Howard E. Mitchell

Multiple motor pathways to single smooth muscle cells in the ferret trachea.

1. We investigated the distribution and characteristics of motor pathways to individual smooth muscle cells activated by electrical stimulation of either, single nerves which enter the tracheal plexus (inlet nerves), or a longitudinal nerve trunk (LNT) located near the entrance of an inlet nerve into the plexus. Excitatory junction potentials (EJPs) were recorded using intracellular microelectrodes as an index of smooth muscle cell activation. In all experiments EJPs were completely blocked by tetrodotoxin and by atropine. 2. In smooth muscle fields located in the caudal direction from the point of inlet or LNT nerve stimulation, neural input decreased as a function of distance. There was evidence of a demarcated area innervated by neurons entering the plexus in one inlet nerve. In smooth muscle fields located in the rostral or transverse direction from the site of nerve stimulation, no such demarcated area could be identified. 3. Of the smooth muscle cells located within the innervated fields studied, 83‐95% were activated following stimulation of a single inlet nerve or LNT. Evoked EJPs were similar in different innervated cells or units of electrically coupled cells located within the same 1 mm2 ‘field’. 4. There was overlapping cholinergic motor input to single smooth muscle cells originating from neurons present in different inlet nerves or different neurons present in the same inlet nerve or region of the LNT. Multiple small step increases in the voltage used to stimulate a LNT resulted in three or four step increases in EJP amplitudes. This gives a minimal value for the number of motor pathways that can be activated by neurons in a region of LNT leading to a single smooth muscle cell. 5. Motor pathways to smooth muscle cells located in caudal and rostral fields ran initially in the LNT and exited in proximity to the smooth muscle cell studied. 6. Motor pathways used in transmitting signals to smooth muscle cells to different areas of trachealis muscle varied in their sensitivity to hexamethonium or curare. EJPs evoked in fields located in the caudal direction from the stimulating electrode were abolished by these drugs. Muscle cells located in different rostral fields showed EJPs that were either sensitive or resistant to these drugs. 7. The rostral hexamethonium‐resistant pathway ran initially in the LNT but it exited from the LNT several millimetres before reaching the level of the smooth muscle field innervated. This pathway followed stimulation frequencies up to 25 Hz. The final neuron in this pathway released acetylcholine and evoked EJPs were entirely inhibited by atropine.(ABSTRACT TRUNCATED AT 400 WORDS)

Capsaicin-sensitive stretch responses in ferret trachealis muscle

1. Stretch‐induced electrical and mechanical responses in segments of ferret trachealis muscle were studied. Stretches and post‐stretch length changes were quantified by measuring distances between two marker spheres placed on the muscle surface. Electrical responses were determined by measuring membrane potential in the muscle cell syncytium. 2. Smooth muscle mechanical and electrical responses to the stretch manoeuvre were characterized by an initial shortening and depolarization phase and a reversal‐repolarization phase. Both phases were resistant to atropine and tetrodotoxin. During the initial phase, the membrane depolarized to potentials as low as ‐20 mV. For stretches to 1.0 Lmax, from a holding length of 0.75 Lmax, 50% repolarization occurred at 6.8 +/‐ 0.4 min post‐stretch; 50% reversal of shortening of the stretched segment occurred at 6.9 +/‐ 0.8 min post‐stretch. 3. Depolarizing currents generated within muscle cells in the stretched segment spread into cells in non‐stretched muscle. Space constants in the transverse and longitudinal directions averaged 480 +/‐ 46 and 146 +/‐ 50 microns, respectively. 4. During infusion of capsaicin (10 microM), muscle cells depolarized by 5.5 +/‐ 2.3 mV. Maximal depolarization was achieved after 15‐20 min. After inhibition of neutral enkephalinase, capsaicin‐evoked depolarization occurred more rapidly. Muscles depolarized by 11.2 +/‐ 2.1 mV after about 10 min of capsaicin and then slowly repolarized during continued treatment. When muscle segments were stretched during administration of capsaicin, the initial phase was similar to that observed before capsaicin, but the reversal‐repolarization phase was prolonged. Following wash exposure to capsaicin, maximal stretch‐induced depolarization was unchanged, but the time for 50% repolarization (t50‐repolarization) decreased from the pre‐capsaicin value of 8.4 +/‐ 1.3 to 4.1 +/‐ 0.5 min. The t50‐reversal of stretch‐evoked muscle shortening decreased to 54% of control values. 5. Short exposures (< 2 min) to substance P (SP, 1‐7.5 microM) depolarized smooth muscle cells. Maximal depolarization was delayed, and occurred after [SP] had decreased to < 10 nM. Repolarization was delayed as long as 6 min following wash‐out of SP. Stretches performed when SP‐induced depolarization had nearly reversed showed no changes in the initial mechanical or electrical responses, but t50‐repolarization increased to 162% of control values. 6. Immunochemical studies showed networks of neurones which react with SP antibodies. 7. These findings suggest that stretch induces SP release from capsaicin‐sensitive C fibres, and that released SP affects smooth muscle ionic mechanisms which control and delay the reversal of stretch‐induced membrane depolarization and shortening.

Counselors' Attitudes toward Technical Aids to the Counseling Process

7. The reasons pensioners seek employment vary. The psychological need for occupation and the material need for financial assistance, however, are the two overriding issues. These color and magnify all the other ascribed reasons. 8. Once having terminated employment, older workers have more difficulty than younger workers in finding new employment; they are unemployed for longer periods of time; they must make more energetic job-seeking efforts; and ordinarily they are not as well organized in their hunt for jobs. In sum, they require some form of organized assistance. 9. Employment is so important to older workers that they are frequently willing to compromise on the positions they accept, the conditions of work and the salaries offered to them. It is important, therefore, to guard them against possible exploitation. 10. On special programs of this nature, 165

The Urban Crisis and the Search for Identity

The resolution of present-day urban conflict demands that all black and white Americans search for new separate and collective identities

Seymour Parker and Robert J. Kleiner. Mental Illness in the Urban Negro Community. Pp. xiv, 408. New York : Free Press, 1966.

would have been quite adequate if Austin’s view that international law was actually only a &dquo;positive morality&dquo; would have been reported and examined. The last chapter, &dquo;The Moral Order and Legal Order,&dquo; offers to the readers the idea that the two orders intersect each other; in somewhat different terms this has been the leitmotiv of the reviewer’s Introduction to the Sociology of Law (Cambridge, Mass., 1939) and will play the same role in a forthcoming work on the same subject. The idea means that law is unthinkable without organized social power supporting it and that it must be consistent with the moral views of the respective nations. NICHOLAS S. TIMASHEFF

9.95:

In spite of enthusiastic attempts in recent years no generally effective and definitive therapeutic approach for schizophrenia has been developed. The project on which our experience is based, was planned as one of many efforts currently being made to acquire new knowledge and find new approaches to this major mental health problem. As we stated in the “Introduction,” our thinking about the actual treatment plan to be followed was based upon the concept of the family as the primary unit of mental illness. Our approach, therefore, was to treat the schizophrenic and his family as a unit via a group therapeutic technique in the home setting.

Methods and plan of treatment

Family treatment is a relatively new field of endeavor, and we are only at the beginning stages of our effort to conceptualize the psychopathology of family functioning. As can be seen from the foregoing, a number of individuals and groups across the country—ours included—are attempting to bridge the gap between thinking about pathology in individual terms and thinking about it in family terms. Much work remains to be done in the future; the intrapsychic and transactional spheres will have to be integrated, in order to refine the techniques of family therapy, and to establish specific indications for this method of treatment.