Kinetics of Utilization of Organic Compounds in the Growth of Mycobacterium tuberculosis.

Bowles, Jean A. (University of Colorado School of Medicine, Denver), and William Segal. Kinetics of utilization of organic compounds in the growth of Mycobacterium tuberculosis. J. Bacteriol. 90:157-163. 1965.-To obtain a workable system for a study of the kinetics of nutrient utilization (based on specific quantitative assay) by Mycobacterium tuberculosis, several cultural refinements were introduced: the use of shake culture, a 40-fold increase in the size of inoculum, substitution of glutamate for asparagine as nitrogen source, and elimination of glucose from the medium with glycerol remaining as carbon source. These modifications resulted in reduction to a tenth of the lag phase of glycerol utilization (from 40 to 4 days), and in a greatly increased rate of growth. Both coordinate and sequential patterns of nutrient utilization were in evidence, except in the case of citrate, which was never utilized under a variety of conditions of culture. The coordinate pattern of glucose-glutamate and glucose-glycerol utilization would appear to rule out catabolite repression by glucose. However, elimination of glucose from the medium resulted in elimination of the 4-day lag period before glutamate utilization was initiated, leaving open to question the role of glucose in this system. Evidence is presented for the hypothesis that the sequential pattern of glutamate-glycerol utilization is a function of glutamate repression of glycerol oxidation in the growth of M. tuberculosis, although no diauxie effect is apparent. In a determination of which nutrient-utilization systems were regulated by induction, only in the case of glycerol was evidence obtained for an inducible system. The enzymatic mechanisms underlying these patterns of nutrient utilization are presently being investigated.     

Effect of exercise training on insulin sensitivity and glucose metabolism in lean, obese, and diabetic men.

To clarify the impact of vigorous physical training on in vivo insulin action and glucose metabolism independent of the intervening effects of concomitant changes in body weight and composition and residual effects of an acute exercise session, 10 lean, 10 obese, and 6 diet-controlled type II diabetic men trained for 12 wk on a cycle ergometer 4 h/wk at approximately 70% of maximal O2 uptake (VO2max) while body composition and weight were maintained by refeeding the energy expended in each training session. Before and 4-5 days after the last training session, euglycemic hyperinsulinemic (40 mU.m2.min-1) clamps were performed at a plasma glucose of 90 mg/dl, combined with indirect calorimetry. Total insulin-stimulated glucose disposal (M) was corrected for residual hepatic glucose output. Body weight, fat, and fat-free mass (FFM) did not change with training, but cardiorespiratory fitness increased by 27% in all groups. Before and after training, M was lower for the obese (5.33 +/- 0.39 mg.kg FFM-1.min-1 pretraining; 5.33 +/- 0.46 posttraining) than for the lean men (9.07 +/- 0.49 and 8.91 +/- 0.60 mg.kg FFM-1.min-1 for pretraining and posttraining, respectively) and lower for the diabetic (3.86 +/- 0.44 and 3.49 +/- 0.21) than for the obese men (P less than 0.001). Insulin sensitivity was not significantly altered by training in any group, but basal hepatic glucose production was reduced by 22% in the diabetic men. Thus, when intervening effects of the last exercise bout or body composition changes were controlled, exercise training per se leading to increased cardiorespiratory fitness had no independent impact on insulin action and did not improve the insulin resistance in obese or diabetic men.     

A numerical analysis of steady flow in a three-dimensional model of the carotid artery bifurcation

A finite element approximation of steady flow in a rigid three-dimensional model of the carotid artery bifurcation is presented. A Reynolds number of 640 and a flow division ratio of about 50/50, simulating systolic flow, was used. To limit the CPU- and I/O-times needed for solving the systems of equations, a mesh-generator was developed, which gives full control over the number of elements into which the bifurcation is divided. A mini-supercomputer, based on parallel and vector processing techniques, was used to solve the system of equations. The numerical results of axial and secondary flow compare favorably with those obtained from previously performed laser-Doppler velocity measurements. Also, the influence of the Reynolds number, the flow division ratio, and the bifurcation angle on axial and secondary flow in the carotid sinus were studied in the three-dimensional model. The influence of the interventions is limited to a relatively small variation in the region with reversed axial flow, more or less pronounced C-shaped axial velocity contours, and increasing or decreasing axial velocity maxima.     

Targeted cytotoxic cells in human peripheral blood lymphocytes.

We have isolated subsets of cells from human PBL and have investigated their abilities to mediate lysis targeted by bispecific antibodies. Targeted cytotoxic cells were divided into two distinct types based on buoyant density. The low buoyant density fraction contained all of the targetable cytotoxic activity in unstimulated PBL, including both T and K cells targeted with anti-CD3 and anti-Fc gamma RIII (CD16) containing bispecific antibodies, respectively. Both types of targetable cytotoxic cells required IL-2 for maintenance of cytotoxic activity, expressed the CD56 (NKH1) marker, and mediated MHC-unrestricted lysis. The targetable T cells in low density PBL were exclusively CD8+ and represented only about 2% of the total PBL. The high buoyant density lymphocytes, depleted of NK cells, had no targetable activity, but were able to generate over several days, targetable T cell activity in the presence of a TCR cross-linking signal plus IL-2. Unlike the low-density cells, the activated high buoyant density effector T cells did not express CD56, consisted of both CD4+ and CD8+ cells, and did not mediate MHC-unrestricted lysis. These cells proliferated more rapidly and generated more total lytic activity than the low-density fraction. Our studies show that targetable cytotoxic activity in human PBL is mediated by several subsets of cells with different activation requirements. Presumably all of these activities could be directed against unwanted cells in clinical or preclinical studies involving targeted cytotoxic cells.     

Induction of lysis by T cell receptor gamma delta+/CD3+ T lymphocytes via CD2 requires triggering via the T11.1 epitope only

The requirements for activation of the lytic machinery through CD2 of TCR gamma delta+/CD3+ cells were examined, by utilizing bispecific heteroconjugates containing anti-CD2 mAb cross-linked to anti-DNP. Contrary to the CD2 activation requirements in TCR alpha beta+/CD3+ cells, cytotoxic activity in TCR gamma delta+/CD3+ clones and TCR-/CD3- NK cell clones can be induced by heteroconjugates containing a single anti-CD2 (OKT11.1) mAb. Activation of TCR gamma delta+/CD3+ cells via CD2 is independent of heteroconjugates binding to CD16 (Fc gamma RIII), because heteroconjugates prepared from Fab fragments induced equal levels of lysis. Moreover, anti-CD16 mAb did not inhibit triggering via CD2 in TCR gamma delta+/CD3+ cells. In TCR-/CD3- NK cells, however, induction of cytotoxicity via CD2 is co-dependent on interplay with CD16. Anti-CD3 mAb blocked the anti-CD2 x anti-DNP heteroconjugate-induced cytotoxicity of TCR gamma delta+/CD3+ cells, indicating a functional linkage between CD2 and CD3 on these cells. We conclude that induction of lysis via CD2 shows qualitatively different activation requirements in TCR gamma delta+/CD3+, TCR alpha beta+/CD3+ CTL and TCR-/CD3- NK cells.     

A recombination outside the BB deletion refines the location of the X linked retinitis pigmentosa locus RP3.

Genetic loci for X-linked retinitis pigmentosa (XLRP) have been mapped between Xp11.22 and Xp22.13 (RP2, RP3, RP6, and RP15). The RP3 gene, which is responsible for the predominant form of XLRP in most Caucasian populations, has been localized to Xp21.1 by linkage analysis and the map positions of chromosomal deletions associated with the disease. Previous linkage studies have suggested that RP3 is flanked by the markers DXS1110 (distal) and OTC (proximal). Patient BB was thought to have RP because of a lesion at the RP3 locus, in addition to chronic granulomatous disease, Duchenne muscular dystrophy (DMD), mild mental retardation, and the McLeod phenotype. This patient carried a deletion extending approximately 3 Mb from DMD in Xp21.3 to Xp21.1, with the proximal breakpoint located approximately 40 kb centromeric to DXS1110. The RP3 gene, therefore, is believed to reside between DXS1110 and the proximal breakpoint of the BB deletion. In order to refine the location of RP3 and to ascertain patients with RP3, we have been analyzing several XLRP families for linkage to Xp markers. Linkage analysis in an American family of 27 individuals demonstrates segregation of XLRP with markers in Xp21.1, consistent with the RP3 subtype. One affected mate shows a recombination event proximal to DXS1110. Additional markers within the DXS1110-OTC interval show that the crossover is between two novel polymorphic markers, DXS8349 and M6, both of which are present in BB DNA and lie centromeric to the proximal breakpoint. This recombination places the XLRP mutation in this family outside the BB deletion and redefines the location of RP3.     

Blown away? Wind speed and foraging success in an acoustic predator

Mammal Research - Foraging animals must contend with fluctuating environmental variables that affect foraging success, including conditions like wind noise, which could diminish the usefulness of...     

La procréation médicalement assistée avec spermatozoïdes immatures: Impératifs cliniques et techniques chirurgicales

The authors report their experience with the use of spermatids in TESE programs where mature spermatozoa could not be isolated from testicular biopsies. The details of the indications for spermatid insemination, the technicity of the procedure and the results are exposed.     

Elemental diet as primary treatment of acute Crohn's disease: a controlled trial.

Acute exacerbations of Crohn''s disease are usually treated with prednisolone or potentially more toxic immunosuppressive drugs or by surgery. In pilot studies replacing the normal diet by a protein free elemental diet also induced remission. A controlled trial was therefore conducted in which 21 patients acutely ill with exacerbations of Crohn''s disease were randomised to receive either prednisolone 0.75 mg/kg/day or an elemental diet (Vivonex) for four weeks. Assessment at four and 12 weeks showed that the patients treated with the elemental diet had improved as much as and by some criteria more than the steroid treated group. Elemental diet is a safe and effective treatment for acute Crohn''s disease.