A rose by any other name... on 'naming of neurones' by Rowe and Stone

Rowe and Stone dispose of descriptive terminologies for retinal units as 'essentialist' and argue for a 'neutral' multifactorial system redefined from previous W, X. Y nomenclatures. It is argued here that descriptive terminology need not be either essentialist or undesirable and that the W, X, Y terminology is too confused with false associations to be satisfactory. The synthetic power of the W, X, Y nomenclature was lost with the discovery of concentric W cell receptive fields, the projection of the W cells to the LGN and the suggestion of overlap between X and W conduction velocity groups. It was made methodologically unsound by its employment for the naming of Nissl stained soma classes before the identity of individual somas with the physiological entities can be demonstrated. Although now redefined, the identity of symbols in the several vintages of the W, X, Y system leads to inevitable confusion. The current tripartite division of a multidimensional quality space without cluster analysis is not neutral because it emphasises conduction velocity but represses the diversity of W receptive fields. The concise, apt and memorable descriptive receptive field terminologies are more desirable in that they are operationally based and approximate the unit's transfer function--the parameter most significant to the central nervous system in its information processing task; thus they are more suited for cross species comparison because of a probably bountiful source of functional hypotheses. The lack of taxonomic neutrality in the W, X, Y system has recently been emphasised by its failure to adequately classify rabbit retinal receptive field categories.

Evidence for intestinal origin of transcobalamin II during vitamin B12 absorption

The plasma binding of newly absorbed, radioactively labelled vitamin B12 was studied during a urinary excretion (Schilling) test. Vitamin B12, after being absorbed from the gut, enters blood attached to transcobalamin II, which seems to be derived from the ileal enterocyte. The absorbed B12 re-enters the blood stream after the transcobalamin II-B12 complex is cleared by the liver and it is then excreted into the urine during the Schilling test.

Stability of ribosomes of Staphylococcus aureus S6 sublethally heated in different buffers

Cells of Staphylococcus aureus heated at 52 degrees C in magnesium-chelating buffers [pH 7.2, 50 mM potassium phosphate or 50 mM tris(hydroxymethyl)-aminomethane containing 1 mM ethylenediaminetetraacetic acid] leaked 260-nm absorbing material, shown to be RNA, and suffered destruction of their ribosomes. These cells did not regain their salt tolerance when repair was carried out in the presence of actinomycin D (5 microgram/ml). Cells similarly heated in magnesium-conserving buffers [pH 7.2, 50 mM tris(hydroxymethyl)aminomethane containing 10 mM MgCl2 or piperazine buffer] did not leak RNA, suffered no ribosomal damage when heated for 15 min, and recovered, at least partially, in the presence of actinomycin D. Ribosomal damage, is therefore, a consequence of Mg2+ loss and is not an effect of heat per se. Cells suspended in either Mg2+-chelating or Mg2+-conserving buffers lost salt tolerance to about the same extent during heating at 52 degrees C. Therefore, sublethal heat injury can not be attributed to ribosomal damage.

Variations in uterine cytosolic oestrogen and progesterone receptor levels during the rat oestrous cycle

The levels of cytosol receptors for both oestradiol and progesterone were simultaneous monitored in the uterus at various stages of the rat oestrous cycle. The use of the synthetic gestagen R-5020, with its high specificity and affinity for the progesterone receptor, eliminated interference arising from corticosteroid binding globulin (CBG) contamination of uterine extracts. The results show that the patterns for both receptors are markedly different over the cycle. The variation can be correlated with changes in ovarian steroid output. The results also suggest that oestradiol and progesterone interact not only with their specific receptor, but also influence the other receptor system.

The pigmented-rat optic nerve: fibre count and fibre diameter spectrum

A well distributed electron microscopic sample of 52,000 fibres from the pigmented rat optic nerve cross section indicates a total count of 120,000 +/- 1,600 (S.E.M.) fibres ranging from 0.437 mu to 5.2 mu in diameter. The fibre diameter spectrum is essentially unimodal with a peak at 1.0 mu with a well developed "tail." These results are identical to those available in the literature for the albino rat.

The rabbit optic nerve: fibre diameter spectrum, fibre count, and comparison with a retinal ganglion cell count

This electron microscopic study indicates that the rabbit optic nerve contains 394,000 +/- 20,000 (p less than 0.05) nerve fibers, of which at least 98% are myelinated. The fibre diameter spectrum of the nerve is unimodal and ranges from 0.25-7 mum with its peak at 0.75 mum. The projection of the visual streak fibres is not apparent in local diameter spectra near the optic nerve head. Integration of a ganglion cell density map of the retina from another rabbit indicates a total ganglion cell count lying between 455,000 and 547,000. The optic nerve fibre and ganglion cell counts are both substantially greater than the maximum fibre count previously reported.

Ovarian-independent fluctuations of estradiol receptor levels in mammalian tissues

Three types of periodic fluctuation in tissue concentrations of estradiol receptor protein have been observed. A seasonal variation is described in the uteri of 12-16-week-old calves and of ovariectomized pigs, and in mammary tumor tissue obtained from postmenopausal women. A circadian rhythm has been demonstrated in uteri of ovariectomized rats. An irregular periodic fluctuation has been found in uteri of ovariectomized and of ovariectomized/hypophysectomized rats, with the period varying from 9 to 15 days. These observations establish that a substantial turnover of receptor occurs in the absence of hormone and that 'normal' baseline values of receptor concentration do not exist.

The cat optic nerve: fibre total count and diameter spectrum

An electron microscopic examination of two cat optic nerves indicates a mean total count of 193,000 fibres ranging from 0.5 mu to 13.5 mu in diameter. This count, although nearly double any previously reported, supports recent minimum estimates of the retinal ganglion cell population of the cat eye. A radial gradient of packing density exists across the nerve close to the globe; a high density "core" with a unimodal fibre diameter spectrum may be identified as the area centralis outflow and a peripheral low density region with a trimodal diameter spectrum contains the projection of the peripheral retina. Division of the peripheral fibre spectrum suggests the percentages of alpha, beta and gamma ganglion cells in the peripheral retina to be 5%, 42% and 53% respectively.

The development of the dorsal funiculus in the human spinal cord

1. The development of the dorsal funiculus of the human cord is described from the second month to the end of the fourth. 2. The fasciculus cuneatus arises as a distinct bundle of fibres near the mid-line in the ninth week. This gradually spreads laterally, and to it is joined the more medial fasciculus gracilis. 3. The original embryonic dorsal marginal layer is displaced laterally, and may possibly become the dorsolateral tract adjacent to the dorsal horn. 4. The appearance of the future 'epicritic' pathway is accompanied by a marked wave of differentiation in cervical and thoracic ganglia. 5. The implications of these findings are discussed in relation to the problems of peripheral and central factors in nervous development.

Magnesium requirement of Staphylococcus aureus for repair from sublethal heat injury

Heating in potassium phosphate buffer causes Staphylococcus aureus to lose its salt tolerance and 30-40% of its cellular Mg2+. Repair from injury (regain of salt tolerance) occurred when injured cells were incubated under optimal conditions in synthetic media containing penicillin to prevent growth. Cells died when phosphates or amin acids were omitted from the medium. Omission of vitamins, glucose, Na+, and K+ had no effect. Omission of Mg2+ diminished repair. In a minimal repair medium (MRM) which contained only 3 X 10(-6) M Mg (as an impurity), injured cells rapidly regained their original Mg content. About 20-50% of the cells also regained their salt tolerance provided that less than 10(9) cells/ml were used. With 10(10) cells/ml there was no repair and cellular Mg content was half that of the control. Addition of 10(-3) M ethylenediamine-tetraacetic acid (EDTA) to MRM also prevented repair. Addition of 10(-2) M Mg to MRM EDTA permitted complete repair.

Enumeration of sublethally heated staphylococci in some dried foods

The effect of 45 substances to restore the salt tolerance of sublethally heat-injured Staphylococcus aureus was tested. Sodium pyruvate, yeast extract, L-histine, casitone (Difco), adenosine triphosphate, and acetylphosphate were effective. For enumeration a repair medium was first used, containing sodium pyruvate and penicillin in 1% skim milk. This step was followed by counting on Baird-Parker agar with penicillinase. This method was selective; fewer than 100 staphylococci/g food could be enumerated and it gave counts about 8 times higher than the method of Giolitti and Cantoni used as a five-tube most probable number technique. Heat injury sensitized S. aureus to polymyxin.

A technique for obtaining linear heat-survivor curves with Staphylococcus aureus and its application to the assay of sublethal heat injury

Staphylococcus aureus was grown in a complex (HK) medium either by a batch technique or by a modified batch technique after growth in a chemostat. These cultures were heat-treated at 52 degrees C, and counted on trypticase soy agar (TSA) or trypticase soy agar containing 7.5% NaCl (TSAS). When linear heat-survivor curves were obtained decimal reduction times (D52 degrees C) could be calculated from the TSA counts and pseudodecimal reduction times (D' 52 degrees C) from the TSAS counts. The D or D' values of batch-grown cells varied from 22 to 133 min and from 3 to 12 min, respectively. With cells grown by the modified technique the values were less variable (D was 22-51 min and D' was 3-7 min). D and D' values could be calculated from the same heat treatment in two of the six estimations with cells grown by the modified technique.

A quantitative analysis of the cat retinal ganglion cell topography

A retinal ganglion cell distribution map has been prepared for the cresyl violet stained cat retina. It differs from previously published maps in revealing the visual streak to be more substantial and in showing a higher peak density of 9-10,000 ganglion cells/mm2 at the presumed visual pole. The map was used to obtain a minimum estimate of the retinal ganglion cell population as 217,000 cells, more than double the total previously reported. The problem of classifying the cells of the ganglion cell layer is discussed in detail and examples of criterion cells illustrated. The paper also includes an account of retinal mensuration (dimensions, area, etc.) and a discussion of the visual streak orientation.

Loss of D-alanine during sublethal heating of Staphylococcus aureus S6 and magnesium binding during repair

Staphylococcus aureus S6 sublethally heated at 52 degrees C for 15 min to 0-1 M-potassium phosphate buffer pH 7-2, lost neither the ribitol teichoic acid of the wall nor the glycerol teichoic acid of the membrane. Hurst et al. (1974) showed that this heating caused 40% loss of the cellular Mg, and we now report the loss of 65% of the ester-bound D-alanine of teichoic acid. Repair from sublethal heat injury, measured by the return of salt tolerance, occurs in a simple no-growth medium provided that the cell concentration is less than 5 x 10(8)/ml. During repair, D-alanine is rapidly synthesized. Fully-repaired cells contain four times more D-alanine than do freshly-injured cells. Magnesium is present in the medium at only 3 x 10(-6) M, yet the cellular Mg concentration returns to normal within 1 h of incubation, even in the presence of EDTA. The results suggest that repair occurs in two stages. Soon after injury, in the absence of the competitive effect of D-alanine, Mg is strongly bound to teichoic acid. In repaired or uninjured cells Mg is less strongly bound. The implications of these findings are discussed in relation to the cation-binding function of teichoic acid.

Teratogenesis and the movement of ions

There is evidence that in early embryos, mechanisms exist for the control of the movement of monovalent ions; that sodium is extruded during gastrulation and neurulation, and that in two- to three-day-old chick embryos with head abnormalities, ratios of sodium to potassium may be abnormally high. It is suggested that the origin of neural tube defects in early development may be associated with failure of control of ionic movements.

Relationship between loss of magnesium and loss of salt tolerance after sublethal heating of Staphylococcus aureus

The effect of sublethal heating on Staphylococcus aureus was followed by plate counting on trypticase soy agar and by calculating decimal reduction times (D52C). Pseudodecimal reduction times (D′52C) were obtained from plate counts on trypticase soy agar containing 7.5% NaCl. D52C was a measure of lethality and the ratio D′52C/D52C was used as a measure of injury. Sublethal heating was carried out in various 100 mM (pH 7.2) solutions.Orthophosphates of potassium, ammonium, and sodium were more lethal than the corresponding chlorides (average D52 values of 18.2 and 29.6 min respectively). Orthophosphates also appeared to be more injurious than chlorides (average D′52C/D52C values of 0.43 and 0.62 respectively). 'Phosphate'-heated cells lost 28.4% of their cellular Mg while 'chloride'-heated cells lost 11% of their Mg. Good correlation exists between D′52C/D52C values and the magnesium lost. Kinetic studies in potassium buffer also showed good correlation between loss of salt tolerance and loss of cellular Mg. This, and other evidence, suggests that loss of Mg is one of the primary events in the sublethal heat injury of S. aureus.

The effect of sublethal heating on Staphylococcus aureus at different physiological ages

Sublethal heat injury was measured by the difference in the numbers of colonies developing on trypticase soy agar and trypticase soy agar containing 7.5% NaCl. This difference was largest with late logarithmic and early stationary phase cells because, at this stage, cells had a greatly increased heat resistance. In contrast, the ability to form colonies on high salt agar after sublethal heating varied little during the growth cycle.

Pysiological studies on the recovery of salt tolerance by Staphylococcus aureus after sublethal heating

Cultures of S. aureus in 100 mM potassium phosphate buffer heated at 52 C for 15 min lost their tolerance to 7.5% NaCl. After incubation in a complex growth medium or in a diluted dialyzed medium in which unheated cells were unable to grow, salt tolerance was regained. Heat injury caused 30% loss of lipid. During recovery, the concentration of C(15) and C(17) fatty acids returned to normal, and there appeared to be an oversynthesis of C(16) and C(18) unsaturated acids. Penicillin abolished the latter reaction without affecting recovery; chloramphenicol did not affect fatty acid oversynthesis but reduced recovery. The K/Na ratio was 12.6 in control cells and 3.4 in injured cells, where it remained during the recovery of salt tolerance. Aspartate uptake was about 10% of the control level after injury and about 35% at recovery. Control cells grew without a lag on subculture, but injured cells which had regained their salt tolerance needed about 2 more h of incubation. Cells recovering with penicillin needed 6 more h, and cells recovering with chloramphenicol did not grow without a prolonged lag. Cells of S. aureus, therefore, may recover their salt tolerance while various membrane functions are still damaged.

Evaluation of various methods for the assay of cytoplasmic oestrogen receptors in extracts of calf uteri and human breast cancers

A calf uterus extract and a human mammary cancer extract were assayed for cytoplasmic oestrogen receptors by six different methods. Highest and almost identical yields were obtained by agar gel electrophoresis and Sephadex chromatography, followed by the charcoal technique (62%, 49%), glass bead adsorption (17%, 41%), density gradient centrifugation (16%, 30%) and protamine precipitation (10%, 23%).

The influence of salicylate on platelets and whole blood adenine nucleotides

1. The addition of sodium salicylate to freshly withdrawn human blood or native platelet-rich plasma significantly delays platelet aggregation in vitro.2. The administration of acetylsalicylic acid to human subjects also significantly delays platelet aggregation in their whole blood and there is a short delay in the formation of fibrin but this is not statistically significant.3. Salicylate, whether added to human blood in vitro as sodium salicylate or given by mouth as acetylsalicylic acid, significantly reduces the platelet clumping activity of adenosine diphosphate (ADP) added to whole blood in vitro.4. The administration of aspirin in high doses for several days produces a marked increase in the total adenine nucleotide content of whole blood. The percentage of adenosine triphosphate (ATP) was increased, that of ADP decreased while there is an obvious increase in the ATP: ADP ratio.5. There is little correlation between the plasma salicylate level and the delay aspirin produces in platelet aggregation in vitro or the changes that occur in the levels of ADP or ATP in whole blood during administration of aspirin.6. Significant correlations do occur, however, between the delay in platelet aggregation in vitro and (i) the percentage increase in the ATP concentration, (ii) the percentage decrease in ADP concentration, (iii) the percentage change in the ATP: ADP ratio observed during aspirin administration.