Food price volatility.

The high food prices experienced over recent years have led to the widespread view that food price volatility has increased. However, volatility has generally been lower over the two most recent decades than previously. Variability over the most recent period has been high but, with the important exception of rice, not out of line with historical experience. There is weak evidence that grains price volatility more generally may be increasing but it is too early to say.

Quantitative analysis of the dendrites of sacral preganglionic neurons in the cat.

Quantitative analyses were performed on the dendrites and somata of 25 electrophysiologically identified preganglionic neurons (PGN) obtained from the sacral spinal cord of the cat by intracellular injection of Neurobiotin or horseradish peroxidase. Total dendritic length and surface area were measured for each dendrite. The sizes of the stem dendrites measured at their base were positively correlated with the sizes of the entire tree and numbers of end branches. Total surface area of somata and dendrites averaged 39,138 microm(2); 90.7% of that was from the dendrites. To obtain measurements of the relative contributions of PGN dendrites to specific regions of the spinal cord, the percentage of each dendrite occupying eight spinal cord regions was recorded. Sixty-three percent of the dendrites projected dorsal to their somata, whereas an average of 33.3% of dendrites were located in the white matter, most of them in the lateral and dorsolateral funiculi. The neurons within this sample formed a continuum with some neurons having a large percentage of dendrites in lamina I but little in the white matter, whereas at the other end of the continuum were cells with the reverse configuration. The intermediate neurons had dendrites in both locations. Taken together, these data indicate a heterogeneous population of PGN in the lateral band of the sacral parasympathetic nucleus.

Axons of sacral preganglionic neurons in the cat: II. Axon collaterals.

Axon collaterals were identified in 21 of 24 preganglionic neurons in the lateral band of the sacral parasympathetic nucleus of the cat. Following the intracellular injection of HRP or neurobiotin the axons from 20 of these neurons were followed and 53 primary axon collaterals were found to originate from unmyelinated segments and from nodes of Ranvier. Detailed mapping done in the five best labeled cells showed bilateral axon collaterals distributions up to 25,000 microm in length with 950 varicosities and unilateral distributions up to 12,561 microm with 491 varicosities. The axon collaterals appeared to be unmyelinated, which was confirmed at EM, and were small in diameter (average 0.3 microm). Varicosities were located mostly in laminae I, V, VII, VIII and X and in the lateral funiculi. Most varicosities were not in contact with visible structures but some were seen in close apposition to Nissl stained somata and proximal dendrites. Varicosities had average minor diameters of 1.3 microm and major diameters of 2.3 microm. Most were boutons en passant while 10-20% were boutons termineaux. EM revealed axodendritic and axoaxonic synapses formed by varicosities and by the axons between varicosities. It is estimated that the most extensive of these axon collaterals systems may contact over 200 spinal neurons in multiple locations. These data lead to the conclusion that sacral preganglionic neurons have multiple functions within the spinal cord in addition to serving their target organ. As most preganglionic neurons in this location innervate the urinary bladder, it is possible that bladder preganglionic neurons have multiple functions.

Axons of sacral preganglionic neurons in the cat: I. Origin, initial segment, and myelination.

Parasympathetic preganglionic neurons in the cat sacral spinal cord innervate intraspinal neurons and pelvic target organs. Retrograde tracing studies have revealed little of the morphology of their axons including their origin, initial segments, or their myelin, due to methodological limitations. Intracellular labeling of single neurons with neurobiotin or HRP has overcome these problems. Axons were studied in 24 preganglionic neurons. In 21 neurons the axon originated as a branch of a dendrite, without a detectable axon hillock, at distances from the soma ranging from 10 to 110 microm (average 34.1 microm ). In 3 neurons the axon was derived from the soma. Initial segments, present in all cells, ranged from 15 to 40 microm (average 26.8 microm). Nearly all axons followed the initial segment with unmyelinated segments that varied between 59 to 630 microm, followed by myelin and nodes of Ranvier. Internodal distances were variable and relatively short (average 93 microm). Axonal diameters measured over the intraspinal course in 18 axons averaged 1.3 microm (range 0.6-2.4 microm) and were relatively constant compared with other neurons. Spine-like protrusions were observed on the initial segments of 12 cells. Axon collaterals originated from unmyelinated sections and nodes of Ranvier. Antidromic action potentials showing initial segment, soma-dendritic inflections, did not differentiate between soma-derived and dendrite-derived axons. The data suggest that axons originating from a dendrite are the normal structure of preganglionic neurons in the lateral sacral parasympathetic nucleus. It is proposed that the particular structure of these axons may be part of a timing mechanism that coordinates preganglionic neurons with other spinal neurons involved in target organ reflexes.

Vasoactive intestinal polypeptide in sacral primary sensory pathways in the cat.

Unmyelinated sensory axons in the sacral spinal cord may play a role in bladder reflexes under certain pathological conditions. Previous data suggested vasoactive intestinal polypeptide (VIP) might be contained exclusively in sensory C-fibers, some of which innervate the bladder. This study was undertaken to describe the morphology of these VIP fibers in the sacral cord of the cat. VIP immunoreactivity was confined to unmyelinated axons observed at several levels of the sensory pathway including the dorsal root ganglia, dorsal roots, Lissauer's tract, and the lateral collateral pathway. A combination of light and electron microscopic observations showed VIP-immunoreactive fibers with labeled varicosities and synaptic terminals in laminae I, IIo, V, VII, and X. VIP-immunolabeled varicosities had a mean diameter of 1.6 microm (range = 0.11-7.4 microm, S.D. = 1.01, n = 311) with a small percentage (8%) being relatively large (3-7.4 microm). VIP varicosities contained a mixture of small clear vesicles (CLV) and large dense core vesicles (LDV). Although most varicosities contained a moderate number of LDVs (14.86 LDVs/microm2), some varicosities contained a large number of LDVs, whereas others contained very few. Varicosities that possessed synaptic specializations were classed as terminals and were divided into three morphological classes. Two of these resembled Gray's Type I terminal, whereas a third was similar to the Gray's Type II terminal. There was no consistent relationship between vesicle content of the terminal and the type of synaptic contact it possessed. This study shows that in the sacral spinal cord of the cat, VIP terminals originate only from C-fibers, terminate primarily in laminae I and V, and exhibit a variety of morphologies consistent with heterogeneous origins and functions of the lower urinary tract.

Bethanechol activates a post-receptor negative feedback mechanism in rabbit urinary bladder smooth muscle.

PURPOSE: Recent studies using vascular and gut smooth muscles indicate that contractile receptor agonists may activate post-receptor down-regulatory mechanisms causing a temporary reduction in the strength of subsequent contractions. Our data indicate a similar mechanism exists in detrusor smooth muscle of the urinary bladder. MATERIALS AND METHODS: Each isolated strip of female rabbit detrusor was placed in a tissue bath, secured to an isometric force transducer, and length-adjusted until depolarization with 110 mM KCl produced a maximum contraction (S0). Subsequent contractions were normalized to S0 (S/S0) or to a first stimulus with 30 mM KCl or caffeine (S/S1). Tissues were pretreated with the muscarinic receptor agonist, bethanechol (BE), then stimulated with KCl, caffeine, or Bay k 8644 to identify potential post-receptor down-regulation. RESULTS: Contractions induced by 30 mM KCl had three phases labeled fast peak (FP), slow peak (SP) and steady-state (SS). In tissues exposed for 30 min. to a maximum BE concentration then washed for 5 min., the KCl-induced FP and SP, but not SS, responses were reduced by approximately 40%. Smaller reductions in peak KCl-induced contractions occurred in tissues pretreated for a shorter duration or with a 100-fold lower BE concentration. This down-regulation induced by bethanechol pretreatment was reversible, lasting approximately 1-2 h. Not only were KCl-induced contractions reduced by BE pretreatment, but also those produced by the intracellular Ca(2+)-mobilizer, caffeine, and the L-type Ca2+ channel agonist, Bay k 8644. CONCLUSIONS: Pretreatment of isolated strips of rabbit detrusor with a muscarinic receptor agonist produced short-term down-regulation of KCl-induced peak contractions that may have involved inhibition of both influx of extracellular Ca2+ and release of intracellular Ca2+. Reductions in the degree of this novel modulatory response during disease conditions and aging could enhance contractile activity, possibly causing detrusor instability.

Intracellular injection of neurobiotin or horseradish peroxidase reveals separate types of preganglionic neurons in the sacral parasympathetic nucleus of the cat.

Sacral preganglionic neurons are essential to the neural control of the excretory and sex organs. Previously employed multi-cell tracing methods have certain limitations in the precise morphological analysis of the neural pathways that control these organs. These limitations were overcome by the intracellular injection of neurobiotin or horseradish peroxidase into single preganglionic neurons in the lateral sacral parasympathetic nucleus of the cat. Following light microscopic examination, these neurons, as a group, were found to have an average of five stem dendrites, which divided into 15 dendritic end-branches that were distributed among eight dendritic terminal fields. These dendrites had a major transverse orientation and were quite long, many of them reaching well into the dorsal and ventral horns and into the dorsal gray commissure. These dendrites also exhibited a major longitudinal orientation, extending an average of 869 microns (combined length of rostral and caudal dendrites) within the nucleus. Two groups of cells emerged on the basis of different dendritic patterns. Cells classed as Type I had dendrites in lamina I and in the ventral horn but lacked a significant projection into the lateral funiculus. Cells classed as Type II had major dendritic projections into the lateral funiculus but lacked dendrites in lamina I. The diverse dendritic patterns of these two cell types indicate dissimilar afferent control mechanisms and suggest that these preganglionic neurons may innervate different target organs.

Axon collaterals indicate broad intraspinal role for sacral preganglionic neurons.

The classic view of preganglionic neurons in spinal autonomic nuclei is that they convey information exclusively from the central nervous system to autonomic neurons in peripheral ganglia. The present morphological study in the cat sacral spinal cord demonstrates that these neurons may also make abundant synaptic connections within the spinal cord. Neurons labeled intracellularly with neurobiotin or horseradish peroxidase exhibited an expansive distribution of axon collaterals in spinal cord laminae I, V, VII, VIII, IX, X, and the ventrolateral funiculi. This broad-ranging axon-collateral system, which has the potential for multiple neuronal contacts, indicates widespread integrative functions for sacral preganglionic neurons within the spinal cord, in addition to functions currently known in the periphery.

Alcoholism treatment: a ten-year follow-up study.

Two hundred male and female patients, selected at random from all patients admitted to an inpatient alcoholism treatment facility in 1973-1974, were surveyed 10 years following treatment. Response rate was 80%, and a validity check was done. Of the 158 unstable responses, 61% reported complete or stable remission of their alcoholism for at least 3 years prior to the survey and 84% reported stable psychosocial status. Successful outcome was possible regardless of severity of drinking history or psychosocial status. Seventy-six percent (76%) of those still alive at follow-up reported remission; at most, 23% of the deceased were reported in remission prior to death. Involvement in Alcoholics Anonymous (AA) predicted abstinence, suggesting successful outcome for patients who undergo a treatment regimen, which bridges patients into AA involvement. Of those respondents who continued to sponsor other AA members throughout the follow-up period, 91% were in remission at the time of survey.

Common fur and mystacial vibrissae parallel sensory pathways: 14 C 2-deoxyglucose and WGA-HRP studies in the rat.

Stimulation of mystacial vibrissae in rows A,B, and C increased (14C) 2-deoxyglucose (2DG) uptake in spinal trigeminal nucleus pars caudalis (Sp5c) mostly in ventral portions of laminae III-IV with less activation of II and V. Stimulation of common fur above the whiskers mainly activated lamina II, with less activation in deeper layers. The patterns of activation were compatible with an inverted head, onion skin Sp5c somatotopy. Wheatgerm Agglutinin-Horseradish Peroxidase (WGA-HRP) injections into common fur between mystacial vibrissae rows A-B and B-C led to anterograde transganglionic labeling only of Sp5c, mainly of lamina II with less label in layer V, and very sparse label in III and IV. WGA-HRP skin injections appear to primarily label small fibers, which along with larger fibers, were metabolically activated during common fur stimulation. Mystacial vibrissae stimulation increased 2DG uptake in ventral ipsilateral spinal trigeminal nuclei pars interpolaris (Sp5i) and oralis (Sp5o) and principal trigeminal sensory nucleus (Pr5). Common fur stimulation above the whiskers slightly increased 2DG uptake in ventral Sp5i, Sp5o, and possibly Pr5. The most dorsal aspect of the ventroposteromedial (VPM) nucleus of thalamus was activated contralateral to whisker stimulation. Stimulation of the common fur dorsal to the whiskers activated a region of dorsal VPM caudal to the VPM region activated during whisker stimulation. This is consistent with previous data showing that ventral whiskers and portions of the face are represented rostrally in VPM, and more dorsal whiskers and dorsal portions of the face are represented progressively more caudally in VPM. Mystacial vibrissae stimulation activated the contralateral primary sensory SI barrelfield cortex and a separate region in the second somatosensory SII cortex. Common fur stimulation above the whiskers activated a cortical region between the SI and SII whisker activated regions of cortex. It is proposed that this region represented the combined SI and SII common fur regions of somatosensory neocortex. Both whisker and common fur stimulation activated all layers of cortex, with layer IV being most activated followed by II-III, V, and VI. These data indicate that sensory input from the mystacial vibrissae in the adult rat is processed in brainstem, thalamic, and cortical pathways which are predominantly parallel to those which process information from the neighboring common fur sensory receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Minute ventilation and oxygen consumption during labor with epidural analgesia.

Oxygen consumption (VO2) and minute ventilation (VE) were measured between and during uterine contractions in the first stage of labor before and after lumbar epidural analgesia (LEA) in 11 women who served as their own controls. VO2 and VE between contractions were essentially unchanged by LEA to a T10 or higher sensory level. Before LEA, both VO2 and VE were increased significantly during contractions by 63% and 74% respectively, whereas following LEA there was no significant increase in VO2 or VE during contractions. In the second stage of labor, VO2 and VE were measured in seven patients electing to have no analgesia or sedation and in 10 patients having complete pain relief produced by LEA. Measurements were obtained 5-10 min before delivery. During contractions with pushing, VO2 and VE were decreased by 25% and 31%, respectively, in patients having LEA as compared with patients having no analgesia or sedation. These results suggest that the increase in VO2 and VE are due primarily to pain associated with uterine contractions and that LEA decreased the work of breathing and the oxygen consumption of the parturient in both the first and second stages of labor.

Anatomical localization of corneal afferent cells in the trigeminal ganglion.

Corneal afferent cells were identified in the trigeminal ganglion in the cat and monkey by the method of retrograde axonal transport of horseradish peroxidase. The corneal cells were found only in the ophthalmic portion of the ganglion and were scattered randomly within that division. These data are compatible with clinical and other experimental descriptions of the organization of the trigeminal ganglion and sensory root.

A nerve stimulator for the cerebellopontine angle. Technical note.

A fine-tipped bipolar nerve-stimulator probe has been developed and has proved especially useful in intracranial surgery of the cranial nerves.

Interferon administered in the cerebrospinal space and its effect on rabies in rabbits.

Because combined administration of intramuscular and intravenous interferon has been partially successful in the incubationary treatment of rabies, the effect of direct interferon administration into the cerebrospinal fluid space was tested. After injecting 1,800 U of interferon into the cisterna magna or the lateral ventricle, periodic samples, obtained by cisternal taps, showed that 1 to 5% remained after 24 h, as opposed to the known clearance of interferon from the bloodstream to this level within minutes. The distributions of interferon and (131)I-labeled albumin were similar as demonstrated by kinetics of clearance monitored over 24 h. Beginning with and after experimental infection of rabbits, daily intraventricular injections of one million units of interferon were given for as long as 3 weeks. Interferon was prepared from cell culture fluids after pressure dialysis and chromatography on Sephadex G-100. This intensive treatment did not prevent encephalitis, but prolonged the length of the incubation period by one- to two-thirds. The outcome after intraventricular administration was not as favorable as when one million units equally divided between intramuscular and intravenous injections were given at the time of challenge. Interferon administered in the subarachnoid space in this fashion is apparently inadequate to protect the rabbit against rabies. Its role as an adjunct measure, or other methods of administration in the nervous system, remains to be examined.