First-in-human in-vivo depiction of paraganglioma metabolism by hyperpolarised 13C-magnetic resonance

Phaeochromocytomas (PCC) and paragangliomas (PGL), cumulatively referred to as PPGLs, are neuroendocrine tumours arising from neural crest-derived cells in the sympathetic and parasympathetic nervous systems. Predicting future tumour behaviour and the likelihood of metastatic disease remains problematic as genotype-phenotype correlations are limited, the disease has variable penetrance and, to date, no reliable molecular, cellular or histological markers have emerged. Tumour metabolism quantification can be considered as a method to delineating tumour aggressiveness by utilising hyperpolarised 13 C-MR (HP-MR). The technique may provide an opportunity to non-invasively characterise disease behaviour. Here, we present the first instance of the analysis of PPGL metabolism via HP-MR in a single case.

Circadian variation in serum cortisol during hydrocortisone replacement is not attributable to changes in cortisol-binding globulin concentrations

BACKGROUND

Patients taking hydrocortisone (HC) replacement for primary or secondary adrenal failure require individual adjustment of their dose. In addition to modifying the administered doses of HC for each patient, physicians are increasingly interested in variations in the bioavailability of glucocorticoid replacement. One potential determinant of the bioavailability of replaced HC is a variation in serum cortisol-binding globulin (CBG) concentration, which may, in turn, affect interpretation of cortisol profiles and individual dose selection for patients on hydrocortisone replacement therapy.

AIM

To investigate the hypothesis that there is a circadian variation in CBG levels.

METHODS AND RESULTS

A total of 34 male patients divided into 3 groups (10 patients with non-somatotroph structural pituitary disease on HC replacement, 11 patients with treated acromegaly on HC replacement and 13 patients with treated acromegaly not on HC replacement) and 10 healthy volunteers were included. Cortisol and CBG levels were measured at 6 time points (0800, 1100, 1300, 1500, 1700 and 1900). No significant circadian variation in CBG concentration was found in any of the 4 groups.

CONCLUSION

Circadian variation in serum cortisol during hydrocortisone replacement is not attributable to changes in cortisol-binding globulin concentration. Changes in serum cortisol levels may thus be explained by other factors including 11 β-hydroxysteroid dehydrogenase type 1 activity or circadian changes in the binding properties of CBG.

Missense mutations in the melanocortin 2 receptor accessory protein that lead to late onset familial glucocorticoid deficiency type 2

BACKGROUND

Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by isolated glucocorticoid deficiency. Mutations in the ACTH receptor [melanocortin 2 receptor (MC2R)] or the MC2R accessory protein (MRAP) cause FGD types 1 and 2, respectively. Typically, type 2 patients present early (median age, 0.1 yr), and no patient reported to date has presented after 1.6 yr.

AIM

The aim of this study was to investigate the cause of disease in two families with late-onset FGD.

PATIENTS

The proband in family 1 was diagnosed at age 4 yr. Family review revealed two older siblings with undiagnosed FGD. One sibling was well, whereas the second had cerebral palsy secondary to hypoglycemic seizures. The proband in family 2 was diagnosed at age 18 yr with symptoms of fatigue, weight loss, and depression.

METHODS

The coding exons of MC2R and MRAP were sequenced. ACTH dose-response curves were generated for MC2R when transfected with wild-type or mutant MRAP constructs using HEK293 cells. MC2R trafficking with both mutant MRAPs was investigated using immunocytochemistry.

RESULTS

MRAP gene analysis identified two novel homozygous missense mutations, c.175T>G (pY59D) in family 1 and c.76T>C (p.V26A) in family 2. In vitro analysis showed that the Y59D mutant had significant impairment of cAMP generation, and both mutants caused a shift in the dose-response curve to the right when compared to wild type. Immunocytochemistry showed normal trafficking of MC2R when transfected with both mutant MRAPs, indicating a probable signaling defect.

CONCLUSION

These results indicate that missense MRAP mutations present with a variable phenotype of ACTH resistance and can present late in life.

Long-term experience of pegvisomant therapy as a treatment for acromegaly

AIMS

To evaluate the long-term efficacy and safety of pegvisomant as a treatment for acromegaly.

DESIGN

Retrospective analysis of clinical and trial data from all patients treated with pegvisomant since 1997 at two centres with common protocols.

RESULTS

Fifty-seven patients (age range 27-78 years) have been treated with pegvisomant since 1997 for up to 91 months (median 18 months). Before commencing pegvisomant, patients had an IGF-I above the upper limit of normal (ULN) of the age-related reference range (median 1.8 x ULN, range 1.2-4.1). Ninety-five per cent normalized IGF-I using a median dose of 15 mg daily (range 10 mg alternate day to 60 mg daily) with no influence of gender on dose requirement. Five patients had combination therapy with either somatostatin analogues (SSA) or cabergoline. Two patients initially controlled on 10 mg and 20 mg required dose increases (to 20 mg + 40 mg) over 24 months to reduce IGF-I. Twenty-seven patients stopped pegvisomant. Reasons included side-effects [abnormal liver function tests (LFTs)] and patient choice. Two patients developed elevated liver transaminases, which normalized on stopping pegvisomant. Patients had 6-12-monthly pituitary magnetic resonance imaging (MRI) scans. One patient had significant tumour size increase.

CONCLUSION

This long-term experience in 57 patients indicates pegvisomant to be effective, safe and well-tolerated. Raised transaminases occurred within the first month of therapy in two patients, and tumour growth was seen in one patient (tumour was growing prior to pegvisomant). In two patients increasing doses of pegvisomant were required to keep IGF-I within the target range.

The majority of adrenocorticotropin receptor (melanocortin 2 receptor) mutations found in familial glucocorticoid deficiency type 1 lead to defective trafficking of the receptor to the cell surface

CONTEXT

There are at least 24 missense, nonconservative mutations found in the ACTH receptor [melanocortin 2 receptor (MC2R)] that have been associated with the autosomal recessive disease familial glucocorticoid deficiency (FGD) type 1. The characterization of these mutations has been hindered by difficulties in establishing a functional heterologous cell transfection system for MC2R. Recently, the melanocortin 2 receptor accessory protein (MRAP) was identified as essential for the trafficking of MC2R to the cell surface; therefore, a functional characterization of MC2R mutations is now possible.

OBJECTIVE

Our objective was to elucidate the molecular mechanisms responsible for defective MC2R function in FGD.

METHODS

Stable cell lines expressing human MRAPalpha were established and transiently transfected with wild-type or mutant MC2R. Functional characterization of mutant MC2R was performed using a cell surface expression assay, a cAMP reporter assay, confocal microscopy, and coimmunoprecipitation of MRAPalpha.

RESULTS

Two thirds of all MC2R mutations had a significant reduction in cell surface trafficking, even though MRAPalpha interacted with all mutants. Analysis of those mutant receptors that reached the cell surface indicated that four of six failed to signal, after stimulation with ACTH.

CONCLUSION

The majority of MC2R mutations found in FGD fail to function because they fail to traffic to the cell surface.

Safety of GH replacement in hypopituitary patients with nonirradiated pituitary and peripituitary tumours

BACKGROUND

Published data suggest that growth hormone replacement (GHR) may be given safely to patients with hypopituitarism consequent upon a pituitary/peripituitary tumour. However, a preponderance of patients treated with external pituitary irradiation were included.

OBJECTIVE

To assess the safety of GHR in nonirradiated pituitary/peripituitary tumour.

DESIGN

Prospective audit.

SETTING

Tertiary university referral centre.

PATIENTS

We imaged prospectively the pituitary glands of 48 patients (18 males; mean age 51.6 years range 21-77) who had adult onset growth hormone deficiency (AO-GHD) after appropriate treatment for a pituitary/peripituitary tumour but who did not receive external pituitary irradiation.

INTERVENTION

All patients were treated with a dose titration regimen of GH to maintain serum IGF-1 between the median and upper end of the age-related reference range. Pituitary surveillance imaging was performed prior to the commencement of GHR, at 6-12 months and then yearly. For patients with secretory tumours, biochemical markers (cortisol and prolactin) were used as evidence of tumour recurrence.

RESULTS

48 patients with median follow up since commencement of GHR was 38 months (range 9-104). Three patients were judged to have an apparent increase in tumour volume and/or marker, although only one was thought to be possibly GH related--a patient with a cystic chromophobe adenoma who demonstrated a marginal increase in residual tumour volume 4 years after commencement of GHR.

CONCLUSION

These data add to the growing body of evidence for the safety of GHR in hypopituitary patients consequent upon pituitary/peripituitary mass lesions and represents the first reported series in a heterogeneous group of nonirradiated patients.

Treatment with GH and IGF-1 in Critical Illness

Trauma, sepsis, and surgery are associated with global hypercatabolism and a negative nitrogen balance. When critical illness is prolonged the relentless loss of lean tissue becomes functionally important. Protein catabolism in the critically ill patient is associated with complex changes in the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis. Many small clinical studies indicate that treatment with recombinant human (rh) GH would be a safe and effective means of limiting the deleterious effects of the catabolic response. Unexpectedly, however, two large prospective randomized controlled trials (PRCTs) demonstrated that administration of rhGH to long-stay critically ill adults increases morbidity and mortality. Some progress has been made in understanding the mechanisms underlying this observation.

Tumour surveillance imaging in patients with extrapituitary tumours receiving growth hormone replacement

OBJECTIVE

GH replacement is widely used in the management of patients with adult-onset (AO)-GH deficiency (GHD). In most cases, AO-GHD arises as a result of pituitary/peripituitary tumours and/or their treatment, but the effect of GH replacement on recurrence/regrowth of these tumours is unknown. The aim of this study was to examine the effect of GH replacement in a group of patients with primary tumours of the parasellar region, many of which (e.g. craniopharyngioma, glioma or germ cell tumours) might be anticipated to have a higher recurrence rate than secretory and nonsecretory anterior pituitary tumours.

PATIENTS AND DESIGN

We report here our experience of prospective imaging in 50 consecutive patients (21 males; mean age 45.9 years) with nonanterior pituitary parasellar tumours treated with GH. All had severe GHD (peak serum GH 9 mU/l or less on dynamic testing) and were treated with an identical dose-titration regimen to maintain serum IGF-I concentrations between the median and upper end of the age-adjusted normal range. The primary diagnoses were: craniopharyngioma (28), germ cell tumour (8), arachnoid cyst (4), meningioma (4), glioma (4) and mensenchymal tumour (2). External pituitary irradiation had been given to 37 (74%) of patients. Measurements Surveillance imaging (magnetic resonance imaging (MRI) 70%, computed tomography (CT) 16%, both 14%) was performed at baseline (prior to GH), at 6--12 months, and then again yearly or as clinically indicated. Median follow-up was 36 months (range 7--129 months). All images were reviewed by the same radiologist.

RESULTS

Four patients had an apparent increase in tumour volume but in only one patient was it considered necessary to abandon GH replacement. In two of the four cases marginal increases in cystic parasellar tumours were not progressive; and in the fourth case apparent recurrence of a suprasellar germ cell tumour was shown to be acellular fibrous tissue only on biopsy. In all other cases either the appearances were unchanged or the amount of tissue was reduced during long-term follow-up on GH.

CONCLUSIONS

Overall, GH appears safe with respect to tumour recurrence over this time period in this patient group. Comparison with similar prospective series in patients not receiving GH replacement is desirable.

Always look beyond the stones: hyperoxaluria overlooked

We report a case which demonstrates the disastrous consequences of late diagnosis of hyperoxaluria in a 24-year-old woman with nephrocalcinosis, a staghorn calculus and recurrent urinary tract infections. Her initial management at another hospital included multiple percutaneous nephrostomies and lithropsies. Metabolic screening was not undertaken. Hyperoxaluria was finally diagnosed by elevated urine oxalate (1.235 mmol/24 h) and renal biopsy, by which time there was already significant reduction of renal function. A diagnosis of hyperoxaluria type I was confirmed by liver biopsy. Despite starting pyridoxine and crystallization inhibitors, her renal function deteriorated, requiring hemodialysis and she was referred for combined liver-renal transplantation. Clinical clues of primary hyperoxaluria type I are a positive family history or presentation with severe renal stones at an unusually early age. Irrespective of the above, all patients with first presentation of renal calculi should undergo metabolic screening, including urine oxalate.

Transverse process of the atlas(C1)--an important surgical landmark of the upper neck

BACKGROUND

The internal carotid artery, the internal jugular vein, and the spinal accessory nerve are the main structures that are preserved in conservative neck dissections. In the upper neck, one surgical landmark used to find these structures is the transverse process of a cervical vertebral body. There is controversy about the origin of the transverse process in the upper neck.

METHODS

We applied three-dimensional computerized tomography (3-D CT), an intraoperative navigational system and cadaver dissection of the neck to clarify the controversy.

RESULTS

The origin of the transverse process was from the atlas (C1).

CONCLUSIONS

The transverse process of the atlas is an important surgical landmark in the upper neck. The neurovascular bundle is located anteriorly. The transverse process of the axis (C2) is less prominent and is situated antero-inferior to the spinal accessory nerve where the nerve emerges from the posterior border of the internal jugular vein.

Use of recombinant Epstein-Barr virus early antigen for detection of antibody in patients with nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is one of the most common cancers in southern China and Taiwan. Serological studies revealed the close-relationship between NPC and Epstein-Barr virus (EBV). Elevated serum and saliva levels of anti-EBV antibodies are detected in patients with NPC. Therefore, Development Center for Biotechnology prepared the EBV-early antigen (EA-D) by recombinant DNA technique for screening the serum and throat washing samples from patients with head and neck cancers.

METHODS

The BMRF1 gene for EBV early antigen (EA-D) was placed into the plasmid pDB18, then transformed into an Escherichia coli strain containing the lambda cI857 temperature-sensitive repressor. Heat treatment of the transformant, at exponential growth phase, inactivated the cI protein and induced an over-expression of the EA-D protein. Next, the EA-D was purified by chromatography and characterized as a protein of molecular weight 47 kDa, by sodium dodecyl sulfate-polyacry lamide gel electrophoresis (SDS-PAGE) and Western blot analysis using monoclonal anti-EA antibody and sera from patients with nasopharyngeal carcinoma (NPC). Enzyme-linked immunosorbent assay (ELISA) with the purified EA-D antigen was used to screen 129 serum and throat washing (TW) samples from patients with head and neck tumors, 24 from patients with a nonmalignant disease and 44 from normal donors.

RESULTS

Experimental results indicated significantly higher positive rates of EA-D IgA (69%) and EA-D IgG (91%) in NPC sera than in the sera of patients with other head and neck tumors and normal controls. TW samples from patients with NPC also showed a higher positive rate (34%) than the other groups (7-20%).

CONCLUSIONS

Results in this study demonstrate that the bacterially expressed EA-D antigen could be recognized by sera from patients with NPC and monoclonal anti-EA antibody. Thus, it has potential use in ELISA for screening EBV-related diseases such as NPC.

Prevalence of Taiwan variant of Epstein-Barr virus in throat washings from patients with head and neck tumors in Taiwan

The prevalence of the Epstein-Barr virus (EBV) Taiwan variant was investigated in the throat washing (TW) samples from patients with head and neck tumors, persons with nonmalignant diseases, and healthy adults in Taiwan. By using the EBV (BNLF-1 gene)-specific primers and PCR, the EBV latent membrane protein gene BNLF-1 was detected in 91 (61%) of the 150 TW samples from patients with tumors, including 25 (78%) of 32 patients with nasopharyngeal carcinoma and 66 (56%) of 118 other patients with head and neck tumors. The TW samples from the 26 patients with nonmalignant tumors and 53 healthy adults were also examined. Approximately 47% of these samples were positive for the EBV gene. The PCR products of the BNLF-1 gene were then subjected to XhoI digestion. Sixty-eight of 91 PCR products (75%) showed the loss of the XhoI site, which indicated the presence of a Taiwan strain of EBV in patients with tumors. The DNA sequence of the BNLF-1 gene of the Taiwan variant revealed that the loss of the XhoI site was due to a nucleotide change from a G to a T at position 169,426 in comparison with the sequence of prototype EBV B95-8 cells. Furthermore, the Taiwan strain appeared significantly more frequently in the TWs and tissue samples from patients with nasopharyngeal carcinoma (88%; P < 0.001) and laryngeal carcinoma (80%; P < 0.02) than in those samples from healthy adults (about 40%). These data indicate that a Taiwan variant of EBV may be closely associated with head and neck tumors and suggest that this variant may be important in the pathogenesis of head and neck tumors.