Role of CMV-serostatus and CX3CR1 on lymphocyte kinetics and left ventricular remodelling in patients with acute myocardial infarction

Background

Patients with latent cytomegalovirus (CMV) infection have higher rates of adverse cardiovascular outcomes, but the reasons for this remain elusive. CMV-induced changes to T-lymphocyte populations, with a proliferation of CMV-specific, CX3CR1+ effector memory cells, may contribute. Effector T-cells are associated with cardiovascular mortality in CMV positive patients, and ischaemia-reperfusion injury after ST-elevation myocardial infarction (STEMI) and primary percutaneous coronary intervention (pPCI).

Purpose

To investigate the effect of CMV status on lymphocyte kinetics and cardiac MRI (cMRI) parameters in 52 STEMI patients receiving pPCI, and examine the prognostic relevance of pre-reperfusion lymphocyte count in a large cohort.

Methods

We retrospectively analysed the association between pre-reperfusion lymphocyte count, troponin, and long-term survival in 4874 consecutive STEMI patients. Using flow cytometry, we analysed lymphocyte kinetics in 52 STEMI patients, of known CMV status, during and after pPCI. We assessed the impact of CMV status on infarct size, left-ventricular (LV) function and microvascular obstruction with cMRI in the first week after reperfusion in 101 patients. Repeat cMRI at 12 weeks, to assess LV remodelling, was obtained in 48 patients.

Results

Pre-reperfusion lymphopenia is an independent predictor of mortality over 7.5 years (hazard ratio for lowest vs highest quartile: 2.0; 95% CI 1.7–2.4; p<0.001), and is associated with higher admission troponins (p<0.001 for lowest vs second-lowest quartile), suggesting lymphocyte count falls prior to reperfusion in response to myocardial injury. CMV positive patients had more cytotoxic T-cells, strongly expressing the fractalkine receptor, CX3CR1. In CMV positive patients these cells fell dramatically by 90 minutes post-reperfusion, and dropped more sharply in patients with extensive microvascular obstruction on cMRI (p≤0.05 in all effector subsets). CX3CR1 expression was lower at 90 minutes post-reperfusion than at 24 hours (return to physiological expression) in all effector T-cell subsets. All subsets lost a similar proportion of their 24-hour value, but consistently lost a larger proportion in CMV positive patients (−27% in CMV+, −18% in CMV−; p=0.007). CX3CR1 expression falls in the presence of fractalkine, and we hypothesise that membrane-bound fractalkine is induced more strongly in CMV positive patients, as soluble fractalkine levels were similar. At 12 weeks, LV remodeling was worse in CMV positive patients (change in end-diastolic volume: +10.7ml vs −6.1ml; p=0.02).

Conclusions

Lymphopenia occurs prior to reperfusion in STEMI, and predicts long-term mortality. Effector T-cells drop substantially after reperfusion only in CMV positive patients, likely mediated by CX3CR1-fractalkine interaction, and this is associated with adverse cMRI findings. Remodeling is worse in CMV positive patients at 12 weeks post-STEMI.

Lymphocytes, troponin and survival

Funding Acknowledgement

Type of funding source: Public Institution(s)

5234KAND567, the first selective small molecule CX3CR1 antagonist in clinical development, mediates anti-inflammatory cardioprotective effects in rodent models of atherosclerosis and myocardial infarction

Background

Fractalkine is a chemokine that mediates recruitment and extravasation of CX3CR1-expressing subsets of leukocytes and monocytes and has been implicated in the inflammation-driven pathology of cardiovascular disease. More specifically, fractalkine signaling has been proposed to contribute to increased infarct size and enhanced atherosclerotic plaque vulnerability in patients and experimental models. Blocking fractalkine/CX3CR1 signaling is suggested as a promising anti-inflammatory strategy for the treatment of both acute and chronic cardiovascular disease. KAND567 is a small molecule, selective, non-competitive, allosteric antagonist of the fractalkine receptor CX3CR1, that is under preparation for a clinical phase IIa study in AMI patients.

Purpose

To explore the therapeutic effects of the short and long term administration of KAND567 in experimental rodent models of acute myocardial infarction and atherosclerosis, respectively.

Methods

Myocardial infarction was induced in Wistar rats (N=6–8 per group) by ligation of the left anterior descending (LAD) coronary artery for 30 minutes followed by 2 h of reperfusion. The drug or vehicle infusion started either 5 min before or 30 min after start of reperfusion and continued during the remainder of the experiment. Hearts were collected and subjected to triphenyl tetrazolium chlorine (TTC) staining and the infarction area/area at risk of the left ventricle was determined by planimetry and compared against vehicle group.

Atherosclerosis-prone LDL-receptor deficient mice on a high-cholesterol diet, (N=15–25 per group) were treated with KAND567 for 15–23 weeks. Atherosclerotic plaque development in the thoracic arch was determined by ultrasound imaging and histology. Immunohistochemistry was used to follow changes in the cellular composition in the atherosclerotic lesions.

Results

In the acute myocardial infarction study, the infusion of KAND567 before the start of reperfusion significantly reduced infarcted/risk area (by up to 50%) as compared to the vehicle group. However, the infusion had no effect on the infarct size when administration was initiated 30 min after start of reperfusion.

In the atherogenesis study, oral treatment with KAND567 significantly reduced vascular macrophage infiltration by 50% and reduced intima media thickness. Furthermore, reduced plaque volume and a more stable plaque phenotype was noted following treatment with KAND567.

KAND567 experimental results

Conclusion

Specific inhibition of fractalkine-driven inflammation by KAND567 provides cardioprotective, anti-atherosclerotic and plaque stabilizing effects via mechanisms related to immune cell infiltration, in rodent models. Further studies should be initiated to test if KAND567 is a potential candidate drug, targeting the excessive inflammatory injury associated with ischemia/reperfusion in myocardial infarction and providing plaque stabilization by reducing inflammatory risk for recurrent coronary events.

Effectiveness of Psychoeducational Interventions for Improving Symptoms, Health-Related Quality of Life, and Psychological well Being in Patients with Stable Angina

Several primary trials report the adjunctive value of psychoeducational interventions for improving stable angina symptoms, health-related quality of life (HRQL) and psychological well-being; however, few high-quality meta-analyses have examined the overall effectiveness of these interventions. We used meta-analysis in order to determine the effectiveness of psychoeducational interventions for improving symptoms, HRQL and psychological well-being in stable angina patients. Seven trials, involving 949 participants total were included. Those who received psychoeducation experienced nearly 3 less angina episodes per week, delta (Delta)= -2.85, 95% CI, -4.04 to -1.66, and used sublingual (SL) nitrates approximately 4 times less per week, Delta= -3.69, 95% CI -5.50 to -1.89, post-intervention (3-6 months). Significant HRQL improvements (Seattle Angina Questionnaire) were also found for physical limitation, Delta= 8.00, 95% CI 4.23 to 11.77, and disease perception, Delta= 4.46, 95% CI 0.15 to 8.77, but CIs were broad. A pooled estimate of effect on psychological well-being was not possible due to heterogeneity of measures. Psychoeducational interventions may significantly reduce angina frequency and decrease SL nitrate use in the short-term. These encouraging results must be interpreted with caution due to heterogeneity in methods and small samples. Larger, robust trials are needed to further determine the effectiveness of psychoeducation for stable angina management.

Rationale and design of ACTIVE: the atrial fibrillation clopidogrel trial with irbesartan for prevention of vascular events

BACKGROUND

Atrial fibrillation (AF) is the most frequently occurring cardiac arrhythmia with often serious clinical consequences. Many patients have contraindications to anticoagulation, and it is often underused in clinical practice. The addition of clopidogrel to aspirin (ASA) has been shown to reduce vascular events in a number of high-risk populations. Irbesartan is an angiotensin receptor-blocking agent that reduces blood pressure and has other vascular protective effects.

METHODS AND RESULTS

ACTIVE W is a noninferiority trial of clopidogrel plus ASA versus oral anticoagulation in patients with AF and at least 1 risk factor for stroke. ACTIVE A is a double-blind, placebo-controlled trial of clopidogrel in patients with AF and with at least 1 risk factor for stroke who receive ASA because they have a contraindication for oral anticoagulation or because they are unwilling to take an oral anticoagulant. ACTIVE I is a partial factorial, double-blind, placebo-controlled trial of irbesartan in patients participating in ACTIVE A or ACTIVE W. The primary outcomes of these studies are composites of vascular events. A total of 14000 patients will be enrolled in these trials.

CONCLUSIONS

ACTIVE is the largest trial yet conducted in AF. Its results will lead to a new understanding of the role of combined antiplatelet therapy and the role of blood pressure lowering with an angiotensin II receptor blocker in patients with AF.

Complementary therapy involvement of physicians: implications for practice and learning

OBJECTIVE

We studied physicians' current and desired clinical role functions within the complementary health paradigm and their perceptions of the necessary educational programs to support them.

DESIGN AND SETTING

A questionnaire to determine clinical activities within different complementary therapies was developed and mailed-out to 837 eligible physicians in Hamilton, Ontario, Canada, using a modified Dillman approach.

RESULTS

The overall response rate to the mailed survey was 49.8% (417/837), with response rates of 50.2% (115/229) for family physicians and 49.7% (302/608) for specialists. The amount of interactions around complementary therapies between physicians, their patients and complementary therapists appears to be low. At the same time, there is a growing interest among physicians about complementary therapies, particularly with respect to developing their knowledge about efficacy and enhancing their skills in assessment and counselling.

CONCLUSIONS

The differential levels of acceptance of different therapies by physicians will influence integration of complementary therapies in mainstream medicine.

The influence of Type A behavior pattern on the response to the panicogenic agent CCK-4

OBJECTIVES

Review of the literature equivocally suggests that subjects with Type A behavioral pattern (TABP) compared to subjects with Type B behavioral pattern display an increased sympathetic activity, a condition associated with sudden cardiac death. The objective of this study was to determine whether healthy subjects classified as Type A or Type B differed in their reactivity to the beta 1 and beta 2 receptor agonist isoproterenol and to the panicogenic agent cholecystokinin-tetrapeptide (CCK-4). By comparing reactivity to CCK-4 after pretreatment with placebo or propranolol, a beta 1 and beta 2 receptor antagonist, the role of the beta adrenergic system in the hypothesized increased response of Type A subjects to CCK-4 was also assessed.

METHODS

The study used a randomized, double-blind, placebo-controlled design. Twenty-seven Type A or B subjects were included in the study. The reactivity to isoproterenol was assessed with the CD25 of isoproterenol (i.e., the intravenous dose of isoproterenol necessary to increase the heart rate of 25 bpm). The panic symptom response and the cardiovascular response to bolus injection of 50 microg of CCK-4 was assessed in subjects pretreated with either propranolol or placebo infusions prior to the CCK-4 challenge. An additional group of subjects was recruited and these subjects received a placebo infusion pretreatment before an injection of placebo.

RESULTS

The CD25 was significantly greater in Type A subjects than in Type B subjects. No difference was found among the groups on behavioral sensitivity to the CCK-4 challenge. However, CCK-4-induced maximum increase in heart rate was greater in Type A subjects.

CONCLUSION

Our finding that Type A subjects exhibited greater CD25 of isoproterenol and greater increases in heart rate following CCK-4 administration compared to Type B subjects suggests that peripheral beta-receptor sensitivity may be increased in individuals with TABP.

Plasma esterase (ES) polymorphism in the tammar wallaby, Macropus eugenii

The major plasma esterase in the tammar wallaby was identified as a carboxylesterase by inhibition studies and polymorphism with six variants was observed by isoelectric focusing (pH 4.2-4.9), followed by staining for esterase activity. Family studies demonstrated an inheritance of six codominant alleles, ESA,B,C,D,E,F, and population studies revealed marked differences in the allele frequencies in five Australian populations of tammar wallabies.

Women and heart attack: a study of women's experiences

Cardiovascular disease in general, and myocardial infarction (MI) in particular, is the major health problem of females after 50 years of age. To date, heart disease research has focused primarily on males. The limited evidence suggests that the physical, psychological, and social ramifications of MI for women are significant, and different from those of men. Since the specific rehabilitation needs of women are not yet clear, this study was designed to explore the unique experiences and needs of women following a first MI. A phenomenological study using focus groups was used to explore the experiences, questions, concerns, and preferred interventions of women after a MI. Participants were female volunteers (n = 14) who had been hospitalized for a MI within the previous 6 months. Focus groups were audio taped and analysed by the investigators. Four major themes emerged: validation; perceived gender differences; role expectations/role tensions; and helps and hindrances to recovery.

Plasma protein polymorphisms in the tammar wallaby, Macropus eugenii

Five populations of the Australian tammar wallaby, Macropus eugenii, from Kangaroo Island, South Australia, and Garden, Abrolhos and Middle Islands and Perup, Western Australia, were examined for plasma protein polymorphisms. Select Kangaroo/Garden Island hybrids and backcross progeny were also included in the study. Vitamin D binding protein (GC), albumin (ALB), transferrin (TF), protease inhibitor (PI), haemopexin (HX), haptoglobin (HP) and immunoglobulin G (IgG) were identified by polyacrylamide gel electrophoresis, pH 7.9, isoelectric focusing, pH 4.2–4.9, and immunoblotting with rabbit antisera to human proteins. Five GC (A, B, C, D, E), two ALB (A, B), two TF (A, B) and five PI (I, J, L, M, P) variants were detected, and limited family studies demonstrated a codominant allelic inheritance for each of the systems.

Genetic polymorphism of cat (Felis catus) plasma orosomucoid

Genetic polymorphism of orosomucoid (ORM) was observed in 22 breeds of cats (Felis catus) using isoelectric focusing (pH 4.0-6.5) of desialylated plasmas followed by immunoblotting with rabbit antiserum to human ORM. From a total of 943 plasma samples examined, 15 phenotypes were identified and family studies demonstrated an inheritance of five codominant alleles, ORMA, ORMB, ORMC, ORMD, and ORME, at a single locus.

Further evidence for an association between a mutation in the APP gene and Lewy body formation

There have been two detailed neuropathological reports of families with a valine to isoleucine substitution at position 717 of the amyloid precursor protein gene. Surprisingly, in one of these families substantial Lewy body formation occurred in addition to Alzheimer's disease, prompting the speculation that such a genetic mutation may predispose to both Lewy body and plaque formation. This report describes the neuropathology of an additional family with the same genetic mutation. Of two affected members who have come to autopsy, one had brainstem Lewy bodies. Some of these Lewy bodies had peripheral halos immunoreactive for beta-amyloid. These findings suggest a greater than chance link between genetic mutations for Alzheimer's disease and Lewy body formation.

Plasma protease inhibitor (PI) system in the laboratory opossum, Monodelphis domestica

Protease inhibitor (PI) polymorphism was observed in the laboratory opossum, Monodelphis domestica, by either one-dimensional acid polyacrylamide gel electrophoresis (PAGE; pH 4.6) or isoelectric focusing (pH 3.5-5.0) followed by immunoblotting with rabbit antiserum to human alpha 1-antitrypsin; but acid PAGE produced superior resolution of the PI proteins. Family studies demonstrated an inheritance of nine codominant autosomal alleles, PID, PIE, PIF, PIG, PIH, PII, PIJ, PIK, and PIM, and a population study revealed frequencies of 0.411, 0.010, 0.341, 0.034, 0.023, 0.071, 0.035, 0.020, and 0.055, respectively.

Nursing curriculum content: an innovative decision-making process to define priorities

Curriculum planning in the health sciences is becoming increasingly complex due to rapid societal change and scientific discovery. The half-life of most curricula is 5 years, which necessitates a periodic close examination and revision of both content and process. For nursing faculty, this exercise is often viewed as an arduous one and traditionally can lead to endless hours of circular debate. Planning is usually in two stages; the first stage being the development of or agreement about a theoretical framework and the second stage is deciding on core content and teaching methodologies. This article focuses on decisions in the second stage. Traditionally, decisions around curriculum are arrived at by much debate. Some argue that all health issues should be addressed in the curriculum in order that the graduate be prepared to deal with a breadth of issues. However, this approach often leads to what has been referred to as 'curriculum hypertrophy', where, in an attempt to be all-inclusive, the curriculum grows without bounds. Rarely is anything dropped from the curriculum when this approach is used. Sometimes priorities are established on the basis of what the individual teaching staff deems important. In other cases a consensus approach is chosen.

An analysis of the impact of a management system on patients waiting for cardiac surgery

The Cardiac Surgery Management System (CSMS) was developed in the Central West region of Ontario to support patients who are waiting for cardiac surgery. This management system provides a consistent mechanism to communicate preoperative information to patients and their families. A questionnaire was developed to analyze the impact of the CSMS on patients waiting for elective surgery in this health region. This descriptive study assesses the patients' perception of the assistance they received preoperatively, through the nurse coordinator. One hundred and fifty study patients were randomly selected from patients who had undergone elective surgery during the previous calendar year and these subjects received questionnaires. The final response rate was 81%. Ninety-three percent of respondents had telephone contact with the coordinator, and 89% of these patients received information/education by mail. Sixty percent of respondents admitted to some degree of anxiety, and 46% of these patients discussed their feelings with the coordinator. Increased levels of anxiety were associated with an increased likelihood of a patient-initiated contact with the coordinator. This contact was associated with decreased levels of anxiety. Patients waiting for surgery demonstrated preoperative anxiety, and opportunities to discuss this should be provided. Patients also feel they benefit from receiving educational material preoperatively. The use of the nurse in an expanded role needs to be maximized, with focus on the nurse as a facilitator for problem solving.

Mutations in the equine plasma transferrin and esterase systems

Eleven apparent mutations of the equine plasma transferrin and esterase gene (10 in TF and one in ES) were found in an analysis of approximately 240,000 thoroughbred horses. Eight of the transferrin mutations produced variants not previously recognized in horses. In the two remaining transferrin mutations and the esterase mutation, reduced plasma concentrations of the proteins were demonstrated by immunological techniques and together with the family data indicated the existence of 'null' alleles.

Student self-evaluations: how useful? How valid?

Skill in self-evaluation is necessary for life-long learning, for competent performances--in short, for professional practice in the health sciences. In addition, self-evaluation skills can be learned and can be taught, although they are not now purposefully taught in most programs. There is research evidence that self-evaluation is more useful for learners as a formative rather than a summative tool. The purposes of this paper are (a) to provide a critical review of the literature on the accuracy of student self-evaluation and (b) to describe our experience and preliminary research findings at McMaster University regarding the most profitable approach to incorporating self-evaluation in baccalaureate nursing education.

Polymorphic drug metabolism in schizophrenic patients with tardive dyskinesia

The metabolism of many neuroleptics cosegregates catalyzed by the polymorphic cytochrome P450 CYP2D6. The population can be phenotyped into extensive metabolizers (EM) and poor metabolizers (PM) with respect to this enzyme's activity. PM are likely to achieve higher than average concentrations of neuroleptic drugs in plasma, with an increased risk of extrapyramidal side effects, possibly including tardive dyskinesia. Sixteen white schizophrenic patients who had developed tardive dyskinesia during long-term neuroleptic treatment were phenotyped with debrisoquine and genotyped by CYP2D6-specific DNA amplification and EcoRI restriction fragment length polymorphism analysis. Only 1 (6%) of the 16 patients had a PM genotype, 8 (50%) were homozygous, and 7 (44%) were heterozygous EM. None had a CYP2D6 genotype indicative of ultrarapid debrisoquine hydroxylation capacity. The patients were also phenotyped with mephenytoin, a probe drug for another polymorphic cytochrome P450, CYP2C19. One patient was a PM of S-mephenytoin, which corresponds to the frequency found in healthy white volunteers. In conclusion, there was no overrepresentation of PM of debrisoquine or of S-mephenytoin among the 16 patients with neuroleptic-induced tardive dyskinesia. However, the PM of debrisoquine had the highest score on the Simpson-Angus Rating Scale and the second highest on the Abnormal Involuntary Movement Scale, despite a very low neuroleptic dose. Also, the debrisoquine MR correlated significantly with the SARS score (rs = 0.685, p < 0.05, N = 10), indicating a relationship between the degree of impaired CYP2D5 activity and the severity of extrapyramidal side effects during neuroleptic treatment.

Antithrombin III (AT3) polymorphism in the marsupial Monodelphis domestica: identification and genetics

Antithrombin III polymorphism was observed in the gray short-tailed opossum, Monodelphis domestica, by either one-dimensional polyacrylamide gel electrophoresis (PAGE; pH 7.9), two-dimensional PAGE (agarose, pH 5.4; 12% T, pH 7.9), or isoelectric focusing (pH 4.2-4.9) followed by immunoblotting with rabbit antiserum to human antithrombin III. Family studies demonstrated an inheritance of three codominant autosomal alleles, AT3A, AT3B, and AT3C, and a population study revealed frequencies of 0.70, 0.10, and 0.20, respectively.

Potential oxyradical damage and energy status in individual muscle fibres from degenerating muscle diseases

Inherited degenerating muscle diseases result in disintegration of muscle fibres, which is initiated by a lack of or alteration to a muscle protein. In Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) the protein is known to be dystrophin. The cellular function of dystrophin is not known in any detail but its absence appears to lead to a weakening of the sarcolemma. It has been proposed by Murphy and Kehrer that this leads ultimately to increased oxyradical production which may accelerate the degeneration. Studies have been carried out on individual muscle fibres derived from biopsy samples from patients with a number of degenerative muscle diseases. The glutathione cycling components, in particular glutathione and glutathione peroxidase, are significantly elevated in DMD, BMD and other diseases. Glutathione reductase is also elevated in some of these diseases. Energy producing systems are also affected particularly in intact fibres of muscle derived from muscle at an advanced stage of the disease. These results suggest that oxyradical damage may occur as a secondary consequence of muscle degenerating disease, leading to a breakdown in the glycogenolytic energy producing system.

A double-blind comparative multicentre study of remoxipride and haloperidol in schizophrenia

In a double-blind multicentre study of parallel group design the efficacy and safety of remoxipride and haloperidol were compared in a total of 96 patients with acute episodes of schizophrenic or schizophreniform disorder according to DSM-III. There were 48 patients in each treatment group; 27 men and 21 women in the remoxipride group, 33 men and 15 women in the haloperidol group. The median duration of illness was 7 years in both groups. The mean daily dose was 437 mg for remoxipride and 10.6 mg for haloperidol during the last week of treatment. No statistically significant differences in total BPRS scores were found between remoxipride and haloperidol. The median total BPRS scores at the start of active treatment were 26 in the remoxipride and 27 in the haloperidol group; these were reduced to 16 and 12.5, respectively, at the last rating. According to Clinical Global Impression (CGI), 43% of patients in the remoxipride group and 68% of those in the haloperidol group improved much or very much during treatment. This difference was not statistically significant. Treatment-emergent extrapyramidal side effects such as akathisia, tremor, and rigidity occurred significantly more frequently in the haloperidol group; this group also made more frequent use of anticholinergic drugs. Neither of the trial drugs seriously affected laboratory or cardiovascular variables. It is concluded that remoxipride has an antipsychotic effect in a dose range of 150-600 mg per day comparable to that of haloperidol in doses up to 20 mg per day but with fewer extrapyramidal side effects.

Micromethods in single muscle fibers. 2. Determination of glutathione reductase and glutathione peroxidase

This paper extends the previous study for systems which control intracellular oxidative events in muscle and describes procedures suitable to assay glutathione peroxidase (GSHPx), glutathione reductase (GR), and total glutathione (GSH + GSSG) after fiber typing of individual muscle fibers. In human skeletal muscle, both GR and GSHPx activities were relatively low when compared to those of other tissue. No difference was found among fiber types (I, IIA, and IIB) with regard to GR activity, but in contrast GSHPx activity was significantly lower in type IIB fibers than in the other types. These results suggest that type IIB fibers may have a reduced ability to cope with hydroperoxides generated during oxidative stress, which, in turn, could lead to increased damage to membrane structures by lipid peroxidation or oxidation of sensitive intracellular thiol (-SH) enzymes by hydrogen peroxide. The Km of skeletal muscle GR for GSSG was 27 microM and for NADPH was 22 microM. If one assumes approximately 95% of total glutathione is present in the reduced state, then GSSG concentration would be of the order of 0.3 mmol/kg and under these conditions skeletal muscle GR would be efficient in all muscle fiber types.

Micromethods in single muscle fibers. 1. Determination of catalase and superoxide dismutase

Methods have been developed for the measurements of catalase and superoxide dismutase (SOD) in single, isolated muscle fibers. These fibers are also classified according to fiber type. Catalase is determined using a fluorescent method for the measurement of hydrogen peroxide consumed. SOD measurements are carried out using a modification of established techniques whereby the inhibition of oxidation of epinephrine by SOD is assayed fluorometrically. Both enzymes may be determined in submicrogram samples of dried muscle. This approach avoids the complication of the inclusion of nonmuscle tissue with varying enzymatic activities which is frequently experienced when using homogenates of muscle, particularly diseased muscle. In addition, these techniques can be used to determine the inherent variation in SOD and catalase activities within individual fibers of the same fiber type. The Km and Vmax for catalase, determined using homogenates of human muscle, were found to be 12 mM and 1.45 mumol/min/mg dry wt, respectively. Catalase of muscle was inhibited 50% by 2 microM sodium azide. Mn-SOD contributes less than one-fifth of the total SOD activity. Therefore the activity is largely due to the Cu-Zn form of SOD. These methods are applicable to a wide variety of tissues.

Plasma lipoproteins in Duchenne muscular dystrophy

Plasma lipoproteins of Duchenne muscular dystrophy patients and carriers of the disease, together with age- and sex-matched controls, were examined by density gradient ultracentrifugation and agarose gel electrophoresis. Analysis of density gradient profiles revealed a significant reduction in absorbance (435 nm) by low density and high density lipoproteins from Duchenne patients when compared with controls. Although no abnormalities were observed on electrophoresis of whole plasma samples, the isolated low density lipoprotein fractions from Duchenne patients and carriers displayed increased electrophoretic mobility compared with controls. The results obtained implicate the plasma lipoproteins, in particular the low density lipoproteins, as the primary site of the lesion in this disease.

Thermodynamic behaviour of membrane enzymes in Duchenne muscular dystrophy

Erythrocyte ghost preparations have been prepared from blood of Duchenne patients (DMD), female carriers of the disease and controls. Arrhenius plots of Na+, K+-ATPase activity of these membrane preparations show a biphasic response for controls. For 75% of DMD and carriers the response is monophasic. This is not an inherent property of the membrane since it can vary over time in the one individual and it can be induced in normal membranes by preincubation with DMD plasma. Arrhenius plots of AChE activity showed no such difference between the three sources of blood.

Biochemical correlations among the thermophilic enteric yeasts Torulopsis bovina, Torulopsis pintolopesii, Saccharomyces telluris, and Candida slooffii

Spontaneous and drug-induced respiration-deficient mutants were isolated from the thermophilic enteric yeasts Torulopsis bovina and Saccharomyces telluris. The biochemical properties of these yeasts were compared with those of the two naturally occurring respiration-deficient thermophilic yeasts T. pintolopesii and Candida slooffii. Succinate dehydrogenase was not detected in mitochondrial fractions from C. slooffii, but was present in all other species. Cytochrome c oxidase, succinate oxidase, and reduced nicotinamide adenine dinucleotide oxidase were not detected in C. slooffii, T. pintolopesii, and the respiration-deficient mutants. Low-temperature cytochrome spectra revealed the presence of cytochromes aa3, b, c1, and c in T. bovina and S. telluris; cytochromes b, c1, and c in C. slooffii and T. pintolopesii; and cytochromes c1 and c in the spontaneous respiration-deficient mutants. Palmitoleic and oleic acids were the major fatty acids in all the species. It was noteworthy that T. pintolopesii was rich in lauric and myristic acids. CsCl equilibrium centrifugation experiments showed the presence in all the yeasts of a light-buoyant-density (1.6785 to 1.6837-g/cm3) deoxyribonucleic acid band which was identified as mitochondrial deoxyribonucleic acid by its selective elimination on treatment of cells with ethidium bromide. The latter result indicated that the spontaneous respiration-deficient mutants were similar to cytoplasmic petite mutants of S. cerevisiae. Although classical assimilation and fermentation tests indicated that the spontaneous respiration-deficient mutants were strains of T. pintolopesii, it was concluded, on the basis of marked physiological and biochemical differences, that this was not the case.

Thermal adaptation in yeast: obligate psychrophiles are obligate aerobes, and obligate thermophiles are facultative anaerobes

The obligate psychrophilic yeasts Torulopsis psychrophila, T. austromarina, Leucosporidium frigidum, L. gelidum, and L. nivalis were obligate aerobes and were unable to grow anaerobically. In contrast, the obligate thermophilic yeasts T. bovina, T. pintolopesii, Candida slooffii, and Saccharomyces telluris were facultative anaerobes.

Cell surface topography of Candida and Leucosporidium yeasts as revealed by scanning electron microscopy

The cell surface topography of the following yeast strains was examined by scanning electron microscopy: Candida slooffii, C. lipolytica, Leucosporidium frigidum, and L. nivalis. Multipolar and lateral budding were observed in the Candida yeasts in contrast to bipolar budding in the Leucosporidium species. The cell surface topography and the morphology of the bud and birth scars in these yeasts differed markedly. Apart from the bud and birth scars, the cells of C. slooffii showed a relatively smooth topography. The bud scars were seen as a circular ridge of wall material surrounding a markedly convex scar plug. Birth scars were raised, rounded structures, which appeared to distend upon cell growth. In contrast, bud scars of C. lipolytica were platelike, lacked a distinct annulus of wall material, and were much less protuberent than those of C. slooffii. Birth scars were a more permanent feature of these cells. The topography of Leucosporidium yeasts was characterized by the presence of numerous protrusions on the cell surface. In some cases, the entire cell surface was covered by these protrusions. There appeared to be some correlations between the age of the cell and the extent of surface protrusions and degree of surface convolution...

Leucosporidium yeasts: obligate psychrophiles which alter membrane-lipid and cytochrome composition with temperature

The temperature limits of growth of three psychorphilic yeasts, Leucosporidium frigidum, L. gelidum and L. nivalis, were examined. All species grew well as subzero temperatures (-I degrees C). The maximum temperature of growth was significantly higher with glucose as substrate (18 to 20 degrees C) than with ethanol (17 to 18 degrees C). There was a positive correlation between the growth temperature and the degree of fatty-acid unsaturation of the cell lipids; the lower the temperature, the greater the degree of fatty-acid unsaturation. At subzero temperatures (-I degrees C) with ethanol as substrate, 90% of the total fatty acid was unsaturated with linolenic (35 to 50%) and linoleic (25 to 30%) acids predominating. At temperatures close to the maximum for growth, linolenic acid accounted for less than 20% of the total fatty acid and oleic (20 to 40%) and linoleic (30 to 50%) acids were the major components. Difference spectra of intact cells showed marked changes in the rations and amounts of individual cytochromes as a function of growth temperature. In L.frigidum with glucose as substrate, the ratios of cytochromes a +a3:b:c at 8 and 19 degrees C were I:I-I:2-9 and I:2-3:16-7 respectively. Similar changes in cytochrome ratios were noted for L.gelidum, but changes were much less marked for L. nivalis. The temperature effects were interpreted as supporting the view that membrane structure and composition are fundamental to temperature adaptation in psychrophilic yeasts.

Thermal adaptation in yeast: growth temperatures, membrane lipid, and cytochrome composition of psychrophilic, mesophilic, and thermophilic yeasts

The temperature limits of growth of a number of yeast species were examined, and on this basis the organisms were classified into different thermal categories. The following species were examined: Leucosporidium frigidum and Leucosporidium nivalis, psychrophilic, temperature limits of growth, -2 to 20 degrees C; Canadian lipolytica mesophilic, temperature limits of growth, 5 to 35 degrees Candida parapsilosis and Saccharomyces telluris, thermotolerant, temperature limits of growth, 8 to 42 degrees C; Torulopsis bovina and Candida slooffi, thermophilic, temperature limits of growth, 25 to 45 degrees C and 28 to 45 degrees C, respectively. The membrane lipid and cytochrome composition of mitochrondrial fractions isolated from these yeasts were compared. There was a direct correlation between the growth temperature and the degree of membrane of lipid unsaturation; the lower the temperature, the greater the degree of lipid unsaturation. The membrane lipid composition of the thermophilic yeasts were distinguished by the high percentage (30 to 40%) of saturated fatty acid, as compared with the mesophilic and psychrophilic yeasts. The latter contained approximately 90% unsaturated fatty acid, 55% of which was linolenic acid, C alpha-18:3. Changes in phospholipid composition in relation to temperature were also noted. The respiratory-deficient thermophile, C. slooffi, was characterized by the absence of cardiolipin (sensitivity 0.1 mug of phosphorus) and cytochrome aa3. The absence of conventional mitochondrial structures in this thermophilic microorganism is tentatively suggested although low concentrations of cytochromes b, c, and c1 were detected by low-temperature spectroscopy. On the other hand, the respiratory-competent thermophile, T. bovina, was characterized by a high cardiolipin (25% of the total phospholipid) and cytochrome aa3 content (1 nmol/mg of mitochrondrial protein). Low-temperature spectra showed the presence of one b-type cytochrome in the thermophilic yeasts, two b-type cytochromes in the mesophilic yeasts, and three b-type cytochromes in the psychrophilic yeasts. It was concluded that a knowledge of the properties of the biological membrane is fundamental to an understanding of the ability of a microorganism to grow and reproduce in different temperature environments.