Effect of a three month training period on the maximal oxygen deficiency in high level performance sprinters

We investigated in vivo expression of myosin heavy chain (MHC) isoforms, 17 kDa myosin light chain (MLC17), and phosphorylation of the 20 kDa MLC (MLC20) as well as mechanical performance of chemically skinned fibers of normal and hypertrophied smooth muscle (SM) of human myometrium. According to their immunological reactivity, we identified three MHC isoenzymes in the human myometrium: two SM-MHC (SM1 with 204 kDa and SM2 with 200 kDa), and one non-muscle specific MHC (NM with 196 kDa). No cross-reactivity was detected with an antibody raised against a peptide corresponding to a seven amino acid insert at the 25K/50K junction of the myosin head (a-25K/50K) in both normal and hypertrophied myometrium. In contrast, SM-MHC of human myomatous tissue strongly reacted with a-25K/50K. Expression of SM1/SM2/NM (%) in normal myometrium was 31.7/34.7/33.6 and 35.1/40.9/24 in hypertrophied myometrium. The increased SM2 and decreased NM expression in the hypertrophied state was statistically significant (P < 0.05). MHC isoform distribution in myomatous tissue was similar to normal myometrium (36.3/35.3/29.4). In vivo expression of MLC17a increased from 25.5% in normal to 44.2% in hypertrophied (P < 0.001) myometrium. Phosphorylation levels of MLC20 upon maximal Ca(2+)-calmodulin activation of skinned myometrial fibers were the same in normal and hypertrophied myometrial fibers. Maximal force of isometric contraction of skinned fibers (pCa 4.5, slack-length) was 2.85 mN/mm2 and 5.6 mN/mm2 in the normal and hypertrophied state, respectively (P < 0.001). Apparent maximal shortening velocity (Vmax(appt), extrapolated from the force-velocity relation) of myometrium rose from 0.13 muscle length s-1 (ML/s) in normal to 0.24 ML/s in hypertrophied fibers (P < 0.001).     

Comparison of alveolar ventilation, oxygenation, pressure support, and respiratory system resistance in response to noninvasive versus conventional mechanical ventilation in foals

OBJECTIVE: To compare the efficacy of positive pressure ventilation applied through a mask versus an endotracheal tube, using anesthetized/paralyzed foals as a model for foals with hypoventilation. ANIMALS: Six 1-month-old foals. PROCEDURE: A crossover design was used to compare the physiologic response of foals to 2 ventilatory techniques, noninvasive mask mechanical ventilation (NIMV) versus endotracheal mechanical ventilation (ETMV), during a single period of anesthesia and paralysis. Arterial pH, PaO2, PaCO2, oxygen saturation, end-tidal CO2 tension, airway pressures, total respiratory system resistance, resistance across the upper airways (proximal to the midtracheal region), and positive end-expiratory pressures (PEEP) were measured. Only tidal volume (VT; 10, 12.5, and 15 ml/kg of body weight) or PEEP (7 cm of H2O) varied. RESULTS: Compared with ETMV, use of NIMV at equivalent VT resulted in PaCO2 and pH values that were significantly higher, but PaO2 was only slightly lower. Between the 2 methods, peak airway pressure was similar, but peak expiratory flow was significantly lower and total respiratory resistance higher at each VT for NIMV. Delivery of PEEP (7 cm of H2O) was slightly better for ETMV (7.1 +/- 1.3 cm of H2O) than for NIMV (5.6 +/- 0.6 cm of H2O). CONCLUSION: These data suggest that use of NIMV induces similar physiologic effects as ETMV, but the nasal cavities and mask contribute greater dead space, manifesting in hypercapnia. Increasing the VT used on a per kilogram of body weight basis, or the use of pressure-cycled ventilation might reduce hypercapnia during NIMV. CLINICAL RELEVANCE: Use of NIMV might be applicable in selected foals, such as those with hypoventilation and minimal changes in lung compliance, during weaning from endotracheal mechanical ventilation, or for short-term ventilation in weak foals.     

Immobilization of β‐amylase using polyacrylamide polymer derivatives

Barley β‐amlyase was immobilized on two polymeric materials; poly(acrylamide–acrylic acid) resin [P(AM‐AAc)] and poly(acrylamide–acrylic acid–diallylamine–HCl) resin [P(P(AM‐AAc‐DAA‐HCl) using two different methods: covalent and cross‐linking immobilization. Thionyl chloride, used to activate the polymers for covalent immobilization, has the advantage that it is able to react with a number of surface groups of protein under very mild conditions. Cross‐linking with glutaraldehyde gave a higher coupling yield (approximately 70%) than covalent immobilization (approximately 20%). The activity and stability of the resulting biopolymers have been compared with those of free β‐amylase. The specific activity of the immobilized enzyme was significantly influenced by the amount of enzyme loaded onto the polymers, the optimal level being 3.5 mg g^?1 polymer. It was found that the immobilized β‐amylase stored at 4°C retained approximately 90% of its original activity after 30 days, whereas free β‐amylase stored in solution at 4°C retained only 47% of its activity after same period. The difference in long term stability was more significant when the enzyme was stored at room temperature; the immobilized enzyme maintained 40% of its activity after 30 days, whereas the residual activity of free enzyme was only 10%. Copyright © 2003 Society of Chemical Industry