Identification of an enhancer element in the estrogen receptor upstream region: implications for regulation of ER transcription in breast cancer

The estrogen receptor (ER) serves as a diagnostic marker for the treatment of breast cancer. Patients with ER-positive breast tumors are likely to respond to hormonal therapies, while ER-negative breast cancers are resistant to endocrine therapies. Most ER-negative tumors do not express detectable levels of ER transcript, highlighting the importance of transcriptional regulation. A novel regulatory element which resembles a steroid hormone response element has been identified in the 5'-flanking region of the human ER gene. We observed 3- to 5-fold higher specific binding to this element in nuclear extracts from ER-expressing MCF-7 breast cancer cells compared to ER-negative MDA-MB-231 breast tumor cells. We termed the factor(s) which bind to this cis-element estrogen receptor upstream binding factor-1 (ERUBF-1). In transient transfection assays in MCF-7 cells, the ERUBF-1 binding site elicited a 20-fold increase in luciferase activity over the ER P1, promoter. This enhancer element was significantly more active in the ER-positive MCF-7 cell line compared to the ER-negative MDA-MB-231 cell line. These data indicate that ERUBF-1 plays an important role in the transcriptional regulation of the ER gene in breast cancer.

Pregnancy induces expression of cPLA2 in ovine uterine artery but not systemic artery endothelium

OBJECTIVE

To determine whether pregnancy increases cytosolic phospholipase A2 (cPLA2) expression in uterine artery (UA) endothelial cells and vascular smooth-muscle (VSM) cells, and whether ovarian steroids mediate this effect.

METHODS

Uterine arteries and omental arteries (systemic control) were isolated from pregnant (120-130 days' gestation) ewes and from nonpregnant ewes synchronized to the corresponding phases of the ovarian cycle (follicular or luteal) or ovariectomized. In addition, ovariectomized ewes were treated with vehicle, estradiol-17 beta (E2 beta), progesterone (P4), or combined E2 beta/P4 for 10 days, and UAs were collected. Arteries from all studies were separated into mechanically isolated endothelial and VSM fractions. Proteins were then solubilized and separated on 7.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western immunoblotting using an affinity-purified mouse monoclonal antibody for cPLA2.

RESULTS

Both UA endothelium and VSM fractions were seen to express cPLA2, detected as a single band with a molecular mass similar to that observed in myometrium (about 100 kD). Distribution of cPLA2, when expressed per microgram of protein, was observed as 40% in UA endothelium compared with 60% in VSM fractions. Uterine artery endothelial cPLA2 expression was specifically increased 1.9-fold in pregnancy (P < .05), whereas there was no significant change from VSM. Furthermore, in ovariectomized sheep versus intact luteal or follicular phase animals, there was no significant change in cPLA2 expression in endothelium or VSM. Administration of E2 beta, P4, or their combination in ovariectomized sheep also failed to reproduce the pregnancy-induced increase in cPLA2 expression in UA endothelium. Omental artery endothelial and VSM cPLA2 expression was observed at similar magnitudes as UA expression, but levels were consistently unchanged by pregnancy, the ovarian cycle, or ovariectomy.

CONCLUSIONS

cPLA2 was expressed throughout the endothelium and VSM of both uterine and omental arteries, but only in UA endothelium was pregnancy associated with elevated cPLA2 expression. The lack of change in cPLA2 expression with the ovarian cycle or in ovariectomized animals, even after prolonged treatment with E2 beta, P4, or E2 beta/P4 combined suggests this pregnancy-induced increase in cPLA2 may not be estrogen and/or progesterone dependent.

Ten-year heart transplantation experience at the MARITIME HEART CENTER: does volume affect results?

OBJECTIVE

To evaluate the experience of a small volume Canadian heart transplantation centre.

DESIGN

Ninety-four consecutive primary heart transplants were performed from 1988 to 1998 at the Maritime Heart Center, Halifax, Nova Scotia, with 100% follow-up. Kaplan-Meier survival analysis was used.

RESULTS

The mean recipient age was 48.5+/-12.3 years and donor age 33+/-13.2 years. Eighty per cent of recipients were men. The prevalence of elevated pulmonary vascular resistance (4 or more Wood units) was 20.2%. Etiology of heart failure was ischemic cardiomyopathy (50%), dilated cardiomyopathy (40.9%) and congenital heart disease (9.1%). Survival was 85.9% at one year (n=71), 75.3% at five years (n=33) and 60.5% at eight years (n=8). There was a trend toward survival benefit with human leukocyte antigen (HLA) -DR matching, body mass index ratio of donor to recipient greater than 0.8, ischemic time less than 90 mins and male donors. There was no effect on survival with donor or recipient age, recipient sex, diabetes, hypertension, hypercholesterolemia, elevated pulmonary vascular resistance and HLA-A/B mismatch.

CONCLUSIONS

Excellent survival at one and five years following heart transplantation is reported that compares favourably with results published by the International Society for Heart and Lung Transplantation.

Transmyocardial laser revascularization does not denervate the canine heart

BACKGROUND

Transmyocardial laser revascularization has been used as an indirect approach to improve myocardial perfusion in patients with refractory angina not amenable to conventional therapy. Three mechanisms have been proposed for its therapeutic effects: direct perfusion of the ischemic myocardium through patent channels; induction of angiogenesis; and regional denervation. We sought to determine whether transmyocardial laser revascularization modifies afferent and efferent axonal function within the affected myocardium.

METHODS

Studies were performed in 9 dogs that were artificially ventilated and underwent thoracotomy. Changes in ventricular dynamics and intrinsic cardiac neuronal activity were monitored before and after creating 20 transmural channels in the left ventricular ventral free wall with a holmium:yttrium-aluminum-garnet laser in response to three stimuli: application of veratridine or bradykinin to the epicardial sensory neurites of intrinsic cardiac afferent neurons; sympathetic or parasympathetic efferent neuronal activation either electrically (4 V, 10 Hz, 5 ms) or chemically (nicotine, 5 microg/kg intravenously), and direct cardiomyocyte beta-adrenergic receptor stimulation (isoproterenol hydrochloride, 5 microg intravenously).

RESULTS

Sensory neurites of right atrial afferent neurons in the studied epicardial region responded similarly to chemical stimulation before and after transmyocardial laser revascularization. Transmyocardial laser treatment did not reduce local ventricular contractile responses to direct activation of sympathetic or parasympathetic efferent neurons by electrical or chemical means, nor did it affect cardiomyocyte augmentor responses elicited by exogenous beta-adrenergic receptor challenge.

CONCLUSIONS

As transmyocardial laser revascularization does not affect afferent or efferent axonal function in the affected ventricle, the efficacy of this form of therapy cannot be ascribed to local denervation.

Plastid translation is required for the expression of nuclear photosynthesis genes in the dark and in roots of the pea lip1 mutant

The expression of nuclear photosynthesis genes in pea seedlings requires both light and a postulated signal produced by developing plastids. The requirement for the plastid signal for the accumulation of transcripts of Lhcb1, RbcS, PetE, and AtpC genes was investigated in the pea mutant lip1, which shows light-independent photomorphogenic development. Lincomycin and erythromycin, inhibitors of plastid translation, decreased the accumulation of transcripts of nuclear photosynthesis genes in shoots of light-grown wild-type and lip1 seedlings, indicating that the plastid signal is required in the lip1 mutant. Treatment with lincomycin or erythromycin also reduced the accumulation of transcripts in shoots of dark-grown lip1 seedlings, indicating that light is not an obligate requirement for the synthesis or activity of the plastid signal. Lincomycin had a similar effect on the accumulation of Lhcb1 transcripts in dark-grown cop1-4 seedlings of Arabidopsis. Accumulation of transcripts of nuclear photosynthesis genes was also observed in roots of light-grown lip1 seedlings, and this accumulation, which was associated with the development of chloroplasts, was again dependent on plastid translation. The plastid signal therefore regulates the expression of nuclear photosynthesis genes in the dark and in roots of the lip1 mutant.

The bisindolylmaleimide protein kinase C inhibitor, Ro 32-2241, reverses multidrug resistance in KB tumour cells

Ro 32-2241 is a bisindolylmaleimide that selectively inhibits protein kinase C (PKC) as compared with other protein kinases. Experiments were carried out to examine its potential as a multidrug resistance-reversing agent. Ro 32-2241 inhibited efflux, and increased accumulation, of [3H]-daunomycin in multidrug-resistant (MDR) KB-8-5 and KB-8-5-11 cells and had no effect on drug-sensitive KB-3-1 cells. Ro 32-2241 completely reversed the doxorubicin resistance of KB-8-5 and KB-8-5-11 cells, showing no effect on the sensitivity of drug-sensitive KB-3-1 cells. The potency of Ro 32-2241 was comparable with that of cyclosporin A and better than that of verapamil, known modulators of multidrug resistance. Ro 32-2241 also completely reversed the taxol resistance of KB-8-5 cells and partially reversed the resistance of KB-8-5-11 cells. Vinblastine resistance was also partially reversed. Mechanistic experiments were carried out to determine whether Ro 32-2241 interacted with P-glycoprotein (Pgp) directly. Increased efflux of [14C]-Ro 32-2241 was seen with the more resistant KB-8-5-11 cells (although the percentage effluxed was very low as compared with [3H]-daunomycin), suggesting that Ro 32-2241 can act as a substrate for Pgp. Direct interaction of Ro 32-2241 with Pgp was confirmed by demonstration that it inhibited binding of [3H]-azidopine to Pgp in KB-8-5-11 membranes. In conclusion, Ro 32-2241, acting directly on Pgp (rather than, or in addition to, an effect on PKC), is effective in reducing or reversing resistance to doxorubicin, taxol and vinblastine in human tumour cells with a clinically relevant degree of MDR. However, results of in vivo experiments conducted to investigate the effects of Ro 32-2241 on resistance to doxorubicin suggest that it may not be possible to achieve sufficiently high levels of Ro 32-2241 in vivo to modulate MDR.

Parental attitudes regarding carrier testing in children at risk for fragile X syndrome

Sixty-five parents of individuals affected by fragile X syndrome who attended the National Fragile X Conference in Portland, Oregon (1996), were asked to complete a survey assessing parental level of concern about carrier testing in children at risk for fragile X syndrome. All subjects completed a 15-item paper and pencil Likert response scale measure that was developed specifically for this study. The items included parental rights and duties, psychological adjustment, adaptation, discrimination, harm, childbearing, and interpersonal relationships. The major concern of the parents was that their children have knowledge of their carrier status prior to becoming sexually active and that their children be able to marry informed of their genetic risk. Mothers were significantly more concerned than fathers about raising their children with the knowledge of their carrier status. A sense of parental right to make the decision regarding carrier testing for children was associated with concerns about (1) behavioral or educational problems, (2) knowledge of carrier status prior to sexual activity or marriage, and (3) adjustment of the children to knowledge of their carrier status. As the sample was drawn from a unique population of parents, the results of this survey should be interpreted with caution. The findings of this study suggest a model of parents providing anticipatory guidance for their children to help them adjust to carrier information and for their children to have this knowledge prior to the possibility of reproduction.

Pediatric flatfoot: evaluation and management

Although the exact incidence of flatfoot in children is unknown, it is a common finding. All children have only a minimal arch at birth, and more than 30% of neonates have a calcaneovalgus deformity of both feet. This condition is not painful and generally resolves without treatment; very rarely is corrective casting necessary. Most children who present to an orthopaedist for evaluation of flatfoot will have a flexible flatfoot that does not require treatment. Nevertheless, the examining physician must rule out other conditions that do require treatment, such as congenital vertical talus, tarsal coalition, and skew-foot. Untreated, congenital vertical talus may result in an awkward gait; manipulation and casting have been tried, but most authors now agree that surgical treatment is required. Although tarsal coalitions can become asymptomatic in adulthood, the anatomy will never be normal. Resection and inter-position of the extensor digitorum brevis is the treatment of choice for calcaneonavicular coalitions; the results of treatment of talocalcaneal coalitions are less predictable. Skewfoot should be treated by manipulation and serial casting as soon as it is detected. In the older child, hindfoot stabilization and realignment of the midfoot may be necessary. Surgical management is rarely indicated for a true flexible flatfoot. A variety of tendon transfers and reconstructive procedures have been advocated, but none has proved uniformly successful. Nor has any of the various types of supports ever been shown to change the arch architecture. Although parents are often concerned about pediatric flatfoot, the child is usually found to be asymptomatic, and no treatment is indicated. In most instances, the best treatment is simply taking enough time to convince the family that no treatment is necessary.

Medtronic mosaic porcine bioprosthesis satisfactory early clinical performance

BACKGROUND

The Medtronic (Minneapolis, MN) Mosaic porcine bioprosthesis is an investigational prosthesis which incorporates zero-pressure fixation, aortic root predilation, low profile stent, and alpha oleic acid antimineralization treatment.

METHODS

From September 1994 to August 1996, 289 patients (mean age 70 years, range, 28 to 88 years) had 227 (78.5%) aortic valve replacements and 62 (21.5%) mitral valve replacements. Concomitant procedures were performed in 61.2% (139) of aortic valve replacements and 54.8% (34) of mitral valve replacements. Of the aortic valve replacement group 70 (30.8%) were in the 61 to 70 age group and 134 (59.0%) were 71 years or older. Of the mitral valve replacements, 23 (37.1%) were 61 to 70 years and 30 (48.4%) 71 years or older.

RESULTS

The early mortality, overall, was 4.2% (12 of 289); for aortic valve replacement it was 4.0% (9) and for mitral valve replacement it was 4.8% (3). The late mortality for aortic valve replacement was 2.6% per patient-year (3 events, 1.3% of total) and for mitral valve replacement it was 3.3% per patient-year (one event, 1.6% of total). The reoperative rate for aortic valve replacement was 3.0% per patient-year (4), while there were no mitral valve replacement reoperations. The freedom from major thromboembolism was 97.3%+/-1.6% for aortic valve replacement and 94.7%+/-3.0% for mitral valve replacement at 1 to 1.5 years. The freedom from reoperation was 96.7%+/-1.7% for aortic valve replacement; there was no reoperation for mitral valve replacement. There were no cases of structural valve deterioration. In the aortic position the mean systolic gradient was low, approximately 11 mm Hg, across all sizes (range 8 to 12 mm Hg at 3 months and 10 to 13 mm Hg at 12 months). In the mitral position the mean diastolic gradient was approximately 5 mm Hg (range, 2 to 6 mm Hg) for all sizes 25 to 31 mm at the early and 1 year follow-up echocardiographic assessment.

CONCLUSIONS

The early clinical performance and in vivo hemodynamics are encouraging.

Medtronic intact porcine bioprosthesis: 10 years' experience

BACKGROUND

The Medtronic Intact porcine bioprosthesis experience was evaluated over a period of 10 years to determine the influence of structural valve deterioration by valve position in various age groupings.

METHODS

From 1986 to 1996 inclusive, at three centers, 1,272 patients had the prosthesis implanted in 1,296 procedures. The mean age of the population was 67 years (range, 9 to 91 years). There were 836 aortic valve replacements (AVR) (64.5%), 333 mitral valve replacements (MVR) (25.7%), and 110 multiple valve replacements (MR) (8.5%).

RESULTS

The early mortality was 7.3% (94 of 1,296 procedures). The early mortality with concomitant procedures (primarily coronary artery bypass grafting) was 9.8% (52 of 528) and without, 5.5% (42 of 768). The late mortality was 4.25%/patient-year. The linearized rate of major thromboembolism was 0.86%/patient-year. The rate of reoperation was 1.19%/patient-year and valve-related mortality, 1.06%/patient-year. There were 36 cases of structural valve deterioration for aortic valve replacement (16), mitral valve replacement (15), tricuspid valve replacement (2), and multiple valve replacement (3). The freedom from structural valve deterioration for aortic valve replacement was in patients 21 to 40 years, 62.5%+/-25.8% at 7 years; 41 to 50 years, 75.0%+/-15.3% at 7 years; 51 to 60 years, 91.0%+/-4.5% at 8 years; 61 to 70 years, 98.7%+/-0.7% at 10 years; and older than 70 years, 98.3%+/-1.0% at 10 years (p < 0.05). The freedom from structural valve deterioration for mitral valve replacement was for patients 41 to 50 years, 91.7%+/-8.0% at 7 years; 51 to 60 years, 85.9%+/-9.9% at 8 years; 61 to 70 years, 86.3%+/-6.8% at 8 years; and older than 70 years, 93.9%+/-4.8% at 8 years (not significant).

CONCLUSIONS

The Medtronic Intact porcine bioprosthesis has acceptable freedom from structural valve deterioration in both the aortic and mitral positions approaching 10 years of evaluation.

Hypertension in the elderly: don't treat too quickly!

In the asymptomatic patient without target organ damage who is seen with severely elevated BP, pseudohypertension is more often than not the cause. Rapid lowering of arterial pressure is unnecessary and even contraindicated. Nurses play an important role in the evaluation and the treatment of elderly patients with hypertension. Both research-based practice and thorough evaluation and monitoring are requisite for safe and effective treatment. Given the seriousness of the adverse effects and the lack of outcome data, the use of sublingual nifedipine capsules in hypertensive emergencies and pseudohypertension should be abandoned.

Effect of pressure on myocardial function after 6-hour preservation with blood cardioplegia

BACKGROUND

This study examined the return of cardiac function in pig hearts after 6 hours' preservation by continuous perfusion with blood cardioplegia at two perfusion pressures compared with preservation with crystalloid solutions.

METHODS

Isolated pig hearts were randomly divided into five groups (n = 8 per group) according to the following treatments: group 1 = fresh hearts (control); group 2 = hearts arrested with Queen's cocktail cardioplegia and then immersion in 0 degrees C saline solution (QS group); group 3 = hearts arrested with (5 degrees C) and simple immersion in 0 degrees C University of Wisconsin solution (UW group); and groups 4 and 5 = hearts arrested with blood cardioplegia at 10 degrees C and then continuously perfused at a pressure of 80 cm H2O or 40 cm H2O, respectively (groups BC80 and BC40). After preservation for 6 hours, donor hearts were reperfused by a cross-circulation support pig. Thereafter, cardiac function and metabolism were examined every half hour for 2 hours. A three-way mixed general linear model was used to analyze data with repeated measures. Bonferroni test was used to determine differences (p < or = 0.05) between groups.

RESULTS

Only 4 hearts recovered electric activity in the BC80 group (p < or = 0.05 versus other groups). There was poor recovery of left ventricular work in the BC80 group compared with the other groups (p < 0.001). Left ventricular work in the QS and UW groups was also lower than in the control and BC40 groups. Left ventricular work in the BC40 group fully recovered. Maximum elastance did not differ between groups. Compliance was reduced in the QS, BC80, and BC40 groups versus controls after preservation (p < 0.006). Coronary flow decreased and coronary vascular resistance increased in the BC80 group versus the other groups (p < or = 0.001). Coronary flow in the QS, UW, and BC40 groups was lower than in the control group (p < 0.001). The magnitude of lactate release was much higher in the BC80 group than in the other groups (p < or = 0.001).

CONCLUSIONS

Continuous perfusion with 10 degrees C blood cardioplegia at 40 cm H2O pressure for 6 hours provided adequate preservation of systolic function in this model. University of Wisconsin solution provided the best protection of diastolic function.

Factors influencing MAC reduction after cardiopulmonary bypass in dogs

BACKGROUND

Anaesthetic requirements may be reduced following surgery employing cardiopulmonary bypass (CPB). This study, in dogs, determined the role of a) volatile agents (enflurane [E] vs isoflurane [I]), b) oxygenator (bubble [B] vs membrane [M]), and c) presence [FL] vs absence [NoFL] of an in-line arterial filter in the bypass circuit in altering anaesthetic requirements following CPB.

METHODS

Male mongrel dogs were anaesthetized with either enflurane (n = 24) or isoflurane (n = 24). They were randomly assigned to one of eight groups (n = 6 per group); Group 1 (E/B/FL), Group 2 (E/M/FL), Group 3 (E/M/NoFL), Group 4 (E/B/NoFL), Group 5 (I/M/FL), Group 6 (I/B/FL), Group 7 (I/M/NoFL) or Group 8 (I/B/NoFL). MAC was determined using the tail-clamp method at hourly intervals, twice before and three times after a one hour normothermic perfusion using aortoatrial cannulation and CPB.

RESULTS

Prior to CPB, MAC was reproducible (enflurane: MAC1 2.17 +/- 0.29 vs MAC2 2.14 +/- 0.28%; isoflurane: MAC1 1.42 +/- 0.31 vs MAC2 1.41 +/- 0.33%) and differed among groups only for the volatile agent employed. Following CPB, MAC was reduced in all groups (P < 0.05 vs pre-CPB measurements) except Group 1 (E/B/FL). The degree of MAC reduction in other groups ranged from 39-64% and was not different based on type of agent employed, use of a membrane or bubble oxygenator, or presence or absence of an in-line arterial filter.

CONCLUSION

In dogs, MAC reduction following CPB was variable, not related to type of volatile agent employed, use of a membrane or bubble oxygenator, or presence or absence of an in-line arterial filter. The explanation for reductions in anaesthetic requirements following CPB in this model remains speculative.

Analysis of polymorphism in porcine MHC class I genes: alterations in signals recognized by human cytotoxic lymphocytes

Elucidation of the mechanism of the immune response against transplanted porcine tissue is critical for the success of xenografting in humans. Both human T cells and NK cells recognize MHC Ags, and human receptors may bind to MHC Ags across species barriers. Molecular characterization of porcine MHC class I clones from two MHC class I loci (P1 and P14) obtained from homozygous inbred miniature swine of three haplotypes (aa, cc, and dd), revealed extensive conservation between loci, suggesting that the genes were products of duplication from a common ancestral sequence. The level of homology between loci was similar to that between the haplotypes at each locus, suggesting that intergenic exchange had limited divergence of these genes. Comparison of the alleles indicated that the polymorphism occurred in the alpha-1 and alpha-2 domains of the class I heavy chain, while the alpha-3 domain was highly conserved among the six genes analyzed. Amino acids in the alpha-2 and alpha-3 domains responsible for the binding of human CD8 to MHC class I were largely conserved in the porcine genes, but several critical residues were altered. Comparison of sequences recognized by human NK cell inhibitory receptors revealed that the residues critical for recognition by these receptors were altered in the porcine genes; thus, the porcine class I molecules would be unable to inhibit lysis by human NK clones characterized to date. This finding provides a likely explanation for the susceptibility of porcine cells to cytolysis by human NK cells.

Analysis of polymorphism in porcine MHC class I genes: alterations in signals recognized by human cytotoxic lymphocytes

Elucidation of the mechanism of the immune response against transplanted porcine tissue is critical for the success of xenografting in humans. Both human T cells and NK cells recognize MHC Ags, and human receptors may bind to MHC Ags across species barriers. Molecular characterization of porcine MHC class I clones from two MHC class I loci (P1 and P14) obtained from homozygous inbred miniature swine of three haplotypes (aa, cc, and dd), revealed extensive conservation between loci, suggesting that the genes were products of duplication from a common ancestral sequence. The level of homology between loci was similar to that between the haplotypes at each locus, suggesting that intergenic exchange had limited divergence of these genes. Comparison of the alleles indicated that the polymorphism occurred in the alpha-1 and alpha-2 domains of the class I heavy chain, while the alpha-3 domain was highly conserved among the six genes analyzed. Amino acids in the alpha-2 and alpha-3 domains responsible for the binding of human CD8 to MHC class I were largely conserved in the porcine genes, but several critical residues were altered. Comparison of sequences recognized by human NK cell inhibitory receptors revealed that the residues critical for recognition by these receptors were altered in the porcine genes; thus, the porcine class I molecules would be unable to inhibit lysis by human NK clones characterized to date. This finding provides a likely explanation for the susceptibility of porcine cells to cytolysis by human NK cells.

Identification of sequence alterations in the upstream regulatory region of the estrogen receptor gene in an ER-negative breast cancer cell line

Given the important role of the estrogen receptor (ER) in the development and physiology of the breast, it is essential to delineate the mechanisms responsible for its failed expression in some breast tumors. We have cloned and sequenced a portion of the ER upstream regulatory region from the ER-positive MCF-7 and the ER-negative MDA-MB-231 breast cancer cell lines to determine if sequence alterations in this region account for the ER-negative phenotype of some tumors. From this, we identified a number of variations between the sequences, two of which were determined to be associated with a 50% decrease in CAT activity.

Different sensitivities of neutrophil responses to a selective protein kinase C inhibitor Ro 31-8425; redundancy in signal transduction

Previous studies implicating a role for protein kinase C (PKC) in mediating stimulation of cellular responses by physiological agonists have relied on use of non-specific inhibitors or direct stimulation of PKC by phorbol esters. However, much of this evidence is questionable. Here, we have investigated the effects of a potent and selective PKC inhibitor, Ro 31-8425, on three different responses of human neutrophils stimulated by either a physiological agonist, C5a, or a phorbol ester, PMA. The responses studied were superoxide generation, collagenase secretion and adhesion to endothelial cells. In each case, the PMA-stimulated response was more sensitive to inhibition than the C5a-stimulated response. Even the PMA-stimulated responses differed in their sensitivity to inhibition, with superoxide production being the most sensitive and adhesion at least sensitive. The different sensitivities of the PMA stimulated responses suggest that, although activation of PKC stimulates the responses, either different degrees of activation or different isozymes are required for the different responses. The lower sensitivity of the C5a-stimulated responses in each case suggests that PKC activation, if needed at all, is not rate limiting in these signal transduction pathways. These results emphasize the redundancy in intracellular signal transduction.

Magnesium in cardioplegia: is it necessary?

OBJECTIVE

To study the effectiveness of magnesium in cardioplegic solution in preventing postoperative arrhythmias and perioperative ischemia.

DESIGN

Randomized, control study.

SETTING

The cardiovascular surgery division of a major referral centre for the maritime provinces of Canada.

PATIENTS

Fifty patients scheduled to undergo coronary artery bypass who had a normal ejection fraction, normal preoperative serum magnesium level and no history of atrial or ventricular arrhythmia were randomized into two groups of 25 patients. One group received magnesium sulfate (15 mmol/L) in the cardioplegic solution (group 1), the other (control) group did not receive magnesium sulfate in the cardioplegic solution (group 2).

INTERVENTION

Coronary artery bypass grafting during which myocardial protection was provided by intermittent cold blood cardioplegia.

OUTCOME MEASURES

Postoperative serum magnesium levels, cardiac-related death, infarction and arrhythmias.

RESULTS

All group 2 patients had a lower postoperative serum magnesium level than group 1 patients. There were no cardiac-related deaths in either group. More group 2 patients had ischemic electrocardiographic changes than group 1 patients (p < 0.03). Non-Q wave myocardial infarction occurred in two patients (one in each group). Eight patients in group 2 had atrial fibrillation compared with five patients in group 1. Ventricular ectopia occurred significantly (p < 0.01) more frequently in group 2 than in group 1.

CONCLUSION

The addition of magnesium to the cardioplegic solution is beneficial in reducing the incidence of perioperative ischemia and ventricular arrhythmia in patients who undergo coronary bypass grafting.

Nitrous oxide compared with intravenous regional anesthesia in pediatric forearm fracture manipulation

A prospective, randomized study of intravenous (i.v.) regional anesthesia compared with nitrous oxide gas was performed in a group of 28 pediatric patients with forearm fractures requiring manipulation in the emergency department. The groups were compared in terms of pain perceived by the patients, success of manipulation, safety, and duration of procedure. The methods showed no significant difference in amount of pain perceived by the patient for the total pain experience. No medical complication was seen in either group. Because of a technical problem with an i.v. regional block, fracture manipulation was not completed in one patient. Nitrous oxide treatment required significantly less time for completion of the procedure.

Osteomyelitis of the calcaneus in children

Eleven cases of calcaneal osteomyelitis in children are reported. Seven were hematogenous cases, and the remaining four were related to puncture wounds. The clinical presentation was less dramatic than that seen in typical long bone osteomyelitis. Laboratory findings were also less striking. A mixture of organisms was isolated from patients in the hematogenous group. In contrast, all puncture-related cases had cultures positive for Pseudomonas aeruginosa. Plain radiographic findings were noted at the time of presentation in 63%. Those findings were characteristically different in hematogenous and puncture-related cases. Oblique lateral radiographs can be important for diagnosis in puncture-related cases. Radionuclide bone scanning was an important diagnostic test in the absence of plain radiographic changes and in the very young patient. Surgery was performed in 82% of the cases. There were no recurrences or chronic infections. Two complications occurred in one patient, including residual scar sensitivity and early fusion of the calcaneal apophysis.

Evidence of type 2 herpes simplex infection in human coronary arteries at the time of coronary artery bypass surgery

OBJECTIVE

To examine histologically biopsies from the coronary arteries of patients undergoing coronary artery bypass grafting (CABG) for evidence of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) antigen and to correlate the incidence with pathological and clinical data.

DESIGN

Sequential patients undergoing CABG in whom adequate tissue could be obtained for histology.

SETTING

University teaching hospital.

PATIENTS

Forty-six patients were enrolled. Thirty-one provided sufficient tissue and clinical information for the analysis.

METHODS

Biopsy material was collected in the operating room and prepared immediately for histology and electron microscopy. Slides were prepared by staining with hematoxylin and eosin, Masson trichrome, avidin biotin complex immunoperoxidase for HSV-1 and HSV-2 protein and specific DNA probes for HSV-1 and HSV-2 by hybridization. Clinical data were obtained in structured interviews.

RESULTS

Sixty-one per cent of biopsies demonstrated evidence of inflammation, 45% were positive for antigen to HSV-2 and only one to HSV-1. Significant positive correlations were detected between inflammatory cells in the biopsy and a recent history of cold sores and between the presence of the infiltrate and positivity to HSV-2 antigen.

CONCLUSION

A correlation exists between HSV-2 infection and the inflammatory response associated with atherosclerosis.