Nuclear cardiology update

This article focuses on the following areas of myocardial perfusion imaging: radiotracer and protocol options, pharmacologic stress agents, and protocols and functional assessment with ECG-gated single photon emission CT.

Surveillance of antibiotic resistance in invasive isolates of Neisseria meningitidis in Australia 1994-1999

A total of 1434 strains of Neisseria meningitidis isolated from cases of invasive meningococcal disease (IMD) in Australia between 1994 and 1999 were examined by standard methods for susceptibility to antibiotics used for treatment and prophylaxis. The proportion of isolates fully susceptible to penicillin decreased from 45% in 1994 to 26% in 1999 (P<0.001). All the other isolates were less sensitive to penicillin except for two meningococci with a penicillin MIC of 1 mg/l. The geometric mean penicillin MIC increased from 0.045 to 0.065 mg/l from 1994 to 1999. There was no significant difference in the geometric mean penicillin MICs of serogroup B and serogroup C meningococci. Penicillin susceptibility was significantly associated with a poorer outcome. Isolates from survivors of IMD had a higher geometric mean penicillin MIC (0.06 mg/l) than those from fatal cases (0.048 mg/l) (P< 0.001). This suggests that factors other than the decrease in susceptibility to penicillin observed were more relevant to outcome in IMD. All isolates were fully susceptible to ceftriaxone. Rifampicin resistance was infrequent (eight isolates in 6 years) and sporadic. A single isolate had decreased quinolone susceptibility. Despite the significant shift in susceptibility to penicillin recorded, this group of antibiotics remains a suitable treatment for IMD in Australia.

Characterisation of agonist binding on human 5-HT2C receptor isoforms

The 5-HT2C receptor is expressed in different isoforms as a result of mRNA editing. Both INI (unedited) and VSV (a fully edited version) isoforms are abundant in rat brain. The VSV isoform lacks the high affinity recognition site for 5-HT, which may be caused by low efficiency coupling to G-proteins. In this study we have investigated the pharmacology of the agonist binding site of these two isoforms of the 5-HT2C receptor. The VSV isoform was expressed in Chinese hamster ovary cells (CHO) and the INI isoform in both Chinese hamster ovary cells and human embryonic kidney cells (HEK-293). Saturation analysis using [3H]5-HT revealed high and low affinity recognition sites on the INI isoform in both cell types whilst the VSV isoform did not have the high affinity binding site for [3H]5-HT. Displacement studies were undertaken using [3H]5-HT to label the receptors. In these studies the affinity of agonists (5-HT, Ro600175 ((S)-2-(6-Chloro-5-fluoroindol-1-yl)-1-methylethylamine), MK212 (6-Chloro-2-(piperazinyl) pyrazine), mCPP (1-(m-chlorophenyl)-piperazine), TfMPP (N-(m-trifluoromethylphenyl)piperazine), DOI (1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane), DOB (1-(4-bromo-2,5-dimethoxyphenyl)-2-aminopropane) and 8OH-DPAT (8-hydroxy-2-(di-N-propylamino)tetralin) was higher at the INI isoform, whilst antagonist affinity (ketanserin and mesulergine) did not change between the two receptor isoforms. There were no differences between the INI isoform expressed in the CHO and HEK-293. This suggests that the INI isoform of the 5-HT2C receptor is pharmacologically similar to the VSV form of the 5-HT2C receptor but that it couples more efficiently to G-proteins.

Expectant management of early pregnancies of unknown location: a prospective evaluation of methods to predict spontaneous resolution of pregnancy

OBJECTIVE

To assess prospectively the ability of two multiparameter diagnostic models and their individual components to predict the outcome of early pregnancies which could not be identified on transvaginal ultrasound scan.

DESIGN

Prospective observational study.

SETTING

Dedicated early pregnancy unit in an inner city teaching hospital.

POPULATION

Women with a positive urine pregnancy test and clinical suspicion of early pregnancy complications.

METHODS

A full medical history, clinical examination and transvaginal ultrasound scan were carried out at the initial visit. When the location of the pregnancy could not be ascertained by ultrasound, serum beta-human chorionic gonadotrophin (beta-hCG) and progesterone levels were measured. All women were managed expectantly until either a normal pregnancy was visualised on scan; the pregnancy resolved spontaneously or intervention was required due to a worsening of clinical symptoms or non-declining beta-hCG levels.

MAIN OUTCOME MEASURES

Spontaneous resolution of pregnancy (i.e. cessation of symptoms and decline in serum beta-hCG level to < 20 iu/L) without need for any active intervention.

RESULTS

Of the 104 women recruited, 72 (69%) pregnancies resolved spontaneously. Both multiparameter diagnostic models identified resolving pregnancies with positive predictive values > or = 95%. Their performances were not significantly better compared with individual progesterone levels which achieved a positive predictive value of 97% using a cutoff level of 20 nmol/L.

CONCLUSION

Serum progesterone measurement alone is as accurate as more complex diagnostic models for the prediction of successful expectant management in pregnancies of unknown location.

One antigen mismatched related donor bone marrow transplant in a patient with acute lymphoblastic leukaemia and beta-thalassaemia major: potential cure of both marrow disorders

We report a case of a 34-year-old man with T-ALL and beta-thalassaemia major who underwent a one antigen mismatched related donor bone marrow transplant. Five months post transplant chimeric studies revealed full donor haemopoiesis and the patient remains leukaemia and thalassaemia free at 12 months post transplant. Cumulative risk factors contributing to the increased transplant-related mortality in patients with two different marrow disorders are discussed.

Cholesterol-lowering effects of psyllium intake adjunctive to diet therapy in men and women with hypercholesterolemia: meta-analysis of 8 controlled trials

BACKGROUND

Soluble fibers, including those from psyllium husk, have been shown to augment the cholesterol-lowering effects of a low-fat diet in persons with hypercholesterolemia. As evidence of this, the US Food and Drug Administration recently authorized the use of health claims on food products containing soluble fiber from psyllium that state that they are associated with a decreased risk of coronary heart disease.

OBJECTIVE

This meta-analysis was conducted to more precisely define the hypolipidemic effects and safety of psyllium when used adjunctive to a low-fat diet in men and women with hypercholesterolemia.

DESIGN

The 8 studies in the meta-analysis included a total of 384 and 272 subjects receiving psyllium or cellulose placebo, respectively. All studies evaluated the hypocholesterolemic effects of 10.2 g psyllium/d adjunctive to a low-fat diet for >/=8 wk in individuals with mild-to-moderate hypercholesterolemia after a low-fat diet lead-in phase lasting >/=8 wk. The safety and adverse events associated with psyllium consumption were summarized from pooled data of 19 clinical studies ranging from 6 wk to 6 mo in duration.

RESULTS

Consumption of 10.2 g psyllium/d lowered serum total cholesterol by 4% (P < 0.0001), LDL cholesterol by 7% (P < 0.0001), and the ratio of apolipoprotein (apo) B to apo A-I by 6% (P < 0.05) relative to placebo in subjects already consuming a low-fat diet, with no effect on serum HDL or triacylglycerol concentrations.

CONCLUSIONS

Psyllium supplementation significantly lowered serum total and LDL-cholesterol concentrations in subjects consuming a low-fat diet. Psyllium is well tolerated and safe when used adjunctive to a low-fat diet in individuals with mild-to-moderate hypercholesterolemia.

Endotracheal cardiac output monitor

BACKGROUND

The endotracheal cardiac output monitor (ECOM) is a new device that uses an endotracheal tube with multiple electrodes to measure cardiac output (CO). It measures the changes in electrical impedance caused by pulsatile blood flow in the aorta. The system was tested for safety and efficacy in 10 swine.

METHODS

Swine (60-80 kg) were chronically instrumented with a transit time flow probe on the ascending aorta and vascular occluders on the vena cava and pulmonary artery. After a minimum recovery of 4 days, the animals were anesthetized and intubated with an ECOM endotracheal tube. CO measurements from the ECOM system were compared to transit time flow probe measurements using linear regression and Bland-Altman analysis. Three different inotropic states were studied: (1) baseline; (2) increased (dobutamine); and (3) decreased (esmolol). CO was changed at each inotropic state by impeding left ventricular filling with the vena cava or pulmonary artery occluders. CO values between 0 and 15 l/min were studied. Pigs were studied for 24 h consecutively.

RESULTS

There was no deterioration of the impedance signal with time and no tracheal injury from the ECOM electrodes. There is a linear relationship between the ECOM and transit time flow probe CO between 0 and 15 l/min (slope = 0.94; intercept = 0.15 l/min; R2= 0.77). The mean difference between the two measures (bias) is 0.15 l/min and the SD is 1.34 l/min. The limits of agreement are -2.53 to 2.82 l/min.

CONCLUSION

Endotracheal CO monitor is a promising technology that needs further evaluation in clinical trials.

Chloramine-induced haemolysis presenting as erythropoietin resistance

BACKGROUND

In December 1996 we identified an outbreak of erythropoietin (rHuEpo) resistance requiring a substantial increase in rHuEpo dosage in one of our four haemodialysis (HD) units. The dialysate chloramine levels in this unit had risen from <0.1 p.p.m. in 1996 to 0.25-0.3 p.p.m. in 1997. In the other three HD units levels remained <0.1 p.p.m. Other parameters of water quality were within accepted standards.

METHODS

Monthly records of haemoglobin level and rHuEpo dose were available for 148 patients between January 1996 and May 1998. Seventy-two patients, with no recognized cause of rHuEpo resistance, were analysed in detail (August 1997 to April 1998). A subgroup of 15 patients was examined for evidence of haemolysis during HD (methaemoglobin and haptoglobin levels, reticulocyte counts and Heinz bodies). Larger carbon columns were installed in December 1997 to effect chloramine removal.

RESULTS

There was an increase in mean methaemoglobinaemia of 23% (P<0.01) and a 21% fall in mean haptoglobin (P<0.01) across HD, although no patient had a reticulocytosis and only one patient with G6PD deficiency had Heinz bodies. Following installation of larger carbon columns there was an 18.6% rise (P<0.001) in mean haemoglobin level and a subsequent 25.0% reduction (P<0.001) in mean rHuEpo dose. Intradialytic changes in methaemoglobin and haptoglobin were abolished. The dialysate chloramine levels fell to < 0.1 p.p.m. Water company records subsequently revealed a sustained twofold increase in mains water chloramine from November 1996.

CONCLUSIONS

This is the first report linking chloramine exposure and rHuEpo resistance, with only subtle signs of haemolysis. Unheralded changes in mains water constituents can directly affect dialysate water quality and clinical outcomes.

An audit of deaths occurring in hospital after discharge from the intensive care unit

The aim of the study was to conduct an audit of patients who died in the ward after discharge from the intensive care unit (ICU). Clinical records of those who died in the ward following discharge between 1991 and 1997 were reviewed. Patients were retrospectively grouped according to whether death was expected, unexpected or likely to die within one year. The causes of death, times in ICU and hospital, demographics, and APACHE II scores were compared. Ninety-nine patients were studied, of whom 60 were triaged to the ward expected to die at the time of ICU discharge. Five of the patients were classified as not expected to die. Of the remaining 34 patients, 65% were debilitated with more than one organ disease and 62% eventually had some treatment withdrawn on the ward. After discharge from ICU, no obvious ward treatment deficiencies were found to contribute to death. However, of those who were admitted to the ICU from the ward and who later died when back in the ward, there seemed to be avoidable events pre-ICU admission in eight (36%) patients, some of which may have contributed to the later death of the patient.

The opioid receptor antagonist nalmefene reduces responding maintained by ethanol presentation: preclinical studies in ethanol-preferring and outbred Wistar rats

Nalmefene, the 6-methylene derivative of naltrexone, was examined after subcutaneous (s.c.) (0.0001 to 8.0 mg/kg) and oral (10 to 80.0 mg/kg) administration in ethanol (EtOH)-preferring rats whose responding (i.e., lever pressing) was maintained by the presentation of EtOH. Naltrexone (0.01 to 40 mg/kg) was used as a reference opioid antagonist. EtOH (10% v/v) and saccharin (0.025 to 0.1% w/v) solutions were concurrently available for 1 hr each day under a two-lever, fixed-ratio schedule in which four responses on one lever produced the EtOH solution and four responses on the other lever produced the saccharin solution. When basal response rates for saccharin were 10% that of EtOH, all routes of nalmefene administration reduced control levels of responding maintained by EtOH by 38 to 84%. When basal response rates for saccharin-maintained responding were 60% or 82% that of EtOH, only lower s.c. naltrexone (e.g., 0.01 to 0.025 mg/kg) and nalmefene (e.g., 0.01 to 0.10 mg/kg) doses produced a selective dose-dependent suppression of EtOH-maintained responding. Higher nalmefene (0.25 to 8.0 mg/kg) and naltrexone (1.0 to 20.0 mg/kg) doses failed to produce a dose-dependent suppression on EtOH or saccharin maintained responding. Both antagonists suppressed responding maintained by EtOH primarily during the initial 10-min period, with little additional suppression occurring across the remainder of the 60-min period. Subcutaneous nalmefene was 3200- to 6400-fold more potent than oral nalmefene, suggesting bioavailability was optimized using the s.c. route. Nalmefene (0.5 mg/kg, s.c.) treatment for 10 consecutive days produced mild tolerance development, whose effects dissipated by day 8. Naltrexone (10 to 40 mg/kg) and nalmefene (1.5 to 3.0 mg/kg), given 8 to 24 hr before the test session, reduced control levels of responding maintained by EtOH by 82%. Thus, immediate opioid receptor occupancy was not required to observe antagonism. These data demonstrate that, under a variety of experimental conditions, nalmefene is an effective antagonist of responding maintained by EtOH and lend support to clinical reports that nalmefene may function as an alternative pharmacotherapy to naltrexone to reduce EtOH-motivated behavior and prevent relapse.

Ovarian dermoid cyst leakage--a cautionary tale

This case illustrates that when a dermoid cyst is punctured, an immediate operative laparoscopy or laparotomy should be performed, along with lavage, to avoid the problems associated with dermoid cyst contents spillage.

Sensitization to dust mites as a dominant risk factor for asthma among adolescents living in central Virginia. Multiple regression analysis of a population-based study

Factors influencing asthma were investigated in a population of school children in central Virginia. A survey of 1,054 children in two middle schools (one urban and one suburban) identified 135 students with symptoms suggestive of asthma. Eighty-eight symptomatic children and 123 control subjects were randomly selected for further evaluation by skin testing using common indoor and outdoor allergens; serum assays for total IgE and specific IgE; dust samples assayed for mite (Der p 1 Der f 1), cat (Fel d 1), and cockroach (Bla g 2) allergens; and provocation with histamine to test for bronchial hyperreactivity. Forty-eight of the children with symptoms responded to < or = 3.9 mumol of histamine and were considered to have asthma. Marginal analysis identified elevated total IgE and dust mite, cat, and cockroach sensitization as significant risk factors for asthma. Using multiple regression, only dust mite sensitization was independently associated with asthma (odds ratio = 6.6; p < 0.0001). Dust from 81% of the houses contained high levels of mite allergen (> 2 micrograms/g), while approximately 40% of the children were exposed to cat and 17% were exposed to cockroach allergen. In this population, there was no significant association between asthma and race, socioeconomic status, home smoking, sensitization to outdoor allergens, or allergen concentration in the child's home. In an area where there is a high prevalence of asthma and most houses contain high concentrations of dust mite allergen, sensitization to this allergen is the dominant risk factor for asthma defined as symptomatic bronchial hyperreactivity

Symptomatic and asymptomatic left-ventricular systolic dysfunction in an urban population

BACKGROUND

In most previous epidemiological studies on the prevalence of chronic heart failure (CHF) the disorder has been defined on clinical criteria. In a cross-sectional survey of 2000 men and women aged 25-74, randomly sampled from one geographical area, we assessed left-ventricular systolic function by echocardiography.

METHODS

1640 (83%) of those invited took part. They completed a questionnaire on current medication, history, and symptoms of breathlessness. Blood pressure was measured and electrocardiography (ECG) and echocardiography were done. Left-ventricular ejection fraction was measurable in 1467 (89.5%) participants by the biplane Simpson's rate method.

FINDINGS

The mean left-ventricular ejection fraction was 47.3%. The prevalence of definite left-ventricular systolic dysfunction (defined as a left-ventricular ejection fraction < or = 30%) was 2.9% overall (43 participants); it increased with age and was higher in men than in women (4.0 vs 2.0%). The left-ventricular systolic dysfunction was symptomatic in 1.5% of participants and asymptomatic in 1.4%, 83% of participants with left-ventricular systolic dysfunction had evidence of ischaemic heart disease (IHD) from history or ECG criteria compared with 21% of those without this abnormality (p < 0.001). Hypertension was also more common in those with left-ventricular systolic dysfunction (72 vs 38%, p < 0.001), but there was no difference between those with and without left-ventricular systolic dysfunction in the rate of hypertension without IHD.

INTERPRETATION

Left-ventricular systolic dysfunction was at least twice as common as symptomatic heart failure defined by clinical criteria. The main risk factors are IHD and hypertension in the presence of IHD; screening of such high-risk groups for left-ventricular systolic dysfunction should be considered.

Late adolescents' perceptions of their caregiver's feeding styles and practices and those they will use with their own children

The purpose of this study was to examine the perceptions of late adolescents regarding their caregivers' feeding styles and practices and their perceptions of those they plan to use with their children. The 546 subjects were from a randomly selected sample of 1,000, nonparenting, 18 to 23-year old college students who responded to a questionnaire. Two distinct feeding styles emerged: adult-controlled and cooperative. The adult-controlled style reflects a perception of control which the adult decides what and how much a child will eat. The cooperative style reflects shared control where the adult decides what food will be presented and the child decides how much and whether to eat. Chi-square analysis of the relationship between subjects' perceptions of their caregivers' feeding styles and their perceptions of the styles they believe they will use with their children, resulted in a positive association. To examine perceived past and future feeding practices, a Pearson's r was computed on subscales from a factor analysis. Results indicated positive correlations between subjects' perceived past and future feeding practices. These results suggest generational transmission of feeding styles and practices. A recommendation is made for parent and nutrition educators to focus on both parenting styles and feeding practices.

The effect of acute ethanol (EtOH) exposure on protein kinase C (PKC) activity in anterior pituitary

Alterations in the protein kinase C (PKC) pathway may interrupt anterior pituitary luteinizing hormone (LH) synthesis and/or secretion, which may impair normal reproductive function. Work by our laboratory and others has shown that EtOH has profound deleterious effects on the regulation of the hypothalamic-pituitary-gonadal (HPG) axis. The present study focuses on PKC translocation from the cytosol to the membrane of anterior pituitary after acute EtOH exposure. Serum levels of LH were measured at three time points (15, 30, and 90 min) after an IP injection of either saline or 3 g/kg EtOH in adult castrated male rats. LH levels dropped significantly (p < 0.03) in EtOH-injected compared to saline-injected control animals. In the same animals, EtOH significantly suppressed PKC localization at its active site at the pituitary cell membrane (p < 0.05). These findings suggest that the mechanism of EtOH's suppression of LH is mediated, at least in part, through a decrease in PKC translocation to the anterior pituitary cell membrane.

Evidence based dentistry

We live in an age of information, innovation and change. Clinical decision making based on good quality evidence should lead to more effective and efficient treatments. Each practitioner has a role in assessing this information. This paper outlines this role, together with the advantages and problems of introducing an evidence based approach to dentistry.

A dissociation in the relation between memory tasks and frontal lobe tests in the normal elderly

In this study a group of elderly subjects were examined on three tests of frontal lobe function. Two of these tests, FAS word fluency and the Alternate Uses Test, were considered tests of spontaneous flexibility, as defined by Eslinger and Grattan [Neuropsychologia 31, 17-28, 1993]. The third, the modified Wisconsin Card Sorting Test (WCST), is considered a test of reactive flexibility. Performance on two tests of memory, release from proactive interference (PI) and a matched recall and recognition test was also measured. The elderly were shown to be impaired on all tests when compared with young controls. Analysis revealed that release from proactive interference was significantly correlated with performance on alternative uses but not WCST while the size of subjects' discrepancy between recall and recognition correlated strongly with WCST but not with Alternate Uses. In addition there was a strong correlation between the two measures of spontaneous flexibility but these measures did not correlate with WCST. Performance on the two measures of memory was also uncorrelated. The data indicate that the pattern of frontal deterioration in the elderly does not comprise a single deficit and, furthermore, that the relationship between frontal dysfunction and normal age-related memory loss is not unidimensional.