Death as an event: a commentary on Robert Morison.

1) We have no need to abandon either the concept of death as an event or the efforts to set forth reasonable criteria for determining that a man has indeed died. 2) We need to recover both an attitude that is more accepting of death and a greater concern for the human needs of the dying patient. But we should not contaminate these concerns with the interests of relatives, potential transplant recipients, or "society." To do so would be both wrong and dangerous. 3) We should pause to note some of the heavy costs of technological progress in medicine: the dehumanization of the end of life, both for those who die and for those who live on; and the befogging of the minds of intelligent and moral men with respect to the most important human matters.

Merging of modalities in the optic tectum: infrared and visual integration in rattlesnakes.

The optic tectum of pit vipers (Crotalinae) contains a layer of infrared-sensitive neurons subjacent to the visual layer; these indirectly receive input from the facial pit organs. They respond transiently to the appearance or motion of warm objects within their 25 degrees to 70 degrees excitatory receptive fields (some have inhibitory regions) and presumably allow the snake to orient or strike toward prey. The infrared and visual spatiotopic tectal maps have similar but not identical axes; the infrared magnification is greater than that for vision. Bimodal neurons have receptive fields for each modality that reflect the disparity of the two maps. This finding suggests that (i) during development the infrared and visual fibers spread out independently to fill available tectal sites and (ii) bimodal neurons form local connections without regard to establishing spatial correspondence between the two modalities.

The UV filter benzophenone 3, alters early follicular assembly in rat whole ovary cultures.

Our goal was to study the effect of BP3 (benzophenone 3) in the follicular assembly and the potential involvement of Foxl2 pathway using whole ovary cultures. Ovaries were collected from Wistar rats at birth, treated in vitro with vehicle (0.01% DMSO), BP3 (5.8 nM, 276 nM, 576 nM and 876 nM) or ESR2 inhibitor (0.1 nM), and cultured for 7 days. Nest breakdown, follicular assembly and the expression of several regulators of these processes (p27, Foxl2, Sox9, Bmp2, Cyp19 and Fst) were evaluated. In vitro exposure to BP3 (5.8 nM) decreased the population of total oocytes, the number of nests per ovary and early primary follicles population. In addition, BP3 (5.8 nM) induced overexpression of Foxl2 mRNA levels through ESR2 but increased Fst mRNA levels independently from ESR2 or Foxl2. We also observed that the number of p27-positive oocytes was decreased after BP3 (5.8 nM). On the other hand, exposure to BP3-276 increased total oocytes, the number of nests per ovary and decreased primary follicles. In addition, BP3-276 induced no changes of Foxl2 mRNA levels through ESR2 but increased Fst mRNA levels independently from ESR2 or Foxl2. In conclusion, our study clearly shows that exposure to BP3 is to perturb the early events of germ cell development as showed here in whole ovary cultures.

Correction to: The effect of acute vs chronic magnesium supplementation on exercise and recovery on resistance exercise, blood pressure and total peripheral resistance on normotensive adults.

The original article [1] contains an error whereby the datum value of '17.7%' in both the Abstract and the first line of the Bench press sub-section of the Results section is incorrect.

Studies on the purification of antihemophilic factor (factor 8. I. Precipitation of antihemophilic factor by concanavalin A.

Concanavalin A precipitates antihemophilic factor from normal plasma. Combining this precipitation with other techniques, we were able to separate fractions rich in antihemophilic activity from human plasma with rapidity. The molecular weight of antihemophilic factor was estimated to be greater than 2 million. Presumably, antihemophilic factor is a large glycoprotein.

Studies on the purification of antihemophilic factor (factor VIII). II. Separation of partially purified antihemophilic factor by gel filtration of plasma.

A high degree of purification of antihemophilic factor was achieved by filtration of chylomicronpoor human plasma through columns of agarose. The final product contained, on the average, 67 units of antihemophilic activity per mg of protein, and was 3360-fold purified compared with the filtered plasma. The molecular weight of antihemophilic factor appeared to be at least two million. Preparations separated by gel filtration were contaminated with appreciable amounts of plasma thromboplastin antecedent (PTA), and traces of Christmas factor and Hageman factor, but no detectable fibrinogen was present. Similar fractions of plasma prepared from the blood of patients with classic hemophilia, von Willebrand's disease, or a circulating anticoagulant directed against antihemophilic factor contained, on the average, somewhat less protein than normal plasma; whether this difference was significant is not yet known. The purified fractions were partially stabilized by the addition of 1% gelatin. Adaptation of the technique of gel filtration to purification of antihemophilic factor for clinical use remains to be explored.

Arginine methyltransferase activity in chronic erythremic myelosis (Diguglielmo syndrome).

Activity of S-adenosylmethionine-dependent arginine methyltransferase was substantially higher in sonicated bone marrow samples from 6 patients with chronic erythremic myelosis than in bone marrow from 3 patients with untreated pernicious anemia, 2 patients with autoimmune hemolytic anemia, and 4 normal persons. Increased activity of this enzyme may be one of the factors contributing to the pathogenesis fo methylated arginines in histones of erythroblasts from patients with chronic erythremic myelosis.

Specificity of serotoninergic inhibition in Limulus lateral eye.

The receptor specificity for synaptically mediated lateral inhibition in Limulus lateral eye retina was studied by structure-activity correlations of the action of the putative indoleaminergic neurotransmitter, serotonin (5-HT), and its isomers and structural analogs, tryptamine (TRYP), 6-hydroxytryptamine (6HT), 5,6-dihydroxytryptamine (5,6-DHT), 5-hydroxydimethyltryptamine (5-HDMT), and 5-hydroxytryptophan (5-HTP). The 5-HT blockers, lysergic acid diethylamide (LSD), bromo-LSD (BOL), and cinanserin, were also tested. The inhibitory action of the indoleaminergic agonists is highly structure-specific. An hydroxyl group in the 5 position of the indole nucleus, sterically unencumbered by hydroxyls in neighboing positions, is essential. In order of decreasing potency, 5-HT, 5-HDMT, and 5-HTP are active agonists; TRYP, 6-HT, and 5,6-DHT are inactive. Configuration and mobility of the side chains of the active agonists also affect the interaction, and these side-chain characteristics correlate with agonist potency. The receptors for inhibitory action and for transmembranal transport in reuptake are different. Both active agonists and inactive analogs appear to be taken up (Adolph and Ehinger, 1975. Cell Tissue Res. 163:1-14). LSD and BOL have bimodal actions: direct inhibition and agonist blockade. These actions may be mediated via low-specificity presynaptic uptake receptor sites rather than highly specific, postsynaptic, agonist receptor sites.

Presynaptic uptake blockade hypothesis for LSD action at the lateral inhibitory synapse in Limulus.

We investigated the action of LSD at the putative indoleaminergic lateral inhibitory synapse in the lateral eye of Limulus polyphemus. We recorded extracellular and intracellular voltage responses from eccentric cells while producing inhibition either by light or by antidromic stimulation of the optic nerve in the presence of LSD, serotonin (5-HT), chlorimipramine, or a bathing medium whose high Mg++ and low Ca++ concentrations partially or completely blocked synaptic transmission. We found (a) light-evoked and antidromically stimulated lateral inhibition is enhanced during superfusion of low (1-5 microM) concentrations of LSD and suppressed by higher (5-20 microM) concentrations; (b) these actions of LSD are markedly reduced by bathing the retina in a medium high in Mg++ and low in Ca++; (c) very low concentrations of chlorimipramine, a putative uptake blocker of serotonin, appear to mimic actions of LSD both on eccentric cell firing rate and on lateral inhibition; (d) superfused 5-HT depresses lateral inhibition at all superthreshold concentrations (0.1-25 microM). These results suggest that LSD's action may require an intact inhibitory transmitter release and postsynaptic response mechanism, whereas serotonin exerts a direct postsynaptic effect. We propose that LSD blocks presynaptic uptake of transmitter at the lateral inhibitory synapse. The concentration dependence of LSD's action can be accounted for as follows: low concentrations partially restrict transmitter reuptake, thereby prolonging the lifetime of the transmitter in the synaptic cleft and thus increasing the magnitude and duration of postsynaptic inhibition. Higher concentrations cause more presynaptic uptake sites to be blocked; this causes accumulation of transmitter in the synaptic cleft, which causes a functional blockade of the synapse because of postsynaptic desensitization. As an alternative, we propose a hypothesis based on LSD action at presynaptic autoreceptors. Similar hypotheses can account for many aspects of LSD's action in mammalian brain.

Nonspecific esterases in normal human blood cells: characterization of isoenzymes by isoelectric focusing in polyacrylamide gel.

Using the high resolution technique of isoelectric focusing in polyacrylamide gel, isoenzymatic components of nonspecific esterase were resolved in esterase-rich extracts obtained from normal human monocytes, lymphocytes, granulocytes and platelets. In the case of each cell type, different isoenzymatic patterns of nonspecific esterase activity could be visualized. These studies extend the cytochemistry of nonspecific esterases by detection of previously undescribed isoenzymatic components, and suggest that the elaboration of nonspecific esterase isoenzymes may be a function of cellular differentiation.

Acid phosphatase in normal human blood cells: characterization by isoelectric focusing in polyacrylamide gel.

Using the high resolution technique of isoelectric focusing in polyacrylamide gel, isoenzymatic components could be discerned in acid phosphatase extracted from normal human lymphocytes, granulocytes, monocytes, and platelets. For each cell type, distinctive isoenzymatic patterns of acid phosphatase activity could be observed. These studies provide further evidence that various types of cellular differentiation are associated with differences in isoenzymatic components of acid phosphatase.

Anatomical and physiological localization of visual and infrared cell layers in tectum of pit vipers.

Visual and infrared cell layers were identified in the tectum of the pit vipers Crotalus viridis and Sistrurus melitus. Histologic reconstructions of 48 lesions utilizing the Prussian Blue technique were correlated with micrometer depth readings for 251 visual, infrared and bimodal single unit recordings. The visual cell layer extends caudally from approximately the level of the habenula to the rostral border of the posterior corpora quadrigemina. Neurons responding to visual stimulation are generally contained within zones 7b-13, i.e., the superficial 600--700 micrometer of the optic tectum (stratum fibrosum et griseum superficiale and the superficial sublayer of stratum griesum centrale). The infrared cell group is found in layer 7 (a and b; stratum griseum centrale) throughout the optic tectum. Eighty percent of the infrared neurons are found within 500--1,200 micrometer of the surface. In layer 7b the visual and infrared cell groups are mixed; bimodal neurons that respond to a combination of visual and infrared input are located predominantly in this sublamina. The lamination pattern for visual and nonvisual cell groups in the rattlesnake tectum appears to more closely resemble the colubrid tectum and mammalian superior colliculus than the tecta of other reptiles.

Connections of the tectum of the rattlesnake Crotalus viridis: an HRP study.

We have studied the connections of the tectum of the rattlesnake by tectal application of horseradish peroxidase. The tectum receives bilateral input from nucleus lentiformis mesencephali, posterolateral tegmental nuclei, anterior tegmental nuclei and periventricular nuclei; ipsilateral input from nucleus geniculatus pretectalis, and lateral geniculate nucleus pars dorsalis; and contralateral input from dorso-lateral posterior tegmental nucleus and the previously undescribed nucleus reticularis caloris (RC). RC is located on the ventro-lateral surface of the medulla and consists of large cells 25--45 micrometer in diameter. Efferent projections from the tectum can be traced to the ipsilateral nucleus lentiformis mesencephali, the ipsilateral lateral geniculate region, anterior tegmental region and a wide bilateral area of the neuropil of the ventral tegmentum and ventral medualla. We have not found any direct tectal projections from the sensory trigeminal nuclei including the nucleus of the lateral descending trigeminal tract (LTTD). We suggest that in the rattlesnake, RC is the intermediate link connecting LTTD to the tectum.

Retinal anatomy of Chorocaris chacei, a deep-sea hydrothermal vent shrimp from the Mid-Atlantic Ridge.

Exploration of deep-sea hydrothermal vents over the past quarter century has revealed that they support unique and diverse biota. Despite the harsh nature of the environment, vents along the Mid-Atlantic Ridge are dominated by large masses of highly motile Bresiliid shrimp. Until 1989, when it was discovered that the vent shrimp Rimicaris exoculata possesses a hypertrophied dorsal eye, many believed that animals populating hydrothermal vents were blind. Chorocaris chacei (originally designated Rimicaris chacei) is a Bresiliid shrimp found at hydrothermal vent fields along the Mid-Atlantic Ridge. Like R. exoculata, C. chacei has a hypertrophied retina that appears to be specialized to detect the very small amount of light emitted from the orifices of black smoker hydrothermal vent chimneys. C. chacei lacks the sophisticated compound eyes common to other decapod crustaceans. Instead, it has a smooth cornea, with no dioptric apparatus, apposed by a tightly packed, massive array of photosensitive membrane. Photoreceptors in the C. chacei retina are segmented into a hypertrophied region that contains the photosensitive membrane and an atrophied cell body that is roughly ten times smaller in volume than the photosensitive segment. The microvillar photosensitive membrane is consistent in structure and ultrastructure with the rhabdoms of decapod and other invertebrate retinas. However, the volume density of photosensitive membrane (> or =60%) exceeds that typically observed in invertebrate retinas. The reflecting pigment cells commonly found in decapod retinas are represented in the form of a matrix of white diffusing cells that exhibit Tyndall scattering and form an axial sheath around the photoreceptors. All photoreceptor screening pigment granules and screening pigment cells are restricted to the region below the photoreceptor nuclei and are thereby removed from the path of incident light. No ultrastructural evidence of rhythmic cycling of photosensitive membrane was observed. The morphological adaptations observed in the C. chacei retina suggest that it is a high-sensitivity photodetector that is of functional significance to the animal.

Identification of lymphocyte subpopulations with a polymethine dye.

Using the polymethine dye p-ethoxyphenyl-p-aminostyryl-1,3,3-trimethyl-3H-indolium chloride as an aqueous stain applied to specimens of peripheral blood or buffy coat fixed in FAA fixative, differential coloration of leukocytes was achieved using darkfield illumination. Neutrophils stained dark maroon and contained green granules, eosinophils contained bright blue granules, basophils revealed yellow and pink granules, and monocytes stained green with green and yellow vacuoles. In studies of purified lymphocyte subpopulations obtained in a cell sorter, T-helper cells stained red, T-suppressor cells were yellow orange, B-cells appeared yellow and often contained yellow annular structures in the cytoplasm, and natural killer (NK) cells stained green and contained large green granules. As a rapid screening technique for identification of T-helper and T-suppressor cells and their ratios in health and disease, the new polymethine stain may complement the more complex monoclonal antibody techniques for identification of these cells.

Megakaryocytes in the giant platelet syndrome. A cytochemical and ultrastructural study.

When compared to normal megakaryocytes, those from a patient with the giant platelet syndrome exhibited numerous cytochemical abnormalities. These reflected disturbances in the metabolism of RNA, glycogen, arginine-rich histone, and various glycolytic enzymes. Ultrastructural studies of the abnormal megakaryocytes also showed decreased glycogen and RNA (ribosomes) as well as aberrations of nuclear lobulation.

Unusual morphologic abnormalities of megaloblasts in pernicious anemia and folate deficiency.

Three types of morphologic abnormalities of megaloblasts in the bone marrows of eight patients with severe untreated pernicious anemia and two patients with folate deficiency are described. A fourth type of abnormality, probably indicating disturbances in hemoglobin synthesis, was also observed in megaloblasts from patients with these conditons. In addition to the phenomenon of erythrophagocytosis in these disorders, the degenerating megaloblasts and those showing disturbances of hemoglobinization may constitute additional cytologic evidence for intramedullary destruction of erythroid precursors contributing to ineffective erythropoiesis in these disorders.

Niagara sky blue 6B--a new stain for granulocytic cells.

Using an acidified solution of Niagara sky blue 6B, granules in mature granulocytic cells from peripheral blood and bone marrow stained bright blue to blue-green. Granules in immature granulocytes like myelocytes and promyelocytes stained purple. In leukemic myeloblasts and leukemic monocytes, granular-appearing structures stained purple. In leukemic lymphoblasts, purple granular structures were not visualized. As such, Niagara sky blue 6B can be used to identify granulocytic cells at all maturational stages.

Cytochemical identification of tetrahydrofolate in human leukocytes.

Utilizing the ability of molybdenum dioxide dichloride to form a black insoluble precipitate with tetrahydrofolate, a cytochemical test for rapid detection of tetrahydrofolate in human leukocytes was developed. The test may be useful in distinguishing deficiency of vitamin B12 or folate or both from other disorders of erythropoiesis characterized by megaloblastic erythropoiesis.

Synacril black AN. A new stain for normal and abnormal human megakaryocytes.

After methanol fixation and ribonuclease digestion, normal and abnormal human megakaryocytes displayed intense red-purple coloration of the cytoplasm and dark brown nuclei when stained with the cationic textile dye Synacril black AN. In other marrow cells, cytoplasm stained cream color or pale blue in the case of eosinophils. In eosinophils, granules stained pink. As a complement to more complex immunologic technics, staining of megakaryocytes with Synacril black AN may represent a rapid screening method for identification of these cells.