Millikelvin Temperatures Measured with a Noise Thermometer: Brownian motion in electrical circuits has been used to measure temperatures as low as 2 millikelvins.

We find that the current-sensitive noise thermometer is a satisfactory sensor of absolute temperature down to 2 mK and possibly below. Its field of application is primarily to magnetically and electrically quiet situations where accuracy is important and high precision is not required. For example the noise thermometer is an ideal instrument for calibrating a secondary thermometer, such as a pressure thermometer, whose calibration can readily and accurately be transferred from one laboratory to another. Further instrumental development for millidegree applications seems unnecessary at present. Rather the major problems in millikelvin noise thermometry that require attention in the immediate future involve establishing thermal contact to the thermometer and reducing its thermal response time.

Serotoninlike immunoreactivity in the cestode Hymenolepis diminuta.

Serotoninlike immunoreactivity in the cestode Hymenolepis diminuta was studied at the light microscope level by using an antibody specific to serotonin. The rostellum, the cerebral ganglia and commissure, and the strobila contained numerous process-free, unipolar and multipolar serotoninlike immunoreactive cells. The suckers contained a plexus of branching immunoreactive fibers. In the strobila the multipolar cell bodies were situated laterodorsal and lateroventral to the longitudinal nerve cords, from which neurites were directed to the contralateral and ipsilateral nerve cord to form up to three transverse commissures per proglottid. Secondary varicose branches passed anteriorly, posteriorly, and obliquely along the proglottids at the level of the deep longitudinal muscles. Other varicose multi-branching neurites passed centrifugally from the primary and secondary neurites, forming vertebratelike en passant or terminal varicosities on the deep longitudinal muscles with bulbous or spinose terminals at the level of the superficial longitudinal muscles, or in the cortical parenchyma. Serotoninlike immunoreactivity was seen on the external seminal vesicle, the sphincter and cirrus sac, and the proximal portion of the vagina. Varicose terminals were concentrated at the sphincter. The close association of serotoninlike immunoreactive terminals and varicosities with the longitudinal muscles gives credence to the concept that serotonin functions as a neuromuscular transmitter or modulator in the platyhelminths.

Intravenous infusions of heparin and penicillins.

The chemical stability and anticoagulant activity of heparin (20 U/ml) were studied in five intravenous fluids at room temperature. Heparin remained stable and active for 24 hours in normal saline, but there was a rapid inactivation of 40 to 55% in solutions containing dextrose or lactate, as measured by chemical and biological methods.High concentrations of benzylpenicillin, ampicillin, or methicillin had no effect on heparin activity in normal saline or dextrose 5%: nor was the stability of the penicillins in these fluids affected to any marked extent by the presence of heparin. Ampicillin was, however, found to be unstable in dextrose 5%, and it would be preferable for it not to be added to dextrose infusions. It is concluded that heparin may be given intravenously in normal saline with benzylpenicillin, ampicillin, or methicillin but several other antibiotics were found to be unsuitable for concurrent infusion with heparin.

Release of exogenously-supplied and endogenous serotonin from tissue slices of Hymenolepis diminuta.

The release of exogenously-supplied [3H]serotonin and of endogenous serotonin from H. diminuta tissue slices was studied using high [K+] depolarization. The release of [3H]serotonin was not calcium-dependent or magnesium-antagonized. While high-magnesium antagonism of endogenous serotonin release was inconclusive, this release was calcium-dependent. These findings suggest that, while exogenous serotonin is not taken into and released from nervous tissue, endogenous serotonin appears to be released from nervous tissue in a neurotransmitter-like manner.

Acetylcholine-like immunoreactivity in the cestode Hymenolepis diminuta.

The localization of acetylcholine in tissues of the cestode Hymenolepis diminuta was determined, following derivatization, using an antibody raised against choline-glutaraldehyde-protein. Specific immunoreactivity was observed in the rostellum and beneath the suckers of the scolex, in the longitudinal nerve cords, in cells adjacent to some deep longitudinal muscles, in the genital primordium, in the wall of the cirrus sac, and in the external and internal seminal vesicle. The distribution of acetylcholine-like immunoreactivity in relation to that of serotonin and glutamate, and the distribution of acetylcholinesterase in H. diminuta is discussed.

Octopamine in Lumbricus terrestris: presence, synthesis and effect of octopamine on the spontaneous rhythmic contractions of the ventral nerve cord.

A radiochemical-enzymatic assay was utilized to measure endogenous levels of octopamine in the nerve cord and blood of the earthworm. The results show the presence of octopamine in the ventral nerve cord and blood at concentrations of 2.79 +/- 0.5 (means +/- S.D.) ng/mg wet tissue weight and 9.5 +/- 1.6 x 10(-8) M (means +/- S.D.) respectively. The ability of the ventral nerve cord to synthesize octopamine was investigated by incubating the tissue in vitro in radiolabeled percursors. The results show the synthesis of [3H]octopamine from both precursor [3H]tyrosine and [3H]tyramine. In vitro incubation of the isolated ventral nerve cord in physiological concentrations of octopamine revealed modulation of the spontaneous rhythmic contractions of the nerve cord. The data provide direct support for a modulatory role of octopamine in L. terrestris.

Characterization of a serotonin transporter and an adenylate cyclase-linked serotonin receptor in the cestode Hymenolepis diminuta.

[3H]5-HT exhibited specific binding in membrane preparations of Hymenolepis diminuta. The specific binding was saturable, reversible and temperature dependent. A non-linear Scatchard plot was obtained in a concentration range of 11 nM - 1000 nM [3H]5-HT, which could be resolved into sites having apparent dissociation constants (KD) of 0.10 microM and 6.25 microM for the high-affinity and low-affinity components, respectively. The latter could be selectively eliminated by binding [3H]5-HT to H. diminuta membranes in the presence of 10(-3) M nitroimipramine. Drug displacement studies, using 0.20 microM and 2.0 microM [3H]5-HT, revealed that while low-affinity [3H]5-HT binding was displaced by unlabelled 5-HT and inhibitors of 5-HT uptake, high affinity [3H]5-HT binding was affected only by tryptamine derivatives and, to a lesser extent, methysergide. In addition, high-affinity binding was stimulated by MgCl2 while low-affinity binding showed sodium-dependency. The data implicate the low-affinity site as a putative 5-HT transporter and the high-affinity site as a putative 5-HT 1 receptor. Exposure of H. diminuta membranes to 5-HT resulted in a 3-4 fold stimulation of cAMP levels. The EC 50 for the 5-HT-induced activation of adenylate cyclase (0.76 microM) was of the same order of magnitude as the apparent KD for high-affinity binding. Furthermore, the order of drug potency for the elevation of cAMP levels by 5-HT agonists and reversal by 5-HT antagonists was identical to the order of drug potency for the inhibition of high-affinity binding, suggesting linkage of the putative 5-HT 1 receptor to adenylate cyclase in H. diminuta.

Anterior segment ischemia in chronic herpes simplex keratouveitis.

Six patients with chronic herpes simplex keratouveitis developed a rapidly progressive ocular inflammation unresponsive to corticosteroid and antiviral therapy. Severe secondary glaucoma unresponsive to maximum medical therapy ensued and was treated by cyclocryotherapy in five patients. Ocular ischemia with secondary corneal and scleral calcification subsequently developed in all six patients. All had also received prolonged topical therapy with topical antiviral agents, corticosteroids, beta adrenergic blockers and epinephrine compounds. Three eyes eventually required enucleation for the relief of pain; one stabilized, and two others became phthisical. One of the phthisical eyes developed a secondary fungal endophthalmitis. Histopathologic examination of the three enucleated globes revealed extensive corneal, scleral and conjunctival calcification, secondary angle closure, iris and ciliary body necrosis, focal choroiditis, retinal necrosis and atrophy. The syndrome recognized in these patients appears to be a rare but devastating complication of herpes simplex keratouveitis, possibly exacerbated by the application of cyclocryotherapy and other factors.

Ultrastructural changes in an unciliated sensory receptor during activation of the metacestode of Hymenolepis microstoma.

The fine structure of an unciliated sensory receptor of the metacestode of Hymenolepis microstoma is described. Each receptor contains a basal body inserted into an electron dense matrix; a terminal cilium is lacking. At this stage of development neurotubules were lacking, but rapidly appeared following excystation. It is suggested that neurotubules play a role in the functioning of the putative proprioceptor.

Occurrence and characterization of a low-affinity choline uptake mechanism in the internal tissues of the cestode Hymenolepis diminuta.

[3H]Choline was taken up by tissue slices of the cestode Hymenolepis diminuta by sodium-dependent and sodium-independent mechanisms. The sodium-dependent uptake was saturable, against an apparent concentration gradient, and by analysis of the kinetics of uptake could be delineated into a high-affinity choline uptake (HAChU) mechanism (Kt of approximately 2.0 microM; Vmax of approximately 0.15 pmol/mg wet weight tissue/min), and a low-affinity choline uptake (LAChU) mechanism (Kt of approximately 20.0 microM and a Vmax of approximately 2.0 pmol/mg wet weight tissue/min). Unlike the HAChU system, the LAChU system was unaffected by potassium. Furthermore, the responses of the LAChU and the HAChU transporters to pharmacological agents were distinctive, indicating that these transporters are two separate entities. Moreover, the entry or exit of choline via the LACh transporter was dependent upon the direction of the sodium gradient. Furthermore, the majority of released radiolabel from preloaded [3H]choline was associated with choline and was via a proteinaceous transporter. The present study is the first to provide direct evidence for a partial chemosmotic coupling of a LAChU system to the sodium electrochemical gradient.

The stimulatory effect of L-glutamate and related agents on inositol 1,4,5-trisphosphate production in the cestode Hymenolepis diminuta.

The effects of L-glutamate, acetylcholine, and serotonin (5HT) were examined on generation of inositol 1,4,5-triphosphate [Ins(1,4,5)P3], in membrane preparations of the cestode Hymenolepis diminuta. Only L-glutamate and acetylcholine stimulated a significant elevation in Ins(1,4,5)P3. The response to L-glutamate was stereospecific; D-glutamate or L-aspartate were not as potent. A role for G-protein(s) was supported by the observations that sodium fluoride stimulated Ins(1,4,5)P3 generation, and the L-glutamate response was potentiated by GTP and GTP-S and was suppressed by GDPS. However, studies with pertussis and cholera toxins indicated that the putative G-protein(s) was not pertussis or cholera toxin sensitive. The pharmacological profile of the L-glutamate response was examined partially. Trans-ACPD was a very effective agonist at 10(-5)M. While 10(-3)M L-glutamate, NMDA, and AMPA significantly elevated Ins(1,4,5)P3 levels, quisqualate and kainate did not. The elevation of Ins(1,4,5)P3 levels by L-glutamate and NMDA was antagonized by the specific glutamatergic antagonists AP-5, AP-7, CNQX, and CPP. While the response to ACPD was antagonized by AP5, CPP and CPG, CNQX was without effect. Collectively, the data support the hypothesis that in the cestode H. diminuta, L-glutamate activation of a metabotropic (ACPD) and/or ionotropic-like AMPA/NMDA receptor subtypes proceeds via a G protein(s) to enhance phospholipase C activity, ultimately resulting in the elevation of Ins(1,4,5)P3 levels in the tissues.

Putative neurosecretory cells of the cestode Hymenolepis microstoma.

Putative neurosecretory cells were observed with the electron microscope in the nerve cords of the neck region of Hymenolepis microstoma. The cells show evidence of glandular activity by the large numbers of dense-core vesicles produced by the Golgi apparatus. The axons contain synaptoidlike structures with surrounding clouds of vesicles; features analogous to known neurosecretory release sites.

Ultrastructural morphology of the nerve cells in the cerebral ganglion of the Acanthocephalan Moniliformis moniliformis.

The morphology of the cerebral ganglion of the Acanthocephalan Moniliformis moniliformis was studied in serial sections using electron microscopy. The organization of the cerebral ganglion was typical of other invertebrates with the cell bodies forming a rind, 1 cell thick, and their processes forming the central core of the neuropile. The ganglion was surrounded by a connective tissue capsule composed of collagen-like fibrils. Externally, the free surface of the cell bodies was covered by an electron-dense extracellular lamina. Seventy-six cells were identified in every ganglion examined and, on the basis of their cellular characteristics, they were divided into 5 distinct cell types, classified as type A, B, C, D and E cells. The characteristic morphological features of each cell type have been described, and the distribution of the different cell types in the cerebral ganglion was mapped.

Preoperative visiting from the perspective of the theatre nurse.

Many issues surround the concept of preoperative visiting. This article explores these issues in the light of recent research findings which question the benefits of using 'psychological' techniques to reduce preoperative anxiety, and examines the strategies in current use.