Accuracy, clinical correlation, and patient acceptance of two handheld prothrombin time monitoring devices in the ambulatory setting.

OBJECTIVE: To evaluate the accuracy, clinical correlation, ease of use, and patient acceptance of the Coaguchek and the ProTime Microcoagulation System as compared with standard laboratory methods for prothrombin time determination. METHODS: A total of 30 prothrombin times, expressed as international normalized ratios (INRs), were determined by each handheld device for comparison with standard laboratory testing. Accuracy was evaluated by calculating the absolute difference for each pair of INR values. Clinical correlation was defined as an INR obtained by the handheld monitor that would have resulted in the same therapeutic decision as the INR obtained by the standard laboratory method. Subjects were surveyed to determine which method of INR determination they preferred and their reasons for that preference. RESULTS: Accuracy was superior with the Coaguchek monitor. The absolute difference (mean +/- SD) in the laboratory and Coaguchek INRs was 0.28+/-0.23 (p = 0.96). The absolute difference (mean +/- SD) in the laboratory and the ProTime Microcoagulation System INRs was 0.56+/-0.34 (p < 0.001). For clinical correlation, two out of 24 (8.3%) INRs with the Coaguchek were sufficiently different from the laboratory INR to have resulted in a different therapeutic decision, compared with 12 out of 24 (50%) with the ProTime Microcoagulation System (p < 0.005). Of subjects surveyed, 77.8% preferred the finger stick method. CONCLUSIONS: The Coaguchek was superior to the ProTime Microcoagulation System in accuracy, clinical correlation, and ease of use. The study also showed that patients preferred capillary blood sampling by finger puncture over venipuncture for INR monitoring.

Structural studies of 5-ethyl-2'-deoxyuridine by selective pulse 1H DPFGSE NOE spectroscopy and PM3 calculations.

The solution conformation of 5-ethyl-2'-deoxyuridine (EDU) has been calculated from the vicinyl proton-proton NMR coupling constants and nuclear Overhauser (NOE) distances using excitation sculpting of selective pulses (Double Pulsed Field Gradient Spin Echo NOE) at 500 MHz and molecular modelling (PM3) studies.

The role of aerobic and anaerobic semen cultures in asymptomatic couples undergoing in vitro fertilization: effects on fertilization and pregnancy rates.

OBJECTIVE: To determine if routine semen culture is useful in asymptomatic couples undergoing in vitro fertilization and embryo transfer (IVF-ET). DESIGN: Prospective data collection. SETTING: All cultures and IVF cycles were performed at the University of North Carolina in Chapel Hill, North Carolina. PARTICIPANTS: All asymptomatic couples undergoing IVF-ET from January 1989 through January 1990. INTERVENTIONS: Aerobic and anaerobic cultures were performed on semen samples obtained before IVF. MAIN OUTCOME MEASURES: Quantitative semen cultures were evaluated for both aerobic and anaerobic bacterial isolates. Fertilization and pregnancy rates (PRs) were compared in patients with positive and negative semen cultures. RESULTS: Eighty percent of cultures contained at least one bacterial isolate. Three of the four most commonly isolated bacteria were normal skin flora. Positive culture results had no effect on either fertilization or PRs. CONCLUSIONS: Bacterial contamination is common with semen collection, yet routine semen cultures are not beneficial in asymptomatic couples undergoing IVF-ET.

Preservation of guinea pig hearts by hypothermic gas perfusion.

The lack of a satisfactory method for long-term preservation of hearts during transport limits the source of human hearts for transplant to the geographic vicinity of the transplant center. Experimentally, reduction of myocardial oxygen requirements with hypothermia and cardioplegia prolong storage time to 48 h, but always with some evidence of myocardial damage. In this study, the combination of hypothermia with a procedure known to increase oxygen tension in cardiac muscle, gas perfusion, preserved contractile activity in guinea pig hearts for 24 h and did not cause edema. Cardioplegia or gas perfusion at temperatures below 10 degrees C or above 20 degrees C resulted in failure of hearts to contract upon rewarming. Contracture, dehydration, elevation of tissue calcium, reduced perfusate flow, and elevated creatine kinase levels occurred if liquid reperfusion was begun at 15 degrees C but not 25 degrees C. The results suggest that under the appropriate conditions, hypothermic gas perfusion is a potentially useful means of extending storage time of hearts for transplant.

Oxidative metabolism in guinea pig ventricular myocytes protected from proteolytic enzyme activity.

Surface structures on guinea pig ventricular myocytes were protected from proteolytic enzyme activity with 100 KIU.ml-2 aprotinin during mechanical disaggregation. Intact myocytes, approximately 7.5 X 10(6) cells.g-1 ventricular wet weight, were separated from debris and damaged cells using Cytodex I tissue culture supports. Cellular ultrastructure did not differ from that observed in intact tissue. Neither spontaneous contractions nor contracture were ever observed in these myocytes in calcium concentrations of 10 mmol.litre-1. Dinitrophenol (0.2 mmol. litre-1) uncoupled respiration in the myocytes but only after the sarcolemma had been disrupted with Triton X100. The adenosine diphosphate to oxygen ratio of mitochondria isolated from the myocytes was 2.4(0.2) and the respiratory control index 2.6(0.3). Calcium (1.8 mmol.litre-1) increased oxygen uptake in the presence of 10 mmol.litre-1 pyruvate or 11 mmol.litre-1 glucose but not 17 mmol. litre-1 succinate. Succinate dependent oxygen consumption was greater than pyruvate dependent oxygen consumption (1090.0(190.0) and 40.1(0.8) nl.min-1.mg-1 protein respectively). The Crabtree effect was present. Oxidative metabolism was normal in cells stored at 10 degrees C for seven days but deteriorated rapidly thereafter. The results indicate that myocytes disaggregated by this procedure retain many of the morphological and metabolic characteristics of intact cardiac muscle cells and are relatively homogeneous with respect to calcium tolerance and metabolic function.

Wilms' tumors in adults.

Four cases of adult Wilms' tumor are reported comparing their diagnoses, treatment, and survival with the world literature. The oldest recorded patient is herein described at age 84. Aggressive surgical and medical therapy is necessary to improve survival. Surgical exploration should be through a transperitoneal approach with the patient positioned such that access to the chest can be obtained for maximum exposure and resection. Chemotherapy consisting of actinomycin D and vincristine should be instituted in all patients. Radiation therapy must also be considered in any patient with the diagnosis of nephroblastoma.

Acute appendicitis during pregnancy.

Forty-one appendectomies were performed on pregnant patients during the period 1973-1983. The preoperative diagnosis of acute appendicitis was correct in 57 per cent of the cases (24 patients). Presenting complaints, physical examinations, and laboratory analysis did not prove helpful in establishing the diagnosis. The incidence of acute appendicitis during pregnancy was 1:4172 (birth/pregnancy). Rapid surgical intervention probably contributed to the low (25%) incidence of perforated appendices. A transverse incision and general anesthesia were preferred. There was no maternal mortality and a 2 per cent rate of fetal loss.

Calcium binding to cardiac myocytes protected from proteolytic enzyme activity.

Excitation-contraction coupling in cardiac muscle is dependent on extracellular calcium and calcium bound to the surface of the myocardial cell. In this study, we examined the physical characteristics of calcium binding to adult guinea pig ventricular myocytes disaggregated mechanically in oxygenated tissue culture medium containing a proteinase inhibitor (aprotinin), and separated from cellular debris by Cytodex beads. Cells prepared in this manner excluded Trypan blue and showed no evidence of spontaneous contraction or contracture. Scatchard plots of calcium binding determined by continuous flow equilibrium dialysis revealed a high-affinity, low-capacity pool, Ka = 65 X 10(3) M-1 and Bt = 1.3 nmol X mg-1 and a low-affinity, high-capacity pool, Ka = 141 M-1 and Bt = 138 nmol X mg-1. The low-affinity pool was not detectable after lanthanum, trypsin or collagenase treatment or in cells prepared without aprotinin in the isolation medium. Both neuraminidase and phospholipase C reduced Bt of the low-affinity pool by one half, but only neuraminidase affected the affinity constant of this pool. Ka was increased to 516.7 M-1, similar to the apparent affinity constant for calcium binding estimated from dP/dtmax measured at several extracellular calcium concentrations (470 M-1). The results suggest that calcium bound to sarcolemmal phospholipids represents the superficial calcium involved in excitation-contraction coupling in the heart.

The role of superficially bound calcium in the regulation of myocardial contractility and the positive inotropic response to ouabain.

Positive inotropic effects induced in hearts by paired pacing and ouabain treatment were found to be dependent on the content of calcium in a superficial pool, Ca1. Two possible mechanisms for the expansion of this pool were investigated in isolated cardiac myocytes in which the cell surface structures were preserved from proteolytic digestion. Guinea pig ventricles were disrupted mechanically to obtain intact myocardial cells. The cell yield from this preparation was enriched by incubation with Cytodex beads and the characteristics of calcium binding to the cell-bed suspension were determined by continuous flow equilibrium dialysis. Scatchard plots revealed two components for calcium binding; a high affinity (Ka approximately 65 mM-1) and a low affinity (Ka approximately 140 M-1) pool. Ouabain (10(-9) to 10(-6)M) increased, in a dose related manner, the KA for calcium binding to the low affinity sites without affecting the total number of binding sites. The calculated amount of calcium bound to the low affinity pool at [Ca]e = 1.8 mM was closely correlated with the positive inotropic effect (PIE) measured in guinea pig hearts perfused with the same calcium concentration. At [Ca]e = 0.45, 0.9, or 3.6 mM, the response to ouabain (1 X 10(-7) and 5 X 10(-7)M) was greater than expected on the basis of the increase in calcium binding to the low affinity sites. The results suggest that at least one event in the inotropic response to ouabain involves increased affinity for calcium binding to low affinity sites on the cell surface, but that the increase in calcium bound at any [Ca]e is insufficient to produce the PIE directly.

Orotic acid prevents changes in cardiac sarcolemmal glycoproteins and contractility associated with muscular dystrophy in hamsters.

Orotic acid included in the diet of cardiomyopathic hamsters during the myolytic phase of the disease (30-60 days of age) prevented the reduction in cardiac sarcolemmal sialic acid, calcium binding, sialyltransferase activity and contractile activity associated with the cardiomyopathy.

Excitation-contraction coupling in normal and myopathic hamster hearts III: functional deficiencies in interstitial glycoproteins.

Extracellular and surface bound Ca is essential to excitation-contraction (E-C) coupling in mammalian cardiac muscle. In intact hearts from cardiomyopathic hamster with congestive heart failure, a concomitant decrease in the Ca content of a superficial pool was associated with the reduced contractility. Ca binding to cardiac sarcolemmal ghosts prepared from these hearts revealed two binding sites by Scatchard plot. In normal hamsters, the low affinity site had a capacity of 114 nmol Ca.mg-1 protein, a KD of 1.5 mmol . litre-1 and was sensitive to neuraminidase treatment but not to 100 mmol . litre-1 Na, K, or Li, Ca binding in vitro approached a 1:1 relationship with the sialic acid content of the ghosts, 159 nmol . mg-1 protein. The activity of the enzyme responsible for glycosidically linking sialic acid to interstitial and sarcolemmal glycoproteins, sialyltransferase, was reduced from 1.80 to 0.41 pmol . mg-1 protein in the myopathic hearts. We suggest the functional defect in the hamster cardiomyopathy is a reduction in sialyltransferase activity leading to the deficiency in surface sialic acid residues. As a consequence, contractility is reduced, but Ca influx is increased. Reflex sympathetic activity increases Ca influx resulting in "Ca overload" and eventual cellular necrosis.

Excitation-contraction coupling in normal and myopathic hamster hearts I: identification of a calcium pool involved in contraction.

The results of this study indicate that two min of Ca-free perfusion did not significantly alter the exchange kinetics of mannitol or Ca in isolated heart preparations. A numerical solution for series Ca exchange between a superficial Ca pool, Ca1, and an intracellular pool, Ca2, was developed in terms of the coefficients and constants determined from a parallel analysis. The series and parallel models for Ca efflux yielded a high correlation between contractile activity and the rate of exchange and Ca content of Ca1. The kinetics of Ca influx were best described by a series model of exchange and agreed closely with the Ca contents and exchange properties measured during Ca efflux. No differences were detected between normal and myopathic hamster hearts in the kinetics of Ca exchange or the role of Ca1 in the E-C coupling process.

Excitation-contraction coupling in normal and myopathic hamster hearts II: changes in contractility and Ca pools associated with development of the cardiomyopathy.

Myocardial contractility and Ca exchange in the pool responsible for E-C coupling was studied in cardiomyopathic (B10 14.6) and control (B10.RB) hamster hearts at three stages in the development of the disease. Contractility (dP/dt) was significantly reduced in the B10 14.6 strain at 26 to 30 days of age, and at all subsequent stages of the disease. Reduced contractility was related directly to a reduction in the Ca content of a superficial pool, Ca1, representing Ca contained in the interstitial space and bound to the sarcolemma and other structures in the interstitium. Increased entry of Ca into cellular pools was associated with the reduction of superficial Ca content. The results suggest that the reduction in surface Ca binding sites may be responsible for the reduction in contractility.

Cytochrome P-450 and hepatic drug biotransformation during progressive cardiac disease in cardiomyopathic hamsters.

Reductions in cytochrome P-450 levels and aminopyrine N-demethylase activity of hepatic microsomes obtained from cardiomyopathic hamsters (BIO 14.6) occurred at all stages of the disease before the development of congestive heart failure (CHF). Cytochrome b5 levels were reduced only in animals with CHF when compared with age-matched controls (BIO.RB). Total microsomal protein and p-nitrophenol glucuronidation were not affected by the disease process. We conclude that the reduction in cytochrome P-450 levels and N-demethylase activity in cardiomyopathic hamsters is not a consequence of CHF, but is one of the manifestations of the disease process.

Comparison of the effects of ouabain and high tissue sodium on the calcium pools involved in excitation-contraction coupling.

According to one hypothesis for the mechanism of action of cardiac glycosides, inhibition of cardiac Na,K-ATPase elevates [Na]i and by increasing Na:Ca exchange, increases [Ca]i to ultimately produce the positive inotropic effect (PIE). Therapeutic concentrations of ouabain specifically increase the Ca content of a superficial pool involved in excitation-contraction coupling. Thus, for this hypothesis to be correct, equivalent increases in total Na by means other than Na,K-ATPase inhibition must also specifically increase the Ca content of this pool and produce a PIE. However, unlike the effects produced by ouabain, contracture, an elevation of tissue K and a nonspecific increase in Ca uptake occurred in Na-loaded hearts. Although Na loading and ouabain treatment increased total tissue Na to the same extent, the results suggest that (a) the increased tissue Na may not reflect an equivalent increase in [Na]i; (b) the Na-loading procedure was not a valid model for Na,K-ATPase inhibition, or (c) the hypothesis for cardiac glycoside action is incorrect.