The duality of macrophage function in chronic lymphocytic leukaemia.

Chronic lymphocytic leukaemia (CLL) is the most common adult leukaemia and, in some patients, is accompanied by resistance to both chemotherapeutics and immunotherapeutics. In this review we will discuss the role of tumour associated macrophages (TAMs) in promoting CLL cell survival and resistance to immunotherapeutics. In addition, we will discuss mechanisms by which TAMs suppress T-cell mediated antitumour responses. Thus, targeting macrophages could be used to i) reduce the leukaemic burden via the induction of T-cell-mediated antitumour responses, ii) to reduce pro-survival signalling and enhance response to conventional chemotherapeutics or iii) enhance the response to therapeutic antibodies in current clinical use.

Carotenoid accumulation in the psychrotrophic bacterium Arthrobacter agilis in response to thermal and salt stress.

A psychrotrophic strain of Arthrobacter agilis, isolated from Antarctic sea ice, grows from 5 degrees C to 40 degrees C and in culture media containing 0-10% (w/v) NaCl. Maximum growth rate occurred at 30-35 degrees C with a drastic decline as the cultivation temperatures diverged. Adaptation to extremes of low temperature may be partially attributed to the production of the C-50 carotenoid bacterioruberin, and its glycosylated derivatives. Lowering of the cultivation temperature resulted in a concomitant increase in carotenoid production, which may contribute to membrane stabilisation at low temperature. Maximum biomass accumulation occurred at 5-30 degrees C with a tenfold reduction at 40 degrees C. Changes in growth rates were minimal in culture media containing 0-2% (w/v) NaCl at 10 degrees C while a gradual decrease in growth rates occurred at higher salinity. Biomass accumulation at different salinity followed a trend similar to that observed with different cultivation temperatures. Maximum biomass accumulation was observed in culture media containing 0-5% (w/v) NaCl with a tenfold reduction at 10% (w/v) NaCl. Carotenoid production also decreased as salinity increased.

Age-associated changes in cardiac matrix and integrins.

The progressive shift from young age to senescence is characterized by structural and functional changes in the cardiac extracellular matrix (ECM), which supports and aligns myocytes and blood vessels, and maintains myocardial mass, structure and function. As cardiac function declines with advancing age, ECM collagen and fibronectin influence diastolic stiffness. ECM binding to membrane-bound receptors, or integrins, directly links ECM to cardiac muscle and fibroblast cells, affording it the permissive role to modulate heart function. To better understand the ECM structure-function relationship in the old heart, we studied the relative protein content of these ECM proteins and integrins across three age groups. Old Balb-c mice (20 months) exhibit biventricular, cardiac hypertrophy, and greater left ventricular (LV) collagen, fibronectin, alpha 1 and alpha 5 integrin protein than middle-aged (12 months) or young (2 months) LV (P<0.05). beta1 integrin protein content is lower in old LV (P<0.05). These data show that advancing age is associated with greater collagen, fibronectin, alpha 1 and alpha 5 integrin content, suggesting that these matrix proteins undergo coordinated regulation in the aging heart. The differential integrin and ECM protein content suggests that there is regulatory signaling to the fibroblasts, which maintain the cardiac ECM.

Sequence bias in edited kinetoplastid RNAs.

Uridylate residues (Us) are inserted and deleted at precise positions in mitochondrial transcripts of Trypanosoma brucei. These sequence changes are determined by interactions with small guide RNAs (gRNAs) that are complementary to edited sequence. Adenylate (A) and guanylate (G) residues in gRNAs across from editing sites pair with inserted Us. We evaluate whether sequence bias exists in the bases surrounding insertion sites. Upon analyzing all reported insertion sites in T. brucei, we find that the predicted base pairs flanking insertion sites show a strong bias. Specifically, guiding As and Gs tend to be flanked by cytosine residues and Us. This bias is expected if precise base-pair interactions at the editing site determine the number of inserted Us.

Uridylate addition and RNA ligation contribute to the specificity of kinetoplastid insertion RNA editing.

RNA editing in Trypanosoma brucei inserts and deletes uridylates (U's) in mitochondrial pre-mRNAs under the direction of guide RNAs (gRNAs). We report here the development of a novel in vitro precleaved editing assay and its use to study the gRNA specificity of the U addition and RNA ligation steps in insertion RNA editing. The 5' fragment of substrate RNA accumulated with the number of added U's specified by gRNA, and U addition products with more than the specified number of U's were rare. U addition up to the number specified occurred in the absence of ligation, but accumulation of U addition products was slowed. The 5' fragments with the correct number of added U's were preferentially ligated, apparently by adenylylated RNA ligase since exogenously added ATP was not required and since ligation was eliminated by treatment with pyrophosphate. gRNA-specified U addition was apparent in the absence of ligation when the pre-mRNA immediately upstream of the editing site was single stranded and more so when it was base paired with gRNA. These results suggest that both the U addition and RNA ligation steps contributed to the precision of RNA editing.

Kinetoplastid RNA editing does not require the terminal 3' hydroxyl of guide RNA, but modifications to the guide RNA terminus can inhibit in vitro U insertion.

During RNA editing in kinetoplastid parasites, trans-acting guide RNAs (gRNAs) direct the insertion and deletion of U residues at precise sites in mitochondrial pre-mRNAs. We show here that some modifications to the 3' terminal ribose of gRNA inhibit its ability to direct in vitro U insertion. However, we found that gRNAs lacking this moiety in some circumstances support in vitro editing. Thus, the 3' OH is not required. Inhibition resulting from gRNA modification can be overcome by increasing the gRNA-pre-mRNA base-pairing potential upstream of the editing site, suggesting an importance for this interaction to productive processing.

Increased open field locomotion and decreased striatal GABAA binding after activity wheel running.

Open-field behavior has been used to model reductions in anxiety-related behaviors in the rat after chronic physical activity. Plausible mechanisms for the increased open field locomotion observed after physical activity have not been studied. Open field locomotion is decreased by gamma-aminobutyric acid (GABA) and its agonists, and increased by GABA antagonists, in the ventral striatum. Hence, we tested the hypothesis that increased open field locomotion following chronic physical activity would be accompanied by a decrease in the number of GABAA receptors in the corpus striatum. Young (approximately 55 days) male Sprague-Dawley rats (N = 24) were randomly assigned to three conditions: 24-h access to an activity wheel (AW), running for 1 h without shock 6 days/week on a motorized treadmill (TM), or sedentary control (C). Open field locomotion (total and center squares traversed), defecation, and urination were assessed on each of 3 consecutive days prior to and again after 8 weeks of physical activity. Open field locomotion (total and center squares) increased after activity wheel running, decreased after treadmill training, and did not change for control animals. GABAA receptor density indicated by [3H] bicuculline binding (fmol/mg) was lower for activity wheel animals compared with treadmill animals and controls. GABA concentration (mumol/g) was not different between activity wheel and treadmill groups but was higher for both groups contrasted with controls. Our findings of decreased GABAA density in the corpus striatum concomitant with an increase in open field locomotion are consistent with an anxiolytic effect of chronic activity wheel running.

Exercise- and hypertension-induced collagen changes are related to left ventricular function in rat hearts.

Chronic hypertension, known to affect the collagen profile of the heart, and exercise result in impaired or improved heart function, respectively. Collagen types I [alpha 1(I)2 and alpha 2(I)] and III [alpha 1(III)3] are the predominant interstitial collagens thought to influence cardiac function, and the ratio of type III to I (collagen III/I) is thought to be a significant factor in the altered relaxation observed in hypertrophy. The present study tested the hypothesis that the myocardial structure and function are different in chronically exercise-trained vs. hypertensive rat hearts. Male rats were either chronically exercised (XTr) or submitted to experimental hypertension by coarctation of the abdominal aorta (Hyp) for 10 wks. Heart rate, blood pressure, and maximal rate of fall of the left ventricular pressure (-dp/dt) were recorded during isoproterenol stimulation. Results showed that both Hyp and XTr had higher heart weight and left ventricular weight-to-body weight ratios (P < 0.05). Mean arterial pressure (MAP) was higher in Hyp and lower in XTr (P < 0.05), whereas (-dP/dt)/MAP was diminished in Hyp but enhanced in XTr. Left ventricular collagen was higher in Hyp than XTr, whereas collagen III/I was reduced in Hyp compared with XTr (P < 0.05). Scanning and transmission electron microscopy also supported an accumulation of left ventricular collagen in Hyp compared with XTr. A negative correlation was observed between collagen III/I and (-dP/dt)/ MAP (r = -0.91; P < 0.05). These results suggest an important relationship between adaptations in left ventricular collagen and the changes in diastolic function observed in both chronic hypertension and exercise cardiac stress.

Integrin-mediated collagen gel contraction by cardiac fibroblasts. Effects of angiotensin II.

Angiotensin II (Ang II), a vasoactive octapeptide, has been implicated in cardiac growth and the development of hypertrophy and fibrosis secondary in hypertensive disease. These consequences of Ang II imply an effect on the function and morphology of cardiac interstitial cells (fibroblasts). The present investigation was designed to (1) determine whether neonatal heart fibroblasts (NHFs) possess functional Ang II receptors on their plasma membrane and (2) examine the effects of Ang II on NHFs in vitro using three- and two-dimensional (3D and 2D, respectively) cultures. Several analytic techniques were used to test the specific questions of the present study. Since cardiac fibroblast phenotype can be influenced by culture conditions, both 2D and 3D cultures were used in the present investigations. Reverse-transcriptase polymerase chain reaction and radioligand binding analysis were used to test for the presence of Ang II receptors on NHFs. Both revealed that NHFs in 2D culture possess Ang II receptor mRNA and Ang II receptors. When isolated NHFs were cultured in 3D collagen gels and treated with Ang II, gel contraction was stimulated by NHFs. This effect was attenuated by the specific Ang II receptor antagonist [Sar1,Ala8]Ang II. Ang II-stimulated gel contraction was completely inhibited by extracellular matrix receptor (beta 1-integrin) antibodies (P < .05), supporting previous studies indicating that collagen gel contraction is mediated via the integrins. Immunofluorescent staining was used to test the localization of cell-surface integrins. A more intense staining pattern for beta 1-integrin in Ang II-treated versus control cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise training alters cardiovascular and hormonal responses to intracranial self-stimulation.

Both reinforcing intracranial self-stimulation (ICSS) and physical exercise result in heightened cardiovascular and endocrine responses. This study compared the cardiovascular and endocrine responses to ICSS in rats after either chronic ICSS or treadmill running. Male rats (n = 35) were implanted with bipolar electrodes aimed at the ventral tegmental area of the brain, and those that performed vigorous lever pressing for ICSS (> 50 presses/min; n = 30) were counter balanced into three groups: chronic ICSS (PRESS), chronic run training (RUN), or sedentary controls (CONT). PRESS, RUN, and CONT rats performed ICSS, ran on a motorized treadmill, or sat quietly in cages for 30 min/day, 5 day/wk, for 12 wk, respectively. All animals then performed 30 min of lever pressing for ICSS and were immediately killed. Oxygen consumption, heart rate, blood pressure, rectal temperature, and plasma norepinephrine, epinephrine, and corticosterone increased (P < 0.05) for all groups during lever pressing. PRESS rats did not differ from CONT rats for any variable studied. However, heart rate was lower and oxygen consumption, norepinephrine, and corticosterone were higher in RUN than in CONT rats. Heart and ventricle weights were higher in PRESS and RUN than in CONT rats; body weights were not different. These data suggest that chronic treadmill running results in adaptations that influence cardiovascular and hormonal responses to ICSS.

Validity of field tests of upper body muscular strength.

The purpose of this study was to determine the validity of five field tests (FTs) of upper body muscular strength and endurance (UBMSE) in 9-10-year-old children. Ninety-four children (38 boys, 56 girls) performed five FTs of UBMSE: pull-ups, flexed arm hang, push-ups, Vermont modified pull-ups (VMPU), and New York modified pull-ups. They also performed three criterion tests (CTs) of strength and three CTs of muscular endurance using a supported weight, set-resistance device. Zero-order correlations between the sum of the standard scores on the three CTs of strength (SUM1RM) and the FTs were nonsignificant. However, when SUM1RM was expressed relative to body weight (SUM1RM.kg-1), significant (p < .01) correlation coefficients were obtained for each FT. Highest correlations with SUM1RM.kg-1 were observed for the VMPU, and this same test yielded the smallest percentage of zero scores. Principal components analysis of the CTs, normalized for body weight, and FTs yielded a factor on which both the FTs and CTs of strength loaded significantly. These data indicate that the five FTs, though invalid as measures of absolute strength and muscular endurance, manifest concurrent and construct validity as measures of weight-relative muscular strength.

Effects of intracranial self-stimulation on selected physiological variables in rats.

The purpose of this investigation was to characterize selected metabolic, cardiovascular, and hormonal responses to reinforcing intracranial self-stimulation (ICSS) of the ventral tegmental area (VTA) in rats. Twenty male Sprague-Dawley rats were stereotaxically implanted with bipolar electrodes aimed at the VTA of the brain. Rats were trained to lever-press for ICSS for 1 wk. While they adapted to the experimental environment by sitting in a metabolic operant chamber, they were connected to the electrode cable but did not lever-press. All animals were instrumented with arterial catheters. Rats receiving contingent stimulation (C-St; n = 10) performed 30 min of lever pressing in the metabolic operant chamber for reinforcing brain stimulation. Oxygen consumption (VO2), heart rate (HR), mean arterial pressure (MAP), and rectal temperature (Trec) increased with the onset and continuation of contingent brain stimulation over 30 min (P < 0.05). In addition, plasma norepinephrine (NE), epinephrine (Epi), and corticosterone increased significantly above resting values in C-St rats (P < 0.05). Five animals received investigator-delivered reinforcing brain stimulation (noncontingent stimulation; NC-St), with MAP, HR, VO2, NE, and Epi increasing significantly above resting values (P < 0.05). Trec and corticosterone were not responsive to noncontingent brain stimulation. With the exception of HR, nonstimulated controls (n = 5) did not experience increases above resting values in any of the variables measured. The responses suggest that contingent brain stimulation reward elicits heightened sympathetic arousal.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen-induced hyperresponsiveness to methacholine in ventilated, anesthetized guinea pigs.

Guinea pigs were actively sensitized to ovalbumin and exposed 2-3 weeks later to an aerosol of ovalbumin or saline. Changes in lung function were assessed 0.5, 1, 6, 24 and 72 h later by measuring the peak increase in pulmonary inflation pressure induced by i.v. methacholine during constant-volume ventilation. Responses to methacholine were significantly potentiated at 0.5, 1, 6 and 24 h but not at 72 h following exposure to antigen. Hyperresponsiveness to methacholine was maximal at 0.5-1 h and, in terms of magnitude, comparable to the early increase in airway reactivity found in mild asthmatics after allergen challenge. Whether the hyperresponsiveness to methacholine induced by antigen in the guinea pig can be attributed solely to an increase in airway reactivity or is due, at least in part, to decreased lung compliance requires further study.

Intracranial self-stimulation motivates treadmill running in rats.

Most animal running models have traditionally used aversive motivators to induce exercise tasks. This study demonstrates treadmill running motivated by reinforcement of intracranial self-stimulation (ICSS), providing an alternative model with which to study physiological responses to exercise. Twenty-nine male Sprague-Dawley rats were stereotaxically implanted with bipolar electrodes aimed at the ventral tegmental area of the brain. After 7 days of operant lever-press training for ICSS, rats that pressed at least 50 presses/min were randomly divided into three conditions: exercise-reinforcing brain stimulation (Ex-St), exercise-aversive shock (Ex-Sh), and sedentary controls (C). Ex-St and Ex-Sh ran for 30 min at 25 m/min at 5% grade for 2 wk with ICSS and electric shock as the motivator, respectively, while C did not run. At the end of 2 wk, Ex-St and Ex-Sh performed an endurance run. Results show that Ex-St ran longer than Ex-Sh [63 +/- 10 vs. 42 +/- 10 (SD) min; P less than 0.05]. HR was higher in Ex-St than in C (P less than 0.05). Rectal temperature increased similarly in both exercise groups. This model provides a highly effective method to motivate treadmill running in rats and as such can be used to characterize physiological responses to exercise without the potentially confounding influence of stress associated with an aversive shock motivator.

RPE, blood glucose, and carbohydrate oxidation during exercise: effects of glucose feedings.

This study examined the effects of glucose ingestion on differentiated and undifferentiated ratings of perceived exertion (RPE) during prolonged cycling exercise. On two occasions, seven trained males cycled for 180 min on a Monark cycle ergometer at 70% peak VO2 (VO2peak). Subjects consumed an 8% glucose/electrolyte drink (G) or a flavored water placebo (P) every 15 min throughout exercise. Measurement of RPE, ventilation (VE), oxygen uptake (VO2), respiration rate (RR), respiratory exchange ratio (RER), heart rate (HR), and venous blood sample collection preceded ingestion of the drink. Subjects were homogenous with respect to height, weight, and VO2peak. RPE for the legs and overall body were significantly attenuated (P less than 0.05) during the last 45 min of exercise. Plasma glucose and insulin were higher (P less than 0.05) in G than in P at virtually all time points. CHO oxidation and work rate were maintained throughout exercise in G but not during the last 30 min of exercise in P (P less than 0.05). Percent changes in plasma volume, plasma lactate, HR, VE, RR, and RPE for the chest were not different between conditions (P greater than 0.05). The data suggest that ingestion of carbohydrate beverages during endurance cycling can maintain plasma glucose and CHO oxidation during the latter stages of prolonged exercise. As a result, it appears that a relationship exists between attenuation of ratings of perceived exertion (especially in the legs), blood glucose, and CHO oxidation late in prolonged exercise. The mechanism for this probably involves the increased availability of blood-borne glucose to serve as substrate for brain and/or muscle energy metabolism during a time when endogenous stores of carbohydrate are low.

Dietary intake of women runners.

One hundred and three women who were habitual distance runners and 74 age-matched physically inactive women provided three-day diet records. Intergroup differences in intakes of energy nutrients, micronutrients, cholesterol and fiber were evaluated via analysis of variance and, to assess qualitative differences, via analysis of covariance with total caloric intake entered as the covariate. Women runners reported consuming more carbohydrate (192.4 vs 165.0 g.d-1) and less fat (57.5 vs 66.1 g.d-1) than did the inactive women (p less than .05). After controlling for the non-significant intergroup difference in caloric intake, these differences persisted and protein intake was lower in the runners. Cholesterol and saturated fat intakes were lower and fiber intake was greater in the runners, with and without control for differences in caloric intake. These data suggest that female runners, when compared to inactive counterparts, tend to follow dietary practices that conform more closely to the current recommendations of health authorities.

Evaluation of the wick catheter as used to measure intracompartmental muscle pressure in equine muscle.

The use of the wick catheter to measure intracompartmental muscle pressure in equine muscle was documented. The presence of muscle compartments involving the extensor carpi radialis muscle and the long head of the triceps brachii was demonstrated by anatomic dissection and radiographic technique. The wick catheter was capable of accurately measuring pressures within both of these compartments. Furthermore, the wick catheter was sensitive to pressure changes resulting from external compression of muscle compartments. Manipulation of systemic blood pressure and PaCO2 in 1 anesthetized horse did not affect intracompartmental muscle pressure.

Effect of protective padding on forelimb intracompartmental muscle pressures in anesthetized horses.

Wick catheters were used to measure intracompartmental muscle pressures (ICMP) within the long heads of the triceps brachii and extensor carpi radialis muscles of 8 horses maintained under halothane anesthesia while their breathing was controlled by intermittent positive-pressure ventilation. Blood gas, cardiac output, and blood pressure determinations were monitored to maintain a stable plane of anesthesia. The horses were positioned in left lateral recumbency and were placed sequentially on each of 4 contact surfaces for 1 hour. The 4 surfaces used for each horse were concrete, foam rubber, air dunnage bag, and a water mattress. Hematologic and biochemical determinations were made before and 24 hours after anesthesia. All horses recovered from the anesthesia. One horse had forelimb lameness for 36 hours after anesthesia, which was clinically diagnosed as a myoneuropathy. The ICMP values were markedly elevated in the muscle bellies of the lower limb of all horses. Supporting the horse on a water mattress caused the least dramatic pressure elevation and foam caused the most. The triceps muscle and, to a lesser extent, the extensor carpi radialis muscle of the lower limb are at risk of ischemia in anesthetized horses because the ICMP may exceed the critical closing pressure of 30 mm of Hg required for capillary blood flow.