Hyperlactaemia without acidosis - an investigation using an in vitro model

OBJECTIVE

To use an in vitro dilutional blood model to simulate aerobic hyperlactaemia, and to question whether base excess and anion gap distinguish aerobic from anaerobic lactate production.

METHODS

Cooled fresh blood was diluted (3:1) with nine different crystalloid solutions, each with a sodium concentration of 140 mmol/L but with strong ion difference values ranging from -5 mEq/L to 40 mEq/L due to varying concentrations of Cl(-), HCO(3)(-) and lactate anions. Normocapnic pH and base excess values post-dilution were determined by gas equilibration. Strong ion difference and anion gap values were measured.

RESULTS

There was close correlation between the normocapnic pH and both the diluent strong ion difference and the final strong ion difference of the diluted specimens (R(2) = 0.96 and 0.89 respectively). This was independent of lactate concentrations in diluent or in post-dilution plasma. Where lactate-containing crystalloid was added, base excess, normocapnic pH and anion gap were strongly correlated with the final plasma lactate concentrations (R(2) >or= 0.99). However, only at final lactate concentrations of approximately 10 - 15 mmol/L did values of base excess, normocapnic pH or anion gap indicate metabolic acidosis.

CONCLUSIONS

Hyperlactaemia from any source reduces strong ion difference and base excess and increases the anion gap, but values may remain in the normal range until hyperlactaemia is severe. Abnormal base excess and anion gap values do not distinguish aerobic from anaerobic lactate production. Normal values merely reflect low sensitivity to small lactate elevations (aerobic or otherwise).

High-resolution mapping and histologic examination of long radiofrequency lesions in canine atria

INTRODUCTION

Catheter ablation may prevent conduction of multiple atrial wavefronts and/or reduce the critical mass of atrial myocardium required to sustain fibrillation. The purpose of this study was to examine the effect of radiofrequency (RF) energy application on conduction in canine atria by performing high-density epicardial mapping and careful histologic examination of the ablation zone.

METHODS AND RESULTS

RF energy was applied to the right atrial endocardium in nine anesthetized mongrel dogs in an attempt to create a line of conduction block spanning the vertical length of a 504-channel epicardial mapping plaque. The mean length and width of the histologically determined ablation zone was 34 +/- 4 and 7.3 +/- 2.6 mm, respectively. No thrombus was present. Conduction block that spanned the mapping plaque in 6 of 9 animals was matched histologically by continuous transmural necrosis in five. In one, only a portion of the ablation zone was transmural; the remainder was wide but nontransmural. In 2 of 3 animals with conduction, a narrow region was present where continuous transmural necrosis was absent. In the other animal, conduction was present despite continuous transmural necrosis.

CONCLUSION

Conduction block usually occurred when continuous transmural necrosis was present, and conduction usually persisted when continuous transmural necrosis was absent. However, important exceptions were observed, including block when the ablation zone was wide but nontransmural, and conduction despite a thin line of continuous transmural necrosis.

Inaccuracies in physicians' perceptions of their patients

OBJECTIVE

The objective was to assess primary care physicians' awareness of their patients' rated emotions, satisfaction, and opinion of the quality of their communication.

DESIGN

Diabetic patients (n = 261) and their primary care physicians (n = 44) each filled in a questionnaire following a routine medical visit. Patients were asked about the quality of communication with their physician, their satisfaction, and their experience of six emotions. Physicians were asked to estimate the patients' views on each of these questions. Physicians' awareness was measured by (1) correlating the physician and patient ratings, and (2) comparing mean ratings between physicians and patients.

RESULTS

Correlations between patients' and physicians' views of patients' emotions and satisfaction were weak to moderate in magnitude; for patients' opinion of communication quality, there was no correlation. All ratings showed a substantial discrepancy between physicians and patients, such that physicians thought patients' responses were more negative than they actually were.

CONCLUSIONS

Although the causes of physicians' weak awareness of their patients' responses are not known, the results suggest that the patients' affective responses may be an especially neglected aspect of communication in the medical visit.

Routine analysis by high precision gas chromatography/mass selective detector/isotope ratio mass spectrometry to 0.1 parts per mil

Stable isotope methods are potentially quite useful for validating natural or enhanced mineral degradation of contaminants. For this reason, a continuous flow gas chromatograph (GC), isotope ratio mass spectrometer (IRMS) has been coupled with a quadrupole mass selective detector (MSD) to allow simultaneous mass spectral and stable carbon isotope ratio data to be obtained from a single chromatographic analysis. This allows the target contaminant and any extra-cellular degradation intermediates to be both qualified and quantified. Previously acceptable limits of precision (0.3 parts per mil) are undesirable given the small fractionation observed during aerobic degradation. To further understand the fate of organic contaminants and to gain information about the metabolic degradative pathway employed by a microorganism, routine isotopic analyses on a range of analytes have been performed. Quantities of sample producing mass-44 ion beam signal (I(44)) of 2 x 10(-10) to 1 x 10(-8) A were analysed. When the IRMS was tuned for high sensitivity, ion source nonlinearities were overcome by peak height correction from an algorithm that was produced using known isotopic standards of varying concentrations. This led to sample accuracy of <0.01 per thousand and sample precision of 0.1 per thousand. Copyright 1999 John Wiley & Sons, Ltd.

Empathy, expectations, and situational preferences: personality influences on the decision to participate in volunteer helping behaviors

Although considerable evidence indicates that dispositional empathy is associated with the degree of help that observers will offer needy targets, little is known about the effect of empathy on one's initial willingness to enter situations in which such needy targets might be found. Three studies were conducted to evaluate two related propositions: (1) that dispositional empathy influences such situational preferences, and (2) that this influence is mediated by the expectancies one holds regarding the emotions likely to occur in those situations. Using hypothetical judgments, Study 1 found support for both propositions. Study 2, in which participants believed that their responses actually committed them to encountering needy targets, provided further support for the model, as did Study 3, which examined the experiences of actual community volunteers. The theoretical and practical implications of these findings are discussed.

Effect of acute gastric dilatation on gastric myoelectic and motor activity in dogs

OBJECTIVE

To investigate the effects of experimentally induced acute gastric dilatation on electrical and mechanical activities of the stomach in dogs.

ANIMALS

7 healthy dogs.

PROCEDURE

Electrodes and strain-gauge force transducers were implanted on the serosal surface of the antrum and pylorus. Eight days later, baseline gastric electrical and contractile activities were recorded. The dogs were anesthetized and mechanically ventilated to maintain normocapnia while the stomach was distended (intragastric pressure, 30 mm Hg) for 180 minutes, using a thin compliant bag. Gastric electrical and contractile activities were recorded again on days 1 and 10 after dilatation. Recordings were analyzed to determine gastric slow-wave frequency, slow-wave dysrhythmia, propagation velocity of slow-waves, coupling of contractions to slow waves, motility index on the basis of relative contractile amplitudes, and onset of contractions after a standardized meal.

RESULTS

Electrical or contractile activities were not significantly different 18 hours after acute gastric dilatation (day 1). Arrhythmias were evident before and after gastric dilatation in dogs from which food was withheld and in dogs after consumption of a meal.

CONCLUSIONS

Variables for assessing gastric electrical and contractile activities were unaffected 18 hours after acute gastric dilatation.

CLINICAL RELEVANCE

Analysis of results of this study indicated that altered electrical and contractile activities in dogs with short-term gastric dilatation are not likely to be secondary to the process of acute gastric dilatation.

Altered substrate selectivity in a mutant of an intrahelical salt bridge in UhpT, the sugar phosphate carrier of Escherichia coli

Site-directed and second site suppressor mutagenesis identify an intrahelical salt bridge in the eleventh transmembrane segment of UhpT, the sugar phosphate carrier of Escherichia coli. Glucose 6-phosphate (G6P) transport by UhpT is inactivated if cysteine replaces either Asp388 or Lys391 but not if both are replaced. This suggests that Asp388 and Lys391 are involved in an intrahelical salt bridge and that neither is required for normal UhpT function. This interpretation is strengthened by the finding that mutations at Lys391 (K391N, K391Q, and K391T) are recovered as revertants of the inactive D388C variant. Further work shows that although the D388C variant is null for G6P transport, movement of 32Pi by homologous Pi/Pi exchange is unaffected. This raises the possibility that this derivative may have latent function, a possibility confirmed by showing that D388C is a gain-of-function mutation in which phosphoenolpyruvate (PEP) is the preferred substrate. Added study of the Pi/Pi exchange shows that in wild type UhpT this partial reaction is readily blocked by G6P but not PEP. By contrast, in the D388C variant, Pi/Pi exchange is unaffected by G6P but is inhibited by both PEP and 3-phosphoglycerate. These latter substrates are used by PgtP, a related Pi-linked antiporter, which lacks the Asp388-Lys391 salt bridge but has instead an uncompensated arginine at position 391. For this reason, we conclude that in both UhpT and PgtP position 391 can serve as a determinant of substrate selectivity by acting as a receptor for the anionic carboxyl brought into the translocation pathway by PEP.

Simultaneous onset of idiopathic dilated cardiomyopathy in identical middle-aged twins

Idiopathic dilated cardiomyopathy is a primary myocardial disease which is characterised by left ventricular, or biventricular, dilatation and impaired contractility. The precise aetiology is unknown and the relative contribution of genetic and environmental factors is debated. We report two identical male twins of Caucasian origin with idiopathic dilated cardiomyopathy who presented within a few months of each other.

Effect of dietary n-6-to-n-3 fatty acid ratio on complete blood and total white blood cell counts, and T-cell subpopulations in aged dogs

OBJECTIVE

To determine effect of diets with variable n-6-to-n-3 fatty acid (FA) ratio on CD4+ and CD8+ T-lymphocyte subpopulations, and on results of routine laboratory analyses (CBC and total WBC count, serum biochemical analyses, and urinalysis).

ANIMALS

20 healthy, aged (9.5 to 11.5 years old) female Beagles.

PROCEDURE

Dogs were fed 1 of 3 diets that contained 6% fat by weight but differed in amounts of n-6 and n-3 FA. For 11 weeks, 6 dogs were fed a low concentration of n-3 FA (ratio, 31:1), 7 were fed a medium concentration (5.4:1), and 7 were fed a high concentration (1.4:1). Preprandial blood and urine samples were collected before beginning the study and at 8 weeks for evaluation of laboratory variables. Before and at 3, 6, and 8 weeks during the study, blood was drawn for total WBC and lymphocyte counts and for characterization of T-cell subpopulations. At 8 and 10 weeks, dogs were vaccinated with keyhole limpet hemocyanin suspension. Blood was drawn 4 days after each vaccination, and lymphocytes were isolated for flow cytometry. Effects of diet and vaccination on each variable were determined.

RESULTS

After vaccination, total lymphocyte count increased and CD4+ T lymphocyte count and the CD4(+)-to-CD8+ ratio decreased in dogs consuming the diet with n-6-to-n-3 FA ratio of 1.4:1.

CONCLUSION

Feeding a diet with n-6-to-n-3 FA ratio of 1.4:1 had significant effects on CD4+ T lymphocytes in healthy, aged Beagles after vaccination.

Diagnosis and treatment of gastric motility disorders

A disorder of gastric motility should be suspected in patients with chronic vomiting. Imaging studies are used to confirm delayed gastric emptying, the most common form of a gastric motility disorder. Other causes of chronic vomiting, for example, metabolic or endocrine disorders, other abdominal disorders, mechanical causes of gastric obstruction, and lower gastrointestinal tract disease, are then ruled out. If no underlying cause is determined, a functional disorder of gastric emptying is presumptively diagnosed. Treatment consists of dietary management and gastric prokinetic agents. Cisapride is the drug of choice for treating delayed gastric emptying followed by erythromycin and ranitidine or nizatidine.

Reversal of severe pulmonary hypertension with beta blockade in a patient with end stage left ventricular failure

A 52 year old man with severe chronic left ventricular failure (New York Heart Association class IV) was considered unsuitable for cardiac transplantation because of high and irreversible pulmonary vascular resistance (PVR). In an attempt to produce symptomatic improvement, metoprolol was cautiously introduced, initially at 6.25 mg twice daily. This was slowly increased to 50 mg twice daily over a two month period and continued thereafter. After four months of treatment the patient's symptoms had improved dramatically. His exercise tolerance had increased and diuretic requirements reduced to frusemide 160 mg/day only. Assessment of right heart pressures was repeated and, other than a drop in resting heart rate, there was little change in his pulmonary artery pressure or PVR. His right heart pressures were reassessed showing a pronounced reduction in pulmonary artery pressure and a significant reduction in PVR, which fell further with inhaled oxygen and sublingual nitrates. He was then accepted onto the active waiting list for cardiac transplantation. A possible mechanism of action was investigated by assessing responses to beta agonists during treatment. Not only was there pronounced improvement in PVR but it was also demonstrated that beta receptor subtype cross-regulation may have contributed to the mechanism of benefit.

Why physician gender matters in shaping the physician-patient relationship

Societal values regarding the nature and consequences of patient autonomy and medical paternalism underscore the current debates surrounding informed consent and shared decision making. The debate is significant in that it both reflects and determines normative expectations for physician and patient conduct as well as the nature and form of the therapeutic relationship. Analysis of the literature describing communication differences between physicians of different genders indicates that female physicians show a greater affinity for collaborative models of patient-physician relationship than do their male colleagues. Female physicians spend more time with their patients, are more likely to engage their patients in discussions of their social and psychologic context, and deal more often with feelings and emotions. Moreover, female physicians facilitate partnership and patient participation in the medical exchange more effectively than do male physicians. The authors propose that the quality of the interactive process is critical to the establishment of a therapeutic relationship and that this process is related to physician gender. They also suggest that physician gender matters in the shaping of the patient-physician relationship through this interactive process.

Postembryonic ontogeny of the spadefoot toad, Scaphiopus intermontanus (Anura: Pelobatidae): skeletal morphology

Postembryonic skeletal ontogeny of the pelobatid frog Scaphiopus intermontanus is described based on a developmental series of cleared-and-stained, whole-mount specimens. The focus is on laboratory-reared individuals fed a herbivorous diet as larvae. Although there is variation in the timing of ossification of individual skeletal elements relative to developmental stages based on external morphological criteia, the sequence of skeletal development generally is conservative. Compared with its close relative, S. bombifrons, ossifications that occur during prometamorphosis tend to be slightly delayed in S. intermontanus; however, cranial bones that ossify during late metamorphic climax in S. intermontanus are delayed until post-metamorphosis in S. bombifrons. The differences in timing between the two species are consistent, however, with differences observed between two developmental series of S. intermontanus raised at two different temperatures. Noteworthy features of skeletal development in S. intermontanus include: 1) presence of palatine ossifications that form from independent centers of ossification and soon fuse with the postnarial portion of the vomers to form the compound vomeropalatine bones; 2) compound sphenethmoid that may arise from four or more endochondral centers of ossification and one dorsal, dermal center of ossification; and 3) presence of transverse processes and vestigal prezygapophyses on the first postsacral vertebra. The morphology of the larval orbitohyoideus and interhyoideus muscles is compared. The record of skeletal ontogeny and muscle morphology presented herein for the herbivorous larval morph can serve as a baseline for comparisons with the ontogeny of the carnivorous larval morph of Scaphiopus.

Medical communication and gender: a summary of research

Communication patterns between physicians and patients during the medical visit reveal behavioral gender differences. Studies suggest varying satisfaction levels depending on physician gender. The communication style of female physicians often includes slightly more focus on the patient's emotional and psychosocial concerns, more positively toned communications, and a more egalitarian style reflected in increased levels of patient participation. However, because patients' satisfaction with female physicians does not typically exceed that for male physicians, other factors may influence satisfaction ratings.

Effectiveness of interventions to improve patient compliance: a meta-analysis

OBJECTIVES

This article summarizes the results of 153 studies published between 1977 and 1994 that evaluated the effectiveness of interventions to improve patient compliance with medical regimens.

METHODS

The compliance interventions were classified by theoretical focus into educational, behavioral, and affective categories within which specific intervention strategies were further distinguished. The compliance indicators broadly represent five classes of compliance-related assessments: (1) health outcomes (eg, blood pressure and hospitalization), (2) direct indicators (eg, urine and blood tracers and weight change), (3) indirect indicators (eg, pill count and refill records), (4) subjective report (eg, patients' or others' reports), and (5) utilization (appointment making and keeping and use of preventive services). An effect size (ES) r, defined as Fisher's Z transformation of the Pearson correlation coefficient, representing the association between each intervention (intervention versus control) and compliance measure was calculated. Both an unweighted and weighted r were calculated because of large sample size variation, and a combined probability across studies was calculated.

RESULTS

The interventions produced significant effects for all the compliance indicators (combined Z values more than 5 and less than 32), with the magnitude of effects ranging from small to large. The largest effects (unweighted) were evident for refill records and pill counts and in blood/urine and weight change studies. Although smaller in magnitude, compliance effects were evident for improved health outcomes and utilization. Chronic disease patients, including those with diabetes and hypertension, as well as cancer patients and those with mental health problems especially benefited from interventions.

CONCLUSIONS

No single strategy or programmatic focus showed any clear advantage compared with another. Comprehensive interventions combining cognitive, behavioral, and affective components were more effective than single-focus interventions.

Open surgical biopsy for nonpalpable mammographic abnormalities: still an option compared with core needle biopsy

OBJECTIVE

Our purpose was to present information about open surgical biopsy. It is hoped that this will be helpful when reviewing information about core needle biopsy

STUDY DESIGN

Review of 461 open surgical biopsies for nonpalpable mammographic abnormalities was performed. All patients were managed by the Women's Health Center of Logansport. Core needle biopsy data came from the literature.

RESULTS

Open surgical biopsy compared favorably to core needle biopsy with regard to accuracy, cost, patient convenience, recovery, adequacy of specimen, identification of primary site, and cosmetics.

CONCLUSION

Despite core needle biopsy marketing, open surgical biopsy has its advantages and should not be relegated to the museum.

Why are sicker patients less satisfied with their medical care? Tests of two explanatory models

Two explanations were tested for why patients who are less healthy tend to be less satisfied with their medical care than healthier patients. The explanations were (a) that poor health produces dissatisfaction directly and (b) that poor health produces dissatisfaction through the mediating effect of physicians' behavior. Two studies are presented that measured patients' health status, patients' satisfaction with care, and their physicians' communication as recorded on audiotape. In Study 1, 114 patients had first visits with rheumatologists; in Study 2, 649 patients had continuing-care visits with physicians in internal and family medicine. Causal modeling revealed that the first study supported the direct explanation. The second study also supported the direct explanation, as well as the mediation explanation with respect to the physician's use of social conversation.

The predictive value of the zona-free hamster egg penetration test in relation to in-vitro fertilization at various insemination concentrations

The aim of the study was to evaluate the predictive value of the zona-free hamster egg penetration test (ZHEPT) for success in in-vitro fertilization (IVF) at various insemination concentrations ranging between 0.1 and >0.6 x 10(6)/ml. The ZHEPT was assessed using sperm samples from 87 couples undergoing IVF treatment. A similar test was simultaneously performed on the same semen sample following ionophore induction of the acrosome reaction (ZHEPTii test). Both the tests were poorly correlated with the fertilization rate of IVF at all the insemination concentrations except at >0.6 x 10(6)/ml, when there was good correlation between the ZHEPTii test and the fertilization rate. Following exclusion of two cases with an oocyte problem, further statistical analysis revealed that both the ZHEPT and ZHEPTii tests were poorly correlated with fertilization rate in IVF in this treatment group. This study suggests that the ZHEPT (with and without ionophore induction of the acrosome reaction) has a poor predictive value for the success of fertilization in IVF treatment at any insemination concentration.

Why are sicker patients less satisfied with their medical care? Tests of two explanatory models

Two explanations were tested for why patients who are less healthy tend to be less satisfied with their medical care than healthier patients. The explanations were (a) that poor health produces dissatisfaction directly and (b) that poor health produces dissatisfaction through the mediating effect of physicians' behavior. Two studies are presented that measured patients' health status, patients' satisfaction with care, and their physicians' communication as recorded on audiotape. In Study 1, 114 patients had first visits with rheumatologists; in Study 2, 649 patients had continuing-care visits with physicians in internal and family medicine. Causal modeling revealed that the first study supported the direct explanation. The second study also supported the direct explanation, as well as the mediation explanation with respect to the physician's use of social conversation.

Patient gender and communication with physicians: results of a community-based study

An observational study of 648 routine medical visits with 69 physicians examined patient gender in relation to patient and physician communication, patient preference for the physician's communication style, patient satisfaction, and the physician's awareness of the patient's satisfaction. Data consisted of audiotapes as well as patient and physician questionnaires. Women appeared to be more actively engaged in the talk of medical visits--they sent and received more emotionally charged talk and were judged by independent raters as more anxious and interested both globally and in terms of voice quality than men. Consistent with the more emotional talk, women reported preferring a more "feeling-oriented" physician than male patients did. Mean levels of satisfaction with communication did not differ by gender, and communication predictors of satisfaction were similar for male and female patients, although they were stronger for male patients. Physicians were significantly less aware of some aspects of female patients' satisfaction compared to male patients' satisfaction. In light of the weaker correlations between patients' communication and their satisfaction for women, we suggest that women provided fewer obvious cues to their satisfaction. Training in communication skills may increase open discussion about feelings and emotions and may also produce greater physician sensitivity to patients' satisfaction, particularly with female patients.

Increased polymorphonuclear granulocytes in seminal plasma in relation to sperm morphology

Much controversy surrounds the clinical significance of an increased concentration of white blood cells (WBC) in the male ejaculate. The World Health Organization's classification of leukocytospermia is a concentration > 1 x 10(6) WBC/ml. The aim of this study was to assess the association of varying concentrations of leukocytes to sperm morphology evaluated by strict criteria. Semen samples were collected from a total of 79 patients. Round cells on the initial semen analysis were stained for identification of polymorphonuclear granulocytes (PMN) as the largest group (50-60%) of white blood cells using the Endtz Method commercially produced as Leucoscreen. Diff Quick Staining Kit was used for sperm morphology assessment and 200 spermatozoa were assessed per slide. Data were evaluated using two cut-off criteria, at 0.5 x 10(6) WBC/ml and 1 x 10(6) WBC/ml. Mann-Whitney U-values at both < and > 0.5 x 10(6)/ml PMN (P < 0.001) and at < and > 1.0 x 10(6)/ml PMN (P < 0.015) showed differences between percentage normal forms. Spearman's rank correlation coefficient for PMN concentration showed a negative correlation (P < 0.01) with percentage normal sperm morphology and positive correlation for midpiece abnormalities (P < 0.04). These data support the hypothesis that PMN have a role in the increase of abnormal spermatozoa, particularly those with midpiece abnormalities, by as yet unknown mechanisms.

Two modes of ligand binding in maltose-binding protein of Escherichia coli. Correlation with the structure of ligands and the structure of binding protein

Ligands that are transported by the maltose transport system of Escherichia coli must first bind to the periplasmic maltose-binding protein (MBP). However, binding of a ligand does not always lead to its transport. As reported earlier, reduced or oxidized maltodextrins bind tightly to MBP but are not transported; some mutant MBPs, such as MalE254, bind maltodextrins tightly but cannot produce their transport. In this study, UV differential spectroscopy and fluorescence emission spectroscopy were used to study the modes by which various ligands bind to MBP. Maltose binding produced a red shift in the fluorescence emission spectrum of wild type MBP and a sharp hypochromatic trend below 265 nm in its UV spectrum (R mode (for red)). On the other hand, binding of reduced, oxidized, or cyclic maltodextrins produced a pronounced blue shift in the fluorescence emission spectrum of wild type MBP and a peak at about 250 nm in its UV difference spectrum (B mode (for blue). Binding of reducing maltodextrins to wild type MBP produced spectral changes that seemed to be a mixture of predominantly R mode binding and some B mode binding, whereas their binding to mutant MBP MalE254 produced changes indicative of pure B mode binding. Thus, the ligands that are bound exclusively via the B mode to either the wild type or MalE254 MBP are not transported.