Calcium entry leads to inactivation of calcium channel in Paramecium.

Under depolarizing voltage clamp of Paramecium an inward calcium current developed and subsequently relaxed within 10 milliseconds. The relaxation was substantially slowed when most of the extracellular calcium was replaced by either strontium or barium. Evidence is presented that the relaxation is not accounted for by a drop in electromotive force acting on calcium, or by activation of a delayed potassium current.

An electrophysiological study of the regulation of ciliary beating frequency in Paramecium.

1. The role of the surface membrane in the control of ciliary beat frequency in Paramecium was examined by intracellular electrophysiological techniques and pressure injection of Ca2+ and EGTA. Experiments were done on wild type P.

Potassium activation associated with intraneuronal free calcium.

Relations between calcium entry and activation of a calcium-dependent outward current during depolarization were examined under voltage clamp in dorid giant neurons injected with the calcium-sensitive photoprotein aequorin. Activation kinetics and amplitude of the slow calcium-dependent component were both found to be related to the rate and extent of free calcium accumulation and to the electromotive force acting on potassium ions, independent of the calcium activation kinetics. This indicates that the activation of the calcium-dependent outward current is more closely related to the transient intracellular accumulation of free calcium ions than to the movement of calcium through the plasma membrane during depolarization.

Calcium-dependent repolarization in Paramecium.

1. Intracellular injection, recording and current-passing methods were used to investigate the role of intracellular Ca in the modulation of electrical behaviour in the ciliate Paramecium caudatum.2.

Studies on column fractionation of immune cells. VII. Electrophoretic mobility and functional behavior of mouse spleen cells after fractionation on a weakly basic ion exchanger.

After passing normal mouse spleen cells through columns of a weakly basic ion-exchanger, the percentage of cells with B cell-typical electrophoretic mobility (EPM) is 90% after fractionation at pH 8.0 and 10--20% at pH 5.0.

Calcium-dependent depression of a late outward current in snail neurons.

Neuron cell bodies of Helix pomatia were voltage-clamped with a 300-millisecond depolarizing test pulse (pulse II) delivered I second after a depolarizing conditioning pulse (pulse I). The outward current, measured 200 milliseconds after the onset of pulse. II, exhibited a strong depression that was dependent on the presence of pulse.

Voltage-dependent facilitation of Ca2+ entry in voltage-clamped, aequorin-injected molluscan neurons.

Voltage-clamp experiments were performed on giant neurons of the nudibranch Anisodoris nobilis injected with the Ca-sensitive photoprotein, aequorin. Depolarization beyond -10 to +5 m V produced an aequorin signal, the amplitude of which depended on the extracellular Ca2+ concentration, the amplitude of the depolarization, and its duration. In paired pulse experiments, the amplitude of the aequorin signal produced in response to the second of two identical depolarizing pulses was larger than that produced during the first, resulting from an increased entry of Ca2+ during the second pulse.

Phosphorylation of cytokinin by adenosine kinase from wheat germ.

Adenosine kinase was partially purified from wheat germ. This enzyme preparation, which was devoid of adenine phosphoribosyltransferase and nearly free of adenosine deaminase but contained adenylate kinase, rapidly phosphorylated adenosine and a cytokinin, N(6)-(delta(2)-isopentenyl)adenosine. Electrophoretic analysis indicated that only N(6)-(delta(2)-isopentenyl)adenosine-monophosphate was formed from the cytokinin while about 55% AMP, 45% ADP, and a trace of ATP were formed from adenosine.

Lymphokines of T and B cells. I. Demonstration that T and B cells of tumor antigensensitised mice produce different lymphokines changing surface charge of target cells.

Lymphocytes from MC sarcoma-bearing mice were exposed to a soluble tumor antigen. The lymphokine-containing supernatant thus obtained was fractionated on Sephadex G-75. Fractions were tested for their activity to reduce the surface charge of indicator macrophages by cell electrophoresis technique.

A voltage-sensitive persistent calcium conductance in neuronal somata of Helix.

1. An intracellular voltage clamp in conjunction with a patch pipette utilizing feed-back to monitor local current from the soma membrane were used to analyse transient and stationary currents in bursting pacemaker neurones in Helix pomatia and H. levantina.

Studies on column fractionation of immune cells. VI. Separation of thymus-derived lymphocytes by means of protein beads coated with antigen-antibody complexes.

Calf serum beads coated with antigen-antibody complexes were used as cellular immuno-adsorbents to separate mouse T-lymphocytes with a purity of more than 90%. The beads coated by means of glutaraldehyde could be used at least three times without loss of cell-binding capacity.

Ureteroduodenal fistula.

A patient with pneumaturia was found to have a ureteroduodenal fistula, only the fourth such lesion reported. However, this patient is unique in that a fistula developed between the stump of a ureter and the duodenum in the absence of a kidney on that side. This case was namaged with a distal skin ureterostomy, thereby avoiding extremely hazardous surgery in the area of the duodenum.

[On the mode of action of heterologous antileukemic sera. Growth of syngeneically transplanted leukemia cells on serum treated neonatally thymectomized mice (author's transl)].

A heterologous antiserum against a Nitrosomethylurea--induced mouse leukemia prevented the outgrowth of syngeneically transplanted leukemia cells in neonatally thymectomized mice. After subcutaneous challenge with 50 000 leukemia-ascites cells thymectomized CBA mice at the age of 8 weeks were given 5 intraperitoneal injections each of 0,1 ml of the heterologous serum. While the antileukemic serum protected 9 out of 11 mice all of the 11 mice treated with normal rabbit serum developed a tumor.

The use of antigen-coated protein beads as immunoadsorbent for the purification of antibodies.

A procedure is described using antigen-coated beads of calf serum as immunadsorbent for the purification of antibodies against ferritin and against leukemia-sarcoma virus-induced antigens.

[The function of different lymphocyte groups and methods for their separation (author's transl)].

A review is given of the participation of T- and B-lymphocytes in the three most important lymphocyte functions: antibody formation, cellular effector reactions, especially cytotoxicity and regulator functions, with particular reference to the concept of "lymphocyte population". The most commonly used methods for the separation of T- and B-lymphocytes and of lymphocytes with the same function are described.

[Methods for the separation of lymphocytes].

The paper reviews the currently available methods for lymphocyte separation, with particular reference to their effectiveness. Procedures based on density and size, such as density gradient centrifugation and sedimentation and size filtration on columns, allow accumulation of lymphocytes of different degree of differentiation, but do not permit any quantitative separation of distinct lymphocyte populations, because density and size of cells are properties strongly varying with the degree of development and physiological state of the cells. Differences of the cells' net potential cause differential adhesion of lymphoid cells to glass or other materials, and lead to varying migration speeds in the electric field.