Sildenafil does not Improve Exercise Capacity under Acute Hypoxia Exposure.

The increase in pulmonary arterial pressure (PAP) due to hypoxic pulmonary vasoconstriction (HPV) could be a limiting factor for physical performance during hypoxic exposure. Sildenafil has been shown to reduce PAP in situations of moderate or severe hypoxia, and consequently its role as an ergogenic aid and even a possible doping substance must be considered. We performed a double-blind crossover study to determine the effects of sildenafil on cardiovascular, respiratory and metabolic parameters in normoxia and during acute exposure to hypobaric hypoxia (4 000 m) at rest and during maximal and submaximal (60% VO2 max) exercise tests. One hour before testing started, sildenafil (100 mg) or a placebo was orally administered to 11 volunteers. In normoxic conditions, sildenafil did not affect performance. Similarly, no significant differences were found in cardiovascular and respiratory parameters in hypoxic conditions at rest or during exercise. The use of sildenafil to improve physical performance in non-acclimatized subjects is not supported by our data.

Heat-induced gelation mechanism of blood plasma modulated by cysteine.

This work aims to determine changes at molecular level of plasma proteins provoked by adding cysteine (Cys, 0.025% to 0.35% w/v) as a reducing agent and their relationship with the heat-induced gel properties obtained when subsequently the solutions were submitted to a thermal treatment. Results show that adding Cys to plasma solutions at concentrations ≥0.15% actually entails modifications in the secondary structure of their main proteins, that is, serum albumin-α-helix rich-and globulin fraction-ß-sheet rich. Basically, a reduction of the intensity of the infrared (IR) bands assigned to both structures takes place concomitant to an increase of extended structures that seem to act as intermediates for the subsequent protein aggregation process through nonnative intermolecular ß-sheets. Cleavage of disulfide bonds is also evidenced at Cys concentrations ≥0.15% by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), with the effects being directly proportional to Cys concentration. However, beneficial effects on gel hardness are gradually obtained at Cys concentrations ≤0.15%, that is, when the effects at molecular level are at most just budding, while not more improvements on this textural parameter are obtained at higher Cys concentrations. By contrast, water retention capacity is gradually diminishing as Cys concentration increases, but with a significant reduction only obtained at the highest tested concentration. These results suggest a negative effect of Cys on gel microstructure at high concentrations, which probably can be attributed to protein aggregation taking place at room temperature.

Functional and quality characteristics of the red blood cell fraction from biopreserved porcine blood as influenced by high pressure processing.

The effects of high hydrostatic pressure (HHP) processing, at 400MPa for 15min at 20°C, on the microbiological and functional characteristics of the red blood cell (RBC) fraction obtained from porcine blood, previously preserved by means of lactic acid bacteria (LAB) was studied. Biopreservation was achieved by incubation of inulin-enriched blood inoculated with a LAB strain (Enterococcus raffinosus PS99) for 72h at 5°C. Results showed that incubation of blood with added E. raffinosus followed by HHP treatment reduced the levels of contaminant coliforms, proteolytic, hemolytic bacteria, and Pseudomonas spp. on RCB. Color parameters, protein solubility, foaming and emulsifying properties, as well as texture and water holding capacity of heat-induced gels from RBC were not seriously damaged by the combined treatments. This is a new approach to process and preserve animal blood fractions for the development of functional and/or nutritional food ingredients with added value.

Simultaneous application of microbial transglutaminase and high hydrostatic pressure to improve heat induced gelation of pork plasma.

The effects of treating porcine plasma with microbial tranglutaminase (MTGase) under high hydrostatic pressure (HHP) were studied as a means of improving its gel-forming properties when subsequently heated at pH 5.5, near the pH of meats. Plasma containing varying levels of commercial MTGase was pressurized (400MPa, room temperature, pH 7) for different times, and adjusted to pH 5.5 prior to heating to induce gelation. MTGase-treatment under HHP led to greater enhancement of heat-induced plasma gel properties as compared to control samples. The greatest improvements were achieved by pressurising plasma with 43.3U MTGase/g protein for 30min, thereby achieving recoveries of 49% and 63% in fracture force (gel strength) and fracture distance (gel deformability) of the subsequently heat-induced gels, respectively, relative to gel properties obtained by heating untreated plasma at physiological conditions (pH 7.5).

Activity of fludarabine in previously treated Waldenström's macroglobulinemia: a report of 71 cases. Groupe Coopératif Macroglobulinémie.

PURPOSE: There is no consensus on the treatment of patients with Waldenström's macroglobulinemia (WM) who develop primary or secondary resistance to frontline therapies. We report our experience on the activity and toxicity of fludarabine in 71 patients with WM resistant to prior chemotherapy regimens. PATIENTS AND METHODS: From January 1991 to June 1995, 71 patients were included in this retrospective study. The median age, median time from diagnosis to treatment, median immunoglobulin M (IgM) level, and median number of previous treatments were 68 years (range, 42 to 81), 5.9 years (range, 0.6 to 20), 35 g/L (range, 5 to 126), and two (range, one to four), respectively. RESULTS: Seventy-one patients received a median of six courses of fludarabine. Twenty-one (30%) responded with a partial response and 50 (70%) were considered as treatment failures. Forty-six patients died: 10 in the responder group and 36 in the failure group. Twenty-five patients were alive with a median follow-up time of 34 months. The overall median survival time of all treated patients was 23 months. The time to treatment failure was 32 months. The only factor that favorably influenced the response to fludarabine was a longer interval between the first treatment and the start of fludarabine. Pretreatment factors associated with shorter survival in the entire population were hemoglobin level less than 95 g/L (P = .02) and platelet count less than 75 x 10(9)/L (P = .02). CONCLUSION: The responses rate in this population with a poor prognosis is close to that reported in shorter series. Patients with WM who are resistant to alkylating agents should be identified early, so that salvage therapy with nucleoside analogs can be started without delay.

Phase II trial of fludarabine monophosphate as first-line treatment in patients with advanced follicular lymphoma: a multicenter study by the Groupe d'Etude des Lymphomes de l'Adulte.

PURPOSE: Fludarabine monophosphate (FAMP) is a major drug in the treatment of chronic lymphocytic leukemia and showed efficacy in selected groups of patients with low-grade lymphomas, most of them pretreated. The aim of this trial was to assess the efficacy and the toxicity of FAMP in untreated patients with follicular lymphoma. PATIENTS AND METHODS: Fifty-four untreated patients with advanced follicular lymphoma were treated with intravenous (i.v.) fludarabine at a dose of 25 mg/m2/d during 5 days every 4 weeks, to a maximum of nine cycles. RESULTS: The toxicity of the drug was mild, mainly granulocytic. Granulocytopenia > or = 3 (World Health Organization [WHO]) was observed during 48 of 328 cycles (14.6%) and in 22 of 53 (41%) patients assessable for toxicity. Fludarabine had to be stopped prematurely because of toxicity in nine patients: marrow toxicity in five, peripheral neuropathy in two, and interstitial pneumonitis and hepatitis in one patient each. Among 49 patients assessable for response, the overall response rate was 65% and the complete response (CR) rate 37%. The median progression-free survival interval for all patients was 13.6 months. CONCLUSION: These results confirm that fludarabine is active when used as first-line treatment in patients with follicular lymphoma and has a low toxicity rate. It may be used as single treatment in elderly patients. Associations of fludarabine with other drugs active against follicular lymphoma need to be determined.

Mechanism of epinephrine enhancement of lidocaine-induced skeletal muscle necrosis.

Epinephrine significantly increases lidocaine-induced skeletal muscle necrosis, even in low concentrations that elicit no damage by themselves. Inasmuch as isoproterenol had no influence on lidocaine myotoxicity, a direct effect of epinephrine on muscle fibers is unlikely. Two vasoconstrictors with dissimilar mechanisms of action, phenylephrine and felypressin, duplicated the potentiating effect of epinephrine on fiber destruction in direct relation to their ability to retard lidocaine absorption from the tissue. It is concluded that the augmentation of muscle necrosis caused by epinephrine is largely due to its ability to increase exposure of skeletal muscle to the local anesthetic.

Comparison of myotoxic effects of lidocaine with epinephrine in rats and humans.

Myotoxic effects of 2% lidocaine with 1:100,000 epinephrine were evaluated in rats and humans. Sprague-Dawley rats were give injections in the left gastrocnemius muscle of 0.5 ml of the lidocaine preparation or a control vehicle; they were killed in groups of four at 0, 8, 24, and 48 hours. Blood samples were taken for serum enzyme determinations, and muscle specimens were removed and processed for histologic evaluation. In eight patients undergoing radical neck dissection, 1.8 ml of lidocaine with epinephrine or its control was injected into the sternocleidomastoid muscle approximately 18 hours before surgery. Patients' muscle specimens obtained at surgery were handled similarly to those of the rat. Serum creatine kinase, aspartate aminotransferase, and alanine aminotransferase activities were markedly elevated in the rat at 8 hours in the experimental group, but not in the control group. Histologically, control injections elicited no damage in the rat other than a mild inflammatory reaction along the presumptive needle track. Lidocaine with epinephrine, however, destroyed most of the muscle in which it was injected. Myonecrosis was qualitatively similar in humans. The rat provides a good model for the study of local anesthetic-induced myonecrosis.