Plasma lactate and ventilation thresholds in trained and untrained cyclists.

Six trained male cyclists and six untrained sedentary men were studied to determine whether the plasma lactate threshold (PLT) and ventilation threshold (VT) occur at the same work rate in both fit and unfit populations. The PLT was determined from a marked increase in plasma lactate concentration ([La]) and VT from a nonlinear increase in expired minute ventilation (VE) during incremental leg-cycling tests; work rate was increased 30 W every 2 min until volitional exhaustion. The trained subjects' mean VO2 max (63.

Haematoma block--a safe method of reducing Colles' fractures.

A total of 136 patients required an anaesthetic to enable distal fractures of the forearm to be reduced. There were no significant differences in the numbers requiring remanipulation between the three methods employed: haematoma block, Bier's block or general anaesthesia. The advantages of the haematoma block are discussed.

Type A behavior and survival after acute myocardial infarction.

To ascertain the influence of personality factors on the course of coronary artery disease, we measured Type A behavior in 516 patients within two weeks after an acute myocardial infarction, using the Jenkins Activity Survey questionnaire. Over a follow-up period of one to three years, there was no relation between the Type A score and total mortality, cardiac mortality, time to death for nonsurvivors, left ventricular ejection fraction, or duration of the stay in the coronary care unit. These negative findings were not changed by restricting the analyses to men below 61 years of age or by comparing extreme score categories.

Complete patency in thrombus-occluded arteries two weeks after laser recanalization.

The potential problem of rethrombosis after laser recanalization was studied in 16 thrombus-occluded canine femoral arteries. Balloon de-endothelialization and thrombin-human blood injection produced adherent, completely occlusive thrombi 4.13 +/- 1.

Absence of distal emboli during in vivo laser recanalization.

We used an argon laser to recanalize occluded arteries in vivo and to determine the extent of any particulate matter resulting from the procedure that might cause embolization. Thrombosis was achieved by balloon de-endothelialization and thrombin injection in 12 canine femoral or carotid arteries in six dogs. The resulting totally occlusive thrombi (2.

Vascular recanalization with the argon laser: the role of blood in the transmission of laser energy.

Successful revascularization of stenosed arteries with the argon laser optical fiber catheter requires delivery of high-power-density energy to the lesion. Because of the high energy absorption by hemoglobin at the argon laser wavelengths, which would attenuate transmission of laser energy to the obstruction, we measured argon laser transmission through blood at different concentrations. We found that no transmission occurred through 1 mm of whole blood with hematocrit of 42 and that blood must be diluted to a hematocrit below 1 for laser energy to be delivered.

Transepithelial transport of nonelectrolytes in the rabbit mandibular salivary gland.

The characteristics of nonelectrolyte secretion by the rabbit mandibular salivary gland have been investigated in an in vitro, perfused preparation. The concentrations of 14C-labeled nonelectrolytes were measured in saliva samples collected over a range of flow rates during the secretory response of the gland to continuous acetylcholine infusion. Of the nine nonelectrolytes studied, the two particularly lipid-soluble molecules, ethanol and antipyrine, appeared in the saliva at approximately the same concentration as in the perfusate, regardless of the secretory flow rate.

Vanadate stimulates rat pancreatic enzyme secretion through the release of calcium from an intracellular store.

Orthovanadate accelerates 45Ca efflux and enzyme secretion from the rat pancreas incubated in either control (2.5 mM Ca) or nominally Ca-free buffers. Secretion induced by vanadate does not appear to be mediated by changes in either adenylate cyclase or sodium pump activity.

The effects of vanadate on 45Ca exchange and enzyme secretion in the rat exocrine pancreas.

The effects of vanadate on calcium homeostasis and enzyme secretion have been assessed in the incubated pancreas of young rats. Vanadate causes an acceleration of 45Ca efflux from pre-loaded uncinate glands; amylase release is reversibly increased for the duration of exposure to vanadate. Alkaline orthovanadate is most effective in eliciting these responses; its effects are greatly reduced at pH 7.

The anionic basis of fluid secretion by the rabbit mandibular salivary gland.

The role played by anions in salivary secretion has been studied in experiments on the isolated, perfused mandibular gland of the rabbit, in which perfusate Cl- and/or HCO3- were replaced by other anions. Replacement of Cl- with Br- had no significant effect on salivary secretion rate, but replacement with the other anions tested caused secretory rate to fall, by 38% (I-), 50% (NO3-), 61% (isethionate, ise -), and 66% ( CH3SO4 -), respectively. Replacement of perfusate Cl- with ise - or CH3SO4 - caused the salivary HCO3- concentration to rise up to 4-fold.

The dependence of fluid secretion by mandibular salivary gland and pancreas on extracellular calcium.

Acetylcholine-stimulated fluid secretion from the perfused rabbit mandibular salivary gland was inhibited in a biphasic manner when extracellular calcium concentration was reduced in the range 5 X 10(-4) - 10(-5)M. An initial rapid inhibition was followed by partial recovery to a plateau, the level of which depended upon the calcium concentration. Since no recovery was observed during substitution of calcium by strontium, recovery may depend upon an increased membrane permeability to calcium.

The influence of pancreatic juice on 64Cu absorption in the rat.

The absorption of 64Cu from closed duodeno-jejunal loops in anaesthetized rats was significantly less in the presence of pancreatic juice compared with that in the presence of saline (9 g sodium chloride/l). The inhibition of 64Cu absorption caused by pancreatic juice was similar to that achieved with bile. Studies using solutions of electrolytes and of pancreatic extracts showed that the inhibitory effect of pancreatic secretions was due to its protein-enzyme content and not to its bicarbonate content.

A new thermal sensor for surface-based measurement of local myocardial perfusion.

The transient response of a new thermal sensor for continuous surface-based measurement of local tissue blood flow was evaluated in the beating dog heart. The sensor is 2.5 mm square, tests on the heart, and responds to flow changes only within a region of tissue 3-4 mm below its location on the epicardial surface.

Lactate accumulation relative to the anaerobic and respiratory compensation thresholds.

Anaerobic thresholds of five male subjects were determined invasively (ATi), from a marked increase in plasma lactate above resting levels (delta La), and noninvasively (ATn), from a nonlinear increase in minute ventilation (VE) during incremental work (IW) leg cycling tests; work rate was increased 30 W every 2 min. Each subject also performed four constant-load work (CLW) tasks just above and just below their ATn and respiratory compensation threshold (RCT), i.e.

Measurement of regional myocardial perfusion using collimated miniature radiation detectors and the method of 133-xenon washout.

A new approach to the measurement of local myocardial perfusion based on the application of highly-collimated miniature cadmium telluride radiation detectors to measure washout of 133-Xenon from well-defined tissue volumes is presented. Single-hole collimators with length/diameter ratios of 1 (L = 4 mm, D = 4 mm) and 4 (L = 12 mm, D = 3 mm) were employed as prototype designs. The probe field of view was characterized theoretically using a spherical model of the myocardium in conjunction with experimental point source response measurements for each collimator.

Steady-state analysis and evaluation of a new thermal sensor for surface measurements of tissue perfusion.

The steady-state response and operating characteristics of a new thermal sensor for surface measurements of local tissue perfusion have been analyzed theoretically and evaluated in vivo. The flow measurement system incorporates an electrically isolated thin-film thermal sensor, which is maintained at a fixed temperature by high frequency response electronic circuitry. The sensor rests on the tissue surface, and the power required to maintain a fixed probe to tissue temperature elevation is measured and related to tissue blood flow.

Reduced human ventricular fibrillation threshold associated with contrast-induced Q-T prolongation.

Injection of contrast dye during selective coronary arteriography prolongs the Q-T interval well beyond that expected for the accompanying bradycardia. A case is presented in which a 5 mA stimulus delivered prematurely by an improperly sensing ventricular demand pacemaker initiated ventricular fibrillation during coronary arteriography, although no evidence of coronary or other cardiac disease was found. An analysis is made of the progressive Q-T and T changes following contrast dye injection, and their relation to the onset of ventricular fibrillation.

Quantitative estimates of beta-lactam residues in raw milk around a reference standard: collaborative study.

A collaborative study was conducted to determine the reliability of a Bacillus stearothermophilus disc assay method for differentiating various concentrations of penicillin in raw milk. Participating laboratories tested 10 different samples (including one negative) in blind duplicate. Triplicate standards were alternated with triplicate unknowns around the periphery of each of 5 different plates.

Breast cancer skin test antigens of increased sensitivity prepared from vesicular stomatitis virus-infected tumor cells.

Crude membrane (CM) extracts were prepared from five cultured breast tumor lines (MDA-MB-157, MDA-MB-231, ZR75-1, HS0578T, and MCF-7) which had been infected with vesicular stomatitis virus (VSV) to augment their antigenicity. In skin test trials, CM extracts of uninfected MCF-7 cells elicited positive response in 0 of 13 (0%) tests in breast cancer patients, while VSV-MCF-7 elicited positive responses in 11 of the same 13 patients (84.6%).

Collaborative evaluation of rolling ball viscometer for measuring somatic cells in abnormal milk.

The Ruakura rolling ball viscometer was evaluated in 3 laboratories along with currently approved instrumental methods for measuring somatic cells in milk and the Wisconsin mastitis test. Replacement of the Teepol reagent with Wisconsin mastitis test reagent in the rolling ball viscometer was also evaluated. Both repeatability and reproducibility were satisfactory for all methods evaluated.

Quantitative Assay of Beta-Lactam Residues in Raw Milk Using a Disc Assay Method.

Numerous methods have been developed to determine presence of antibiotics in raw milk. Until recently, major effort had been placed on qualitative considerations, and primarily for detecting presence of penicillin (beta-lactam) residues. Only one method, the Sarcina lutea Cylinder Plate (CP) procedure, has been modified to provide for quantitative estimates.