BONE MARROW RESTORATION AFTER LOCALIZED DEPLETION

Studies have been made of marrow restoration after localized depletion of the rabbit femur by dextran perfusion. Restoration was shown to involve an initial period of reorganization which blends with a more prolonged period of hemic cell repopulation. Cellularity returned to normal levels by 35 days, the recovery of myeloid cells being somewhat more rapid than that of the erythroid elements. In either case, the evolution of immature hemic cells was soon followed by the appearance of more mature forms even at the earliest stages of marrow repopulation. ³H-TdR uptake per cell increased rapidly to a level approximately twice normal after the first week. The augmented incorporation of thymidine, revealed by scintillation spectrometry and confirmed upon autoradiography, was shown to be due to an increase in DNA synthesis rate as well as in the fraction of participating cells. It is suggested that the enhanced cell production is brought about by a decrease in the proliferative cell cycle and an increase in the growth fraction. The origin of the repopulating cells remains a moot point. Cell migration from the epiphyseal marrow is apparently not involved. Irrespective of the source of stem-type cells, the stimulus for regeneration appears to be locally determined.     

Localization of pheochromocytoma by selective venous catheterization and assay of plasma catecholamines.

The diagnosis of pheochromocytoma rests primarily on determination of the 24-hour urinary excretion of catecholamines and their metabolites. In most cases nephrotomography and selective arteriography or venography, or both, are sufficient to localize the tumour. Selective venous catheterization and the assay of plasma catecholamines should be considered for pheochromocytoma localization in: (a) patients in whom standard techniques fail to localize the tumour; (b) patients who exhibit idiosyncratic reactions to the angiographic contrast materials; (c) young patients or patients with familial pheochromocytoma, including those with multiple neurofibromatosis or multiple endocrine adenomatosis, type 2; (d) patients with recurrent, malignant, or suspected multicentric or extra-adrenal tumours; and (e) patients excreting only norepinephrine in the urine. The validity of the results is particularly dependent on the skill with which venous catheterization is carried out.     

Ectogalactosyltransferase studies in fibroblasts and concanavalin A- stimulated lymphocytes

In this communication, we have demonstrated that hydrolysis of the nucleotide sugar can cause errors in the detection of an ectoglycosyltransferase. Spleen cell suspensions can incorporate radioactivity when incubated with labeled UDP-galactose, but all the activity is due to decomposition of the nucleotide sugar and uptake of the free sugar. The fibroblast cell lines can incroporate carbohydrate directly from UDP-galactose. Several criteria are presented with can be used to demonstrate that a nucleotide sugar is the direct carbohydrate donor.     

Activation of soluble guanylate cyclase from rat lung by incubation or by hydrogen peroxide.

A 37,000 X g supernatant fraction prepared from fat lung homogenate demonstrated a 2- to 3-fold increase in guanylate cyclase activity after incubation at 30 degrees for 30 min (preincubation). Treatment of the supernatant fraction with Triton X-100 increased activity to approximately the same extent as preincubation, but would not increase the activity after preincubation. By chromatography on Sepharose 2B, before and after preincubation, it was demonstrated that the increase in activity was only associated with the soluble guanylate cyclase, and not the particulate enzyme. Activation by preincubation required O2. It was completely inhibited by thiols such as 2-mercaptoethanol, and by bovine serum albumin, KCN, and sodium diethyldithiocarbamate. These inhibitors suggested a copper requirement for activation, and this was confirmed by demonstrating that 20 to 60 muM CuCl2 could relieve the inhibition by 0.1 mM sodium diethyldithiocarbamate. 2-Mercaptoethanol inhibition could also be reversed by removal of the thiol on a Sephadex G-25 column, however, this treatment partially activated the enzyme. Addition of 2-mercaptoethanol to a preincubated preparation would not reverse the activation. H2O2 was found to activate guanylate cyclase, either by its generation in the lung supernatant with glucose oxidase and glucose, or by its addition to a preparation in which the catalase was inhibited with KCN. KCN or bovine serum albumin was able to partially inhibit activation by glucose oxidase plus glucose, however, larger amounts of glucose oxidase could overcome that inhibition, indicating a catalytic role for Cu2+ at low H2O2 concentrations. No direct evidence for H2O2 formation during preincubation could be found, however, indirect evidence was obtained by the spectrophotometric detection of choleglobin formation from hemoglobin present in the lung supernatant fluid. The H2O2 is believed to result from the reaction of oxyhemoglobin with ascorbate.     

GRANULOCYTE DYNAMICS AND THE QUESTION OF INEFFECTIVE GRANULOPOIESIS

A simple analysis was developed to compare granulocyte production in marrow with granulocyte turnover in peripheral blood of the dog. the analysis is anchored to the relative number of granulopoietic and erythropoietic cells that are flashlabeled with tritiated thymidine. This provides a convenient measure of relative production rates, since there is little, if any, difference in the duration of the respective DNA synthesis periods. the latter was confirmed in the present work by comparison of myeloid and erythroid cells in respect to (1) labeled mitosis curves and (2) changes in labeling intensity with constant infusion of tritiated thymidine. the ratio of flash-labeled granulocyte to erythrocyte progenitors was unity (1.02 ± 0.05) in the eight dogs studied, which means that gross production rates were essentially the same. Since net production as revealed by peripheral blood turnover is greater for erythrocytes than for granulocytes, it follows that there must be some ineffective granulopoiesis. This may correspond to over half of the total production. It is suggested that this phenomenon, which apparently occurs in man as well as in dog, could represent an important feature of granulocyte regulation.     

Searching Responses of a Hunting Spider to Cues Associated with Lepidopteran Eggs

Cheiracanthium inclusum (Hentz), a hunting spider, feeds on eggs of Helicoverpa zea (Boddie) and other moths. This study investigated whether C. inclusum can use chemical compounds present in H. zea scales and egg residues as kairomones to find these non-motile prey items. In a series of no- choice tests, spiders were presented with a piece of florist paper containing scales alone, scales + egg residues, or untreated controls. Next, spiders were presented with solvent extracts of either scales or eggs. Polar and non-polar solvents were used in the extractions. Contact with scales alone, scales + egg residues, and non-polar solvent extracts of both scales and eggs resulted in retention and/or induction of local searching behavior. Extracts made with polar solvents induced no apparent response, indicating that the chemostimulatory compounds are lipophilic. These results show that C. inclusum responds to kairomones left by ovipositing H. zea and use these chemical cues to detect and locate H. zea eggs.     

Do Bells Affect Behaviour and Heart Rate Variability in Grazing Dairy Cows?

In alpine regions cows are often equipped with bells. The present study investigated the impact of wearing a bell on behaviour and heart rate variability in dairy cows. Nineteen non-lactating Brown-Swiss cows with bell experience were assigned to three different treatments. For 3 days each, cows were equipped with no bell (control), with a bell with inactivated clapper (silent bell) or with a functional bell (functional bell). The bells weighed 5.5 kg and had frequencies between 532 Hz and 2.8 kHz and amplitudes between 90 and 113 dB at a distance of 20 cm. Data were collected on either the first and third or on all 3 days of each treatment. Whereas duration of rumination was reduced with a functional bell and a silent bell compared with no bell, feeding duration was reduced with a silent bell and was intermediate with a functional bell. Head movements were reduced when wearing a silent bell compared with no bell and tended to be reduced when wearing a functional compared to no bell. With a functional bell, lying duration was reduced by almost 4 hours on the third day of treatment compared with the first day with a functional bell and compared with no bell or a silent bell. All additional behavioural measures are consistent with the hypothesis of a restriction in the behaviour of the cows wearing bells, although this pattern did not reach significance. There was no treatment effect on heart rate variability, suggesting that the bells did not affect vago-sympathetic balance. An effect of experimental day was found for only 1 out of 10 behavioural parameters, as shown by a decrease in lying with a functional bell on day 3. The results indicate behavioural changes in the cows wearing a bell over 3 days, without indication of habituation to the bell. Altogether, the behavioural changes suggest that the behaviour of the cows was disturbed by wearing a bell. If long-lasting, these effects may have implications for animal welfare.     

Kinetics and mechanism of the comproportionation reaction between oxoammonium cation and hydroxylamine derived from cyclic nitroxides

Cyclic nitroxides demonstrate antioxidative activity in numerous in vitro and in vivo models, which frequently involves the participation of the reduced and oxidized forms of the nitroxide, namely, the hydroxylamine and oxoammonium cation. Generally, cellular reducing equivalents facilitate rapid enzymatic as well as nonenzymatic reduction of nitroxides in the tissue. On the other hand, the reaction of nitroxides with various radicals yields the highly oxidizing oxoammonium cation, which mediates the catalytic effect of nitroxides in selective oxidation of alcohols. Hence, nitroxides might act as both anti- and pro-oxidants. Therefore, the comproportionation reaction between the oxoammonium cation and the hydroxylamine might play a role in lowering the pro-oxidative activity of nitroxides. Although the comproportionation reaction has previously been studied, there is no agreement regarding its kinetic features. We investigated the reaction of the reduced forms of 2,2,6,6-tetramethylpiperidinoxyl (TPO) and 4-OH-2,2,6,6-tetramethylpiperidinoxyl (4-OH-TPO) with the oxoammonium cation derived from TPO at various pHs using rapid-mixing stopped-flow and EPR spectrometry. From the pH dependence of the reaction rate constants we determined the pK(1) of the respective hydroxylamines to be 7.5 and 6.9, respectively. The reduction potentials of the hydroxylamines were determined by cyclic voltammetry, and from their dependence on pH, we obtained the same pK(1) values. The rate constant of the comproportionation reaction does not exceed 20 M(-1) s(-1) in the physiological pH range and, therefore, cannot greatly contribute toward recycling of the nitroxides in the tissue.     

Measurement of the trunk musculature of active males using CT scan radiography: implications for force and moment generating capacity about the L4/L5 joint

The purpose of this study was to add to the growing database of cross-sectional areas and moment arm lengths of trunk musculature using the methods of computerized tomographic scanning. An attempt was also made to estimate muscle force and moment generating capacity under various reported values of muscle force per unit cross-sectional area. The data were obtained on 13 active men 40.5 +/- 11.9 years of age, 173.8 +/- 5.9 cm tall and 89.1 +/- 11.7 kg body mass. Transverse CT scans were taken at the level of the L4/L5 disc with the subjects supine. Muscle cross-sectional areas were measured from 35 mm slides of the scans using a planimeter and moment arm length in the transverse plane were taken from the centroid of the L4/L5 disc to the centroid of the muscle section. Prior to estimating force and moment generating capacity, areas were corrected, where necessary, for fibre pennation angle to produce a physiological cross-sectional area. The physiological cross-sectional areas (cm2) for one side of the body were (mean +/- S.D.): sacrospinalis (SS) 15.9 +/- 2.5; multifidus (Mu) 4.2 +/- 0.7; psoas (Ps) 17.6 +/- 4.0; rectus abdominis (RA) 7.9 +/- 2.5; external oblique (EO) 9.4 +/- 2.7; internal oblique (IO) 8.1 +/- 2.3; transverse abdominus (TA) 2.9 +/- 1.3. The anterior posterior moment arm lengths were: erector mass (SS and Mu combined) 5.90 +/- 0.52; Ps 0.58 +/- 0.40; R.A. 10.28 +/- 2.07; E.O. (anterior portion) 5.94 +/- 1.39; E.O. (posterior portion) 2.08 +/- 1.39; I.O. (anterior portion) 6.92 +/- 1.63; I.O. (posterior portion) 3.85 +/- 1.54. The corresponding lateral moment arm lengths were: 3.26 +/- 0.36; 4.88 +/- 0.36; 4.35 +/- 1.31; 12.86 +/- 1.93; 13.95 +/- 1.16; 10.77 +/- 2.02; 12.52 +/- 1.26. The maximum force per unit cross-section that human muscles are capable of generating is not well defined. However, assuming an intermediate value of 50 N cm-2 of physiological cross-section, the erector musculature observed at the L4/L5 level should be capable of generating an extensor moment of about 118 N.m. At a muscle stress of 30 or 90 N cm-2, values also reported on human muscle, the moment would be 71 and 213 Nm, respectively. It must be remembered, however, that muscles not observable at the L4/L5 level can create moments around that center of rotation.(ABSTRACT TRUNCATED AT 400 WORDS)