Decellularized periodontal ligament cell sheets with recellularization potential.

The periodontal ligament is the key tissue facilitating periodontal regeneration. This study aimed to fabricate decellularized human periodontal ligament cell sheets for subsequent periodontal tissue engineering applications. The decellularization protocol involved the transfer of intact human periodontal ligament cell sheets onto melt electrospun polycaprolactone membranes and subsequent bi-directional perfusion with NH4OH/Triton X-100 and DNase solutions. The protocol was shown to remove 92% of DNA content. The structural integrity of the decellularized cell sheets was confirmed by a collagen quantification assay, immunostaining of human collagen type I and fibronectin, and scanning electron microscopy. ELISA was used to demonstrate the presence of residual basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) in the decellularized cell sheet constructs. The decellularized cell sheets were shown to have the ability to support recellularization by allogenic human periodontal ligament cells. This study describes the fabrication of decellularized periodontal ligament cell sheets that retain an intact extracellular matrix and resident growth factors and can support repopulation by allogenic cells. The decellularized hPDL cell sheet concept has the potential to be utilized in future "off-the-shelf" periodontal tissue engineering strategies.

The influence of surface microroughness and hydrophilicity of titanium on the up-regulation of TGFß/BMP signalling in osteoblasts.

The topography of titanium implants has been identified as an important factor affecting the osseointegration of surgically placed dental implants. Further modification to produce a hydrophilic microrough titanium implant surface has been shown to increase osseointegration compared with microrough topology alone. This study aimed to determine possible molecular mechanisms to explain this clinical observation by examining differences in the whole genome mRNA expression profile of primary human osteoblasts in response to sand-blasted acid-etched (SLA) and hydrophilic SLA (modSLA) titanium surfaces. A decrease in osteoblast proliferation associated with the titanium surfaces (modSLA > SLA > control) correlated with an increase in expression of the osteogenic differentiation markers BSPII and osteocalcin. Pathway analysis demonstrated that a number of genes associated with the TGFß­BMP signalling cascade (BMP2, BMP6, SP1, CREBBP, RBL2, TBS3, ACVR1 and ZFYVE16) were significantly differentially up-regulated with culture on the modSLA surface. BMP2 was shown to have the largest fold change increase in expression which was subsequently confirmed at the protein level by ELISA. Several other genes associated with the functionally important mechanisms relevant to bone healing, such as Wnt signalling (CTNNA1, FBX4, FZD6), angiogenesis (KDR), osteoclastogenesis (HSF2, MCL1) and proteolysis (HEXB, TPP1), were also differentially regulated. These results suggest that chemical (hydrophilic) modification of the SLA surface may result in more successful osseointegration through BMP signalling.

Progression of periodontal disease and interleukin-10 gene polymorphism.

BACKGROUND AND OBJECTIVE: Interleukin-10 is a key immunoregulatory cytokine that may be of significance in the immunopathogenesis of chronic inflammatory diseases such as periodontal disease. Molecular genetic studies have defined a number of haplotypes that may be associated with differing levels of interleukin-10 secretion. The present study investigated the possible association between interleukin-10 gene polymorphism and periodontal disease progression. MATERIAL AND METHODS: Genomic DNA was obtained from 252 adults who were part of a prospective longitudinal study on the progression of periodontal disease in a general adult Australian population. Single nucleotide polymorphisms at positions -592 and -1082 in the interleukin-10 promoter were analysed using an induced heteroduplex methodology and used to determine interleukin-10 promoter haplotypes in individual samples. Periodontitis progression was assessed by measuring probing depths and relative attachment levels at regular intervals over a 5-year period. A generalized linear model was used to analyse the data, with age, gender, smoking status, interleukin-1 genotype and Porphyromonas gingivalis included as possible confounders. RESULTS: There was a significant (p approximately 0.02) main effect of interleukin-10 haplotypes, with individuals having either the ATA/ACC or the ACC/ACC genotype experiencing around 20% fewer probing depths of >or= 4 mm compared to individuals with other genotypes. Age and smoking had significant (p < 0.001) additional effects. CONCLUSION: These data suggest that the interleukin-10 genotype contributes to the progression of periodontal disease.

A 5-year longitudinal study of Tannerella forsythia prtH genotype: association with loss of attachment.

BACKGROUND: Tannerella forsythia (previously T. forsythensis) in subgingival plaque has been recognized as a defined periodontal pathogen, but its mere presence may be insufficient for disease initiation and/or progression. The organism may produce a cysteine protease, encoded by the prtH gene, which may play a role in the transition from commensal organism to opportunistic pathogen. This study aimed to relate changes in the level of T. forsythia prtH genotype over a 5-year period to a concomitant loss of attachment. METHODS: Real-time polymerase chain reaction was used to quantify the level of the prtH gene in plaque samples from subjects with and without attachment loss (> or =2 mm in at least two sites) over a 5-year period. Clinical measures and subgingival plaque samples were obtained at yearly intervals. RESULTS: Baseline levels of the prtH genotype were significantly lower in the subjects without loss of attachment compared to those who lost attachment over 1, 2, 4, or 5 years. In the subjects with loss of attachment, the higher prtH levels at baseline were not maintained until the end of the observation period. CONCLUSION: Higher levels of the prtH genotype were associated significantly with future attachment loss.

Cross-reactivity of GroEL antibodies with human heat shock protein 60 and quantification of pathogens in atherosclerosis.

BACKGROUND/AIMS: Chronic infections such as those caused by Chlamydia pneumoniae and periodontopathic bacteria such as Porphyromonas gingivalis have been associated with atherosclerosis, possibly due to cross-reactivity of the immune response to bacterial GroEL with human heat shock protein (hHSP) 60. METHODS: We examined the cross-reactivity of anti-GroEL and anti-P. gingivalis antibodies with hHSP60 in atherosclerosis patients and quantified a panel of six pathogens in atheromas. RESULTS: After absorption of plasma samples with hHSP60, there were variable reductions in the levels of anti-GroEL and anti-P. gingivalis antibodies, suggesting that these antibodies cross-reacted with hHSP60. All of the artery specimens were positive for P. gingivalis. Fusobacterium nucleatum, Tannerella forsythia, C. pneumoniae, Helicobacter pylori, and Haemophilus influenzae were found in 84%, 48%, 28%, 4%, and 4% of arteries, respectively. The prevalence of the three periodontopathic microorganisms, P. gingivalis, F. nucleatum and T. forsythia, was significantly higher than that of the remaining three microorganisms. CONCLUSIONS: These results support the hypothesis that in some patients, cross-reactivity of the immune response to bacterial HSPs including those of periodontal pathogens, with arterial endothelial cells expressing hHSP60 may be a possible mechanism for the association between atherosclerosis and periodontal infection.

Acquisition and loss of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia over a 5-year period: effect of a triclosan/copolymer dentifrice.

OBJECTIVES: The present study describes the natural history of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia over a 5-year period and the effect of a triclosan/copolymer dentifrice on these organisms in a normal adult population. MATERIAL AND METHODS: Subgingival plaque samples were collected from 504 adult volunteers. Probing pocket depths (PPD) and relative attachment levels were measured using an automated probe. Participants were matched for disease status (CPI), plaque index, age and gender, and allocated to receive either a triclosan/copolymer or placebo dentifrice. Re-examination and subgingival plaque sampling was repeated after 1, 2, 3, 4 and 5 years. P. gingivalis, A. actinomycetemcomitans and P. intermedia were detected and quantitated using an enzyme linked immunosorbent assay. Logistic regression and generalised linear modelling were used to analyse the data. RESULTS: This 5-year longitudinal study showed considerable volatility in acquisition and loss (below the level of detection) of all three organisms in this population. Relatively few subjects had these organisms on multiple occasions. While P. gingivalis was related to loss of attachment and to PPD >/=3.5 mm, there was no relationship between A. actinomycetemcomitans or P. intermedia and disease progression over the 5 years of the study. Smokers with P. gingivalis had more PPD >/=3.5 mm than smokers without this organism. There was no significant effect of the triclosan dentifrice on P. gingivalis or A. actinomycetemcomitans. Subjects using triclosan were more likely to have P. intermedia than those not using the dentifrice; however this did not translate into these subjects having higher levels of P. intermedia and its presence was uniform showing no signs of increasing over the course of the study. CONCLUSION: The present 5-year longitudinal study has shown the transient nature of colonisation with P. gingivalis, A. actinomycetemcomitans and P. intermedia in a normal adult population. The use of a triclosan-containing dentifrice did not lead to an overgrowth of these organisms. The clinical effect of the dentifrice would appear to be independent of its antimicrobial properties.

The effect of a triclosan-containing dentifrice on the progression of periodontal disease in an adult population.

OBJECTIVES: The aim of the present study was to determine the effect of unsupervised, long-term use of a 0.3% triclosan/2% copolymer dentifrice on the progression of periodontal disease in a general adult population. METHODS: Five hundred and four volunteers were enrolled in a double-blind, controlled clinical trial. Participants were matched for disease status, plaque index, age and gender. At the baseline examination, probing pocket depths and relative attachment levels were recorded and participants were assigned to either the test or control group. Re-examinations took place after 6, 12, 24, 36, 48 and 60 months. Subgingival plaque samples were collected at each examination and assayed for Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia. A generalised linear model was used to analyse the data, with a number of covariates thought to influence the responses included as the possible confounding effects. RESULTS: The triclosan/copolymer dentifrice had a significant effect in subjects with interproximal probing depths > or =3.5 mm, where it significantly reduced the number of sites with probing depths > or =3.5 mm at the following examination, when compared with the control group (p<0.001). Furthermore, this effect increased with increasing numbers of affected sites. There was no effect of the triclosan/copolymer dentifrice in individuals without probing depths > or =3.5 mm at the previous examination. Other factors significantly affecting probing pocket depths (PPD) included increasing age, smoking and presence of P. gingivalis. PPD > or =3.5 mm were positively associated with loss of attachment some 2 years later. CONCLUSION: This study showed that in a normal adult population, unsupervised use of a triclosan/copolymer dentifrice is effective in slowing the progression of periodontal disease.

A longitudinal study of interleukin-1 gene polymorphisms and periodontal disease in a general adult population.

BACKGROUND: Cross-sectional studies have demonstrated that a specific polymorphism (allele 2 of both IL-1A +4845 and IL-1B +3954) in the IL-1 gene cluster has been associated with an increased susceptibility to severe periodontal disease and to an increased bleeding tendency during periodontal maintenance. The aim of the present study was to investigate the relationship between IL-1 genotype and periodontitis in a prospective longitudinal study in an adult population of essentially European heritage. METHODS: From an ongoing study of the Oral Care Research Programme of The University of Queensland, 295 subjects consented to genotyping for IL-1 allele 2 polymorphisms. Probing depths and relative attachment levels were recorded at baseline, 6, 12, 24, 36, 48 and 60 months using the Florida probe. Periodontitis progression at a given site was defined as attachment loss > or =2 mm at any observation period during the 5 years of the study and the extent of disease progression determined by the number of sites showing attachment loss. Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia were detected using ELISA. RESULTS: 38.9% of the subjects were positive for the composite IL-1 genotype. A relationship between the IL-1 positive genotype and increased mean probing pocket depth in non-smokers greater than 50 years of age was found. Further, IL-1 genotype positive smokers and genotype positive subjects with P. gingivalis in their plaque had an increase in the number of probing depths > or =3.5 mm. There was a consistent trend for IL-1 genotype positive subjects to experience attachment loss when compared with IL-1 genotype negative subjects. CONCLUSION: The results of this study have shown an interaction of the IL-1 positive genotype with age, smoking and P. gingivalis which suggests that IL-1 genotype is a contributory but non-essential risk factor for periodontal disease progression in this population.

Distribution of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia in an Australian population.

BACKGROUND/AIM: The present study describes (i) the natural distribution of the three putative periodontopathogens Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans in an Australian population and (ii) the relationship between these organisms, pocket depths and supragingival plaque scores. METHODS: Subgingival plaque was collected from the shallowest and deepest probing site in each sextant of the dentition. In total, 6030 subgingival plaque samples were collected from 504 subjects. An ELISA utilising pathogen-specific monoclonal antibodies was used to quantitate bacterial numbers. RESULTS: : A. actinomycetemcomitans was the most frequently detected organism (22.8% of subjects) followed by P. gingivalis and P. intermedia (14.7% and 9.5% of subjects respectively). The majority of infected subjects (83%) were colonised by a single species of organism. A. actinomycetemcomitans presence was over-represented in the youngest age group but under-represented in the older age groups. Conversely, P. gingivalis and P. intermedia presence was under-represented in the youngest age group but over-represented in the older age groups. Differing trends in the distribution of these bacteria were observed between subjects depending upon the site of the infection or whether a single or mixed infection was present; however, these differences did not reach significance. Bacterial presence was strongly associated with pocket depth for both A. actinomycetemcomitans and P. gingivalis. For A. actinomycetemcomitans, the odds of a site containing this bacterium decrease with deeper pockets. In contrast, for P. gingivalis the odds of a site being positive are almost six times greater for pockets >3 mm than for pockets < or =3 mm. These odds increase further to 15.3 for pockets deeper than 5 mm. The odds of a site being P. intermedia positive were marginally greater (1.16) for pockets deeper than 3 mm. CONCLUSIONS: This cross-sectional study in a volunteer Australian population, demonstrated recognised periodontal pathogens occur as part of the flora of the subgingival plaque. Prospective longitudinal studies are needed to examine the positive relationship between pocket depth and pathogen presence with periodontal disease initiation and/or progression.

Reduced adrenal secretory mass after unilateral adrenalectomy for aldosterone-producing adenoma may explain unexpected incidence of hypotension.

In a prospective study of 37 patients who had unilateral adrenalectomy for an aldosterone-producing adenoma, five of 33 (15%) were symptomatically hypotensive after at least 1 year, and eight of 29 (28%) who were observed 3, 6, 12, 18 and 24 months after the operation showed 2-year blood pressures below the fifth percentile for age- and sex-matched controls. Postoperatively, plasma aldosterone was lower, and plasma renin activity higher than in controls, these differences being more marked in the hypotensive group. Pre-operatively elevated atrial natriuretic factor fell to levels lower than in controls. These serial changes in volume-regulatory hormones are consistent with chronic hypovolaemia, due to relative hypoaldosteronism. Plasma cortisol was lower 6 months after the operation and plasma adrenaline levels fell by half. A reduced adrenocortical (aldosterone and cortisol) and adrenomedullary (adrenaline) secretory mass may play a role in the hypotension observed after unilateral adrenalectomy.

Levels of atrial natriuretic peptide are not always consistent with atrial pressure: is there alternative regulation as evidenced in Gordon's and Bartter's syndromes?

1. In Bartter's syndrome, atrial pressures were low, consistent with volume contraction, while atrial natriuretic peptide (ANP) levels were unexpectedly elevated. Infusion of normal saline increased both right atrial pressure (RAP) and ANP levels, while administration of prostaglandin inhibitors raised RAP, probably due to volume expansion, but ANP levels fell paradoxically. 2. In Gordon's syndrome, atrial pressures were unexpectedly low or normal despite volume expansion, while ANP levels were normal. Pressor infusions of angiotensin II either raised right and left atrial pressures (LAP) without increasing ANP, or increased ANP without increasing atrial pressures. 3. In these two syndromes, atrial pressures and ANP levels were poorly correlated, leading to the proposal that other regulators of ANP may be important.

Effects of altitude on atrial natriuretic peptide: the Bicentennial Mount Everest Expedition.

1. Overnight recumbent atrial natriuretic peptide levels were significantly elevated in all ten subjects of the Australian Bicentennial Mount Everest Expedition during the first week at 5400 m, during acclimatization. 2. Twenty-four hour urine volume and urine sodium increased markedly at altitude. 3. Plasma renin activity and plasma aldosterone levels decreased significantly at altitude. 4. No significant changes in plasma cortisol, plasma sodium or potassium, body temperature, systolic or diastolic blood pressure or heart rate were observed. 5. Although it was impossible to control or measure salt and water intake during the study, results suggest that atrial natriuretic peptide may be important in the reduction in renin and aldosterone levels and in the diuresis and natriuresis necessary to adapt to hypoxia at altitude.

Unexpected incidence of low blood pressure 2 years after unilateral adrenalectomy for primary aldosteronism.

1. Serial observations of blood pressure after unilateral adrenalectomy for aldosterone-producing adenoma revealed an incidence of hypotension (systolic BP less than fifth percentile for age- and sex-matched normal population) of 27% at 2 years, more than 5 times that predicted. 2. Serial observations of volume regulatory hormones showed significantly raised mean levels of plasma renin activity consistent with hypovolaemia. Significantly reduced mean aldosterone levels despite significantly raised mean plasma renin activity levels may reflect reduced responsiveness of the remaining adrenal. 3. Reduction of significantly elevated preoperative ANP levels to significantly reduced levels postoperatively is also in keeping with postoperative hypovolaemia. 4. A 50% reduction in plasma adrenaline after unilateral adrenalectomy might contribute to reduced noradrenergic activity (prejunctional beta-receptor) and reduced blood pressure, but plasma noradrenaline did not fall significantly postoperatively. 5. Postoperative levels of renin, aldosterone, adrenaline and noradrenaline were not significantly different between those who did, and those who did not, become hypotensive.

A new Australian kindred with the syndrome of hypertension and hyperkalaemia has dysregulation of atrial natriuretic factor.

A family with the syndrome of hypertension and hyperkalaemia affecting six members in two generations is reported from Australia, where the first two sporadic cases were described. All family members had hyperkalaemia, hyperchloraemia and normal creatinine clearance. Only one affected adult and no affected children were hypertensive, possibly because of habitual low-salt diets. Plasma potassium fell significantly during fludrocortisone acetate administration, and urine potassium increased during saline infusion, consistent with renal tubular responsiveness to mineralocorticoid. Low plasma renin activity and pressor hyper-responsiveness to angiotensin II suggested sodium volume overload, but atrial natriuretic factor (ANF) was normal or only slightly elevated when compared with clearly elevated levels in primary aldosteronism. Plasma ANF was unresponsive to the usually reliable stimulus of angiotensin infusion in the two brothers affected and to saline infusion in one of them. These findings are consistent with a renal tubular avidity for sodium, leading to volume expansion, suppression of renin, and, depending on dietary sodium intake, hypertension. A role for dysregulation of ANF in the pathophysiology is possible.

Diagnosis of unilateral renovascular hypertension: comparative effect of intravenous enalaprilat and oral captopril.

The effectiveness of 2 angiotensin converting enzyme inhibitors, intravenous enalaprilat and oral captopril, in stimulating renin secretion was compared in 47 hypertensive patients with suspected renovascular hypertension. Both inhibitors were more effective stimuli to renin secretion than head-up tilting of the patient. In patients with unilateral renovascular hypertension single doses of angiotensin converting enzyme inhibitors increased the renal venous renin ratio compared to the recumbent ratio. This therapy reduced the number of false negative studies more effectively than head-up tilting and was tolerated better. Contralateral suppression of renin in the unaffected kidney, an important ancillary diagnostic marker of unilateral renovascular hypertension, was preserved. No false positive studies owing to the use of angiotensin converting enzyme inhibitors acutely were apparent. Mean arterial pressure decreased by 5 minutes with intravenous enalaprilat and by 20 minutes with oral captopril, and it continued to decrease gradually for at least 2 hours. No significant syncopal symptoms were observed with either inhibitor. Plasma renin activity increased by 5 and 15 minutes with enalaprilat and captopril, respectively. Plasma aldosterone levels decreased by 10 minutes with enalaprilat and by 30 minutes with captopril, and these changes increased in magnitude during the 2 hours of observation. To achieve the maximum diagnostic effectiveness from the renal venous renin ratio, single dose angiotensin converting enzyme inhibitors warrant consideration for routine use. Intravenous enalaprilat may be preferable because of certain achievement of an effective blood level.

Effects of volume expansion and contraction on plasma levels of atrial natriuretic peptide in man.

1. Effects of saline infusion and blood removal on atrial natriuretic peptide (ANP) in normal subjects were examined in order to better define the magnitude of acute central volume regulatory influences on ANP. 2. Plasma ANP levels increased progressively during volume expansion with saline infusion, increasing by 18% after 30 min and by 93% after 120 min, and did not change during recumbency alone. 3. Plasma ANP levels immediately after a standard blood donation performed semirecumbent were significantly lower than before blood donation; they fell by 18%. 4. The magnitude of the fall in ANP induced by blood donation correlated significantly with basal plasma ANP. 5. In man, ANP responds to both increases and decreases in central blood volume, consistent with a role for ANP in blood volume homeostasis.

Altering angiotensin levels by administration of captopril or indomethacin, or by angiotensin infusion, contributes to an understanding of atrial natriuretic peptide regulation in man.

1. Plasma atrial natriuretic peptide (ANP) levels were positively correlated with plasma renin activity (PRA) levels, when blood volume and blood pressure (BP) were not raised in normal subjects (NLS) or patients with postoperative aldosterone-producing adenoma (APA), Bartter's syndrome (BS), Addison's disease, anorexia nervosa, diuretic abuse or salt-losing congenital adrenal hyperplasia. 2. Angiotensin II infusion raised ANP levels in NLS, and patients with BS, pre- and postoperative APA, only when BP rose, suggesting that this effect might be mediated by the rise in BP. 3. Captopril lowered aldosterone and ANP levels in renal artery stenosis, but falling BP levels could mediate this effect. Captopril lowered aldosterone and BP in BS, but did not lower ANP, perhaps because angiotensin remained elevated. 4. Indomethacin lowered ANP when PRA was initially normal or raised (NLS and BS), but not when PRA was suppressed (APA). This effect could not be mediated by BP, which rose, but could be mediated by renin-angiotensin, which fell. 5. Factors other than central blood volume and atrial stretch may modulate ANP levels. Plasma angiotensin II may be such a factor, and may exert an important influence at high levels, especially when blood volume is low.

Adrenal transitional zone steroids, 18-oxo and 18-hydroxycortisol, useful in the diagnosis of primary aldosteronism, are ACTH-dependent.

1. The adrenal cortical 'hybrid' steroids 18-oxocortisol (18-OF) and 18-hydroxycortisol (18-OHF) are elevated in patients with typical angiotensin-unresponsive aldosterone-producing adenoma (AII-unresponsive APA) and fall to normal following surgical removal of the adrenal containing the tumour. Since 18-OF was six times the upper limit of normal pre-operatively, the tumour was the site of overproduction of hybrid steroids. 2. The failure of angiotensin-responsive APA to overproduce the hybrid steroids may be linked to their more 'normal' production of cortisol, which falls significantly on removal of the tumours. 3. Hybrid steroid levels were also normal in patients with idiopathic hyperplasia of the adrenals (IHA) and in low renin essential hypertension. 4. In AII-responsive APA, glucocorticoid-suppressible hyperaldosteronism (GSH) and IHA, the hybrid steroids showed brisk responses to stimulation by ACTH and suppression by dexamethasone of endogenous ACTH. 5. Long-term suppression by dexamethasone of hybrid steroids in GSH is consistent with ACTH dependence, rather than angiotensin dependence. 6. Studies of the regulation of hybrid steroid secretion in various categories of hypertension will further define the biosynthetic distinctiveness which is already useful diagnostically.

Angiotensin-responsive aldosterone-producing adenoma masquerades as idiopathic hyperaldosteronism (IHA: adrenal hyperplasia) or low-renin essential hypertension.

We have identified a subgroup of patients with aldosterone-producing adenoma (APA) who are responsive to angiotensin. Thus, a fall in plasma aldosterone (PA) during saline infusion may cause confusion with low-renin essential hypertension. Responsiveness of PA to angiotensin infusion and to upright posture may cause confusion with bilateral hyperplasia. Renin levels were not as completely suppressed in this angiotensin-responsive subgroup, leading to speculation that non-tumorous adrenal glomerulosa might also be less suppressed and might respond to angiotensin. This is unlikely, since angiotensin infusion soon after removal of the adenoma produced aldosterone levels of less than 10% of those achieved preoperatively. A biosynthetic peculiarity of the tumours is more likely, since urinary 18-oxo-cortisol levels were normal in this subgroup (as in bilateral hyperplasia) and raised in the more typical angiotensin-unresponsive subgroup (as in glucocorticoid-suppressible hyperaldosteronism). Since angiotensin-responsive tumours respond just as well to surgery as angiotensin-unresponsive tumours, it is important not to misdiagnose this subgroup as bilateral hyperplasia or low-renin essential hypertension.

Aldosterone-producing adenomas responsive to angiotensin pose problems in diagnosis.

1. A subgroup of patients with aldosterone-producing adenoma (APA) have been identified who lack many of the biochemical features regarded as characteristic of APA and used to distinguish APA from bilateral adrenal hyperplasia. 2. In these patients, aldosterone is responsive to infused angiotensin II (angiotensin-responsive APA), which explains their uncharacteristic responses to upright posture, saline infusion and fludrocortisone acetate administration. 3. The angiotensin-responsiveness of these patients may derive from the contralateral adrenal gland, since renin levels are less completely suppressed in angiotensin-responsive APA than in angiotensin-unresponsive APA. 4. However, while the excretion of 18-oxo-cortisol was consistently increased in angiotensin-unresponsive APA, it was normal in angiotensin-responsive APA, consistent with biochemical and biosynthetic distinctiveness residing in the tumours. 5. Angiotensin-responsive APA should always be considered as an alternative diagnosis to bilateral hyperplasia causing primary aldosteronism.