SARS-CoV-2 infections elicit higher levels of original antigenic sin antibodies compared with SARS-CoV-2 mRNA vaccinations

It is important to determine if severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and SARS-CoV-2 mRNA vaccinations elicit different types of antibodies. Here, we characterize the magnitude and specificity of SARS-CoV-2 spike-reactive antibodies from 10 acutely infected health care workers with no prior SARS-CoV-2 exposure history and 23 participants who received SARS-CoV-2 mRNA vaccines. We found that infection and primary mRNA vaccination elicit S1- and S2-reactive antibodies, while secondary vaccination boosts mostly S1 antibodies. Using absorption assays, we found that SARS-CoV-2 infections elicit a large proportion of original antigenic sin-like antibodies that bind efficiently to the spike of common seasonal human coronaviruses but poorly to the spike of SARS-CoV-2. In converse, vaccination modestly boosts antibodies reactive to the spike of common seasonal human coronaviruses, and these antibodies cross-react more efficiently to the spike of SARS-CoV-2. Our data indicate that SARS-CoV-2 infections and mRNA vaccinations elicit fundamentally different antibody responses.

Signaling Through FcγRIIA and the C5a-C5aR Pathway Mediate Platelet Hyperactivation in COVID-19

Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibited higher basal levels of activation measured by P-selectin surface expression and had poor functional reserve upon in vitro stimulation. To investigate this question in more detail, we developed an assay to assess the capacity of plasma from COVID-19 patients to activate platelets from healthy donors. Platelet activation was a common feature of plasma from COVID-19 patients and correlated with key measures of clinical outcome including kidney and liver injury, and APACHEIII scores. Further, we identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with in vitro platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions. These data identified these potentially actionable pathways as central for platelet activation and/or vascular complications and clinical outcomes in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect.

Canine coronavirus subtype 2a associated with outbreaks of fatal diarrhoea in bush dog (Speothos venaticus) groups

INTRODUCTION

Three outbreaks of fatal diarrhoea occurred in bush dog (Speothos venaticus) groups at two zoological collections in the United Kingdom between 2009 and 2017. In all cases, the predominant clinical signs were diarrhoea, anorexia and severe loss of condition. Despite supportive treatment, a number of fatalities occurred during each outbreak. Common gross post mortem findings were emaciation, with erythema, mucosal haemorrhage, and ulceration of the gastrointestinal tract. Histopathological features included villus blunting and fusion, crypt epithelial loss and lymphoid depletion, supporting a viral aetiology and canine coronavirus was suspected. Diagnosis was confirmed on the basis of serology (rising antibody titres) and the detection of viral nucleic acid using polymerase chain reaction. The canine coronavirus was subtyped as type 2a, which is known to cause systemic fatal disease in immature domestic dogs. To the authors' knowledge, these are the first reported cases of fatal diarrhoea associated with canine coronavirus type 2a in bush dogs. These outbreaks suggest that adult bush dogs are highly susceptible to canine coronavirus infection and may succumb to viral enteritis.

Health care worker seromonitoring reveals complex relationships between common coronavirus antibodies and COVID-19 symptom duration

Some studies suggest that recent common coronavirus (CCV) infections are associated with reduced COVID-19 severity upon SARS-CoV-2 infection. We completed serological assays using samples collected from health care workers to identify antibody types associated with SARS-CoV-2 protection and COVID-19 symptom duration. Rare SARS-CoV-2 cross-reactive antibodies elicited by past CCV infections were not associated with protection; however, the duration of symptoms following SARS-CoV-2 infections was significantly reduced in individuals with higher common betacoronavirus (βCoV) antibody titers. Since antibody titers decline over time after CCV infections, individuals in our cohort with higher βCoV antibody titers were more likely recently infected with common βCoVs compared with individuals with lower antibody titers. Therefore, our data suggest that recent βCoV infections potentially limit the duration of symptoms following SARS-CoV-2 infections through mechanisms that do not involve cross-reactive antibodies. Our data are consistent with the emerging hypothesis that cellular immune responses elicited by recent common βCoV infections transiently reduce symptom duration following SARS-CoV-2 infections.

Signaling through FcγRIIA and the C5a-C5aR pathway mediates platelet hyperactivation in COVID-19

Patients with COVID-19 present with a wide variety of clinical manifestations. Thromboembolic events constitute a significant cause of morbidity and mortality in patients infected with SARS-CoV-2. Severe COVID-19 has been associated with hyperinflammation and pre-existing cardiovascular disease. Platelets are important mediators and sensors of inflammation and are directly affected by cardiovascular stressors. In this report, we found that platelets from severely ill, hospitalized COVID-19 patients exhibit higher basal levels of activation measured by P-selectin surface expression, and have a poor functional reserve upon in vitro stimulation. Correlating clinical features to the ability of plasma from COVID-19 patients to stimulate control platelets identified ferritin as a pivotal clinical marker associated with platelet hyperactivation. The COVID-19 plasma-mediated effect on control platelets was highest for patients that subsequently developed inpatient thrombotic events. Proteomic analysis of plasma from COVID-19 patients identified key mediators of inflammation and cardiovascular disease that positively correlated with in vitro platelet activation. Mechanistically, blocking the signaling of the FcγRIIa-Syk and C5a-C5aR pathways on platelets, using antibody-mediated neutralization, IgG depletion or the Syk inhibitor fostamatinib, reversed this hyperactivity driven by COVID-19 plasma and prevented platelet aggregation in endothelial microfluidic chamber conditions, thus identifying these potentially actionable pathways as central for platelet activation and/or vascular complications in COVID-19 patients. In conclusion, we reveal a key role of platelet-mediated immunothrombosis in COVID-19 and identify distinct, clinically relevant, targetable signaling pathways that mediate this effect. These studies have implications for the role of platelet hyperactivation in complications associated with SARS-CoV-2 infection.

COVER ILLUSTRATION

ONE-SENTENCE SUMMARY

The FcγRIIA and C5a-C5aR pathways mediate platelet hyperactivation in COVID-19.

Sero-monitoring of health care workers reveals complex relationships between common coronavirus antibodies and SARS-CoV-2 severity

Recent common coronavirus (CCV) infections are associated with reduced COVID-19 severity upon SARS-CoV-2 infection, however the immunological mechanisms involved are unknown. We completed serological assays using samples collected from health care workers to identify antibody types associated with SARS-CoV-2 protection and COVID-19 severity. Rare SARS-CoV-2 cross-reactive antibodies elicited by past CCV infections were not associated with protection; however, the duration of symptoms following SARS-CoV-2 infections was significantly reduced in individuals with higher common betacoronavirus (βCoV) antibody titers. Since antibody titers decline over time after CCV infections, individuals in our cohort with higher βCoV antibody titers were more likely recently infected with common βCoVs compared to individuals with lower antibody titers. Therefore, our data suggest that recent βCoV infections potentially limit the severity of SARS-CoV-2 infections through mechanisms that do not involve cross-reactive antibodies. Our data are consistent with the emerging hypothesis that cellular immune responses elicited by recent common βCoV infections transiently reduce disease severity following SARS-CoV-2 infections.

Lessons for Patient Education Around Long-Acting Injectable PrEP: Findings from a Mixed-Method Study of Phase II Trial Participants

This study aimed to identify patients' physical and psychosocial experiences of an investigational long-acting injectable PrEP product to aid in the development of patient and provider education materials. Twenty-eight participants of a Phase 2 safety, tolerability, and acceptability study of long-acting integrase inhibitor cabotegravir (CAB-LA) were interviewed on their physical and psychosocial experiences of the injections. Five themes emerged through a framework analysis on these interview transcripts: (1) injection-related pain is highly variable across individuals; (2) pain is more impactful after the injections than during; (3) patient anxiety is critical, but does not determine the experience of injections and decreases over time; (4) intimacy and awkwardness of gluteal injections impacts patients' experiences; (5) patient education and care strategies can mitigate the above factors. These findings can inform further sociobehavioral research within Phase 3 efficacy trials of CAB-LA, as well as patient education and provider guidance for future injectable PrEP products.

Going social: Success in online recruitment of men who have sex with men for prevention HIV vaccine research

OBJECTIVE

To compare the use of four different social media sites to recruit men who have sex with men (MSM) and transgender women to a phase 2b HIV prevention vaccine trial, HVTN 505.

DESIGN

Retrospective, observational study.

METHODS

The University of Pennsylvania HIV Vaccine Trials Unit (Penn HVTU) employed street outreach and online recruitment methods to recruit participants for HVTN 505 using a combination of national recruitment images/messages with Philadelphia-specific language and imagery. We compared the efficiency (number of enrolled participants per number of completed phone screens) and effectiveness (number of enrolled participants per time interval employed) of each strategy, as well as the demographics and risk behaviors of the populations.

RESULTS

Online recruitment strategies populated 37% (71/191) of trial participants at our site. Among the four social media strategies employed, 45.1% (32/71) were enrolled through Facebook, 16.9% (12/71) through Craigslist, 15.5% (11/71) through a web-based marketing company (WBMC), and 22.5% (16/71) via GRINDR. The number of participants enrolled per month of strategy and the months the strategy was employed were Facebook - 32(33months), Craigslist - 12(33months), WBMC - 11(6months), and GRINDR - 16(0.56months). In-person and online recruitment strategies yielded participants of similar demographics and levels of risk behavior.

CONCLUSION

Use of several social media recruitment modalities produced large numbers of MSM engaging in high risk behavior and willing to participate in an HIV prevention vaccine trial. In comparison to other social media and online strategies, recruitment via GRINDR was the most effective.

Feasibility of identifying a cohort of US women at high risk for HIV infection for HIV vaccine efficacy trials: longitudinal results of HVTN 906

BACKGROUND

Identifying cohorts of US women with HIV infection rates sufficient for inclusion in vaccine efficacy trials has been challenging. Using geography and sexual network characteristics to inform recruitment strategies, HVTN 906 determined the feasibility of recruiting a cohort of women at high risk for HIV acquisition.

METHODS

HIV uninfected women who reported unprotected sex in the prior 6 months, resided or engaged in risk behavior in local geographical high-risk pockets and/or had a male partner who had been incarcerated, injected drugs, or had concurrent partners were eligible. Behavioral risk assessment, HIV counseling and testing, and pregnancy testing were done at baseline, 6, 12, and 18 months.

RESULTS

Among 799 women, 71% were from local high-risk pockets and had high-risk male partners. Median age was 37 years; 79% were Black; and 15% Latina. Over half (55%) reported a new partner in the prior 6 months, 57% reported a male partner who had concurrent female sexual partners, and 37% reported a male partner who had been incarcerated. Retention at 18 months was 79.5%. Annual pregnancy incidence was 12%. Annual HIV incidence was 0.31% (95% confidence interval: 0.06% to 0.91%). Risk behaviors decreased between screening and 6 months with smaller changes thereafter.

DISCUSSION

This cohort of women recruited using new strategies based on geography and sexual network characteristics did not have an HIV incidence high enough for HIV vaccine efficacy trials, despite high baseline levels of risk and a high pregnancy rate. New strategies to identify cohorts of US women for efficacy trials are needed.

Recruitment of urban US women at risk for HIV infection and willingness to participate in future HIV vaccine trials

Enrollment of US women with sufficient risk of HIV infection into HIV vaccine efficacy trials has proved challenging. A cohort of 799 HIV-negative women, aged 18-45, recruited from three US cities was enrolled to assess recruitment strategies based on geographic risk pockets, social and sexual networks and occurrence of sexual concurrency and to assess HIV seroincidence during follow-up (to be reported later). Among enrolled women, 90 % lived or engaged in risk behaviors within a local risk pocket, 64 % had a male partner who had concurrent partners and 50 % had a male partner who had been recently incarcerated. Nearly half (46 %) were recruited through peer referral. At enrollment, 86 % of women said they were willing to participate in a vaccine efficacy trial. Results indicate that participant and partner risk behaviors combined with a peer referral recruitment strategy may best identify an at-risk cohort willing to participate in future trials.

Associations between blood pressure and overweight defined by new standards for body mass index in childhood

BACKGROUND

Using data from a longitudinal study of young Australians, we applied recent international standards for overweight and obesity to examine associations with blood pressure (BP) and to determine the prevalence and degree of tracking of overweight and obesity. We also aimed to examine socioeconomic status in relation to these variables.

METHODS

BP, height, and weight were measured at 3-year intervals from age 9 to 18, and then at 25 years of age in a Western Australian cohort. At these stages, data were available for 1,036, 1,310, 618, 615 and 600 individuals, respectively.

RESULTS

We found 10% of 9-year-old males to be overweight or obese, while among 12-year-olds, 13% were overweight or obese; at age 15, and still at age 18, overweight or obesity was registered in 17% of this population and it rose to 42% among the 25-year-old young men. The percentage of overweight or obese females at these stages was initially 8, then 12 (at age 12), 11 (at age 15), 14 (at age 18) and finally 32. Overweight or obesity tracked to young adult life in 16% of those overweight or obese at 9, 24% at 12, 34% at 15 and 35% at 18 years. Systolic BP was significantly higher in the overweight or obese except in 12-year-olds. At the age of 25 years, 53% of men had high normal BP or were hypertensive.

CONCLUSIONS

Increasing overweight or obesity in young Australians, consistent with international trends, has serious health implications. Overweight and obesity show tracking and are predictors of higher blood pressure, except in early adolescence.

Tracking of blood pressure in Australian children

OBJECTIVE

Tracking of blood pressure (BP) from childhood occurs in populations but, for individuals, prediction of adult BP from childhood levels is poor. We examined factors that may influence tracking of BP to identify better predictors of higher BP in early adult life.

DESIGN

A prospective study of children recruited at the age of 9 years by random sampling of Perth metropolitan schools stratified by socio-economic status.

SETTING

Community based with re-surveys 3-yearly for 9 years.

PARTICIPANTS

A total of 516 boys and 520 girls at 9 years; 680 boys and 630 girls at 12 years; 318 boys and 300 girls at 15 years; 330 men and 326 women at 18 years.

MAIN OUTCOME MEASURES

Systolic (SBP) and diastolic (DBP) BP.

RESULTS

Persistence in the highest quartile for SBP between surveys was seen in 34-48% of subjects and in 37% between the ages of 9 and 18 years. The proportion increased to around 60% in those in the highest quartile for body mass index (BMI), to 70% in those in the highest quartile for change in BMI and to 60% if there was a family history of hypertension. In log-linear models, persistence in a quartile for SBP was significantly related to a family history of hypertension, previous SBP, BMI and change in BMI. Relationships were similar for DBP.

CONCLUSIONS

Excessive weight gain in adolescence and a family history of hypertension substantially increase the risk of higher BP persisting into early adult life. Recognition of children at risk would allow early intervention emphasizing weight control with potential long-term benefits.

Induction of CYP1A by Benzo[k]fluoranthene in Human Hepatocytes: CYP1A1 or CYP1A2?

While fresh human hepatocyte cultures are widely used to model hepatic cytochrome P450 (CYP) regulation and activity, their CYP1A subfamily composition induced by, e.g., polycyclic aromatic hydrocarbons is ambiguous. CYP1A1, CYP1A2, or both have been reported to be expressed, and their varied roles in chemical carcinogenesis makes resolution of which CYPs are expressed essential. We have used an immunoblot system with Bis-Tris-HCl-buffered polyacrylamide gel, which clearly resolves human CYP1A1 and CYP1A2, and polyclonal goat anti-human CYP1A1/CYP1A2 and rabbit anti-human CYP1A2 antibodies to probe the expressed CYP1A1 and CYP1A2 composition of seven individual human hepatocyte cultures induced with 5 microM benzo[k]fluoranthene (BKF) for 24 h. In six of the cultures only CYP1A1 was detected, and in the seventh both CYPs were detected. In most vehicle-treated hepatocyte cultures, neither CYP1A1 nor CYP1A2 was detected. In three additional hepatocyte cultures treated individually with BKF and 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD), the resultant induced CYP1A1/1A2 profiles were essentially not influenced by the nature of the inducing agents. To develop an activity-based assay to differentiate between CYP1A1 and CYP1A2 expression in human hepatocytes, our previously published R warfarin assay (Drug Metab. Disp. (1995) 23, 1339-1345) was applied to TCDD (10 nM)-treated hepatocyte culture. The low concentration of TCDD did not produce inhibition of the warfarin metabolism-such inhibition could confound the results. Based on the ratios of 6- to 8-hydroxywarfarin formed in two cultures, the ratios of CYP1A1/CYP1A2 expressed in these cultures were determined and they agreed with the ratios determined by immunoblot analysis. Thus each individual human hepatocyte culture must be characterized for induced CYP1A1 and CYP1A2 expression in studies of CYP1A activity. The warfarin assay provides a means of characterizing the cultures.

Metabolic characterization of the major human small intestinal cytochrome p450s

Human small intestine epithelial cells (enterocytes) provide the first site for cytochrome P450 (CYP)-catalyzed metabolism of orally ingested xenobiotics. CYP3A4 is the major form of CYP expressed in enterocytes and CYP2C is also expressed at a significant level. In this study, we further characterized the expression of CYP3A4 and CYP2C in human enterocytes and their interindividual variations by examining the metabolic activities from 10 individuals. CYP3A4 in human jejunum microsomes, as determined by 6beta-testosterone hydroxylase activity, varied from 0.36 to 2.46 nmol/min/mg. The apparent average K(m) and V(max) values from two representative individuals were 54 microM and 3.2 nmol/min/mg, respectively. CYP2C9 and CYP2C19 in human jejunum microsomes, as determined by diclofenac 4'-hydroxylase and mephenytoin 4'-hydroxylase activities, varied over an 18-fold range (7.3-129 pmol/min/mg) and 17-fold range (0.8-13.1 pmol/min/mg), respectively. The mean apparent K(m) for diclofenac 4'-hydroxylase was 9.9 microM , whereas the apparent mean K(m) for S-mephenytoin 4'-hydroxylase was 79.3 microM . The mean intrinsic clearance (V(max)/K(m)) was approximately 130-fold greater for diclofenac 4'-hydroxylase than for mephenytoin 4'-hydroxylase. The metabolic activities of CYP2C9 and CYP2C19 were confirmed by inhibition by sulfaphenazole for CYP2C9 and ticlopidine for CYP2C19. In addition, CYP2C9 activities did not correlate with CYP3A4 activities, while CYP2C19 activities had a significant but poor correlation with those of CYP3A4. Thus the major CYP activities in human enterocytes have large interindividual variabilities that are not strongly related.

Family lifestyle and parental body mass index as predictors of body mass index in Australian children: a longitudinal study

OBJECTIVE

To investigate associations between body mass index (BMI) and family characteristics, including lifestyle, in parents and offspring from Australian families.

DESIGN AND SUBJECTS

Longitudinal survey of 219 families of Australian children who had been surveyed 3-yearly between the ages of 9 and 18 y.

MEASUREMENTS

Socio-economic status, weight and height, diet from 3 day records or food frequency questionnaires, alcohol consumption, smoking habits and physical fitness in offspring (bicycle ergometry in 18-y-olds).

RESULTS

In 18-y-olds, in models examining offspring's lifestyle variables, BMI was predicted negatively by physical fitness (P=0.012), and positively by alcohol intake (P=0.046) in sons while, in daughters, only a negative association with physical fitness was significant. In models including parental characteristics, BMI in 18-y-old sons and daughters was significantly predicted by mothers' and fathers' BMI, independently of offsprings' alcohol intake, smoking, physical fitness and parents' education, and, in daughters, by fathers' alcohol intake. These models explained 48% of variance in daughters and 33% in sons. In both sons and daughters, BMI over the 9 y of the survey was consistently higher in offspring with overweight or obese fathers (P=0.033 for sons, P=0.024 for daughters) or mothers (P=0.031 for sons, P=0.037 for daughters). Physical fitness at the ages of 12, 15 and 18 y was negatively related to fathers' obesity in daughters and mothers' obesity in sons. Obesity in fathers was associated with a four-fold increase in risk of obesity at the age of 18 y in both sons and daughters with an independent eight-fold increase in risk for daughters if mothers were obese. Birthweight was unrelated to overweight or obesity in the 18-y-olds. Alcohol intake in sons related significantly to alcohol intake in either parent while, for daughters, there was a significant association only with fathers' alcohol consumption. In daughters, fat intake was positively associated with fat intake score in both fathers and mothers.

CONCLUSION

Parental overweight or obesity may identify children at risk for a range of unhealthy behaviours. Promotion of a healthy lifestyle targeting overweight families, particularly in lower socio-economic groups, should be a priority.

Human cytochrome P-450 metabolism of retinals to retinoic acids

Retinoic acids have important pleiotropic biological effects and thus the potential for human cytochrome P-450s (CYPs) to mediate retinoic acid synthesis was investigated. We examined the retinoic acid synthetic activity of human cDNA-expressed CYP1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4, 3A4+ cytochrome b(5) (b(5)), 3A5, and 4A11, expressed individually in insect cells together with NADPH-P-450 reductase. Only CYP1A1, 1A2, 1B1, and 3A4+b(5) converted all-trans-retinal (20 microM) to all-trans-retinoic acid with turnover numbers of 0.53, 0.18, 0.20, and 0.41 nmol/min/nmol P-450, respectively. With 9-cis-retinal as substrate, CYP1A2 exhibited a turnover number of 1.58 nmol/min/nmol P-450 whereas CYP1A1, 2C19, and 3A4+b(5) had turnover numbers of 0.40, 0.27, and 0.41 nmol/min/nmol P-450, respectively. For CYP3A4 activities with both retinals, b(5) was required. Kinetic analyses revealed that CYP1A1, 1A2, and 3A4+b(5) with all-trans-retinal had apparent K(m) values of 55, 356, and 255 microM, and V(max) values of 2.0, 8.3, and 6.3 nmol/min/nmol P-450, respectively, and with 9-cis-retinal had K(m) values of 77, 91, and 368 microM, and V(max) values of 2.7, 9.7, and 7.6 nmol/min/nmol P-450, respectively. The 9-cis retinoic acid synthetic activity of a group of 12 human liver microsomes correlated only with the CYP1A2 activity (r = 0.96), implicating CYP1A2 in human liver microsomal metabolism of 9-cis- retinal to 9-cis-retinoic acid. These studies have indicated that human CYPs are capable of catalyzing retinal to retinoic acid metabolism, but the physiological relevance of this metabolism is still unclear.

Induction of rat small intestinal cytochrome P-450 2J4

Cytochrome P-450 (CYP) 2J4 is a member of the recently identified CYP2J subfamily-part of the CYP superfamily-and is primarily expressed in rat small intestinal epithelium (enterocytes). Studies to determine small intestinal CYP2J4 inducibility by prototypic CYP inducers have been undertaken. Immunoblot analysis of enterocyte microsomes from rats treated with beta-naphthoflavone, dexamethasone, or phenobarbital revealed unchanged, diminished, or slightly increased levels of CYP2J4 protein, respectively, relative to vehicle-treated rats, whereas rats treated with pyrazole (200 mg/kg) had 3- to 4-fold increased levels of CYP2J4. Pyrazole administration also increased CYP2J4 metabolic activity, as probed by retinoic acid formation from retinal, approximately 3-fold, and the activity was inhibited by 90% by a polyclonal anti-CYP2J4 antibody. CYP2J4 mRNA levels were increased 2.5-fold by pyrazole administration. The route of pyrazole administration-oral or i.p.-did not affect the extent or time course of intestinal CYP2J4 induction. However, at >300 mg/kg pyrazole, oral administration produced higher levels of CYP2J4 activity than i.p. administration. Pyrazole also produced increased hepatic and olfactory mucosal levels of CYP2J4. We speculate, based on our data and on published mechanisms of pyrazole induction, that pyrazole induces rat intestinal CYP2J4 by stabilization of mRNA primarily, and by stabilization of protein to a lesser extent. This study documents for the first time the induction of a CYP2J subfamily member by a xenobiotic and provides the basis for a mechanism by which xenobiotics could modulate biological processes.

Characterization of human small intestinal cytochromes P-450

Human small intestine epithelial cells (enterocytes) provide the first site for cytochrome P-450 (CYP)-catalyzed metabolism of orally ingested xenobiotics. The CYP composition of enterocytes could thus affect the potential toxicity or therapeutic efficacy of xenobiotics by modifying systemic uptake. We have characterized human enterocyte CYP composition to enable assessment of its functional roles. An isolation method for enterocytes from human small intestine was developed using EDTA buffer-mediated elution. Villous enterocytes were isolated in high yield, separated from crypt cells. Reverse transcriptase-polymerase chain reaction of total RNA from enterocytes revealed that CYP1A1, 1B1, 2C, 2D6, 2E1, 3A4, and 3A5 mRNA were expressed, but only CYP2C and 3A4 were detectable by Western immunoblotting in enterocyte microsomes from 10 human small intestines, whereas CYP1A1 was weakly detectable in two of eight intestines tested. Microsomal protein content decreased markedly along the small intestine from the duodenum to the ileum, whereas total CYP content and CYP3A4 erythromycin N-demethylase activity increased slightly in progressing from the duodenum to the jejunum and then decreased markedly toward the ileum. Levels of CYP3A4 and 2C protein did not decrease in concert as a function of length along the intestine distally. Maximal CYP content for the 10 intestines varied from 0.06 to 0.18 nmol/mg microsomal protein and maximal CYP3A4 erythromycin N-demethylase activity varied from 0.30 to 0.76 nmol/min/mg microsomal protein. In conclusion, CYP3A4 is the major form of CYP expressed in human small intestine enterocytes, CYP3A5 expression was not detected, CYP2C and, in some intestines, CYP1A1 were expressed. The highest metabolic activity occurred in the proximal intestine.

Characterization of the cytochrome P450 CYP2J4: expression in rat small intestine and role in retinoic acid biotransformation from retinal

The sites of expression in the small intestine and the function of CYP2J4, a recently identified rat cytochrome (P450) isoform found to be predominantly expressed in the small intestine, were characterized. Immunoblot analysis with a polyclonal antibody to heterologously expressed CYP2J4 revealed that expression of CYP2J4 was at the highest level in the distal duodenum and jejunum and decreased toward the ileum. Villous cells expressed higher levels of CYP2J4 than crypt cells. Isoform-specific RNA polymerase chain reaction indicated that a related P450 isoform, CYP2J3, was only a minor form in rat small intestine. Since the intestinal mucosa is exposed to high levels of dietary nutrients, we hypothesized that CYP2J4 may be active toward diet-derived factors. We determined that purified, heterologously expressed CYP2J4 is active toward all-trans- and 9-cis-retinal in reconstituted systems, producing the corresponding retinoic acids as the major products. Apparent K(m) values for the formation of retinoic acids were 54 and 49 microM, respectively, and apparent Vmax values were 20 and 21 nmol/min/nmol P450, respectively. These activities were readily inhibited by a polyclonal anti-CYP2J4 antibody. Rat enterocyte microsomes were also active with all-trans-retinal to produce all-trans-retinoic acid in the presence of NADPH, and the majority of retinoic acid synthesis activity was inhibited by the polyclonal anti-CYP2J4 antibody. These findings suggest that CYP2J4 plays a major role in intestinal microsomal metabolism of retinal to retinoic acid and may be involved in the maintenance of retinoid homeostasis in the small intestine in vivo.

A tRNA suppressor mutation in human mitochondria

Mitochondrial mutations are associated with a wide spectrum of human diseases. A common class of point mutations affects tRNA genes, and mutations in the tRNA-leu(UUR) gene (MTTL1) are the most frequently detected. In earlier studies, we showed that lung carcinoma cybrid cells containing high levels (greater than 95%) of mutated mtDNA from a patient with the pathological nucleotide pair (np) 3243 tRNA-leu(UUR) mutation can remain genotypically stable over time, and exhibit severe defects in mitochondrial respiratory metabolism. From such a cybrid containing 99% mutated mtDNA, we have isolated a spontaneous derivative that retains mutant mtDNA at this level but which has nevertheless reverted to the wild-type phenotype, based on studies of respiration, growth in selective media, mitochondrial protein synthesis and biogenesis of mitochondrial membrane complexes. The cells are heteroplasmic for a novel anticodon mutation in tRNA-leu(CUN) at np 12300, predicted to generate a suppressor tRNA capable of decoding UUR leucine codons. The suppressor mutation represents approximately 10% of the total mtDNA, but was undetectable in a muscle biopsy sample taken from the original patient or in the parental cybrid. These results indicate that the primary biochemical defect in cells with high levels of np 3243 mutated mtDNA is the inability to translate UUR leucine codons.

The three-dimensional passive support characteristics of ankle braces

Studies of the passive support provided by ankle braces have focused primarily on inversion support. The goal of this study was to develop a technique to measure the support provided by ankle braces in all rotational directions and to use this technique to compare four common braces (Ascend, Swede-O, Aircast, and Active Ankle). For this purpose, a 6 degrees-of-freedom linkage was used to measure the flexibility of the ankle complex in 10 healthy subjects. Each subject was tested without brace support and with each of the four braces. Testing was repeated on each subject on two different occasions. The angular displacement at specified moment values and the four segmental flexibility values obtained from the loading portion of the moment-angular displacement data were used in the data analysis. Repeated measure analysis of variance followed by a Student Neuman-Keuls test at p < 0.05 was performed. This statistical analysis was used to identify significant differences among the braces and differences between each brace and the no brace condition. Each of the four braces provided significant support in inversion, eversion, and internal rotation, but the amount of support varied significantly among the braces. In external rotation, only the stirrup braces provided significant support. The braces also varied significantly in the amount of interference with dorsiflexion and plantar flexion. Clinicians may be assisted by objective data on the amount and nature of passive support when prescribing braces to their patients.

Health-related behaviours and psycho-social characteristics of 18 year-old Australians

Psychosocial variables associated with health-related behaviours for diet, physical activity, alcohol consumption and smoking were examined in 18 year-old Australian men (n = 301) and women (n = 282). These psychosocial variables included Type A behaviour and depression, perceived self-efficacy for engaging in healthy behaviours and perceived barriers to performing these behaviours. Self-efficacy for following a healthy diet and moderating alcohol intake was greater in females but males had higher self-efficacy for physical activity. Self-efficacy for smoking did not differ according to gender. Lack of willpower was perceived as a barrier to desirable dietary, smoking and physical activity behaviours. Other perceived diet-related barriers included buying suitable foods when eating out, ignorance about appropriate foods and, in young women, perceived expense. Barriers for desirable levels of physical activity included planning time, tiredness, limiting social life and lack of social support. Social occasions were the main perceived barriers preventing both alcohol moderation and quitting smoking. Lack of family support, stress and concerns about weight gain, particularly in women, were perceived barriers to smoking cessation. Type A behaviour was associated with smoking and "unsafe" drinking in both men and women, generally unhealthy dietary choices in young women but with greater physical activity in young men. Depressive affect was significantly higher in female smokers and "unsafe" drinkers and tended to have an inverse relationship with physical activity in men and women. Depressive affect was inversely related to self-efficacy in both men and women for each of the health behaviours examined. Health promotion in young adults should therefore attempt to increase self-efficacy and address perceived barriers to change, taking into account gender-related differences in attitudes and the influence of depression and Type A characteristics on health-related behaviours.

Clustering of health-related behaviors among 18-year-old Australians

BACKGROUND

Few studies among young adults have examined clustering of health behaviors affecting risk for lifestyle diseases.

METHODS

Smoking, alcohol consumption, physical activity, and diet were examined among Australian 18-year-olds (301 males, 282 females) initially recruited at the age of 9 years from 26 schools. Association analysis was used to recognize behavior clustering.

RESULTS

Fat intake was greater among male smokers than nonsmokers (36% energy vs 34% energy). Women smokers ate less fiber (14.1 g/day) than did nonsmokers (17.8 g/day). Smoking was significantly related, among males, to unsafe drinking (odds ratio 2.38) and higher fat intake (odds ratio 1.06) and, among females, to unsafe drinking (odds ratio 1.59), lower dietary fiber (odds ratio 0.93), and less physical activity (odds ratio 0.36). Cluster analysis defined separate behavior clusters for men and women with smoking status identifying further subgroups. Smoking, drinking alcohol to excess, and adverse dietary choices clustered among men and women, with physical inactivity also clustering among women.

CONCLUSION

Smoking among adolescents is an important indicator of behaviors influencing risk for later cardiovascular disease and other medical disorders. Multimodal approaches allowing for gender differences in health-related behaviors are likely to be more successful than targeting a single behavior in this age group.

Induction of CYP1A1 by beta-naphthoflavone in IEC-18 rat intestinal epithelial cells and potentiation of induction by dibutyryl cAMP

We have examined the inducibility of CYP1A1 by beta-naphthoflavone (BNF) in a rat intestinal epithelial cell line, IEC-18, and the associated interaction between cAMP and BNF. CYP1A1 was not constitutively expressed in IEC-18 cells. Upon treatment with BNF, CYP1A1 RNA, protein, and microsomal 7-ethoxyresorufin O-deethylase activity were detected. Treatment with dibutyryl cAMP resulted in a 2-fold increase in the extent of induction at both RNA and protein levels, with corresponding increases in CYP1A1 enzymatic activity. These results support the involvement of protein kinase A in Ah receptor-mediated induction of CYP1A1 and provide an in vitro model for further studies on the mechanisms underlying regional and cellular differences in the regulation of CYP1A1 gene expression in the small intestine.

Regulation of cytochrome P4501A1 expression in rat small intestine

The predominant inducible cytochrome P450 (CYP) in rat small intestine is CYP1A1, which, when induced to elevated levels by xenobiotics or dietary constituents, has the potential to metabolize and consequently reduce the systemic uptake of low concentrations of orally ingested, bioactivatable polycyclic aromatic hydrocarbons and heterocyclic aromatic amines. We investigated the regulation of small intestinal CYP1A1 in an effort to develop its anticancer potential. The time courses of hepatic and intestinal CYP1A1 induction by beta-naphthoflavone (BNF) were compared quantitatively at the protein and mRNA levels by immunoblot and competitive RNA-polymerase chain reaction analyses. CYP1A1 mRNA levels in both organs increased sharply and were maximal at approximately 6 hr and returned to near basal levels by 12 hr after BNF treatment. In contrast, hepatic CYP1A2 mRNA levels increased much more gradually. Small intestinal CYP1A2 mRNA concentrations were insufficient to support translation of detectable protein. Maximal levels of intestinal and hepatic CYP1A1 protein occurred between 12 and 24 hr, and 24 and 48 hr, respectively, after BNF. Intestinal CYP1A1 protein was detectable earlier and for a shorter duration than hepatic CYP1A1. CYP1A1 induction was first detected in crypt cells 3 hr before the appearance of activity in villous cells, and maximal levels of activity were reached in crypt cells 12 to 18 hr before maximal and 1.5-fold (per mg protein) higher responses in villous cells-induction thus occurs in both villous and crypt cells. Previously detected decreases in CYP1A1 inducibility from duodenum to ileum correlated with decreases in immunoblot determined-Ah receptor levels. Intestinal CYP1A1 induction does not involve the glucocorticoid receptor in contrast to hepatic induction. These studies have revealed several novel features of small intestinal CYP1A1 regulation.

Anesthetic efficacy of the intraosseous injection after an inferior alveolar nerve block

The purpose of this study was to determine the contribution of the intraosseous (IO) injection to the inferior alveolar nerve (IAN) block in human first molars. Using a repeated-measures design, 40 subjects randomly received either a combination IAN block + IO injection (on the distal of the first molar) using 2% lidocaine with 1:100,000 epinephrine or an IAN block+mock IO injection (gingival penetration only) at two successive appointments. The first molar and adjacent teeth, and contralateral canine (+/-controls) were blindly tested with an Analytic Technology pulp tester at 2-min cycles for 60 min. An 80 reading was used as the criterion for pulpal anesthesia. One hundred percent of the subjects had lip numbness with the IAN block. For the first molar, anesthetic success, defined as achieving an 80 reading within 15 min and keeping this reading for 60 min, was 42% with the IAN and 90% with the IAN + IO. Anesthetic failure defined as never achieving two 80 readings during the 60 min was 32% with the IAN and 0% with the IAN + IO. The onset of anesthesia was immediate with the IO injection. Eighty percent of the subjects sampled had a subjective increase in heart rate with the IO injection. The IO injection and postinjection questionnaire recorded low pain ratings.

Characterization of rat small intestinal cytochrome P450 composition and inducibility

The composition and inducibility of cytochrome P450 (P450) in rat small intestinal epithelial cells were investigated with the use of RNA-polymerase chain reaction and immunoblot techniques. The complement of intestinal P450s is more restricted than hepatic forms. P450s 1A1, 2B1, and 3A1 were detected in enterocytes of untreated rats and were inducible by beta-naphthoflavone (BNF), phenobarbital, and pregnenolone-16alpha-carbonitrile or dexamethasone, respectively. In addition, P450s 2C6 and 2C11 were both constitutively expressed at low levels. In contrast, several P450 forms, which are found in the liver, were not detected in enterocytes of untreated or induced rats, including P450s 2A1, 2B2, 2E1, 3A2, and 4A1. P4501A2 mRNA was detected only in BNF-induced rat small intestine and at levels that did not result in its detectable translation. The most prominent inducible form in rat small intestine is P4501A1. Its inducibility diminishes markedly along the length of the small intestine from the duodenum to the ileum. Furthermore, the induction of P4501A1 in enterocytes was affected by the route of administration of the inducing agent. Thus, intestinal P4501A1 was more sensitive to orally administered BNF, whereas induction of hepatic P4501A1 was more sensitive to intraperitoneal administered BNF. Overall, the results demonstrate the differential regulation of P450s between the liver and small intestine, and provide a basis for further studies in assessing the potential of intestinal P450s to protect against orally ingested polycyclic aromatic hydrocarbon carcinogens.

Tuberculin reactions among attendees at a methadone clinic: relation to infection with the human immunodeficiency virus

We tested 403 clients at an inner-city methadone clinic to determine the rate of positive tuberculin test reactions and to determine how this rate was influenced by race, gender, and infection with the human immunodeficiency virus (HIV). In addition to skin testing, an experimental urine test for antibody to HIV was offered; 73% of the clients provided urine specimens. Positive urine test results were confirmed by serum antibody testing. Of the subjects who returned for follow-up, 33.9% had indurations > or = 10 mm; 49.7% of these subjects were Black, 30% were Hispanic, and 18% were White. Antibodies to HIV were present in 12.5% of urine specimens. Tuberculin reactions of > or = 5 mm were observed for 32.7% of HIV-positive subjects and 48.4% of HIV-negative subjects. Screening of urine for antibodies to HIV proved to be simple, specific, and well accepted by the subjects. Providing prophylaxis for tuberculosis should be a high priority in populations with rates of tuberculin reactions and HIV infection that are comparable to those for clients of our methadone clinic.

Rifampin-resistant Mycobacterium kansasii

We identified 36 rifampin-resistant Mycobacterium kansasii isolates, including 17 (4%) of 464 isolates recovered in Texas between 1989 and 1992. Of 29 patients infected with rifampin-resistant M. kansasii whose history of medication was known, 90% had previously received rifampin, and 58% of these patients had been treated with one or two effective drugs. Thirty-two percent of rifampin-resistant isolates recovered since 1989 were from patients who were seropositive for human immunodeficiency virus (HIV) infection. Twenty courses of therapy with a four-drug regimen determined on the basis of in vitro susceptibilities were administered to 16 patients from whom rifampin-resistant isolates were recovered; the therapy did not include surgery. Sputum cultures converted to negative as the result of 90% of treatments (time to conversion: mean, 11 weeks; range, 4-20 weeks). Bacteriologic relapses occurred in four of five patients who withdrew from therapy after being culture negative for < or = 6 months of therapy and in one of 12 patients who were culture negative for at least 12 months of therapy (mean, 16.3 months). This study suggests that the prognosis for cure of infection due to rifampin-resistant M. kansasii with chemotherapy alone is excellent, although the number of cases appears to be increasing, in part because of the HIV disease epidemic.

Low-energy transvenous cardioversion defibrillation of atrial tachyarrhythmias in the canine: an assessment of electrode configurations and monophasic pulse sequencing

Prevention of recurrent atrial fibrillation and flutter remains a difficult clinical problem. Consequently, development of an easily implantable automatic atrial cardioverter defibrillator is appealing. In this context we have examined the feasibility of intracavitary low-energy shocks delivered via transvenously positioned electrodes for termination of induced atrial tachyarrhythmias in canine models. This study extends these observations with use of single-pathway (5 msec pulse duration) and dual-pathway sequential (5/5 msec, 0.2 msec separation) shocks of varying leading edge voltages (100 to 400 V) in a closed-chest canine talc-pericarditis model. Bipolar 9.5 French electrode catheters (electrode surface areas, 0.62 cm2) were positioned at the superior vena cava-right atrium (SVC-RA) junction (labeled SVC) and right ventricular (RV) apex, with a subcutaneous plate over the chest wall. For single-pathway shocks, overall treatment effectiveness was comparable among the three vectors tested (RV apex to SVC, 35%; RV apex to subcutaneous plate, 17%; and SVC to subcutaneous plate, 35%). Furthermore, there was no evident relationship between leading edge voltage and shock effectiveness. In contrast, although each of the dual-pathway shock vector combinations tested also showed similar overall effectiveness, there was an apparent dose-response effect as leading edge voltage increased. The SVC (common) to RV apex (pulse 1) and subcutaneous plate (pulse 2) achieved 60% effectiveness at 400 V (approximately 4 joules). Thus this study provides additional evidence favoring feasibility of low-energy transvenous atrial cardioversion defibrillation. However, further refinement of energy delivery is essential for the implantable automatic atrial cardioverter defibrillator concept to become clinically accepted.

Nurse practitioner managed care for persons with HIV infection

This exploratory study examined whether outcomes of care for HIV-infected patients are related to whether the patient's primary provider is a physician (MD) or a nurse practitioner (NP). Functional status, symptom occurrence, self management, health service use and patients' assessment of their care were evaluated for 87 HIV-infected patients in a teaching hospital outpatient setting. NP patients were three times as likely to report their health status as only fair or poor (odds-ratio = 3.06, p = .028), and reported significantly more unpleasant symptoms over a four-week period. Despite being in poorer health than patients cared for by physicians, NP patients functioned at comparable levels and used no more health care services than MD patients. NP patients reported 45 percent fewer problems with their care (p = 0.003). Findings suggest that more extensive use of nurse practitioners could safely enhance access to care for persons with HIV-related illnesses.

Rat liver metabolism and toxicity of 2,2,2-trifluoroethanol

2,2,2-Trifluoroethanol (TFE) is a metabolite of anesthetic agents and chlorofluorocarbon alternatives. Its toxicity in rats is a consequence of its metabolism to 2,2,2-trifluoroacetaldehyde (TFAld) and then to trifluoroacetic acid (TFAA). The enzymes involved in the toxic metabolic pathway have been investigated in this study. For the reaction of TFE to TFAld, the major hepatic metabolism associated with toxicity (as assessed by pyrazole-inhibitability) was NADPH dependent and occurred in the microsomes, whereas for TFAld conversion to TFAA, NADPH-dependent microsomal metabolism was significant, but mitochondrial and cytosolic metabolism in the presence of NADPH were also major contributors. NADPH-dependent hepatic microsomal metabolism of TFE to TFAld and TFAld to TFAA was inhibited by carbon monoxide, 2-allyl-2-isopropylacetamide, SKF-525A, metyrapone, imidazole, and pyrazole, and both reactions were oxygen dependent. The metabolism of TFE to TFAld was inhibited by diethyldithiocarbamate, a specific inhibitor of cytochrome P450E1, and by a monoclonal antibody to P4502E1, whereas the metabolism of TFAld was inhibited by neither. Ethanol pretreatment of rats enhanced the Vmax for hepatic microsomal metabolism of TFE to TFAld from 5.3 to 9.7 nmol/mg protein/min, while for TFAld to TFAA the Vmax was increased from 4.3 to 6.5 and the Km was unaffected for both reactions. Phenobarbital pretreatment of the rats did not affect any of these kinetic parameters. Coadministration of ethanol and a lethal dose of TFE very markedly decreased the lethality. Both the lethality (LD50 0.21 to 0.44 g/kg) and the metabolic kinetic parameters [(Vmax/Km)H(Vmax/Km)D = 4.2] were affected markedly when deuterated TFE replaced TFE. In contrast, deuteration of TFAld did not affect its lethality or rates of metabolism, but did affect its Km. Taken together these results indicate that P4502E1 catalyzed toxicity-associated hepatic metabolism of TFE to TFAld, while TFAld metabolism was catalyzed by a P450 which was not P4502E1. The hepatic metabolism of TFAld was not associated with its toxicity, which has been determined previously to be associated with its intestinal metabolism.

Reflotron cholesterol measurements in 1112 Australian children aged 10-12 years

OBJECTIVE

To study the distribution of blood cholesterol concentration in a sample of Western Australian schoolchildren.

DESIGN

The Reflotron dry-chemistry system (Boehringer Mannheim, Germany) was used to measure cholesterol in finger-prick blood samples obtained from Year 6 children aged 10-12 years attending government schools in metropolitan Perth. Recruitment methods ensured that children from different socioeconomic strata were represented.

PARTICIPANTS

For the 1239 children enrolled in Year 6 in 30 government schools, parental consent to participate was obtained for 1144; of these cholesterol concentration was measured in 1112.

RESULTS

The measurement method proved practicable and was generally well accepted. Cholesterol levels were somewhat lower than those obtained using a laboratory reference method and a bias, relative to national quality assurance standards, was estimated to be -0.32 mmol/L. Mean cholesterol level in boys (4.28 mmol/L, SD 0.69) was not significantly different from that in girls (4.35 mmol/L, SD 0.72). Allowing for measurement bias, 52% of boys and 57% of girls had cholesterol levels exceeding the National Heart Foundation's designated "desirable" level of 4.5 mmol/L for children.

CONCLUSIONS

The distribution of cholesterol levels in Australian children compares unfavourably with distributions in children in countries with low rates of cardiovascular disease and indicates a need for widespread, appropriate diet and lifestyle changes.

Comparison of diets supplemented with fish oil or olive oil on plasma lipoproteins in insulin-dependent diabetics

This study was designed to compare changes in high-density lipoprotein (HDL)- and low-density lipoprotein (LDL)-cholesterol in normolipidaemic male insulin-dependent diabetics (IDD) following dietary supplementation with either the fish oil concentrate Max EPA or olive oil. The contribution of the small quantity of cholesterol in Max EPA to these changes was also examined. Twenty-seven subjects were matched in groups of three and randomly allocated to one of three treatment groups of nine subjects each. Subjects were given 15 1-g capsules of oil daily for 3 weeks, consisting of either Max EPA, olive oil, or olive oil to which was added the same amount of cholesterol as contained in Max EPA, respectively. There was a significant increase in eicosapentaenoic acid, and a decrease in arachidonic acid, in the platelet membrane phospholipids of subjects taking Max EPA. In this group, there was an approximately 30% increase in serum HDL2-cholesterol (0.59 +/- 0.07 to 0.77 +/- 0.11 mmol/L, mean +/- SEM; P less than .01) and a corresponding decrease in HDL3-cholesterol (0.79 +/- 0.03 to 0.71 +/- 0.03 mmol/L; P less than .05). Although total and LDL-cholesterol concentrations were also higher after Max EPA, the changes were not significant. Triglycerides were significantly decreased by Max EPA. There were no significant changes in lipids in the groups given olive oil. These results show that compared with olive oil, dietary supplementation with Max EPA substantially increases HDL2-cholesterol in insulin-dependent diabetics. This is most likely due to a selective effect of omega 3 fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Timing and magnitude of serum creatine kinase-MB after transcatheter cardiac tissue fulguration in man

This study examined the impact of transcatheter fulguration on creatine kinase-MB release in 21 patients (age range 17-71 years). Arrhythmia diagnoses were ventricular tachycardia 9, atrial fibrillation with a rapid ventricular response 7, atrioventricular nodal reentry 2, and reciprocating tachycardia utilizing a posteroseptal accessory pathway 3. Seven patients had apparently normal hearts while 8 had ischemic heart disease and 6 cardiomyopathy. Timing of initial elevated creatine kinase-MB activity (mean 1.34 +/- 0.69 SD hours) and peak creatine kinase-MB activity (mean 3.73 +/- 0.89 SD hours) was relatively uniform in all patients. Time to peak creatine kinase-MB activity was unrelated to either underlying cardiac disease (normal: 3.9 +/- 1.0 hours; ischemic heart disease: 3.5 +/- 0.9 hours; cardiomyopathy: 3.8 +/- 0.9 hours), or fulguration site (His bundle (n = 9): 4.2 +/- 0.9 hours, proximal coronary sinus (n = 3): 3.3 +/- 0.3 hours, ventricle (n = 9): 3.4 +/- 0.8 hours). The magnitude of peak serum creatine kinase-MB activity was independent of myocardial diagnosis or fulguration site, but was linearly related to total energy delivered (r = 0.5, P less than 0.022). The latter correlation was particularly strong within cardiac diagnosis subgroups (normal: r = 0.92, P less than 0.002; ischemic heart disease: 0.73, P less than 0.04; non-ischemic cardiomyopathy: r = 0.57, P = NS). Thus, serum creatine kinase-MB activity following transcatheter fulguration is linearly related to the magnitude of delivered energy, and is similar to that observed after transient coronary artery occlusion and reperfusion.

Dietary fish oils increase serum lipids in insulin-dependent diabetics compared with healthy controls

The effect of daily dietary supplementation with fish oil on serum lipids and platelet total phospholipid fatty acids was examined in male normolipidemic insulin-dependent diabetics and normal controls. They were given 15 g/d of fish oil as Max EPA (equivalent to 2.7 g/d of eicosapentaenoic acid) for 3 weeks. The diabetics showed a rise in total cholesterol, attributable to increases in LDL- and HDL-cholesterol. The increase in HDL-cholesterol was largely due to a rise in its HDL2 subclass. There was also a decrease in triglycerides in both groups. Similar changes in lipids were seen in the normal controls, although these were not significant. The more pronounced effect in diabetics suggests an altered metabolic response to omega-3 fatty acids in that disorder. However, the results indicate that the possible detrimental effect of the rise in total and LDL-cholesterol following fish oil may be offset by the increase in the protective HDL2 subclass.

Diet and blood pressure in 9-year-old Australian children

Relationships between blood pressure and dietary factors were investigated in 884 9-y-old Australian children. Data on usual diet were obtained from a food frequency questionnaire completed by parents. The data were used to estimate daily energy intake and intakes of 14 nutrients considered to have some potential for influencing blood pressure. Systolic and diastolic blood pressure were tested for relationships with absolute intakes and calorie-adjusted intakes of each nutrient after adjustment for potential confounders. Diastolic pressure in boys was negatively related to energy intake and to calorie-adjusted fiber intake. Mean adjusted diastolic pressure in boys in the top fiber-intake quartile was 2.5 mm Hg lower than that in the bottom fiber-intake quartile. Systolic pressure in girls was negatively related to calorie-adjusted intakes of protein and cholesterol. There were no detectable relationships between blood pressure and calorie-adjusted intakes of fats, carbohydrates, sodium, potassium, calcium, or magnesium.

Serum lipids in insulin-dependent diabetics are markedly altered by dietary fish oils

1. The effect of dietary fish oil supplementation on serum lipids was examined in normolipidaemic insulin-dependent male diabetics and healthy controls. Fish oil was given as Max eicosapentaenoic acid (EPA), 15 g daily (equivalent to 2.7 g/day of EPA) for 3 weeks. 2. There was a substantial increase in EPA but a depletion of arachidonic acid content of platelet phospholipids. 3. Diabetics showed a rise in total cholesterol, attributable to increases in low density and high density lipoprotein (LDL and HDL) cholesterol. The rise in HDL cholesterol was largely due to an increase in its HDL2 subclass. Similar changes were found in the healthy men although these were not as marked. A decrease in triglycerides was observed in both diabetics and normal controls. 4. Generally, diabetics showed greater changes in lipid concentrations which may suggest an altered metabolic response to w3 fatty acids. Therefore, the possible detrimental effect of the rise in total cholesterol and LDL cholesterol following fish oil administration may be offset by the increase in the protective HDL2 subclass.

Intracellular lactate dehydrogenase concentration as an index of cytotoxicity in rat hepatocyte primary culture

In searching for a reliable index for cytotoxicity testing in rat hepatocyte primary culture, lactate dehydrogenase (LDH) concentrations in lysates of attached hepatocytes and LDH released into the culture medium were compared under conditions of exposure to various dosages of sodium chloride, sodium salicylate, R-warfarin, acetaminophen, phenylbutazone, and furosemide (frusemide). The amount of intracellular LDH was assessed by inducing the cells to release the enzyme with 0.1% Triton X-100. The induced LDH leakage was completed in 1 hr and the LDH activity was stable in storage at 10 degrees for 2 weeks. We found that intracellular LDH is a direct indicator of the number of viable hepatocytes in contrast to the LDH released, because released LDH does not account for the significant number of cells detached from monolayer but which are not leaky, during the 6-hr test period. Based on IC50 values (50% inhibitory concentration), the relative cytotoxicities are R-warfarin greater than phenylbutazone greater than furosemide greater than acetaminophen greater than sodium salicylate greater than sodium chloride.

Environmental temperature and blood pressure in 9-year-old Australian children

Relationships between blood pressure (BP) and environmental temperature were investigated as part of a broader study of constitutional and environmental determinants of BP in a sample of 1037 9-year-old Australian children. A Dinamap semi-automatic device was used to obtain three BP readings for each child. Average systolic blood pressure (SBP) and diastolic blood pressure (DBP) differed according to month of examination, with higher levels in the colder months. Negative relationships were observed between BP and temperature on the measurement day; computed regression equations indicated that a rise in maximum daily temperature of 10 degrees C was associated with falls of 5-7 mmHg in SBP and DBP. The relationships were independent of age, weight, height, socio-economic status and heart rate (HR). The results emphasize the importance of taking environmental temperatures into account in epidemiological studies of BP.

Hypokalemia after cardioversion from ventricular tachycardia induced in the electrophysiology laboratory

Serum potassium is often low after resuscitation from out-of-hospital ventricular fibrillation. We hypothesized that hypokalemia develops after ventricular tachycardia induced by programmed electrical stimulation. We measured serum potassium in 10 patients before induction of ventricular tachycardia and 15 minutes, 45 minutes, and 3 hours following cardioversion from ventricular tachycardia. Ventricular tachycardia rate was 243 +/- 71 bpm and duration was 57 +/- 87 seconds. Mean serum potassium (mEq/L) decreased from 4.1 +/- 0.3 at baseline to 3.8 +/- 0.5 at 15 minutes (p less than 0.01 vs baseline) and 3.7 +/- 0.6 at 45 minutes (p less than 0.005 vs baseline), but returned to 4.1 +/- 0.5 at 3 hours. Although no patients were hypokalemic (potassium less than 3.5 mEq/L) at baseline, 33% were hypokalemic at 15 minutes and 40% were hypokalemic at 45 minutes (p = 0.06 vs baseline). A low serum potassium was found in several of these patients immediately after the clinical arrhythmia that led to electrophysiologic study, and rapid resolution of the hypokalemia was observed. Thus, serum potassium decreases rapidly in man after resuscitation from brief but hemodynamically significant ventricular tachycardia. This suggests that patients with hypokalemia after resuscitation from out-of-hospital ventricular fibrillation have hypokalemia secondary to the event. The electrophysiologic effects of post-cardioversion hypokalemia are unknown.