Effect of TEA on light emission from aequorin-injected aplysia central neurons

Aplysia central neurons were injected with the calcium-sensitive photoprotein aequorin and stimulated with trains of identical depolarizing voltage-clamp pulses. The light emissions grew and the outward currents declined in successive pulses. Tetraethylammonium (TEA) enhanced the light emissions to single depolarizing pulses and suppressed the outward current. The remaining net inward current is carried primarily by calcium ions and does not facilitate. The aequorin emissions were larger at all amplitudes of depolarizing pulses that elicited emissions, and the facilitation of emissions in a train of pulses was reduced. The effect of TEA on outward current was nearly maximal when sodium ions were partially replaced with 0.1 M TEA, while the aequorin emissions were further enhanced by increasing the TEA concentration to 0.459 M. TEA enhanced the aequorin emissions at all voltages. These observations suggest that the action of TEA on aequorin emissions is not strictly a consequence of its better known outward current blocking action. The effects of TEA could be partly due to the lowered sodium concentration of these solutions. Replacement of sodium by Tris, sucrose or mannose, however, all produced no enhancement of emissions. Tetramethylammonium (TMA) replacement of sodium had effects similar to those of TEA. Thus TEA and TMA appear to have a specific effect. Part of the enhancement of light emissions by TEA is due to the removal of a series resistance error in the voltage clamp, and this may also account partly for the reduced facilitation of aequorin emissions in TEA. The remainder of the action of TEA on aequorin emissions evidently reflects a specific but previously unrecognized action on the cellular metabolism of calcium ions or on the voltage-dependent calcium channels.

Current-voltage relationships of repetitively firing neurons

The current-voltage curves of repetitively firing neurons show non-linearities in the subthreshold region. Microsurgically isolated molluscan neuron somata were studied under voltage clamp using ramp voltage command signals. During the depolarizing 1/2 cycle a region of negative slope conductance was observed. Ion substitution experiments suggest that this results from non-inactivating or slowly inactivating Na+ and Ca2+ currents. The hyperpolarizing 1/2 cycle reveals a hysteresis effect which results at least in part from a Ca2+ activated 5+ current. Similar characteristics have been described in bursting neurons. Their occurrence in the non-bursting neurons studied here shows that they are not unique to this class of neurons and suggests that their primary contribution is to create electrical instability necessary for repetitive firing.

Treatment of cervical intraepithelial neoplasia with the carbon dioxide laser beam. A preliminary report

Forty-five patients with histologically proved cervical dysplasia or carcinoma in situ were treated by the carbon dioxide-laser method. The carbon dioxide laser induces cell vaporization by causing intracellular steam combustion stimulated by the emission of a mixture of carbon dioxide, nitrogen, and helium. This method of treatment is easily performed in the outpatient clinic without anesthesia, is inexpensive, and is effective in the treatment of cervical intraepithelial neoplasia. The treatment allows preservation of the transformation zone, thus permitting future colposcopic visualization.

Regulation of pyruvate dehydrogenase activity in rat epididymal fat-pads and isolated adipocytes by adrenaline

1. Dose-dependent effects of adrenaline on PDHa activity were investigated with both incubated rat epidiymal fat-pads and isolated adipocytes. 2. Adrenaline (10nM- 5 micrometer) decreased PDHa activity in fat-pads incubated with 5 mM-[U-14C]glucose + insulin (20 munits/ml). Changes in [U-14C]glucose incorporation into fatty acids in these tissues correlated only loosely with changes in PDHa activity. There was a good inverse relationship between adrenaline-induced changes in PDHa activity and increases in lipolysis (glycerol release). 3. Adrenaline (10nM - 0.5 micrometer) decreased PDHa activity in fat-pads incubated with 5 mM-[U-14C]pyruvate + insulin (20 munits/ml), whereas 1 micrometer- and 5 micrometer-adrenaline slightly increased PDHa activity. All concentrations of adrenaline tested decreased [U-14C]pyruvate incorporation into fatty acids. Between 10nM- and 0.5 micrometer-adrenaline percentage decreases in PDHa activity paralleled decreases in faty acid synthesis. 4. Effects of adrenaline on PDHa activity and fatty acid synthesis in fat-pads incubated with 5mM-[U-14C]pyruvate + insulin (20 munits/ml) could not be mimicked by addition of albumin-bound palmitate. 5. The response of PDHa activity to adrenaline (0.1 nM - 1 micrometer) in isolated adipocytes differed with the carbohydrate substrate used in the incubations. With 5 mM-glucose + insulin (20 munits/ml), PDHa activity was significantly increased by 10 nM-adrenaline, but not by 1 micrometer-adrenaline, the response to adrenaline being biphasic. There was some correlation between PDHa activity and accumulation of non-esterified fatty acids. With 5 mM-glucose alone adrenaline (0.1 nM - 1 micrometer) had no effect on PDHa activity even though lipolysis was increased by adrenaline (0.1 micrometer - 1 micrometer). With 5mM-fructose in the presence and absence of insulin, lipolytic doses of adrenaline decreased PDHa activity. No tested concentrations of adrenaline increased PDHa with this substrate. 6. In the presence of 5 mM-fructose, palmitate was significantly more effective than adrenaline with respect to the maximum decrease in PDHa activity that could be elicited. 4. The relationship of changes in PDHa activity to changes in lipogenesis and the likelihood of adrenaline-induced changes in PDHa activity being secondary to changes in non-esterified fatty acid metabolism are discussed.

Lowering of serum 3,3',5-triiodothyronine thyroxine ratio in patients with myocardial infarction; relationship with extent of tissue injury

Serial measurements of haematocrit (Ht), plasma thyroxine (T4), triiodothyronine (T3) and alpha-hydroxybutyrate dehydroxygenase (alpha-HBDH) were performed in patients following myocardial infarction (MI). Infarct size was estimated by mathematical analysis of the change in plasma alpha-HBDH activity with time. After an initial small increase Ht decreased 12% until day 9 and remained constant thereafter. Serum T4 did not change during the entire study. Serum T3 decreased to 66% at day 9 and then returned to normal within 2 months. These figures are expressed relative to determinations in the first blood sample obtained within 12 h after MI. A significant correlation between the lowest serum T3/T4 ratio and infarct size was observed. These observations suggest that in these patients the peripheral conversion of T4 into T3 is reduced. This was accompanied by an increased production of reverse T3 as evidenced by observations in one patient.

Acute-phase proteins from the liver and enzymes from myocardial infarction; a quantitative relationship

In 14 patients with acute myocardial infarction (M.I.) not having any other disease, the possible quantitative relationship between enzymes from M.I. and changes in concentration of acute phase reactants coming from the liver were studied. The patients were followed up until 1 1/2 years after M.I. and comparison of baseline-protein values took place using a control group of 18 healthy individuals. Quantitation of protein changes was done by planimetric determination of the area under the concentration curve and by taking peak values. The myocardial infarction was quantitatively estimated by mathematical analysis of the time course of alpha-hydroxybutyrate dehydrogenase (alpha-HBDH) plasma concentrations and by taking peak values. A quantitative relationship with enzymatic infarct size was found for haptoglobin, alpha1-acid glycoprotein, alpha1-antitrypsin, C-reactive protein, fibrinogen and E.S.R. Albumin and transferrin did not show a negative quantitative relationship with enzymatic infarct size. Humoral factors originating from the site of tissue injury and evoking in proportion a positive acute phase reaction by the liver are probably the basis for this observed quantitative relationship.

Decreased sensitivity to insulin in white adipose tissue from adrenalectomised rats

The ability of insulin to increase both [14C]-glucose incorporation into fatty acids and pyruvate dehydrogenase activity in incubated rat epididymal adipose tissues was considerably lessened after adrenalectomy. Insulin antagonism of adrenaline-stimulated lipolysis in isolated fat cells was abolished after adrenalectomy. Percentage stimulation of lipolysis above basal by adrenaline was not appreciably altered by adrenalectomy.

Secondary neoplasms of the small bowel

Patterns of small bowel involvement from primary neoplasms elsewhere in the body were studied in order to determine whether the location of the lesions or their radiological appearance could provide criteria for distinguishing secondary from primary lesions. Multiplicity of lesions and the finding of "transverse stretch" were found to be highly indicative of secondary neoplastic involvement of the small bowel.

High-performance liquid chromatographic determination of chlordiazepoxide and major related impurities in pharmaceuticals

A rapid, precise, forward-phase (adsorption) high-performance liquid chromatographic procedure is presented for the determination of chlordiazepoxide and two common impurities, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide and 2-amino-5-chlorobenzophenone, in commercial formulations and for the determination of the benzophenone in the chlordiazepoxide drug substance. The method involves simultaneous quantitation of chlordiazepoxide and the 1,3-dihhydro impurity, followed by quantitation of the benzophenone from a separate sample extract using a second mobile phase. A single microparticulate silica gel column is used throughout. Nitrazepam and o-dinitrobenzene are the internal standards, Quantitation is by peak area using a computing integrator, except that the peak due to the benzophenone is quantitated by peak height. The described procedure is of equivalent precision, but superior accuracy, to the BP 1973 spectrophotometric procedure for the analysis of chlordiazepoxide in chlordiazepoxide formulations. Quantitation of the 1,3-dihydro and the benzophenone impurities at levels as low as 6.3 and 0.9 ng, respectively, is demonstrated.

Liver reaction to tissue injury: do therapeutic measures trigger the acute phase reaction?

In 30 healthy people we investigated the hypothesis that therapeutic measures trigger the acute phase reaction. In order of severity we analyzed: (1) the effects of an intramuscular injection of 2.5 ml 0.14 molar NaCl (6 patients), (2) the effects of an indwelling venous catheter for 24 h (7 patients), and for 72 h (8 patients), (3) the effects of cardiac catheterization (arterial and venous catheterization) carried out in 9 patients. In clinical investigations of the acute phase reaction, an intramuscular injection and a 24- or 72-h indwelling catheter, brought in by venipuncture, are acceptable because they do not provoke an acute phase reaction. A venous cutdown associated with an arterial puncture is not acceptable because this injury evokes a positive acute phase reaction. This was also observed in two patients who developed phlebitis during a 24-h indwelling venous catheter. Only a positive acute phase reaction was found, not a negative one.

The influence of plasma volume changes on enzymatic estimation of infarct size

In 18 patients, myocardial injury was estimated by mathematical analysis of the rise in plasma activity of alpha-hydroxybutyrate (alpha-HBDH) dehydrogenase as observed by multiple sampling after admission. This enzyme represents the lactate dehydrogenase isoenzymes LDH1 and LDH2. Changes in plasma volume were assessed by determining hematocrit values at the same time as the enzyme activities. Infarct size was expressed in IU/liter of plasma and in grams of heart muscle per liter of plasma (g/liter). Significant changes in plasma volume, reflected in hematocrit changes, occurred (average 12%): 10 patients without pulmonary edema showed an average change of 7%; for the group of eight patients with pulmonary edema, the change was 17%. When calculated infarct size was not correlated for plasma volume changes, a significant overestimation occurred (11.7%, range 0.7-29.7%). In the subgroup of patients with pulmonary edema the mean overestimation was 15.8%, and in patients without pulmonary edema, the mean overestimation was 8.5%. It is concluded that plasma volume changes after an acute myocardial infarction have to be taken into account when infarct size is calculated on the basis of plasma enzyme levels.

Depolarizing afterpotentials and burst production in molluscan pacemaker neurons

1. Spikes in molluscan bursting cells are followed by depolarizing afterpotentials (DAPs) which are not seen in nonbursting cells in the same ganglia. DAPs from successive spikes sum to provide a depolarizing drive capable of sustaining multiple discharge. 2. Subthreshold depolarization activates a DAP-like process in bursters. 3. DAP amplitude increases as the cell is hyperpolarized beyond the potassium equilibrium potential. The amplitude is not changed by intracellular iontophoresis of TEA-Cl. DAP amplitude is reduced by 39% after a 10-min exposure to CA++-free saline, and by 66% after 10 min in 4% Na+ (Tris substituted) saline. The amplitude is unchanged by exposure to K+-free saline. 4. During repetitive stimulation the amplitude of the summed DAP declines. 5. It is concluded that DAP results from a slowly decaying component of Ca++ and Na+ permeability.

Determination of major impurity in chlordiazepoxide formulations and drug substance

Procedures for quantitating the lactam impurity, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide, which can be present in chlordiazepoxide formulations, is presented. The method consists of trapping chlordiazepoxide in sulfuric acid in kieselguhr, eluting the impurity with ether, and quantitating by UV spectrophotometry in absolute alcohol at 312 nm.