The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold

The purpose of this investigation was to determine the effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption (VO2max). Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of VO2max (range, 72-80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ.day-1 low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWCFT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWCFT test. A paired t-test indicated that there was no significant (p greater than 0.05) difference between the means of the PWCFT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated at r = 0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWCFT.     

The development of the sensory organs of the legs in the blowfly,Phormia regina

Summary The development of the sensory neurons of the legs of the blowfly,Phormia regina has been described from the third instar larva to the late pupa using immunohistochemical staining. The leg discs of the third instar larva contain 8 neurons of which 5 come to lie in the fifth tarsomere of the developing leg. Whereas 2 neurons persist at least to the late pupa, the other cells degenerate. The first neurons of gustatory sensilla arise in the fifth tarsomere at about 1.5 h after formation of the puparium. Most of these sensilla, however, appear within a short time period beginning at about 18 h. The femoral chordotonal sensory neurons first appear at the time of formation of the puparium, as a mass of cells situated in the distal femur. During later pupal development 2 groups of these cells come to lie at the femur-trochanter border, where they become the proximal femoral chordotonal organ of the adult; the remaining cells become the distal femoral chordotonal organ. Other scolopidial neurons appear later in development. The nerve pathways of the late pupal leg are established either by the axons of the cells that are present in the larval leg disc or by new outgrowing processes of sensory neurons. In the tibia, the initial direction of new outgrowth differs in different regions of the segment: proximal tibial neurons grow distally, while distal tibial neurons grow initially proximally.     

Acute asthma: emergency department management and prospective evaluation of outcome.

To determine the current management of acute asthma in the emergency department and to evaluate outcome we reviewed the charts of 99 patients aged 15 to 55 years who presented to the emergency department of a tertiary referral, university-affiliated hospital and were subsequently discharged with a diagnosis of acute asthma. Outcome was evaluated prospectively, with a structured questionnaire, by telephone. During the visit pulsus paradoxus was documented in four patients. Spirometry was done in 63 patients; postbronchodilator values ranged from 0.9 to 4.1 L. A total of 92 patients received inhaled bronchodilator therapy, most by wet nebulization. Sixteen patients received anticholinergic agents and three received theophylline. Ingested corticosteroids were given to 27 patients. Of the 71 patients contacted, a mean of 12 days after the visit, 26 (37%) had sought further medical attention, 19 at the emergency department; 9 had required admission. Forty-six patients reported that their condition had improved, but over 60% continued to have cough, sputum production, nocturnal waking and early-morning chest tightness. The results indicate that asthma continues to be undertreated in the emergency department and highlight the importance of routine spirometry in all patients and the need for systemic corticosteroid therapy.     

Stereoselective pharmacokinetics of 3,4-methylenedioxymethamphetamine in the rat

Studies to characterize the pharmacokinetics of the enantiomers of MDMA were conducted in rats using the iliac arterial cannulation. Two routes of administration, intravenous and subcutaneous, were evaluated at two dose levels for each route [20 and 40 mg/kg (+/-)-MDMA for subcutaneous, 10 and 20 mg/kg (+/-)-MDMA for intravenous administrations]. The average half-life (+/- SD) for all dosing groups was 2.5 +/- 0.8 h for (-)-(R)-MDMA and 2.2 +/- 0.8 h for (+)-(S)-MDMA. The more rapid clearance of (+)-(S)-MDMA compared with (-)-(R)-MDMA is consistent with the area under the curve (AUC) data of the parent drug and its primary metabolite MDA. The mean (+/- SD) AUC S/R ratios of MDMA and MDA were 0.70 +/- 0.05 and 3.1 +/- 0.8, respectively. Following a 20 mg/kg dose of racemic MDMA iv the mean (+/- SD) of the percent dose excreted as (-)-(R)-MDMA, (+)-(S)-MDMA, (-)-(R)-MDA, and (+)-(S)-MDA were 20 +/- 10, 12 +/- 6, 3 +/- 1, and 6 +/- 2, respectively.     

Spectral mechanisms in the tree squirrel retina

Summary The retina of the gray squirrel (Sciurus carolinensis) contains rods and cones in a ratio of about 23. The spectral mechanisms in this retina were examined in behavioral and electrophysiological experiments. Tests of color vision revealed that this animal has a spectral neutral point at about 500 nm and, thus, dichromatic color vision. Recordings made from single optic nerve fibers and results obtained from an analysis of the flicker photometric electroretinogram (ERG) indicated that vision in the gray squirrel is based on three spectral mechanisms. One of these, presumably rod-based, has peak sensitivity at about 502 nm. The other two mechanisms reflect the presence of two classes of cone having average peak sensitivity of about 444 nm and 543 nm.     

Sexual maturation of ewes raised without ram exposure in a controlled lighting environment

Finn x Dorset ewe lambs (n = 70) born in the spring (March 28 to April 6) from two successive lambing seasons were evaluated for age at first ovulation in the absence of mature rams. Ewe lambs were born in a controlled, short light (8L:16D) photoperiod or in ambient light (13L:11D). At about 10 to 11 wk of age, ewe lambs were allocated to a short (8L:16D) or long (16L:8D) light environment. Plasma progesterone (P(4)) concentrations were measured as an index of first ovulation. First exposure of ewes to sexually mature rams was in November. Most ewe lambs (77%) ovulated before ram exposure. More lambs (P < 0.025) born in ambient light and raised in short light reached puberty with typical cycles of plasma progesterone compared to other treatments. Long days tended to retard the onset of puberty. Although pregnancy rate did not differ across light treatments, more ewes became pregnant from the ambient-light born and short-light raised treatment. Photoperiod is an important factor affecting the onset of sexual maturation and genesis of normal luteal progesterone secretion in the ewe lamb.     

Cloning and characterization of the tetracycline resistance determinant of and several promoters from within the conjugative transposon Tn919

Tn919 is a 15- to 16-kilobase (kb) tetracycline resistance conjugative transposon that was originally isolated from Streptococcus sanguis FC1. The tetracycline resistance determinant (tet) was found on a 4.2-kb HindII fragment by in vitro deletion analysis. This fragment was subcloned to a pWV01 origin capable of directing replication in Escherichia coli, Bacillus subtilis, and Streptococcus lactis, and expression was observed in all three genera. In all cases, expression was weaker when only the 4.2-kb cloned fragment rather than the full transposon was present. The resistance gene is of the streptococcal tetM class and codes for a protein of approximately 70 kilodaltons. The restriction map resembles that of the tetM gene of Tn1545 (P. Martin, P. Trieu-Cuot, and P. Courvalin, Nucleic Acids Res. 14:7047-7058, 1986), which codes for a protein of 72.5 kilodaltons. A number of transposon-derived promoter-bearing fragments were also cloned and sequenced. These closely resemble the consensus sequence of E. coli and B. subtilis promoters. Fusion experiments with a truncated lacZ gene indicate the possibility of an open reading frame for one of the promoters.