Treatment of primary aldosteronism is associated with a reduction in the severity of obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is known to commonly co-exist with primary aldosteronism (PA), but it is unknown if treatment of PA improves sleep apnoea parameters in these patients. We therefore aimed to determine whether specific medical or surgical treatment of PA improves OSA, as measured by the apnoea-hypopnoea index (AHI). We recruited patients undergoing diagnostic workup for PA if they had symptoms suggestive of OSA. Patients with confirmed PA underwent polysomnography (PSG) at baseline and again at least 3 months after specific treatment for PA. Of 34 patients with PA, 7 (21%) had no evidence of OSA (AHI <5), 9 (26%) had mild (AHI ⩾5 and <15), 8 (24%) moderate (AHI ⩾15 and <30) and 10 (29%) severe OSA (AHI ⩾30). Body mass index tertile, neck circumference and 24 h urinary sodium correlated with the AHI. Twenty patients had repeat PSG performed after treatment for PA (mineralocorticoid receptor antagonists in 13 with bilateral PA and adrenalectomy in 7 with unilateral PA). In this group the median (s.d.) AHI reduced from 22.5 (14.7) to 12.3 (12.1) (P=0.02). Neck circumference reduced with PA treatment (41.6 vs 41.2 cm, P=0.012). OSA is common in patients with primary aldosteronism and may improve with specific therapy for this disease. Aldosterone and sodium-mediated fluid retention in the upper airways and neck region may be a potential mechanism for this relationship.

CNS-specific regulatory elements in brain-derived HIV-1 strains affect responses to latency-reversing agents with implications for cure strategies

Latency-reversing agents (LRAs), including histone deacetylase inhibitors (HDACi), are being investigated as a strategy to eliminate latency in HIV-infected patients on suppressive antiretroviral therapy. The effectiveness of LRAs in activating latent infection in HIV strains derived from the central nervous system (CNS) is unknown. Here we show that CNS-derived HIV-1 strains possess polymorphisms within and surrounding the Sp transcription factor motifs in the long terminal repeat (LTR). These polymorphisms result in decreased ability of the transcription factor specificity protein 1 to bind CNS-derived LTRs, reducing the transcriptional activity of CNS-derived viruses. These mutations result in CNS-derived viruses being less responsive to activation by the HDACi panobinostat and romidepsin compared with lymphoid-derived viruses from the same subjects. Our findings suggest that HIV-1 strains residing in the CNS have unique transcriptional regulatory mechanisms, which impact the regulation of latency, the consideration of which is essential for the development of HIV-1 eradication strategies.

Collection and determination of nucleotide metabolites in neonatal and adult saliva by high performance liquid chromatography with tandem mass spectrometry

Saliva contains a number of biochemical components which may be useful for diagnosis/monitoring of metabolic disorders, and as markers of cancer or heart disease. Saliva collection is attractive as a non-invasive sampling method for infants and elderly patients. We present a method suitable for saliva collection from neonates. We have applied this technique for the determination of salivary nucleotide metabolites. Saliva was collected from 10 healthy neonates using washed cotton swabs, and directly from 10 adults. Two methods for saliva extraction from oral swabs were evaluated. The analytes were then separated using high performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS). The limits of detection for 14 purine/pyrimidine metabolites were variable, ranging from 0.01 to 1.0μM. Recovery of hydrophobic purine/pyrimidine metabolites from cotton tips was consistently high using water/acetonitrile extraction (92.7-111%) compared with water extraction alone. The concentrations of these metabolites were significantly higher in neonatal saliva than in adults. Preliminary ranges for nucleotide metabolites in neonatal and adult saliva are reported. Hypoxanthine and xanthine were grossly raised in neonates (49.3±25.4; 30.9±19.5μM respectively) compared to adults (4.3±3.3; 4.6±4.5μM); nucleosides were also markedly raised in neonates. This study focuses on three essential details: contamination of oral swabs during manufacturing and how to overcome this; weighing swabs to accurately measure small saliva volumes; and methods for extracting saliva metabolites of interest from cotton swabs. A method is described for determining nucleotide metabolites using HPLC with photodiode array or MS/MS. The advantages of utilising saliva are highlighted. Nucleotide metabolites were not simply in equilibrium with plasma, but may be actively secreted into saliva, and this process is more active in neonates than adults.

Associations of serum vitamin D concentrations with obstetric glucose metabolism in a subset of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study cohort

AIMS

To assess associations between maternal serum vitamin D concentration and glucose metabolism in a cohort of pregnant women living in an Australian subtropical environment.

METHODS

Cross-sectional assessment of 25-hydroxy vitamin D concentrations in 399 Hyperglycemia and Adverse Pregnancy Outcome ancillary study participants, treated at an obstetric teaching hospital in Brisbane, Australia. All patients underwent a blinded 75-g oral glucose tolerance test at 24-32 (target 28) weeks' gestation.

RESULTS

The mean (± standard deviation) fasting plasma glucose was 4.5 ± 0.4 mmol/l. Mean (± standard deviation) serum 25-hydroxy vitamin D was 132.5 ± 44.0 nmol/l. A difference of one standard deviation in maternal 25-hydroxy vitamin D was inversely related to fasting glucose (fasting glucose lower by 0.047 mmol/l, P=0.012) when assessed with multiple linear regression after adjusting for confounders. Maternal 25-hydroxy vitamin D correlated with β-cell function as estimated by the log-transformed homeostasis model assessment-β-cell function equation (r=0.131, P=0.009), but not with the homeostasis model assessment of insulin resistance.

CONCLUSIONS

An association between mid-gestational 25-hydroxy vitamin D and fasting glucose was confirmed in a largely normoglycaemic and vitamin D-replete pregnant population. The correlation between 25-hydroxy vitamin D and β-cell function suggests that vitamin D may influence glucose metabolism through this mechanism. Intervention studies are required to determine causality and the role of vitamin D replacement in deficient individuals.

Raised tryptase without anaphylaxis or mastocytosis: heterophilic antibody interference in the serum tryptase assay

Mast cell tryptase (MCT) is a key diagnostic test for mastocytosis and anaphylaxis. High serum tryptase levels are also one of the risk factors for adverse reaction in venom immunotherapy, yet occasional patients are seen with raised levels in the absence of either diagnosis. False positive results can be due to assay interference by heterophilic antibodies such as rheumatoid factor (RF) and human anti-mouse antibodies (HAMA). We therefore investigated heterophilic antibody interference by rheumatoid factor activity and HAMA as a cause of raised MCT results in the Phadia tryptase assay. Serum samples from 83 patients were assayed for MCT and rheumatoid factor before and after the use of heterophilic antibody blocking tubes (HBT). Samples with more than 17% reduction in MCT with detectable RF were then assayed for HAMA. Fourteen (17%) of the 83 samples with positive RF showed a >17% decrease in mast cell tryptase after HBT blocking. Post-HBT, eight of 14 (57%) reverted from elevated to normal range values with falls of up to 98%. RF levels were also decreased significantly (up to 75%). Only one of the 83 tested was apparently affected by HAMA in the absence of detectable IgM RF. In conclusion, any suspicious MCT result should be checked for heterophilic antibodies to evaluate possible interference. False positive MCT levels can be caused by rheumatoid factor. We suggest a strategy for identifying assay interference, and show that it is essential to incorporate this caveat into guidance for interpretation of MCT results.

Phenotypic and genotypic anti-microbial resistance profiles of campylobacters from untreated feedlot cattle and their environment

Anti-microbial resistance is an emerging public health issue. Farmed animals may act as reservoirs and potential sources of anti-microbial resistant Campylobacters. The aim of this study was to investigate the anti-microbial resistance profile of cattle and environmental Campylobacter isolates from normal untreated feedlot cattle, the role of the gyrA Thr-86-Ile mutation in ciprofloxacin-resistant Campylobacter jejuni isolates and the involvement of the tripartite CmeABC efflux system for multi-resistant C. jejuni isolates. The phenotypic anti-microbial resistance testing was carried out on 500 Campylobacter isolates (445 cattle isolates and 55 environmental isolates). In general, there was a higher level of anti-microbial resistance for the environmental isolates compared with the animal isolates, 45% of the animal isolates were resistant to one or more of the seven anti-microbials compared with 84% of the environmental isolates. The combined cattle and environmental Campylobacters had 34 (6.8%) isolates resistant to three or more of the seven anti-microbials tested on all isolates and 11 (2.2%) isolates were resistant to the seven anti-microbials. There was a substantial level of ciprofloxacin-resistant Campylobacters in both animal (8.5%) and environmental (21.8%) isolates. The gyrA Thr-86-Ile mutation was only present in five of 22 ciprofloxacin-resistant C. jejuni isolates investigated. No multi-drug-resistant associated mutation was detected in the CmeB or the CmeR regions investigated. In conclusion, our study observed a substantial level of Campylobacter anti-microbial resistance, highlighting the need for an active anti-microbial surveillance program for food animals in Ireland and the importance of the chosen sampling point can have on the findings of such a program.

Antibiotic resistance of retail food and human Campylobacter isolates on the island of Ireland from 2001-2002

The antimicrobial resistance profiles of Campylobacter isolates recovered from a range of retail food samples (n=374) and humans (n=314) to eight antimicrobial compounds were investigated. High levels of resistance in food C. jejuni isolates were observed for ceftiofur (58%), ampicillin (25%) and nalidixic acid (17%) with lower levels observed for streptomycin (7.9%) and chloramphenicol (8.3%). A total of 80% of human C. jejuni isolates were resistant to ceftiofur, while 17% showed resistance to ampicillin and nalidixic acid, 8.6% to streptomycin and 4.1% to chloramphenicol. Resistance to clinically relevant antimicrobials such as erythromycin, ciprofloxacin and tetracycline was 6.7, 12, and 15% respectively for all food isolates and was similar to corresponding resistance prevalences observed for human isolates, where 6.4, 12 and 13% respectively were found to be resistant. Comparisons of C. jejuni isolates in each location showed a high degree of similarity although some regional variations did exist. Comparison of total C. jejuni and C. coli populations showed minor differences, with C. jejuni isolates more resistant to ampicillin and ceftiofur. Multidrug resistance patterns showed some profiles common to human and clinical isolates.

Occurrence of Campylobacter in retail foods in Ireland

A surveillance study was carried out to determine the prevalence of Campylobacter in a range of retail foods purchased in three Irish cities over a 20-month period between March 2001 and October 2002. In total 2391 food samples were analysed during this period. Campylobacter was isolated from 444 raw chicken (49.9%), 33 turkey (37.5%) and 11 duck samples (45.8%). Lower isolation rates of 7/221 (3.2%), 10/197 (5.1%) and 31/262 (11.8%) were observed for raw beef, pork and lamb, respectively. One sample of pork paté from 120 samples analysed (0.8%) was Campylobacter-positive. A total of three shellfish samples (oysters) from 129 raw specimens examined (2.3%) were found to contain Campylobacter. Low prevalences of the organism (0.9%) were also isolated from fresh mushrooms. Of 62 raw bulk tank milk samples analysed, Campylobacter was recovered in a single sample (1.6%). Campylobacter was not detected in any of the comminuted pork puddings, prepared vegetables and salads, retail sandwiches or cheeses made from unpasteurised milk. In total, 543 Campylobacter were isolated from all of the food samples analysed, of which 453 (83.4%) were confirmed as Campylobacter jejuni and the remaining 90 (16.6%) as Campylobacter coli.

A comparison of two culture media for the recovery of thermophilic campylobacters in broiler farm samples

A study to evaluate the performance of two different brands of media (Oxoid, Basingstoke, UK, and Mast Diagnostics, Merseyside, UK) for the isolation of thermophilic campylobacters from a range of broiler farm samples was undertaken. Oxoid media performed significantly better than the Mast formulations with overall Campylobacter recovery rates of 46% and 30.5%, respectively, observed from 213 samples tested (p< or =0.05). Consistently higher recoveries of campylobacters were observed from all samples when the results using both types of media were combined.

Non-anaemic iron deficiency identified by ZPP test in extremely premature infants: prevalence, dietary risk factors, and association with neurodevelopmental problems

INTRODUCTION

The aims of this study were to determine, in a cohort of extremely premature infants, the prevalence of iron deficiency identified by zinc protoporphyrin/heme ratio (ZPP) testing, and its association with neurodevelopmental problems and dietary risk factors for iron deficiency.

METHODS

Infants of less than 29 weeks' gestation or less than 1000 g birth weight were studied prospectively at a multidisciplinary follow-up clinic. Assessments were made at a corrected age of either 12 months (n=72) or 2 years (n=69). Physical examination, Griffiths Developmental Scale, and neurosensory-motor assessment were administered, information on diet and behaviour was obtained by questionnaire, and a fingerprick ZPP ratio was performed to identify iron deficiency.

RESULTS

18.4% of infants had positive ZPP tests. There was no significant association between a positive ZPP test result and dietary risk factors, or symptoms of lethargy, irritability or poor attention. In children without cerebral palsy, there was no difference on Griffiths scores or neurosensory-motor assessment between ZPP-positive and ZPP-negative groups. The diagnosis of cerebral palsy (n=12) was significantly associated with both a positive ZPP test and a lower Griffiths general quotient (GQ) score.

CONCLUSIONS

Iron deficiency occurs commonly in extremely low birth weight (ELBW) children in early childhood, and is not predicted by dietary risk factors. The prevalence of iron deficiency is increased in ELBW children with cerebral palsy. Non-anaemic iron deficiency (NAID) does not impair development or significantly affect behaviour of ELBW subjects who do not have cerebral palsy.

Placental growth hormone is not suppressed by oral glucose loading in normal human pregnancy

Placental growth hormone (PGH) progressively replaces pituitary growth hormone in the maternal circulation from mid-gestation onwards in human pregnancy. Our previous investigations have shown that placental growth hormone concentrations correlate well with foetal growth. Despite the apparent correlation between PGH and birthweight, the physiology of its secretion during pregnancy has not been well defined. We investigated the response of maternal serum PGH to oral glucose loading in pregnant women (n = 24) who demonstrated normal glucose tolerance at a mean gestation of 29 weeks. Mean (SEM) fasting PGH concentrations were high (36.9 [6.4] ng/ml). No suppression of PGH was noted at one, two or three hours after a 75 g oral glucose load. Similarly, no changes were noted in growth hormone binding protein or in calculated free PGH over the course of the glucose tolerance test. As expected, insulin concentrations rose sixfold and insulin like growth factor binding protein 1 concentrations fell by 20 % with glucose loading. Correlation analysis showed maternal weight, BMI, fasting serum glucose serum insulin to be significantly correlated with the babies' birthweight. Our results support the proposition that PGH concentrations in maternal serum are not suppressed by oral glucose loading in non-diabetic mothers.

Placental growth hormone (GH), GH-binding protein, and insulin-like growth factor axis in normal, growth-retarded, and diabetic pregnancies: correlations with fetal growth

We previously described significant changes in GH-binding protein (GHBP) in pathological human pregnancy. There was a substantial elevation of GHBP in cases ofnoninsulin-dependent diabetes mellitus and a reduction in insulin-dependent diabetes mellitus. GHBP has the potential to modulate the proportion of free placental GH (PGH) and hence the impact on the maternal GH/insulin-like growth factor I (IGF-I) axis, fetal growth, and maternal glycemic status. The present study was undertaken to investigate the relationship among glycemia, GHBP, and PGH during pregnancy and to assess the impact of GHBP on the concentration of free PGH. We have extended the analysis of specimens to include measurements of GHBP, PGH, IGF-I, IGF-II, IGF-binding protein-1 (IGFBP-1), IGFBP-2, and IGFBP-3 and have related these to maternal characteristics, fetal growth, and glycemia. The simultaneous measurement of GHBP and PGH has for the first time allowed calculation of the free component of PGH and correlation of the free component to indexes of fetal growth and other endocrine markers. PGH, free PGH, IGF-I, and IGF-II were substantially decreased in IUGR at 28-30 weeks gestation (K28) and 36-38 weeks gestation (K36). The mean concentration (+/-SEM) of total PGH increased significantly from K28 to K36 (30.0 +/- 2.2 to 50.7 +/- 6.2 ng/mL; n = 40), as did the concentration of free PGH (23.4 +/- 2.3 to 43.7 +/- 6.0 ng/mL; n = 38). The mean percentage of free PGH was significantly less in IUGR than in normal subjects (67% vs. 79%; P < 0.01). Macrosomia was associated with an increase in these parameters that did not reach statistical significance. Multiple regression analysis revealed that PGH/IGF-I and IGFBP-3 account for 40% of the variance in birth weight. IGFBP-3 showed a significant correlation with IGF-I, IGF-II, and free and total PGH at K28 and K36. Noninsulin-dependent diabetes mellitus patients had a lower mean percentage of free PGH (65%; P < 0.01), and insulin-dependent diabetics had a higher mean percentage of free PGH (87%; P < 0.01) than normal subjects. Mean postprandial glucose at K28 correlated positively with PGH and free PGH (consistent with the hyperglycemic action of GH). GHBP correlated negatively with both postprandial and fasting glucose. Although GHBP correlated negatively with PGH (r = -0.52; P < .001), free PGH and total PGH correlated very closely (r = 0.98). The results are consistent with an inhibitory function for GHBP in vivo and support a critical role for placental GH and IGF-I in driving normal fetal growth.

Maternal gonadal mosaicism causing ornithine transcarbamylase deficiency

Ornithine transcarbamylase (OTC) deficiency (McKusick 311250), an X-linked inherited disorder, often presents in males with severe neonatal onset of hyperammonemia. Maternal gonadal mosaicism in OTC deficiency was postulated previously, but no cases have been reported. We report on a family in which two consecutive males were affected with OTC deficiency, which was proven biochemically with characteristic metabolites and absent enzyme activity in liver. OTC genotyping in both brothers showed a new mutation in exon 6 (Met206Arg: ATG-->AGG), which encodes part of the equatorial H6 alpha-helix. Biochemical investigations confirmed normal results in the mother and grandmother and the absence of OTC activity in the affected males. Genotyping of the mother and grandmother was performed on peripheral blood leukocytes and skin fibroblasts and showed no mutation in the somatic cells. The recurrence of OTC deficiency in offsprings of a woman with normal genotype strongly suggests gonadal mosaicism. Gonadal mosaicism needs to be considered when counseling couples in which the mother has had a previously affected child with OTC deficiency but apparently is not a carrier.

Sodium lactate and hypertonic sodium chloride induce equivalent panic incidence, panic symptoms, and hypernatremia in panic disorder

BACKGROUND

Although experimental induction of panic by infusion of 0.5 mol/L sodium lactate in persons with panic disorder was described three decades ago, the mechanism underlying this observation remains unclear. Here we asked if the rapid administration of the large sodium load contained in the 0.5-mol/L sodium lactate infusion might be involved in panic induction.

METHODS

We compared in panic disorder and healthy subjects behavioral, electrolyte, endocrine, and acid-base responses to three double-blind randomly ordered equal volume 20-min infusions: 0.5 mol/L sodium lactate, hypertonic saline (3% sodium chloride), and normal saline placebo.

RESULTS

Sodium lactate (0.5 mol/L) and hypertonic saline produced the same high incidence of panic and equivalent increases in panic symptoms, serum sodium, and plasma vasopressin in the panic disorder subjects. Neither hypertonic infusion increased cortisol or adrenocorticotropin. No normal subject experienced panic in any condition. The 0.5-mol/L sodium lactate infusion induced alkalosis, whereas hypertonic saline and normal saline induced a mild acidosis.

CONCLUSIONS

Hypertonic sodium solution containing either chloride or lactate anion induces panic in panic disorder. The large sodium loads delivered by hypertonic saline and 0.5 mol/L sodium lactate may be involved in the mechanism of panic induction.

Is parathyroid hormone-related protein a sensitive serum marker in advanced breast cancer?

BACKGROUND

To compare already used serum markers in advanced breast cancer, namely erythrocyte sedimentation rate (ESR), carcino-embryonic antigen (CEA), and polymorphic epithelial mucins (e.g. CA15-3) with a newer potential marker: parathyroid hormone related protein (PTHrP).

METHODS

A study group of 33 patients of proven advanced breast cancer was compared with 11 patients with benign breast lumps who were undergoing surgery, and eight patients with humoral hypercalcaemia of malignancy of non-breast origin. ESR, CA15-3, CEA, PTHrP, parathormone (PTH), liver and renal function were measured using commercially available kits. Using given reference ranges, results were classified into normal versus abnormal, and univariate statistical comparisons were made using Fisher's exact test. For multivariate analysis, absolute serum levels were used, and multivariate logistic regression models were employed.

RESULTS

By univariate analysis, only CA15-3 (P = 0.007), and CEA (P = 0.004), were significant markers of metastatic disease. By multivariate analysis the only independently significant serum marker was CA15-3 (P = 0.043). PTHrP was neither a sensitive (22%) nor specific (90.1%) serum marker when compared to CEA or CA15-3. ESR was the most sensitive single serum marker (93%). An incidental finding of elevations of serum parathormone was found in as many patients as in the study group as there were elevations of PTHrP.

CONCLUSIONS

PTHrP would not have revealed any patients with metastatic disease that would not have been predicted by any existing tumour markers including CA15-3, CEA and ESR. The finding of elevated PTH in as many patients as PTHrP indicates the possible need for a study inclusive of other polypeptide hormones as markers in advanced breast cancer.

Fibronectin as a predictor of preeclampsia: a pilot study

The measurement of serum fibronectin levels in women carrying a singleton pregnancy at between 25-30 weeks' gestation has allowed the separation of those women who will remain normotensive from those who develop preeclampsia in this pilot study. The fibronectin assays were performed using nephelometry. It is recognized that some severe cases of preeclampsia will have already declared themselves clinically by 28 weeks' gestation, but if a screening test is to be limited by cost to a single test event, then this pilot study suggests the 28-week gestation time to be the most suitable. Further studies are being undertaken to test this hypothesis and to adequately assess the test's reliability, predictability and its cost-effectiveness.

The effects of substance use disorder on the clinical presentation of anxiety and depression in an outpatient psychiatric clinic

BACKGROUND

The comorbidity of substance abuse or dependence and psychiatric illness can complicate the diagnosis, clinical course, and treatment of dually diagnosed patients. In this study, we examined the relationship between substance use disorder (SUD) and psychopathology in an outpatient psychiatric setting.

METHOD

Among 391 patients evaluated at an anxiety and effective disorders clinic, 54 patients met DSM-III-R criteria for lifetime substance use disorder and current unipolar depression or anxiety disorder. We selected 54 sex- and age-matched controls with psychiatric illness without SUD as a comparison group. All patients were given a structured diagnostic interview and symptom rating scales. In addition to comparing dual and single diagnosis groups, we compared those within the dual diagnosis group and those with primary psychiatric disorder with those with primary SUD; we also compared those with current versus past SUD.

RESULTS

In contrast to findings in other settings, there were no significant differences in the severity of psychopathology between patients with and without substance abuse/dependence. Within dually diagnosed patients, those with primary mental disorder were more anxious and depressed than those with primary SUD. Patients with primary mental disorder had a significantly higher number of psychiatric diagnoses, an earlier onset of any psychiatric disorder, and were more likely to have received treatment. Conversely, patients with primary SUD had a higher number of substance use disorder diagnoses and an earlier onset of SUD.

CONCLUSION

Dually diagnosed patients had the same degree of psychopathology as patients with only psychiatric disorders in this outpatient psychiatric population. The primary/secondary classification may be useful to distinguish between subgroups of dual diagnosis patients. Future studies are necessary to determine if this distinction can be useful to predict course and outcome in dually diagnosed patients.

Psychopharmacologic treatment of panic, generalized anxiety disorder, and social phobia

The anxiety disorders discussed in this article are common, affecting 5% to 10% of the general population. They may cause significant distress and disability and are often complicated by substance abuse and depression. Fortunately, these disorders can be treated successfully in the majority of patients, with alleviation of the most distressing symptoms and significant improvement in occupational and social functioning. Systematic research studies during the past decade have identified both specific medication-responsive anxiety syndromes and a variety of psychopharmacologic agents effective in their management. Psychopharmacologic treatment, often in combination with cognitive-behavioral therapies, can be tailored for the individual patient based on that patient's specific anxiety syndrome, comorbid disorders, and vulnerability to side effects. Careful monitoring of target symptoms can be used to assess the efficacy of treatment. Future research will help to develop new classes of antianxiety agents for currently treatment-resistant patients, and to investigate further the necessary duration of psychopharmacologic treatment.

Individualizing aminophylline doses in premature infants using bioelectrical impedance: a non-invasive approach

The role of bioelectrical impedance (BI) in estimating the pharmacokinetics and, therefore, individualized doses, of aminophylline in preterm infants (gestational age 26-35 weeks) was assessed in a two-phase study. Multiple regression analysis in the first group of neonates (phase I, n = 19) identified resistance, reactance, weight and length as optimal predictors of distribution volume (adjusted R2 = 0.84, coefficient of variation (CV) = 10.17%), and length2/impedance and postconceptual age as predictors of clearance (adjusted R2 = 0.74, CV = 26.73%). Application of these models to an independent group (phase II, n = 20) generated doses which satisfactorily achieved target theophylline loading and steady-state (SS) 'peaks' of 10 micrograms/mL and SS 'troughs' of 7.7 +/- 0.6 micrograms/mL. A better understanding of specific criteria and limitations of the impedance technique in neonates is necessary in order to refine BI measurements.

The structure and partial synthesis of canaric acid

Canaric acid, the triterpene acid present in Canarium muelleri oleoresin, is shown by proton magnetic resonance studies, and by synthesis from lupeol, to have the 3,4-seco structure (VI).