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Biomedical subjects

J F Rondinone

Publications and source records attributed to J F Rondinone.

8 recordsLinked to original sources
PubMed2001

A multicenter, prospective, randomized trial evaluating a new hemostatic agent for spinal surgery.

STUDY DESIGN: A prospective, randomized trial comparing Proceed, a gelatin-based hemostatic sealant (treatment), with Gelfoam-thrombin (control) in stopping intraoperative bleeding during spinal surgery. OBJECTIVES: To determine the effectiveness and safety of Proceed. SUMMARY OF BACKGROUND DATA: Proceed has been tested in animal models to determine its safety and effectiveness as a hemostatic agent. The current study was conducted under a Food and Drug Administration-approved Investigational Device Exemption to evaluate the effectiveness and safety of Proceed in humans. METHODS: For this study, 127 patients undergoing spinal surgery were randomized into either the treatment or control group after standard surgical means to control bleeding had failed. The bleeding site was evaluated at 1, 2, 3, 6, and 10 minutes after the hemostatic agent was applied. The application was considered successful if the bleeding stopped within 10 minutes. Follow-up evaluation was performed at 12 to 36 hours, then at 6 to 8 weeks after surgery. RESULTS: Proceed stopped bleeding in 98% of the patients (first bleeding site only) within 10 minutes, as compared with 90% of the control patients (P = 0.001). At 3 minutes, successful hemostasis had been achieved in 97% of the Proceed group, as compared with 71% of the control group (P = 0.0001). There was no difference in the adverse event profile between the two groups. CONCLUSIONS: A significantly larger number of bleeding sites had achieved hemostasis with Proceed than with Gelfoam-thrombin at 1, 2, and 3 minutes after application. Proceed was as safe as Gelfoam-thrombin when used for hemostasis during spinal surgery procedures.

Administration, Topical↗
PubMed1992

Acute effects of topical methyl tert-butyl ether or ethyl propionate on gallbladder histology in animals: a comparison of two solvents for contact dissolution of cholesterol gallstones.

Experiments were performed in anesthetized rabbits and piglets to assess gallbladder mucosal injury during irrigation with methyl tert-butyl ether, a C5 ether, or ethyl propionate, a C5 ester--two organic solvents used in the contact dissolution of cholesterol gallstones. In 44 New Zealand White rabbits, the gallbladder was exposed to individual solvents or saline solution through a transhepatic catheter for 2 hr. Gallbladders were then harvested and fixed immediately or after a recovery period of 1, 4 or 8 days. Tissue sections were examined under light microscopy, and severity of injury was graded with predefined criteria by two pathologists blinded to the animals' treatment regimens. Histological assessment showed severe mucosal injury such as necrosis of the cells at the villus tips immediately after 2 hr of exposure to either solvent. After 4 days, injury had decreased significantly; after 8 days, complete mucosal healing had taken place. A similar study was performed in 32 piglets. Solvent or saline solution was oscillated in and out of the gallbladders of these piglets with a computer-controlled syringe pump at a pressure less than the leakage pressure of the gallbladder. Histological assessment was performed on tissue samples obtained immediately after the procedure or 8 days later. Both solvents caused severe mucosal injury; however, after 8 days complete mucosal healing had occurred, so that gallbladders exposed to solvent were indistinguishable from gallbladders exposed to saline solution, which was used as control. We conclude that both methyl tert-butyl ether and ethyl propionate cause moderate to severe epithelial injury but that the gallbladder epithelium regenerates within a few days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The dependence of force and velocity on calcium and length in cardiac muscle segments.

The segment length (SL) dependence of force (F) and light load shortening velocity (VL) was determined for central segments of ferret papillary muscles at different extracellular calcium concentrations. Muscles were maintained at 27 degrees C in a physiological solution which contained in mM: NaCl 140; KCl 5.0; MgSO4 1.0; NaH2PO4 1.0; acetate 20; the pH was 7.4. Calcium concentrations were 1.125, 2.25, 4.5 and 9.0 mM. Total force-segment length relations were determined from both muscle length isometric ( auxotonic ) and segment isometric contractions, and were found to be the same for each contraction mode. The peak force generated at a particular segment length was independent of both the amount of shortening during a contraction and the initial SL. Increasing extracellular Ca2+ shifted the F-SL relation toward greater force and the SL axis intercept toward shorter SL. Maximum peak twitch tension was achieved in 9.0 mM Ca2+. Calcium variations also changed the shape of the total F-SL relation from linear in high Ca2+, to concave in low Ca2+. In order to estimate the active F-SL relations, corrections were made for passive force by two methods. The first assumed that passive force was related to SL, and yielded F-SL relations which were nearly identical to those found for total force. This similarity included the curvature changes observed in different Ca2+ concentrations, a finding which is consistent with the hypothesis that length dependent activation is the cause of force decline at short SL. The second method assumed passive force to be related to muscle length, an approach which would be appropriate if, for example, a connective tissue sheath on the muscle dominated passive behavior. These F-SL curves displayed a plateau above 90% SLmax and appeared to be vertically shifted versions of each other. Such characteristics are consistent with the possible role of an internal load in causing the decline of force at short SL. VL-SL relations were obtained from load clamps to 1 mM, imposed at various times during a segment isometric twitch. The results indicate that 1) VL declines linearly with SL below 90% SLmax and 2) VL-SL relations are shifted to higher velocity and shorter SL axis intercepts by increasing Ca2+. The slopes of the VL-SL relations obtained in different calciums are similar. Although an internal load could explain the calcium dependence of VL, it would not explain the similarity of the slopes of the VL-SL relations found in different calciums .

Animals↗
PubMed1983

Force-length relations in cardiac muscle segments.

Using a new technique that measures the length of a segment in the central region of isolated papillaries, we have determined the force-segment length relation for ferret papillary muscles at 27 degrees C. The muscles contracted under muscle length isometric (auxotonic) and segment isometric conditions in physiological solutions containing 9.0, 4.5, 2.25, and 1.125 mM Ca2+. Force-segment length relations obtained from auxotonic and segment isometric contractions were identical in a given Ca2+ concentration. Calcium variations, however, changed the position, shape, and segment length intercept of the force-segment length relation. Force, at a given segment length, increased with increasing Ca2+ up to 9.0 mM Ca2+. The force-segment length relation changed shape from linear, in 4.5 mM Ca2+, to concave in 1.125 mM Ca2+. The segment length intercept was found by extrapolation to be 68, 69, and 74% SLmax in 4.5, 2.25, and 1.125 mM Ca2+, respectively. Two passive force corrections were used to calculate the developed force-segment length relations. Assuming passive force to be related primarily to segment length yields curves that change shape with Ca2+ concentration, suggesting length-dependent activation. On the other hand, assuming passive force to be related to muscle length results in curves for different Ca2+ concentrations that are nearly vertically shifted versions of each other, suggesting the influence of internal loads.

Animals↗
PubMed1983

Myocardial segment velocity at a low load: time, length, and calcium dependence.

The length and time dependence of shortening velocity (VL) at a very light load (1 mN) was determined for central segments of ferret papillary muscle at 27 degrees C. A recently developed technique that measures the cross-sectional area of the chosen segment was used to assess segment length. Segment length (SL) or force could be used as a feedback control signal. VL was determined by releasing the muscle to a 1-mN load (less than or equal to 3% maximum force) at various times during a segment isometric twitch. Segment isometric twitches were typically performed at 95-98% SLmax, SLmax being the longest segment length attainable in the preparation. VL, as a function of time and SL, was determined from SL shortening during the load clamp. Muscle responses were sampled, stored, and analyzed with an on-line digital computer. The data indicate that 1) at a given SL, VL declines from 20 to 50% of its peak value by the time of peak force production, 2) VL declines linearly with SL below 90% SLmax in 1.125, 2.25, and 4.5 mM extracellular Ca2+, 3) VL exhibits a dependence on extracellular Ca2+, having peak values at 90% SLmax of 3.32 +/- 0.33, 2.66 +/- 0.17, and 1.89 +/- 0.17 SL/s in 4.5, 2.25, and 1.125 mM extracellular Ca2+, respectively.

Animals↗
PubMed1983

Onset of relaxation in cardiac muscle segments.

The onset of relaxation has been studied in undamaged central segments of isolated ferret papillary muscles at 27 degrees C, 12 beats/min. A technique that provides a signal proportional to the length of a chosen segment was used to assess segment velocity and length. Feedback control was employed to obtain segment isometric contractions. At a variety of times during segment isometric twitches, rapid load clamps were imposed using a range of loads from resting force to greater than half peak developed force. For the purposes of this study, the onset of relaxation was defined as occurring when active segment shortening ceased and elongation began (i.e., Vseg = 0). Early load clamps to low loads resulted in V = 0 at comparatively short segment lengths and early times. Later load clamps caused zero velocity to occur at longer segment lengths and later times. The V = 0 points in fact formed a line in the segment length-time plane. Contractions clamped to higher loads exhibited reduced shortening and a prolonged time course so that the V = 0 points showed the same dependence on length and time. Remarkably, all the variations of load-clamp load, time, and initial length yielded V = 0 points that were intermixed along a single line. Increasing or decreasing extracellular Ca2+ caused the V equal to O points to shift to later times and shorter segment lengths or earlier times and longer segment lengths, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗