ALT Group Research Articles

Hypertriglyceridemia: An explanation of persistant ALT elevation despite favorable virologic response to interferon/ribavirin treatment of chronic hepatitis C

Background and Aim: Hepatitis C continues to be a major cause for chronic hepatitis. Presently, alpha interferons are available to treat it with limited success. Interferon/Ribavirin treatment has been shown to be efficacious in sustaining virological, biochemical, and histological remission. In some cases, there have been a discordance between virologic and biochemical responses, e.g. persistence of ALT elevation despite undetectable HCV-RNA. The aim of this study is to determine if hypertriglyceridemia or other factors explain the discordance between ALT and HCV-RNA responses. Patient and Methods: 37 patients who were part of an Interferon/Ribavirin protocol for non-responders and relapsers were evaluated. Ages ranged from 32 to 53 years (mean age 44 years); there were 23 males and 14 females. All patients were treated with alpha interferon, 5 million units t.i.w, and Ribavirin 600 -1000 mg/day based on randomization. HCV-RNA, ALT and AST were evaluated at baseline and at 12 weeks. Results: 27/37 patients had >50% reduction in HCV-RNA with normalization of ALT (Group 1). 10/37 patient had >50% reduction in HCV-RNA, but had ~ersistent elevation of ALT (Group 2).

Training-induced increases in sea level VO2max and endurance are not enhanced by acute hypobaric exposure.

The present study used untrained subjects to examine the effect of acute hypobaric exposure during endurance training on subsequent exercise performance at sea level. Two groups, each of nine subjects, completed 5 weeks of endurance training [cycle ergometer exercise for 45 min, three times per week at a heart rate corresponding to 70% of that achieved at the maximal O2 consumption (VO2max) either at sea level or at high altitude] in a hypobaric chamber, under either normobaric [sea level, SL; 750 mmHg (100 kPa) approximately 90 m] or hypobaric [altitude, ALT; 554 mmHg (73.4 kPa) approximately 2500 m] conditions and the changes in SL VO2max, SL endurance time and peak blood lactate during the endurance test compared. While each group showed increases in both SL VO2max (approximately 12%) and SL endurance time (approximately 71%), there were no significant differences between the groups [SL VO2max, mean (SE)-SL group: pre-training = 42.4 (3.5), post-training = 46.1 (3.5) ml.kg-1.min-1, P < 0.005; ALT group: pre-training = 40.8 (2.6), post-training = 47.2 (3.4) ml.kg-1.min-1, P < 0.01; SL endurance time-SL group: pre-training 7.1 (1.5), post-training 11.8 (2.9) min, P < 0.01; ALT group: pre-training = 7.5 (0.6), post-training = 13.3 (1.4) min, P < 0.001]. Peak blood lactate during the endurance test was not altered by either training regimen. It is concluded that acute exposure of untrained subjects to hypobaric hypoxia during endurance training has no synergistic effect on the degree of improvement in either SL VO2max or endurance time.

MEDIUM ALTITUDE TRAINING AND SEA-LEVEL PERFORMANCE 741

Despite a paucity of controlled studies with elite athletes and controversy surrounding its effectiveness, medium altitude training is widely used with a view to improving sea-level (SL) performance. We recruited 18 elite male distance runners of (mean±SD) age 26±5.0 yr and VO2max 73.2±3.8 ml/kg·min. Tests carried out at, or close to SL were: 3.2 k time trial; VO2max; steady-state heart-rate at 16 and 18 kph (HR 16, 18); short duration treadmill run (SDR) to exhaustion at 18kph and 10% gradient (mean time 170s); hemoglobin concentration (HC); and total body hemoglobin (TH, CO rebreathing technique). Two groups of 9 were selected based on pairs matched for previous and planned training, and the above test results. One group lived for 4 weeks at 1760m (ALT) and trained at 1700-2000m except for one track session/week at 610 m. The other group lived and trained at SL. At ALT, interval training was of similar speed to SL but longer recoveries were utilized. Retesting occurred at or close to SL in the week following the training camps. The effect of ALT, i.e. the difference between the (post-pre) ALT and (post-pre) SL means, was tested by ANOVA. Using p<0.05 to indicate significance, a 3% relative increase in VO2max at ALT was NS (p=0.1), but HR 16, 18 were both 5% lower after ALT than SL(p<0.01). TH was unchanged (p=0.3) and a 3% relative increase in mean HC in the ALT group was not significant (p=0.08). Mean improvement in SDR time was 10% greater in the SL group but also NS (p=0.09). The “bottom line” performance test was the 3.2k run which was 10s quicker in both ALT and SL groups but the difference between groups was NS (p=0.78). This emphasizes the importance of the control group. We conclude that 4 weeks of medium altitude training at 1760-2000m offers no advantages over SL in improving SL 3.2k running performance in already well-trained elite runners.

Discrete-trial probability learning in rats: Effects of local contingencies of reinforcement

Three groups of rats were trained using a noncorrection procedure on a probability learning task in which responses on one lever produced reinforcement on 61% of the trials and responses on the other lever produced reinforcement on the remaining trials. For Group RAN, there were no sequential constraints, but for Groups REP and ALT, the lever on which reinforcement was produced on a given trial depended upon the lever that had been designated correct on the previous trial. For Group REP, the locus of reinforcement was repeated on approximately 80% of trials; Group ALT was required to switch to the other lever on approximately 80% of trials. The maximizing strategy for Group RAN was exclusive responding to the majority lever, for Group ALT, it was “win-shift, lose-stay,” and for Group REP, “win-stay, lose-shift.” Subjects from both the REP and ALT groups tended to maximize momentarily, thereby showing a lower relative frequency of majority responses than did subjects from the RAN group. The differences between groups cannot be accounted for by a molar analysis; a molecular analysis is needed.