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E A Arendt

Publications and source records attributed to E A Arendt.

7 recordsLinked to original sources
PubMed1991

31P-NMR study of normoxic and anoxic perfused turtle heart during graded CO2 and lactic acidosis.

We studied the effects of graded acidosis (both CO2 and lactic acid) and anoxia on intracellular pH (pHi) regulation, high-energy phosphates, and mechanical function of isolated perfused hearts of the turtle (Chrysemys picta bellii) at 20 degrees C using 31P-nuclear magnetic resonance (NMR) spectroscopy. During CO2 acidosis, anoxia had no effect on apparent nonbicarbonate buffer value (d[HCO3-]/dpHi = 71 and 89 mM/pH in normoxia and anoxia, respectively) or on pHi regulation (dpHi/dpHe = 0.52 and 0.43 in normoxia and anoxia, respectively, where pHe is extracellular pH). During normoxic lactic acidosis, dpHi/dpHe was similar to the values observed in CO2 acidosis and averaged 0.55 overall. During anoxic lactic acidosis, however, similar regulation occurred over only a narrow range of pHe, and then dpHi/dpHe increased to greater than 1.0 at pHe less than 7.1. Creatine phosphate (CP), calculated as the area of the NMR peak, fell more in response to normoxic CO2 acidosis than to normoxic lactic acidosis; in anoxia, the fall in CP was further increased but to similar extreme levels (10-20% of control) in both acid perfusions. Cardiac output and maximum rate of pressure development each fell during acidosis in similar fashion in all protocols, and the responses were similar in normoxic and anoxic hearts. Heart rate, in contrast, decreased during acidosis, but this effect was more pronounced when hearts were anoxic. We conclude that the effect of acidosis on cardiac function can depend on the type of acidosis imposed. Based on the heart's insensitivity to anoxia alone, we suggest that anoxia may normally depress function indirectly via its effect on intracellular acid-base state.

Acidosis, Lactic↗
PubMed1990

31P-NMR measurements of pHi and high-energy phosphates in isolated turtle hearts during anoxia and acidosis.

We used 31P-nuclear magnetic resonance (NMR) spectroscopy to measure intracellular pH (pHi) and high-energy phosphate levels in hearts of turtles (Chrysemys picta bellii) during either 4 h of anoxia [extracellular pH (pHo) 7.8, 97% N2-3% CO2], 4 h of lactic acidosis (pHo 7.0, 97% O2-3% CO2), or 1.5 h of combined anoxia + lactic acidosis (pHo 7.0, 97% N2-3% CO2) followed by 2 h of oxygenated recovery (pHo 7.8) at 20 degrees C. We also measured heart rate, maximum ventricular-developed pressure, and rate of pressure development (dP/dtmax). 31P-NMR spectra were characterized by the seven peaks typical of mammalian hearts, although turtle spectra were dominated by a large phosphodiester peak. Anoxia caused an increase in Pi to 165% and a decrease in creatine phosphate (CP) to 42% of control, whereas ATP levels remained unchanged. pHi declined from 7.37 +/- 0.01 to 7.22 +/- 0.03 at 1 h of anoxia and remained unchanged through hour 4. Lactic acidosis caused a 59% decrease in Pi, whereas CP and ATP levels remained unchanged. pHi fell to 6.88 +/- 0.04 by hour 1 and then climbed steadily to 7.14 +/- 0.05 at hour 4. During recovery from acidosis, pHi exceeded control values and returned to control by 2 h. Combined anoxia + acidosis caused profound decreases in CP to 14% and pHi to 6.56 +/- 0.03. In anoxic hearts, cardiodynamic variables remained at control levels through hour 3, after which cardiac output, heart rate, and dP/dtmax declined. Cardiodynamic variables were essentially unchanged from control throughout 4 h of acidosis except for dP/dtmax, which declined rapidly. In the combined protocol, all measures of cardiac function decreased. Recovery in all three cases was complete by approximately 2 h. We conclude that turtle hearts were relatively resistant to the stresses imposed in all three protocols compared with mammalian hearts, although anoxia + acidosis depressed the measured cardiac variables more profoundly than predicted from responses to the conditions imposed separately. Our results from the anoxia protocol suggest no direct causal relationship between myocardial CP (or ATP) levels and cardiac function.

Acidosis↗
PubMed1989

Vascularized patella tendon anterior cruciate ligament reconstruction.

Forty-seven patients with a chronic anterior cruciate ligament (ACL) deficiency were treated with patella tendon ACL reconstructions from July 1980 to September 1983. All patients had a minimum two-year follow-up period (range, 24-54 months). Forty-two patients (89%) had meniscal damage in association with the ACL deficiency. This included seven menisci (17%) that had a stable tear and were left in place without suture fixation. Only five patients (11%) had normal menisci at the time of reconstruction. Functional and subjective results were obtained from a questionnaire that included a comprehensive evaluation of patients' symptoms and activities. Objective results were analyzed on the basis of a thorough physical examination, augmented with arthrometer instrumented drawer testing. The detailed questionnaire was returned by 42 patients (89%). Follow-up examinations were obtained for 37 patients (79%), with arthrometer testing of 35 patients (75%). A 100-point rating scale defined objective, subjective, and functional results. Stability testing, using Lachman's test, was judged to be less than or equal to 5 mm of anteroposterior tibiofemoral translation in 51% of the patients examined and less than or equal to 10 mm of translation in 89%. Stability by arthrometer testing was less than or equal to 5 mm side-to-side difference in 83%. No patient lost a menisci after reconstruction. This included six patients with stable tears that were left unsutured. Subjective results were good or better in 60%. Functional results were good or better in 52%, with 41 of 42 patients participating in some form of recreational sports postoperatively. There was a large discrepancy between objective findings and the subjective and functional results (14% poor results compared with 31% and 43%, respectively). Although objective stability could be surgically restored in an ACL-deficient knee, the quality of the knee at the time of reconstruction as well as the postoperative and rehabilitative regimen are implicated in patients with poor subjective and functional results.

Adolescent↗
PubMed1988

Multidirectional shoulder instability.

Multi-directional shoulder instability is a difficult problem to both diagnose and treat. Knowledge of shoulder anatomy and its pathological states has expanded dramatically in recent years. Aiding diagnostic acumen are new tools including CT arthrograms, glenohumeral arthroscopy, and evaluation under anesthesia. MDI of the shoulder is increasingly recognized as a clinical entity. Diagnosing this problem demands great skill in correlating the history with the physical examination and radiographic procedures. Conservative treatment is the initial treatment of choice. Surgical treatment is exacting both in its preoperative assessment and surgical technique.

Adult↗
PubMed1985

Muscle fiber types.

Muscle fiber can be typed according to histologic, biochemical, neurophysiologic, and ultrastructural differences. The relationship between muscle fiber typing and clinical areas of investigation is summarized. Genetic factors are largely responsible for the distribution of main muscle fiber types. Strength training produces relatively slight alterations in muscle properties, as defined by present analytic techniques. The functional adaptation of skeletal muscle are dependent on a multitude of factors, which at the present time are not completely understood.

Adenosine Triphosphatases↗
PubMedDate not supplied

Catheter with an anchoring tip for chronic joint capsule perfusion.

An orthopedic catheter for long-term access to the synovial joint is anchored by a hollow threaded tap that penetrates the capsule through a hole drilled in the surrounding bone. The proximal end of the catheter is connected to either an implantable drug infusion pump or an implantable access port for continuous or intermittent perfusion or sampling. Four catheters were evaluated in dogs. Three were attached to ports, the fourth to a pump. Water (one trial, 22 weeks) and hyaluronic acid (HA) (5 mg/ml; two trials of 8 weeks each) were administered through ports twice weekly in 1.5 ml boluses; 5 mg/ml HA was delivered by pump (1 trial of 33 weeks) at 0.31 ml/day.

Animals↗