their surface and can function as antigen-presenting cells. These results are significant for the understanding of local cellular interaction in the pathogenesis of rheumatoid arthritis.

Class II histocompatibility antigen-mediated immunologic function of normal articular chondrocytes

Using monoclonal antibodies, we examined the display of rabbit Ia by articular chondrocytes. We found that 29 to 46% of chondrocytes displayed Ia antigen compared with 46 to 60% of spleen cells. Ia antigen expression was not likely to be the result of enzyme treatment. To investigate antigen presenting activity of enzyme dissociated normal articular chondrocytes, adult rabbits were immunized in the front foot pads with ovalbumin (OVA) in complete Freund's adjuvant. Four to six weeks later, draining popliteal lymph node cells (LNC) were obtained. Articular chondrocytes were obtained by overnight collagenase, DNase, and hyaluronidase digestion of cartilage from both ends of femurs and proximal end of tibias. Antigen-presenting cells from spleen were used as positive controls. LNC and nylon wool-purified T cells were cultured with OVA pulsed and mitomycin C-treated chondrocytes or spleen cells, and lymphocyte proliferation was measured by 3H-TdR uptake. Both chondrocytes and spleen cells showed antigen presenting activity, and stimulation of lymphocyte proliferation was inhibited by murine monoclonal anti-rabbit Ia antibody (2C4), whereas control plasmacytoma cell supernatants had no effect. When T cells were purified first by Sephadex G-10 and later by nylon wool columns, these cells were dependent on antigen-presenting cells for immunogen (OVA)-induced lymphocyte proliferation. Again, chondrocytes under these strict experimental conditions presented antigen to T cells. Chondrocytes also stimulated autologous and allogeneic normal lymphocytes. Thus, normal chondrocytes have Ia antigens on their surface and can function as antigen-presenting cells. These results are significant for the understanding of local cellular interaction in the pathogenesis of rheumatoid arthritis.

Retrograde amnesia effects of intravenous diazepam in endoscopy patients

The presence of a retrograde amnesia, when caused by medications given prior to a medical procedure, can pose the medicolegal question of informed consent. This study investigated the retrograde amnesic effects of intravenous diazepam administered prior to gastrointestinal endoscopy. No significant retrograde amnesia was found in case subjects when compared with controls.

Radioimmunofocus assay for detection and quantitation of human rotavirus

A radioimmunofocus assay suitable for quantitation of cell culture-adapted human rotavirus was developed. The method was reproducible, more sensitive than plaque assay, and useful to detect and quantify strains of rotavirus which do not produce plaques. Preliminary results also suggested that the technique will be a useful means of serotyping cell culture-adapted strains of the virus.