Catheter Break-in for Continuous Ambulatory Peritoneal Dialysisuniversity of Missouri Experience

Retrospective analysis of the results of several break-in techniques in our institution revealed that a 10 day delay in CAPD initiation after a midline Tenckhoff catheter insertion is sufficient to prevent leakage in patients maintained on intermittent peritoneal dialysis. A leak or obstruction related to an insufficient surgical technique can be promptly diagnosed and corrected. An irrigation technique seems to be useful in non-uremic patients, but frequently fails to disclose a one-way obstruction with a consequent delay in a surgical correction. Recently we have introduced a modification of this technique in which the patency of the catheter is checked with one in and out exchange using a small volume of dialysate during outpatient clinic visits every 2– 3 days.

Physiological factors influencing the growth of skeletal muscle

The growth of muscle can be regulated by developmental changes or by alterations in hormone levels or in the rate or amount of work demanded. The mechanisms and structures involved in growth processes can be studied by controlling these factors. The models used are chicken anterior latissimus dorsi (ALD) muscle under the influence of overloading and rabbit tibialis anterior (TA) muscle under the influence of chronic nerve stimulation. Both models involve changes in the isoform of myosin that is expressed. Methods of study include quantitative ultrastructural analysis, immunofluorescence and in situ mRNA hybridization. In overloaded chick ALD fibres polysomes are nonuniformly distributed between the myofibrils and in a peripheral annulus even though subcellular concentrations of the new isoform are not found. In normal rabbit muscle the highest concentration of myosin mRNA detected by in situ hybridization is found in the subsarcolemmal zone. In stimulated TA polysomes are found between myofibrils. It appears that the myosin mRNA accumulates at specific cell locations before translation; then diffusion of isomyosin and rapid exchange into myofibrils follows. Therefore, regulation of growth may be possible at the transcriptional, translational and assembly stages.

Drug absorption from the small intestine in immediate postoperative patients

BACKGROUND

The effects of surgery on gastric emptying have been documented for a considerable time, but less is known about the effects in the small intestine. It is thought that there is minimal diminution in the absorptive capacity of the small intestine after operation, although there is no literature on drug absorption in the early period after surgery. This study investigated drug absorption from the small bowel in patients undergoing abdominal surgery.

METHODS

A prospective study of patients undergoing major abdominal surgery in which patients acted as their own preoperative controls was carried out. Patients were administered the test substances, acetaminophen and (99m)TcDTPA, before operation and 2 days after operation. Small intestine transit times, plasma concentrations and other pharmacokinetic variables were compared using Student's paired t-test. Two complementary studies were carried out to establish pharmacokinetic parameters.

RESULTS

There were no significant differences in the pre- and postoperative values of t(max), area under the curve, and area under the moment curve (AUMC) before and after operation (P>0.05). There were significant differences between the pre- and postoperative values of C(max) [C(max (preop))>C(max (postop)); P<0.05] and the pre- and postoperative values of mean residence time (MRT) [MRT((preop))<MRT((postop)); P<0.01].

CONCLUSIONS

Drug absorption from the small bowel in the postoperative patient does not differ significantly from its preoperative absorptive capacity.

Comparative efficacy and pharmacokinetics of racemic bupivacaine and S-bupivacaine in third molar surgery

PURPOSE

To compare the efficacy and pharmacokinetics of racemic bupivacaine (rac-bupivacaine) with S-bupivacaine as primary local anesthetic agent in bilateral impacted third molar extractions.

METHOD

A randomised, double blind, two period cross-over design was employed. Six subjects (2 males, 4 females; age 19-25 years; weight 69.2+/-9.4 kg) received bupivacaine hydrochloride injection (6.6 ml) as rac-bupivacaine (0.5% as salt) or S-bupivacaine (0.5% as base) prior to extraction of impacted third molars on one side and three weeks later on the other side. Anesthesia, blood loss associated with surgery and post-operative pain experience were evaluated. Plasma samples were analysed for bupivacaine enantiomers by chiral HPLC.

RESULTS

In 7/12 operations, anesthesia adequate for surgery was delayed (>10 min) or unsatisfactory requiring lidocaine rescue medication. Despite this, there were no significant differences in onset and duration of anesthesia, blood loss or post-operative pain experience between the two arms of the study. Pharmacokinetic parameters were not significantly different and there was no evidence of chiral inversion after dosing with S-bupivacaine.

CONCLUSIONS

Both study drugs were inadequate as single anesthetic agent for third molar surgery. Any decision to use S-bupivacaine for oral surgery must rest on evidence that it is less toxic than the racemic drug.

Screening patients with chest pain in the emergency department using electron beam tomography: a follow-up study

OBJECTIVES

The high sensitivity of electron beam tomography (EBT) in the detection of coronary artery calcium (CAC) and obstructive coronary artery disease prompted us to investigate the association between CAC detection and future cardiac events in patients with acute chest pain syndromes requiring hospitalization.

BACKGROUND

Three studies have documented that EBT is a rapid and efficient screening tool for patients admitted to the emergency department (ED) with chest pain, but there is a paucity of long-term follow-up data on these chest pain patients.

METHODS

We conducted a prospective observational study of 192 patients admitted to the ED of a large tertiary care hospital for chest pain syndromes. Upon admission, patients underwent EBT scanning in addition to the usual care for chest pain syndromes. During the 17-month enrollment period, 221 patients were scanned (54% men with a mean age of 53 +/- 9 years). Average follow-up was 50 +/- 10 months using chart review.

RESULTS

Fifty-eight patients had coronary events confirmed by a blinded medical record review. The presence of CAC (a total calcium score >0) and increasing score quartiles were strongly related to the occurrence of hard cardiac events including myocardial infarction and death (p < 0.001) and all cardiovascular events (p < 0.001). Stratification by age- and gender-matching further increased the prognostic ability of EBT (for scores above vs. below the age- and gender-matched CAC scores; odds ratio: 13.1, 95% confidence intervals: 5.62, 35.9).

CONCLUSIONS

These data support previous reports demonstrating that the presence of CAC in a symptomatic cohort is a strong predictor of future cardiac events. This study supports the use of EBT in a symptomatic cohort with prompt discharge of those patients with negative scans. Furthermore, the absence of CAC is associated with a very low risk of future cardiac risk events in this population over the subsequent seven years (annual event rate <1%).

Depictions of motion devised by a blind person

A blind man (E.A.) was asked to draw pictures suggesting wheels in various kinds of motion. Six pictures were drawn by E.A. The pictures were shown to sighted subjects, who were asked to assign labels to the pictures, in a multiple-choice format. The labels were assigned at a rate above chance. We argue that the pictures are metaphoric and that pictorial metaphor relies on common properties of the static picture and the kinetic referent.

The regenerative deficit of peripheral nerves in experimental diabetes: its extent, timing and possible mechanisms

Diabetes mellitus is reported to impair peripheral nerve regeneration, but the extent, timing and selectivity of the deficit is unclear. We studied regeneration of motor and sensory fibres in mice with experimental diabetes induced using streptozotocin (STZ). The mouse model featured several advantages over its counterpart in rats given STZ, while exhibiting the expected slowing of motor conduction velocity. Serial studies addressed fibre regrowth for up to 10 weeks after both sciatic nerve crush injury and complete sciatic nerve transection. Following nerve crush, there was a delay in motor fibre reinnervation of tibial innervated interosseous muscles of diabetics, manifest as a slow recovery of the M-wave recorded from these muscles. Despite an apparent recovery in M-waves by 6 weeks, this was not accounted for by restitution of tibial axon numbers in diabetic mice. Histological studies distal to crush or transection identified substantial delays in the regrowth of the numbers and calibre of regenerating myelinated fibres in diabetics for up to 8-10 weeks. Moreover, this delay was observed in both the tibial (largely motor) and sural (non-motor) distal sciatic branches. There was an associated delay in macrophage invasion and their later resorption in the diabetic nerves, indicating that a potential mechanism of impaired regeneration might be abnormal macrophage participation in nerve repair. Our findings indicate that during nerve regeneration, diabetic motor and sensory fibres have substantial and persistent deficits in regrowth associated with abnormalities in macrophage participation.

Cavanagh and Leclerc shape-from-shadow pictures: do line versions fail because of the polarity of the regions or the contour?

Shape-from-shadow perception fails when the contour bordering a shadowed area is reduced to a black line, and the shadow area becomes white. It might be that the polarity of the shadowed and illuminated areas has to be from dark on the shadowed side to light on the illuminated side for successful perception. Or it may be that the line, which has two contours, has one too many for shape-from-shadow processing. Alternatively, the problem might be that one of the contours of the line is incorrectly polarised. To test these explanations, three shape-from-shadow figures were prepared, each depicting the same referent--an elderly person. All three figures had two correctly polarised areas. One figure had a correctly polarised contour at the border between the areas. One had two correctly polarised contours. The other had one correctly polarised contour and one incorrectly polarised contour. The referent of the figure with one incorrectly polarised contour was the one difficult to make out. The result has implications for several theories, including an account of a demonstration by Hering involving penumbra.

Are metaphors elliptical similes?

What is the relation between metaphors and similes? Aristotle's "comparison theory" holds that metaphors are elliptical similes: "Sam is a pig" is simply a short form of "Sam is like a pig." In contrast, it has been suggested that metaphors cannot be elliptical similes because metaphors are "stronger" than similes. We know metaphors are stronger, it is argued, because of examples involving corrections, such as "Peter is not just like a rock, he is a rock." The argument from corrections can be challenged on logical and empirical grounds. The ability to correct a simile with a metaphor does not entail that metaphors are stronger than similes when used on their own, which is likely to be the most frequent case. Although four experiments indicate that when corrections are involved, metaphors are indeed stronger than similes in several respects, alas a further four experiments indicate that these differences are largely eliminated when metaphors and similes are used on their own. We note that this pattern of results is consistent with the comparison theory, and we offer an explanation of the effects of corrections.

Exercise testing and electron beam computed tomography in the evaluation of coronary artery disease

OBJECTIVES

This study compared coronary artery calcium (CC) as detected by electron beam computed tomography (EBCT) with conventional stress testing in the evaluation of patients with symptoms suggestive of coronary artery disease (CAD).

BACKGROUND

Exercise electrocardiogram treadmill stress testing (treadmill-ECG) is limited by its requirement of a normal resting ECG and the ability of the patient to exercise adequately. The addition of myocardial imaging agents such as technetium improves the sensitivity and specificity but substantially increases the cost and prolongs the testing time. The use of EBCT provides a noninvasive and rapid method for identifying the presence and amount of CC, which has been shown to be related to atherosclerosis, and may provide additional information in combination with more traditional noninvasive testing methods.

METHODS

A total of 97 patients underwent technetium stress testing (technetium-stress), treadmill-ECG, and EBCT coronary scanning within three months of coronary angiography for the evaluation of chest pain.

RESULTS

The relative risk (RR) of obstructive angiographic CAD for an abnormal test was higher for EBCT (4.53) than either treadmill-ECG (1.72) or technetium-stress (1.96). The low specificity of EBCT (47%) was improved by the addition of treadmill-ECG (83%, p < 0.05).

CONCLUSIONS

Electron beam computed tomography has a higher diagnostic ability than either treadmill-ECG or technetium-stress for the detection of obstructive angiographic CAD. Electron beam computed tomography is an accurate and noninvasive alternative to traditional stress testing for the detection of obstructive CAD in symptomatic patients.

Polypharmacy in a general surgical unit and consequences of drug withdrawal

AIMS

To identify drug usage/withdrawal in surgical patients and the relative risk this imposes on postoperative surgical complications.

METHODS

A prospective survey of patients' medicines, oral intake (food/fluids/ medicines) and postoperative complications was carried out in the General Surgical Unit, Dunedin Hospital, Dunedin, New Zealand.

RESULTS

One thousand and twenty-five general surgical patients aged >/= 16 years, were entered into the study. Half of the patients were taking medicines unrelated to surgery. On average these patients received 9 different drugs (range 1-47) from a selection of 251, of which 21% were released in the last 10 years. The mean number of these drugs taken increased with age, vascular surgery and other major procedures. The majority of patients (53%) were taking drugs for cardiovascular problems. Only 8% of admissions were on the drugs more traditionally recognized to be of importance to the surgery, i.e. steroids and diabetic therapy. With respect to risk, taking a drug unrelated to surgery was associated with an increased relative risk of a postoperative complication by 2.7 (95% C.I. 1.76-4.04) compared with those who were not taking any drug. Cardiovascular drugs contributed significantly to this risk; when they were excluded from analysis, the risk dropped to 1.8 (95% C.I. 1.14-2.93). Death may be more common in those taking ACE inhibitors. Drug withdrawal and complications were analysed and as the time without medicines increased (range 1-42 days) so did the complication rate (chi2 = 14.7, DF = 2, P = 0.007). Of those patients who were taking a cardiovascular medicine and were without their normal medicines for a period of time postoperatively, 12% suffered a cardiac complication.

CONCLUSIONS

Many patients admitted to a general surgical ward, are taking medicines unrelated to surgery. Drug therapy unrelated to surgery is a useful predictor for increased postoperative complications and one for which preventive action can be taken. This study provides evidence that withdrawal of regular medicines may add significant risk to the surgery and further complicate outcome. The longer patients were without their regular medicines the more nonsurgical complications they suffered. Reintroduction of patients' regular medicines early in their postoperative course may decrease morbidity and mortality in-patients.

Polypharmacy in a general surgical unit and consequences of drug withdrawal

AIMS

To identify drug usage/withdrawal in surgical patients and the relative risk this imposes on postoperative surgical complications.

METHODS

A prospective survey of patients' medicines, oral intake (food/fluids/ medicines) and postoperative complications was carried out in the General Surgical Unit, Dunedin Hospital, Dunedin, New Zealand.

RESULTS

One thousand and twenty-five general surgical patients aged >/= 16 years, were entered into the study. Half of the patients were taking medicines unrelated to surgery. On average these patients received 9 different drugs (range 1-47) from a selection of 251, of which 21% were released in the last 10 years. The mean number of these drugs taken increased with age, vascular surgery and other major procedures. The majority of patients (53%) were taking drugs for cardiovascular problems. Only 8% of admissions were on the drugs more traditionally recognized to be of importance to the surgery, i.e. steroids and diabetic therapy. With respect to risk, taking a drug unrelated to surgery was associated with an increased relative risk of a postoperative complication by 2.7 (95% C.I. 1.76-4.04) compared with those who were not taking any drug. Cardiovascular drugs contributed significantly to this risk; when they were excluded from analysis, the risk dropped to 1.8 (95% C.I. 1.14-2.93). Death may be more common in those taking ACE inhibitors. Drug withdrawal and complications were analysed and as the time without medicines increased (range 1-42 days) so did the complication rate (chi2 = 14.7, DF = 2, P = 0.007). Of those patients who were taking a cardiovascular medicine and were without their normal medicines for a period of time postoperatively, 12% suffered a cardiac complication.

CONCLUSIONS

Many patients admitted to a general surgical ward, are taking medicines unrelated to surgery. Drug therapy unrelated to surgery is a useful predictor for increased postoperative complications and one for which preventive action can be taken. This study provides evidence that withdrawal of regular medicines may add significant risk to the surgery and further complicate outcome. The longer patients were without their regular medicines the more nonsurgical complications they suffered. Reintroduction of patients' regular medicines early in their postoperative course may decrease morbidity and mortality in-patients.

Stereoselective glucuronidation of formoterol by human liver microsomes

AIMS

Formoterol is a beta2-adrenoceptor agonist marketed as a racemic mixture of the active (R; R)- and inactive (S; S)-enantiomers (rac-formoterol). The drug produces prolonged bronchodilation by inhalation but there is significant interpatient variability in duration of effect. Previous work has shown that in humans formoterol is metabolized by conjugation with glucuronic acid but little is known about the stereoselectivity of this reaction. The aim of the present study was to investigate the glucuronidation of formoterol enantiomers in vitro by human liver microsomes.

METHODS

The kinetics of formation of formoterol glucuronides during incubation of racemate and of single formoterol enantiomers with human liver microsomes (n=9) was characterized by chiral h.p.l.c. assay.

RESULTS

The kinetics of glucuronidation of the two formoterol enantiomers obeyed the Michaelis-Menten equation. Glucuronidation of formoterol was stereoselective and occurred more than two times faster for (S; S)-formoterol than for (R; R)-formoterol. In incubations with single formoterol enantiomers, the median (n=9) Km values for (R; R)-glucuronide and (S; S)-glucuronide were 827.6 and 840.4 microm, respectively, and the median V max values were 2625 and 4304 pmol min-1 mg-1, respectively. Corresponding values determined in incubations with rac-formoterol were 357.2 and 312.1 microm and 1435 and 2086 pmol min-1 mg-1 for (R; R)- and (S; S)-glucuronide, respectively. Interindividual variation was large with the ratio of V max/Km (S; S/R; R) ranging from 0.57 to 6.90 for incubations with rac-formoterol.

CONCLUSIONS

Our study demonstrates that glucuronidation of formoterol by human liver microsomes is stereoselective and subject to high interindividual variability. These findings suggest that clearance of formoterol in humans is subject to variable stereoselectivity which could explain the variation in duration of bronchodilation produced by inhaled formoterol in patients with asthma.

Heavy long-term ethanol consumption induces an alpha- to beta-myosin heavy chain isoform transition in rat

Alcoholic heart muscle disease is characterized by structural changes which include chamber dilation, ventricular hypertrophy, and myocyte damage. These effects often lead to contractile dysfunction and ultimately to heart failure if alcohol consumption is not terminated. In rat models for heart failure in which heart failure is induced by pressure or volume overload, there is a shift in the myosin heavy chain (MHC) isoforms, from alpha to beta. As a result of this MHC transition, there is typically a decrease in myosin ATPase activity. We utilized a rat model of chronic alcohol consumption in order to determine if alcohol causes a similar shift in MHC isoforms and changes in myosin ATPase activity. A liquid diet containing 9% ethanol (46% of daily calories; 11.8 g/kg/day) was administered to adult rats for a period of 60 or 90 days. This heavy consumption of ethanol resulted in an average blood ethanol content of 150 mg %. The relative abundance of beta-MHC isoform protein increased from a control level of 9.7% to 35.1% in hearts of ethanol-fed rats, following 90 days of ethanol consumption. In a separate set of experiments, the levels of alpha-MHC and beta-MHC mRNA were demonstrated to increase by 150% and 230%, respectively. Following a 60 day treatment, there was a significant reduction in the actomyosin Mg2+ -ATPase activity in the myofibrillar preparations from hearts of ethanol-fed rats compared to hearts from control-fed rats. In addition, the myosin Ca2+ -ATPase activity was decreased 17% and 30% after 60 and 90 days of ethanol consumption, respectively. The present study demonstrates that chronic ethanol consumption induces an increase in the proportion of the total MHC content composed of the beta-isoform. This isoform transition is accompanied by an accumulation of beta-MHC mRNA, suggesting that the switch is organized pretranslationally. A functional consequence of this transition in MHC phenotype is demonstrated by significant decreases in the myofibrillar and myosin ATPase activities.

Aptness predicts preference for metaphors or similes, as well as recall bias

Why might we sometimes prefer a metaphor such as "genes are blueprints" to a simile such as "genes are like blueprints"? One possibility is that metaphors are preferred when the comparison between a tenor (e.g., genes) and a vehicle (e.g., blueprints) seems especially apt. That is, metaphors might be used when the comparison captures many salient features of the tenor in question. The present experiments examined the relation between the aptness of comparisons and people's preferences for expressing those comparisons as metaphors or as similes. In Experiment 1, it was found that there is consensus on how to express particular comparisons. In Experiment 2, it was found that this preference can be predicted from the aptness of a comparison. It was also found that aptness can predict errors in the recall of comparisons. These findings have implications for theories of metaphor.

Which way is upright and normal? Haptic perception of letters above head level

In three experiments, the perception of the apparent orientation of block letters shown in various orientations above the subject's head in the horizontal plane was examined. A block letter F with its front facing down toward the observer has two crossbars on its right side; the top is the part with the long crossbar, and the base has no bar. The experiments involved changing the locations of these parts with respect to the observer. In Experiment 1, the subjects using touch most often identified a letter as having its left and right sides in a normal orientation if the front of the block letter faced upwards away from the observer, with the bar on the right and the top of the letter farther from the subject than the letter's base. In Experiment 2, the subjects judging visual uprightness favored positions in which the bars were on the right, the top of the block letter was near them, and the letter's front faced downwards toward the observer. In Experiment 3, the subjects using touch most often assessed letters as being upright if the top of the letter was the farthest part and the bar was on the right. The results suggest that, when assessing orientation, subjects using touch favored positions that would be reached by a letter moving vertically upwards from table height, but subjects relying on vision favored positions reached by a letter moving in an are centered on the subject's head (on the eyes, in particular).

Usefulness of electron beam computed tomography scanning for distinguishing ischemic from nonischemic cardiomyopathy

OBJECTIVES

This study was undertaken to evaluate the ability of electron beam computed tomography (EBCT) to distinguish ischemic from nonischemic causes of cardiomyopathy by evaluating heart failure patients for coronary calcification (CC).

BACKGROUND

The etiology of heart failure, whether coronary-induced or nonischemic, may be difficult to discern clinically. Differentiation of ischemic from nonischemic etiology is clinically important for both therapeutic and prognostic implications. With its ability to noninvasively discern and quantitate coronary artery calcification, EBCT correlates well with angiographic stenosis and thus may be useful in distinguishing ischemic and nonischemic cardiomyopathies.

METHODS

One hundred and twenty-five patients with cardiomyopathy (ejection fraction <0.40) and known coronary anatomy underwent EBCT coronary scanning to evaluate for CCs within 3 months of coronary angiography.

RESULTS

Of the 72 patients who were found to have ischemic cardiomyopathy, 71 patients had CC by EBCT (sensitivity 99%, p < 0.001), mean score 798+/-899. In comparison, among the 53 patients without significant coronary artery disease (CAD) (nonischemic cardiomyopathy), the mean score was significantly lower (17+/-51; p < 0.0001), and 44 patients had a CC score of 0 (no CC present). The specificity of EBCT to exclude CAD in patients with cardiomyopathy was 83%, using a threshold CC score of 0, and 92% for scores <80 (p < 0.001). Overall accuracy for determining the etiology of cardiomyopathy (differentiating ischemic from nonischemic) was 92% for this technique.

CONCLUSIONS

This prospective, blinded study indicates that EBCT detected CC accurately and can noninvasively distinguish between cardiomyopathy because of CAD and nonischemic causes of left ventricular dysfunction.

Effects of surgery on the pharmacokinetic parameters of drugs

As with other forms of stress, surgery is a time of fluctuating haemodynamics, physiological shifts, intense metabolic changes, and protein catabolism and anabolism. At times, these changes can occur within hours. There is a reasonable body of literature concerning the adverse effects of surgery on gastric emptying, but not on the effects of surgery on the distribution, metabolism and excretion of drugs. Gastric emptying is diminished or absent following major procedures, which prevent the delivery of orally administered drugs to their major site of absorption, the small bowel. Changes in the paracellular absorption of drugs may occur postoperatively, although transcellular absorption appears to be unimpaired. Distribution is affected by changes in blood volume, alterations in circulation, increases in the extracellular fluid and changes in the circulating plasma protein levels, such as albumin and alpha 1-acid glycoprotein. Little is known about alterations in drug metabolism following surgery. However, it has been shown that systemic hypoxia alters the function of some of the cytochrome P450 (CYP) system and increased levels of cytokines have an effect on the metabolism of at least 1 drug. In addition, the renal elimination of drugs is affected in patients postoperatively, although the effects of biliary clearance in this period are difficult to determine. Despite the lack of research into pharmacokinetics during the postoperative period, and given the immense and often sudden changes observed in patients post-surgery, it is reasonable to recommend vigilance with respect to drug therapy during this period.

AZT decreases rat myocardial cytochrome oxidase activity and increases beta-myosin heavy chain content

AZT, a widely-utilized drug for the treatment of HIV infection, inhibits the polymerase responsible for mitochondrial DNA replication (mtDNA). The aim of this study was to assess myocardial alterations caused by this action. Ventricular muscle from rats treated for > or = 35 days with 1 mg/ml of AZT in their drinking water was analysed for cytochrome oxidase activity and the content of mRNAs for the nuclear-encoded cytochrome oxidase (COX) subunit VIc and the mitochondrial-encoded COX subunit III. In addition contractile protein expression was assessed by examining mRNA levels for alpha- and beta-myosin heavy chains (MHC). Changes in MHC mRNA levels were correlated with changes in alpha- and beta-MHC proteins and changes in myofibrillar ATPase activity. Results show that AZT caused a reduction in COX activity, COX subunit III mRNA, and mtDNA levels. There was no decrease in the COX subunit VIc mRNA. MHC expression was altered such that the relative content of beta-MHC protein and mRNA were increased. Accumulation of beta-MHC was reflected in the reduction of myofibrillar ATPase activity at pCa values of 5.875 and 6.125. These data demonstrate that AZT induces a reorganization of cardiac gene expression indicative of changes in cardiac contractile properties. The observed decreases in mtDNA levels along with mRNA for a mitochondrial-encoded protein and COX activity is consistent with the postulated mechanism whereby AZT induces a myopathy by diminishing mtDNA replication.

Blind children recognizing tactile pictures respond like sighted children given guidance in exploration

Theory of tactile pictures argues that untrained blind subjects can recognize raised, outline pictures. It contends the blind person's knowledge of the shapes of common objects is like that of the sighted, and the blind person's pictorial abilities use the same principles as the sighted person's. To test this theory, blind children (aged 8-13) and blindfolded age-matched sighted children were asked to identify raised-line drawings of common objects. Their performances were correlated. In addition, the blind children identified more than sighted children exploring the pictures actively, but the same number of pictures as sighted children who were given passive, guided exploration. We argue blind and sighted children use the same principles to identify the pictures, but the blind have superior exploration skills. The differences in the effects of exploration skills on recognition scores are minimized when the sighted children are given guidance, since the sighted children then have efficient contact with the displays, and the performance of the sighted and the blind is then governed by the same principles, without one group benefitting from advantages in exploration skills.

Developmentally regulated expression of cytochrome-c oxidase isoforms in regenerating rat skeletal muscle

The developmental expression of tissue-specific isoforms of cytochrome-c oxidase (COX) subunit VIII [heart (COX VIII-H) and liver (COX VIII-L)] and the influence of innervation were examined in regenerating fast [extensor digitorum longus (EDL)] and slow (soleus) muscles. In adult muscles, COX VIII-H was the predominant isoform. The COX VIII-L mRNA was expressed 3 days after induction of regeneration, and it progressively decreased after 7, 10, 14, and 30 days of regeneration in both muscles. In contrast, the expression of COX VIII-H mRNA accumulated as myogenesis proceeded to the myotube stage between 7 and 10 days of regeneration and progressively increased to near control levels by 30 days. The influence of innervation on the expression of COX VIII and alpha-actin isoforms was examined in control, innervated, and denervated regenerating muscles at 3 and 10 days. The relative expression of COX VIII-L mRNA in denervated regenerating EDL muscles was significantly greater, while that of COX VIII-H was significantly less than in innervated regenerating EDL muscles after 10 days of regeneration. Similarly, cardiac alpha-actin mRNA levels were elevated in denervated regenerating EDL muscles after 10 days of regeneration. In conclusion, motor innervation influences the transition from the COX VIII-L to COX VIII-H isoform during myogenesis in regenerating muscles.

Mitochondrial gene expression is impaired by ethanol exposure in cultured chick cardiac myocytes

OBJECTIVE

A depression in cytochrome c oxidase (COX) activity occurs following chronic embryonic ethanol exposure in vivo. The aim of this study was to examine the effect of chronic ethanol exposure on COX activity in isolated cardiac cells maintained in vitro. Additionally, the mechanism by which ethanol produces an impairment in COX activity was evaluated by examining mitochondrial gene expression.

METHODS

Spontaneously beating cardiac myocyte cultures were established from 10-day embryonic chick hearts. Various concentrations of ethanol (0-250 mM) were introduced at the time of plating and cells were harvested over 7 days. COX activity was determined in myocyte homogenates. The levels of nuclear-encoded (COXIV) and mitochondrial-encoded (COXII) subunit proteins were measured by Western blotting. Relative levels of mitochondrial DNA and the mitochondrially-encoded COXIII mRNA were determined by Southern and Northern blotting.

RESULTS

A consistent decrease in COX activity in ethanol-exposed cardiac myocytes of approximately 30% was observed with an ethanol concentration of 25 mM. Increasing the ethanol concentration to 250 mM produced only a minor enhancement of this effect, while severely decreasing cellular viability. The content of the mitochondrially-encoded COXII subunit was reduced by ethanol exposure, while that of the nuclear-encoded COXIV subunit was unchanged. The content of the mitochondrially-encoded COXIII mRNA was unchanged by ethanol exposure. However, prolonged ethanol exposure produced an increase in mitochondrial DNA levels in cardiac myocytes.

CONCLUSIONS

Ethanol exposure of cardiac myocytes produces deficits in COX activity in the absence of systemic variables, indicating that ethanol has a direct effect on cardiac mitochondria. The ethanol-induced decrease in COX activity is correlated with a specific decrease in at least one mitochondrially-encoded gene product, COXII. No changes were observed in the level of the nuclear-encoded COXIV subunit, indicating that expression of this nuclear-encoded gene is not impaired by ethanol exposure.

Influence of thyroid hormone on the tissue-specific expression of cytochrome c oxidase isoforms during cardiac development

In mammals, cytochrome c oxidase (COX) is composed of 13 different protein subunits. In the rat, two nuclear-encoded subunits, COX VIa and VIII, exist as tissue-specific isoforms: heart and liver. Using Northern-blot analysis, the levels of transcripts for the heart and liver isoforms of VIa and VIII were examined in developing rat hearts. The liver isoform was found to be the predominant form of subunit VIa and the exclusive form of VIII in the 18-day fetal hearts. The mRNA levels of the heart isoform of both subunits increased dramatically to reach adult levels by 14 days. Although the levels of the VIa- and VIII-liver isoform mRNAs remained stable throughout early development, their levels decreased by 40 and 36% respectively between the 18-day fetal stage and 18-day neonatal stage. Therefore the up-regulation of the heart isoforms and down-regulation of the liver isoforms appear to be regulated in a co-ordinated manner during development. To determine if thyroid hormone influences the expression of these developmentally regulated isoforms, the RNA was also extracted from the hearts of 2-week-old hypothyroid rats. The results showed that the levels of VIII-heart and VIa-liver COX mRNAs were approx. 40% lower in the hypothyroid hearts, while VIII-liver and VIa-heart COX isoform expression remained unchanged. These data demonstrate that the isoforms of COX subunits VIa and VIII are not co-ordinately regulated by changes in thyroid hormone levels. Therefore we conclude that, although thyroid hormone influences the expression of isoforms, it appears to do so via a different mechanism from that which regulates the developmental transition.

Specification and initial evaluation of a multiple application teleradiology system

The digitization and transmission of medical images is becoming increasingly more important and available. The selection of appropriate clinical applications for teleradiology systems is an important factor in determining the success of such ventures. In this paper, the selection of such applications and the evaluation of the teleradiology system is described. The system (LIAISON, CAPTEC Ltd, Malahide, Ireland) is PC based and is capable of digitization and transmission of three categories of medical images: (1) plain film radiographs; (2) CT film data and (3) video sequences such as ultrasound scans. A comprehensive technical evaluation was carried out on the acquisition and display station in which various parameters such as spatial resolution, signal-to-noise ratio (SNR), and distortion were investigated. Results showed that the system performed well within specifications. An exploratory clinical evaluation was performed using a case mix of subtle fractures, chests and dislocations, and CT scans. Here the system performed well with a diagnostic accuracy of 95% for the digital image compared with the analogue image.

Skeletal muscle mitochondria from AZT-treated rats have a diminished response to chronic electrical stimulation

Inhibition of DNA polymerase gamma-function mediated by 3'-azido-3'-deoxythymidine (AZT) has been proposed to cause a myopathy by reducing mitochondrial DNA (mtDNA) replication. Repeated bouts of exercise stimulate an increase in mtDNA replication, mitochondrial content, and mitochondrial volume fraction. Therefore, adaptation of rat skeletal muscle [tibialis anterior (TA)] mitochondria exposed to AZT (1 mg/ml for 35 days) and then to electrical stimulation for 8 h/day (7, 14, 21 days) with continued AZT treatment was examined. Fourteen and 21 days of stimulation increased TA cytochrome oxidase (CO) activity, mtDNA, and CO subunit III and VIc mRNA levels in both groups. The TA CO activity and CO III mRNA increases after 14 and 21 days of stimulation were diminished in AZT-treated rats. TA glyceraldehyde-3-phosphate dehydrogenase was reduced in normal rats after chronic stimulation but was unchanged in AZT-treated rats. Chronic stimulation increased the mitochondrial volume fraction by 80 and 40% in normal and AZT-treated rats, respectively. These results indicate diminution, but not complete inhibition, of mitochondrial adaptation by AZT-treated skeletal muscle in response to stimulation.

Long-term compressive property durability of carbon fibre-reinforced polyetheretherketone composite in physiological saline

In total hip arthroplasty, concerns such as corrosion and stress shielding associated with stiff metallic femoral components have led to the development of low stiffness advanced fibre-reinforced polymer (FRP) composite femoral components. Carbon fibre-reinforced polyetheretherketone (CF/PEEK) composite material is now one of the primary material systems being considered for composite hip stem development. As a hip stem, a composite material must be able to support a complex state of stress in the in vivo environment without failure. Considering the loading conditions of a hip stem (superimposed compression and bending), and the fact that FRP composites typically possess lower compressive than tensile strength, the compressive behaviour of FRP composites becomes very important for femoral component design. This paper presents an investigation of the long-term durability of 0 degree and 90 degrees compressive strengths of CF/PEEK composite following physiological saline saturation. 0 degree and 90 degrees compressive moduli and Poisson ratio (v12) properties are also reported. Samples were tested following conditioning in physiological saline at 37, 65 and 95 degrees C for time periods from 0 to 5000 h. Dry samples were tested as controls. Results show no significant loss in compressive property values of the saline-saturated or the dry control samples as a function of conditioning time or temperature.

Foreshortening in cube drawings by children and adults

The lengths of lines and the sizes of angles were measured in freehand drawings of cubes produced by 190 children and 158 adults. The lengths of oblique lines depicting receding cube edges were foreshortened relative to horizontal lines showing nonreceding edges. In the drawings from children aged 9 and 10 years the obliques were foreshortened by about 40%, compared with 30% in adults' drawings. The amount of foreshortening was not correlated with the angle at which the obliques were drawn. Line lengths were also foreshortened in "transparent" drawings, which are often said to show "what is known" about cube structure. One explanation of the results is that line lengths are foreshortened by children and adults to create the visual impression of equal-length cube edges, even in transparent drawings. This foreshortening fits with how the receding edges of a square face of a cube project to a vantage point. Children and adults who use foreshortening are not depicting the structure of cubes by matching features such as equal-length edges with similar features in the physical lines on the page, as has been suggested in some recent approaches to drawing development.

Production and interpretation of pictures of houses by blind people

Subjects were exposed to a three-dimensional model of a house and were asked to draw it using a raised-line drawing kit. Independent groups of ten each of sighted controls, early-blind, and late-blind subjects were told to identify the vantage point of tangible pictures of the model, including side views, 'bird's-eye' views from above, and views involving linear perspective. The ease or difficulty of picture interpretation depended upon the nature of the tangible drawing, with much better performance being recorded for side views. Performance was poor for foreshortened 3/4 views. Early-blind subjects were particularly unlikely to recognize views from above. In a control experiment with blindfolded sighted subjects the influence of prior information was examined: some subjects were told that the drawings could consist of side view or bird's-eye, top view, or 3/4 view drawings. This experiment showed that performance can be greatly improved through prior information about the nature of the tangible pictures.

Misalignment effects in 3-D versions of Poggendorff displays

Strong misalignment effects are found in three-dimensional (3-D) versions of Poggendorff displays viewed binocularly. The components of the standard 2-D Poggendorff figure--the parallels and the oblique segments--were presented in 3-D depth as a flat rectangular object with occluding edges and an oblique line situated behind the object. Three experiments investigated the misalignment effects under three different observation instructions: Subjects were told to look at the oblique (Experiment 1), at the rectangle (Experiment 2), or at the background (Experiment 3). Experiments 1 and 2 examined the effects on judgments of alignment of varying the distance in depth that separates the oblique from the rectangle. Experiment 3 examined the effects of varying the distance between the fixated background and the 3-D Poggendorff figure. Both standard and reversed misalignment effects were obtained. When the viewing condition produces crossed disparity for the oblique, perceived misalignment occurs in the usual Poggendorff direction, but it is reversed with uncrossed disparity. Moreover, the amount of misalignment is related to the amount of disparity, and it can be much stronger than is usual in the 2-D versions of the Poggendorff. The misalignment effects can be explained by binocular integration to produce a single cyclopean image.

Differential expression of TnI and TnT isoforms in rabbit heart during the perinatal period and during cardiovascular stress

We have investigated developmental transitions of TnI and TnT isoforms in fetal, neonatal, and adult rabbit hearts by western blot analysis. Our results provide the first evidence for the existence of two developmentally regulated isoforms of TnI in rabbit heart. These isoforms comigrate with adult rabbit cardiac TnI (cTnI) and slow skeletal TnI (ssTnI). At 23 days of gestation, ssTnI was the predominant TnI isoform. At 29 days of gestation, there was a significant increase in the relative amount of cTnI, that continued with maturation. The TnI isoform transition was significantly faster in right than left ventricles at gestation 30 and 32 days. Four TnT isoforms were detected in fetal rabbit ventricles. The relative amount of TnT isoforms did not change from 23 to 29 days of gestation. However, the relative amount of the adult TnT isoform increased significantly around the time of birth with the increase being significantly more prominent in left than in right ventricles. Maternal injection of phenylephrine (PHE), an alpha-1 adrenergic agonist, increased fetal cardiac force and arterial blood pressure, facilitated TnT, but not TnI, isoform transition in fetal heart. Our results indicate that the developmental transition of rabbit cardiac TnI and TnT isoforms is not coordinated and might be regulated by different mechanisms. Our results also provide evidence that the TnT isoform population is influenced by adrenergic stimulation and stress on the cardiovascular system during development.

Tricompartmental knee replacement. A comparison of orthopaedic surgeons' self reported performance rates with surgical indications, contraindications, and expected outcomes. Knee Replacement Patient Outcomes Research Team

The chance of a person with osteoarthritis of the knee receiving a knee replacement is highly variable. To understand better the reasons for this variation, all practicing orthopaedists in Indiana were surveyed about their management of severe knee osteoarthritis and their perception of tricompartmental knee replacement as a therapeutic option. Their perceptions of indications and outcomes of knee replacement were compared with the self reported annual number of patients for whom they performed (or referred to other surgeons for) tricompartmental knee replacements. A completed survey was returned by 220 (79%) of the 280 orthopaedists surveyed; analyses were limited to the 188 respondents who had cared for at least one patient with osteoarthritis of the knee in the prior 2 weeks (mean = 13). These surgeons reported performing (or referring patients for) a mean of 31 knee replacements in the prior year (SD 45, median 21, range 0-480 knee replacements). There was strong agreement (> 95%) among respondents for seven (21%) of 33 surgical indications and contraindications, and more general agreement (> 60%) for 21 (64%). In the five factors (15%) for which there was disagreement, there was no consistent relationship between opinions and self reported knee replacement performance rate. Surgeons reporting more knee replacements had significantly higher estimates of pain relief and functional improvement following surgery, and lower estimates of prosthesis infection and failure rates. When all responses were considered together, four decision factors correlated independently with the performance of more knee replacements, but these four factors explained only 24% of the variation in self reported knee replacement performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Angular subtense effects on perception of polar and parallel projections of cubes

Many authors contend that the perception of 2-D drawings of a 3-D object is governed by polar projective geometry. A problem for this position is that observers accept parallel projections, which are not produced with polar projective geometry, as accurate representations of 3-D objects. In Experiments 1 and 2, we used two different standards of comparison to study the perceptions of three line drawings of cubes--correct polar projections of cubes with subtenses of 15 degrees and 35 degrees, and a parallel projection--at five different angular subtenses. In Experiment 1, 14 observers judged each drawing when it subtended about 35 degrees, 15 degrees, 5 degrees, 4 degrees, and 2 degrees in width. Subjects used an 8-point rating scale to compare each drawing with a correct polar projection of a cube subtending 35 degrees, viewed with the drawing subtending 15 degrees. As predicted, both polar projections had their highest ratings at their correct vantage points. Ratings for the parallel projection were highest at small angular subtenses and decreased when it subtended 35 degrees. These findings were supported by a second experiment in which the 15 degrees polar projection was set at a 5 degrees viewing angle as a standard. In Experiment 3, 15 observers compared the three drawings, viewed at a second set of angular subtenses (30 degrees, 35 degrees, 40 degrees, 45 degrees, and 50 degrees), with a standard, the 35 degrees polar set at 45 degrees. Ratings fell with increases in viewing angle, and the parallel projection was rated lowest. The results indicate that parallel projections are assessed as polar projections that are correct for objects at a small angular subtense. Furthermore, projections at a small angular subtense are robust; that is, they are acceptable over a wide range of angular subtenses. We suggest that robustness can be explained by the modest variability in the proportions of pictures of cubes subtending small angles.

Foreshortening and the perception of parallel projections

Does picture perception follow polar projective geometry? Parallel projection drawings, which are not produced by using rules of polar projection, are widely regarded as visually acceptable representations of three-dimensional (3-D) objects in free viewing. One explanation is that they are perceived by means of a system in which there is no foreshortening. If so, edges of a 3-D block in 1:1 proportions should be denoted by lines in 1:1 proportions on the picture surface. However, three experiments suggest that the perception of parallel projections of a block involves foreshortening. In Experiment 1, 90 subjects were shown a set of parallel projections of a cube, in which each drawing depicted three sides of the cube, drawn as a square with obliques--a frontal square with receding edges shown by parallel obliques of various lengths. The subjects preferred a drawing with a receding side length that was considerably foreshortened in relation to the front side. In Experiments 2 and 3, subjects viewed drawings of three blocks that differed in the ratios of the lengths of their receding edges to their frontal edges (1:1, 1:2, and 1:0.65). In Experiment 2, the subjects were shown square-with-obliques drawings of the three blocks with receding edges shown by parallel obliques of various lengths. Again, the subjects preferred drawings with a receding side that was foreshortened. In Experiment 3, the drawings showed two sides of a block. The receding dimension was drawn with parallel or converging lines. The preferred foreshortening was not a fixed ratio of the dimensions of the 3-D blocks. We suggest that square-with-obliques parallel projections showing cubes are taken by vision to be approximations to projections using foreshortening. We suggest also that as the line showing the receding edge elongates, foreshortening becomes less of a factor.

Ventricular mitochondrial gene expression during development and following embryonic ethanol exposure

The effects of chronic embryonic ethanol exposure were evaluated in chick ventricular muscle. Ethanol treatments were administered on embryonic days 11, 13, 15, and 17 and chicks were sacrificed at various time points following treatments. Fluctuations in embryonic blood ethanol levels were examined following treatments. Developmental increases in the activities of mitochondrial enzymes, cytochrome oxidase (CO) and citrate synthase (CS), were observed. Ethanol exposure resulted in a depression in CO activity, but not CS activity. Since, a maximal depression in CO activity was seen with ethanol treatments of 75 mg/100 g, this dosing paradigm was adopted for subsequent experiments. A tissue-specific effect of ethanol was demonstrated as CO activity was unchanged in atrial, liver, pectoralis, and brain tissues. The role of mitochondrial DNA replication and transcription during the developmental up-regulation and ethanol-induced down-regulation of CO activity was evaluated using a cDNA probe for cytochrome oxidase subunit III (COIII). The relative levels of COIII mRNA and mitochondrial DNA (cpm/mg protein) decreased by 3-fold and 4-fold, respectively, across the developmental time course, while CO activity increased by 3.5-fold. Therefore, increases in mitochondrial DNA and mitochondrial mRNA transcripts are unlikely to be responsible for the developmentally-regulated increases in CO activity. Similarly, embryonic ethanol exposure failed to elicit alterations in COIII mRNA levels, indicating that the ethanol-induced depression in CO activity was not transcriptionally regulated. However, ventricular mitochondrial DNA concentrations were elevated in ethanol-treated embryos, indicating that ethanol-exposure either directly or indirectly induces mitochondrial DNA replication.

Passive sound localization of prey by the pallid bat (Antrozous p. pallidus)

The pallid bat (Antrozous p. pallidus) uses passive sound localization to capture terrestrial prey. This study of captive pallid bats examined the roles of echolocation and passive sound localization in prey capture, and focused on their spectral requirements for accurate passive sound localization. Crickets were used as prey throughout these studies. All tests were conducted in dim, red light in an effort to preclude the use of vision. Hunting performance did not differ significantly in red light and total darkness, nor did it differ when visual contrast between the terrestrial prey and the substrate was varied, demonstrating that the bats did not use vision to locate prey. Our bats apparently used echolocation for general orientation, but not to locate prey. They did not increase their pulse emission rate prior to prey capture, suggesting that they were not actively scanning prey. Instead, they required prey-generated sounds for localization. The bats attended to the sound of walking crickets for localization, and also attacked small, inanimate objects dragged across the floor. Stationary and/or anesthetized crickets were ignored, as were crickets walking on substrates that greatly attenuated walking sounds. Cricket communication sounds were not used in prey localization; the bats never captured stationary, calling crickets. The accuracy of their passive sound localization was tested with an open-loop passive sound localization task that required them to land upon an anesthetized cricket tossed on the floor. The impact of a cricket produced a single 10-20 ms duration sound, yet with this information, the bats were able to land within 7.6 cm of the cricket from a maximum distance of 4.9 m. This performance suggests a sound localization accuracy of approximately +/- 1 degree in the horizontal and vertical dimensions of auditory space. The lower frequency limit for accurate sound localization was between 3-8 kHz. A physiological survey of frequency representation in the pallid bat inferior colliculus suggests that this lower frequency limit is around 5 kHz.

Repression of the embryonic myosin heavy chain phenotype in regenerating chicken slow muscle is dependent on innervation

Ventricular-like and fast myosin heavy chains (VL-MHC and FMHC) are transiently expressed during slow skeletal muscle development. The influence of innervation on repression of these MHC isoforms is investigated over an 84-day time course in: (1) normal anterior latissimus dorsi (N-ALD) muscles, (2) regenerating ALD (R-ALD) muscles, (3) denervated ALD (D-ALD) muscles, and (4) regenerating and denervated ALD (RD-ALD) muscles. Western blotting demonstrates that the VL-MHC is expressed in R-, D-, and RD-ALD muscles, but not in N-ALD muscles. Expression of the VL-MHC is transient in R-ALD muscles. In contrast, VL-MHC expression persists in RD-ALD muscles, and appears with time in D-ALD muscles. FMHC was not detected in N-ALD muscles by Western blotting. Two FMHCs are seen in R-ALD and RD-ALD muscles, and in 13-day embryonic ALD muscles. The slower migrating FMHC (FMHCA) comigrates with developmentally regulated FMHCs in fast pectoralis muscle, while the faster migrating FMHC (FMHCB) comigrates with the faster migrating FMHC in embryonic ALD muscle (13 days in ovo). FMHCB decreases in amount over the time course in R-ALD muscles, while FMHCA persists. In contrast, substantial levels of both FMHCs persist in RD-ALD muscles, and appear with time in D-ALD muscles. The cellular distribution of MHCs is followed by immunocytochemistry. Regenerating cells expressing VL-MHC and FMHC are replaced by a mature population in R-ALD muscles. Some of the mature myofibers in R-ALD muscles express FMHC, but not VL-MHC. In RD-ALD and D-ALD muscles, both regenerating and mature muscle cells are seen which express VL-MHC and FMHC. Our results indicate that innervation is required for the repression of VL-MHC and FMHCB during regeneration of slow muscle.

Drawing development: from similarity of features to direction

Children often are said to pass through a series of stages in learning to represent 3-dimensional objects, such as cubes, on a 2-dimensional picture surface. Drawings of cubes from 1,734 children and adults were collected. They were classified into 10 drawing types (5 distinguished by Willats, and some additional types, one taken from Caron-Pargue). Over 80% of 5-year-olds produced a single square to represent a cube. Also, over 80% of 14- and 15-year-olds and over 80% of adults produced a parallel-projection drawing. However, there are several routes between these two milestones of drawing development, since no other drawing type captured more than 23% of the drawings at any age between 6 and 13. It is instructive that some children produced drawings that never were made by any of the adults, while some adults produced drawings of cubes that young children did not. We suggest that these differences between children and adults show that the younger children use a similarity geometry with "feature-based" criteria, while the older children and adults use a vantage-point geometry that includes "direction-based" criteria.

Mitochondrial DNA replication and transcription are dissociated during embryonic cardiac hypertrophy

Cardiac hypertrophy was produced in embryonic chicks by decreasing the incubation temperature from 38 degrees C to 32 degrees C on day 11. Increases in ventricular protein, RNA, and DNA support the cardiac enlargement. Cytochrome-c oxidase activity and citrate synthase activity were depressed in hypothermic ventricles by 63% and 56%, respectively. No significant differences were seen in enzyme activities in pectoralis muscles. The involvement of mitochondrial gene replication and transcription was evaluated using a cDNA clone for the mitochondrially encoded subunit III of cytochrome-c oxidase (CO III). Quantitative slot-blot analysis demonstrated that the relative CO III mRNA concentration was reduced in hypothermic ventricles. In contrast, the relative mitochondrial DNA concentration was increased in hypothermic ventricles. Taken together, these data indicate that a hypothermia-induced decrease in cytochrome-c oxidase activity is associated with a decrease in CO III mRNA, which is not coupled to a decrease in the mitochondrial DNA copy number. This dissociation of mitochondrial gene replication and transcription may provide a useful model for examining the regulation of mitochondrial biogenesis.

Myosin expression in hypertrophied fast twitch and slow tonic muscles of normal and dystrophic chickens

Disruption of the development program of myosin gene expression has been reported in chicken muscular dystrophy. In the present report, the relationship between muscular dystrophy and the ability of muscle to respond to an increased work load with a transition in the myosin phenotype has been investigated. Hypertrophy of slow tonic anterior latissimus dorsi (ALD) and fast twitch patagialis (PAT) muscles was induced by overloading for 35 days and myosin expression was analyzed by electrophoresis and immunocytochemistry. Normal and dystrophic chicken ALD muscles have nearly identical proportions of SM-1 and SM-2 isomyosins and both exhibit an age-related repression of the SM-1 isomyosin which is enhanced and accelerated by overloading. Immunocytochemistry with anti-myosin heavy chain (MHC) antibodies demonstrates the appearance of nascent myofibers in overloaded ALD muscles from both normal and dystrophic chickens. A minor fast twitch fiber population is also identified which doubles in number with overloading in normal ALD muscles. There are only half as many fast twitch fibers in control dystrophic ALD muscles and this number does not increase with overloading. In contrast to ALD muscles, the isomyosin profile of normal and dystrophic PAT muscles is quite different. There is significantly more FM-3 and significantly less FM-1 isomyosin in the dystrophic PAT muscle. However, both normal and dystrophic PAT muscles exhibit an overload-induced accumulation of the FM-3 isomyosin. Immunocytochemistry reveals that, unlike the normal PAT muscle, the dystrophic PAT muscle contains a population of myofibers which express slow MHCs. As in the ALD muscle, overload-induced hypertrophy is associated with a repression of the SM-1 MHC in these fibers. Nascent myofiber formation does not occur in either normal or dystrophic overloaded PAT muscles.

Perspective taking, pictures, and the blind

Congenitally blind, late blind, and blindfolded sighted controls attempted a Piagetian perspective-taking (three-mountain) task. Piaget used the term perspective to mean point of view (Piaget & Inhelder, 1967, p. 210), and the present usage does not imply linear perspective. Subjects used raised-line drawings to depict alternative points of view of an array of three geometric solid forms (cube, cone, and ball). They then identified the point of view of raised-line drawings. The effect of visual status on accuracy was nonsignificant for both response measures. Using alternating vision of the array and drawings, sighted subjects in a control condition performed like the congenitally blind. However, congenitally blind individuals did require more time than the other subjects for the perspective-taking task. In an additional experiment, no difference was found between the three groups in the accuracy or speed of tactile shape matching. The results suggest that visual imagery and visual experience are not necessary for tactile perspective taking.

Regulation of 5'-aminolevulinate synthase activity in overloaded skeletal muscle

The regulation of the mitochondrial enzyme 5'-aminolevulinate synthase (ALV synthase) activity during chronic weight-bearing activity (overload) in chicken skeletal muscle was investigated. Maximal enzyme activity was increased 2.5- and 4.0-fold after 3 and 7 days of overload. The content of ALV synthase mRNA (ng/mg total RNA) was not changed after 3 days but increased (20%; P less than 0.05) after 7 days of overload. Normalizing the content of ALV synthase mRNA relative to the increase in total RNA indicated that ALV synthase mRNA increased by 1.6- and 2.0-fold at 3 and 7 days, respectively. On this basis, the increase in enzyme activity per gram protein exceeded the increase in mRNA content per gram protein by 60-70%. During overload, the activity of cytochrome oxidase was unchanged after 3 days but increased by 1.5-fold (P less than 0.05) after 7 days of overload. The data indicate that 1) the initial rise in ALV synthase mRNA and activity due to overload occurs in the absence of a prior change in the level of cytochrome oxidase, an enzyme that requires heme for its assembly, and 2) induction of ALV synthase activity is regulated largely by processes at the translational or posttranslational steps.