Time to reposition sulfonylureas in type 2 diabetes management in Indian context: A pragmatic practical approach

Sulfonylureas (SU) continue to be a vital therapeutic category of oral hypoglycemic agents (OHAs) for the management of type 2 diabetes mellitus (T2DM). Physicians consider modern SU (gliclazide and glimepiride) as "safe and smart" choices for T2DM management. The presence of multiple international guidelines and scarcity of a national guideline may contribute to the challenges faced by few physicians in choosing the right therapeutic strategy. The role of SU in diabetes management is explicit, and the present consensus aims to emphasize the benefits and reposition SU in India. This pragmatic, practical approach aims to define expert recommendations for the physicians to improve caregivers' knowledge of the management of T2DM, leading to superior patient outcomes.

Consensus on Use of Insulins in Gestational Diabetes

INTRODUCTION

Gestational Diabetes Mellitus (GDM), diabetes diagnosed during pregnancy is associated with maternal (caesarean delivery, hypoglycaemia, hyperbilirubinaemia, shoulder dystocia, pre-term delivery and birth trauma) and fetal (Hyperbilirubinaemia in offspring, Neonatal hypoglycaemia, Macrosomia) complications. Despite, insulin being the standard treatment for GDM cases, there is no existing comprehensive consensus update on use of insulin in Indian patients with GDM.

OBJECTIVE

To provide simple and easily implementable guidelines to healthcare physicians on use of insulin in GDM.

METHODS

Each consensus based on indications, choice of insulin regimen , titration and insulin therapy during intrapartum and postpartum was presented based on established guidelines and published scientific literature. These evaluations were then factored into the national context based on the expert committee representatives' patient-physician experience in their clinical practice and common therapeutic practices followed in India for successful GDM management.

RESULTS

Recommendations based on use of insulin in GDM has been developed. The key recommendations are:to monitor fasting plasma glucose (FPG) and 2-hour post prandial glucose PPG levels and the glycaemic targets are: FPG < 95 mg/dL and 2-hour PPG < 120 mg/dL, short-and intermediate acting human insulin are the first choice of insulin regimens, rapid-acting (Insulin Aspart or Lispro) may be considered, use basal/intermediate acting insulin at bedtime, if FPG>110 mg/dL. During intrapartum, start IV insulin infusion with hourly glucose monitoring. Those women who require insulin < 20 U over 24 hours prior to labor may not need interpartum use of insulin infusion and Insulin dosing is stopped after birth and capillary glucose monitoring for 24-48 hours.

CONCLUSIONS

We hope that the consensus based recommendations mentioned in this paper will be a useful reference tool for healthcare practitioners to achieve glycaemic targets in GDM patients.

Consensus recommendations for the management of hyperglycaemia in critically ill patients in the Indian setting

Hyperglycaemia occurs frequently in critically-ill patients. Not only does it occur among patients with pre-existing diabetes mellitus but elevated blood glucose values during an acute illness can also be seen in previously glucose-tolerant individuals (stress hyperglycaemia). Numerous observational studies have shown an increase in morbidity and mortality in critically ill patients with hyperglycaemia. Interestingly, outcomes in individuals with stress hyperglycaemia are worse than that in critically ill hyperglycaemic patients with pre-existing diabetes. Proper management of hyperglycaemia has been shown to result in improved clinical outcomes. Critically ill patients with hyperglycaemia should primarily be managed with intravenous insulin infusion to allow dynamic adjustment of treatment to suit the rapid changes in blood glucose values in these patients. Currently, there are in existence a fair number of published protocols to administer intensive intravenous insulin therapy that range from the relatively simple to the fairly complex. Different management strategies have been proposed depending upon whether the critically ill hyperglycaemic patient is stationed in the emergency department, the medical intensive care unit (ICU), the surgical ICU or the coronary care unit. Moreover, the ideal target blood glucose value to maintain in this group of patients remains controversial. Keeping these issues in mind, a group of leading experts in the fields of diabetes and critical care extensively reviewed the literature and framed recommendations with special attention to clinical practice in India. The aim was to formulate recommendations which are based on sound evidence and yet are simple and easy to understand and implement across the ICU throughout the country. In the current recommendations, intensive intravenous insulin therapy has been suggested as the preferred mode of managing hyperglycaemia in patients admitted to critical care settings. The current recommendations suggest using a simple and similar protocol for managing hyperglycaemia in critically-ill patients irrespective of their location among the various critical care units in a hospital. Recommendations have also been made for transition from intravenous to subcutaneous administration of insulin when the patient is transferred out of the critical care setting. It is hoped that the current recommendations shall form the basis for the management of hyperglycaemia in critically ill patients across the country.

Dual blockade of the renin-angiotensin-aldosterone system is safe and effective in reducing albuminuria in Asian type 2 diabetic patients with nephropathy

INTRODUCTION

Blockade of the renin-angiotensin-aldosterone system (RAAS) by either the angiotensin converting enzyme inhibitor (ACE-I) or the angiotensin II receptor blocker (ARB) has been shown to reduce albuminuria and delay the progression of diabetic nephropathy. This study evaluated the effect of dual blockade of the RAAS by adding an ACEI or an ARB to the administration of either drug alone on albuminuria in Asian type 2 diabetic patients with nephropathy.

METHODS

34 patients were randomly assigned to receive either enalapril 20 mg or losartan 100 mg once daily for eight weeks. Following this, all patients received a combination of enalapril 10 mg and losartan 50 mg daily for eight weeks, followed by enalapril 20 mg and losartan 100 mg daily for another eight weeks. The blood pressure and 24-hour urinary albumin excretion (UAE) were monitored.

RESULTS

Following monotherapy with enalapril, there was a mean and standard error (SE) reduction in the UAE and mean arterial pressure (MAP) of 9.8 (SE 6.8) percent (p-value is 0.061) and 5.3 (SE 2.2) mmHg (p-value is 0.026), respectively; the reduction in UAE and MAP following monotherapy with losartan was by 10.9 (SE 14.1) percent (p-value is 0.053) and 4.5 (SE 1.9) mmHg (p-value is 0.034), respectively. Combination therapy with enalapril and losartan further reduced the UAE (11.2 [SE 8.7] percent, p-value is 0.009] despite there being no significant change in the MAP (-1.2 [SE 1.47] mmHg, p-value is 0.42). The adverse effects included dry cough (seven [19.4 percent] patients, resulting in the withdrawal of medication in two patients), and transient hyperkalaemia (two [six percent] patients).

CONCLUSION

Dual blockade of the RAAS is safe and effective in reducing albuminuria in Asian type 2 diabetic patients with nephropathy.

Type 2 diabetic patients with resistant hypertension should be screened for primary aldosteronism

BP control in diabetic patients is often poor. The contribution of secondary hypertension due to undiagnosed PA in hypertensive type 2 diabetic patients is not well studied. We prospectively screened 100 consecutive Asian type 2 diabetic patients with difficult-to-control or resistant hypertension for PA. PAC (pmol/L) to PRA (ng/mL/h) ratio was measured; those with PAC-to-PRA ratio >550 (corresponding PAC >415) underwent intravenous 0.9% SLT. Patients with PAC >/=140 following SLT had CT adrenals and bilateral AVS. Thirteen patients (13%) were confirmed to have PA, and all had resistant hypertension. Eight had a surgically correctable form of PA. Patients with PA had higher mean (SD) systolic [159.0 (10.6) vs. 146.0 (10.7) mmHg, p=0.001] and diastolic BP [94.6 (6.0) vs. 87.6 (5.9) mmHg, p=0.001], lower serum potassium [3.5 (0.6) vs. 4.3 (0.5) mmol/L, p=0.001], and higher PAC [679.3 (291.0) vs. 239.5 (169.4) pmol/L, p=0.001]. Identification and institution of definitive treatment for PA resulted in better BP control and in a reduction in the use of antihypertensive medications. Our findings demonstrate a high prevalence of PA in type 2 diabetic patients with resistant hypertension. Systematic screening for PA in this select group is recommended, as targeted treatment improves BP control.

Contrast extravasation after bilateral inferior petrosal sinus sampling masquerading as venous subarachnoid haemorrhage

When performed properly, bilateral inferior petrosal sinus sampling (BIPSS) for adrenocorticotropic hormone (ACTH) is rarely associated with complications. Major complications reported to date include thromboembolism, brain stem infarction, pontine haemorrhage, isolated sixth nerve palsy and venous subarachnoid haemorrhage. We describe a rare case where a predominant contrast extravasation into the subarachnoid space, admixed with a small quantity of venous blood, occurring during BIPSS in a 58-year-old woman with ACTH-dependent Cushing's syndrome, was misinterpreted as venous subarachnoid haemorrhage.

A Hyperthyroid Patient with Measurable Thyroid-stimulating Hormone Concentration – A Trap for the Unwary

Introduction: In a patient with hyperthyroidism, the detection of elevated thyroid hormone concentration with measurable thyroid-stimulating hormone (TSH) value poses considerable diagnostic difficulties. Clinical Picture: This 38-year-old lady presented with clinical features of thyrotoxicosis. Her serum free thyroxine concentrations were unequivocally elevated [45 to 82 pmol/L (reference interval, 10 to 20 pmol/L)] but the serum TSH values were persistently within the reference interval [0.49 to 2.48 mIU/L (reference interval, 0.45 to 4.5 mIU/L)]. Treatment: Investigations excluded a TSH-secreting pituitary adenoma and a thyroid hormone resistance state and confirmed false elevation in serum TSH concentration due to assay interference from heterophile antibodies. The patient was treated with carbimazole for 18 months. Outcome: The heterophile antibody-mediated assay interference disappeared 10 months following the initiation of treatment with carbimazole, but returned when the patient relapsed. It disappeared again 2 months after the initiation of treatment. Conclusions: Clinicians should be aware of the potential for interference in immunoassays, and suspect it whenever the test results seem inappropriate to the patient’s clinical state. Misinterpretation of test values, arising as a result of assay interference, may lead to misdiagnosis, unnecessary and at times expensive investigations, delay in initiation of treatment and worst of all, the initiation of inappropriate treatment. Key words: Heterophile antibodies, Immunoradiometric assay, Thyroid function tests, Thyrotoxicosis

A hyperthyroid patient with measurable thyroid-stimulating hormone concentration - a trap for the unwary

INTRODUCTION

In a patient with hyperthyroidism, the detection of elevated thyroid hormone concentration with measurable thyroid-stimulating hormone (TSH) value poses considerable diagnostic difficulties.

CLINICAL PICTURE

This 38-year-old lady presented with clinical features of thyrotoxicosis. Her serum free thyroxine concentrations were unequivocally elevated [45 to 82 pmol/L (reference interval, 10 to 20 pmol/L)] but the serum TSH values were persistently within the reference interval [0.49 to 2.48 mIU/L (reference interval, 0.45 to 4.5 mIU/L)].

TREATMENT

Investigations excluded a TSH-secreting pituitary adenoma and a thyroid hormone resistance state and confirmed false elevation in serum TSH concentration due to assay interference from heterophile antibodies. The patient was treated with carbimazole for 18 months.

OUTCOME

The heterophile antibody-mediated assay interference disappeared 10 months following the initiation of treatment with carbimazole, but returned when the patient relapsed. It disappeared again 2 months after the initiation of treatment.

CONCLUSIONS

Clinicians should be aware of the potential for interference in immunoassays, and suspect it whenever the test results seem inappropriate to the patient's clinical state. Misinterpretation of test values, arising as a result of assay interference, may lead to misdiagnosis, unnecessary and at times expensive investigations, delay in initiation of treatment and worst of all, the initiation of inappropriate treatment.

Recurrent episodes of arthritis in a hyperthyroid patient

Antineutrophil cytoplasmic antibody (ANCA)- associated vasculitis is a potentially life-threatening adverse effect of antithyroid medications. We present a 22-year-old woman with Graves' disease who developed recurrent episodes of arthritis while on treatment with propylthiouracil. A diagnosis of propylthiouracil-induced ANCA-associated vasculitis was established only after exhaustive rheumatological investigations failed to establish a cause for her arthritis. Anti-myeloperoxidase antibody (anti-MPO) titres were grossly elevated at 172.7 RU/mL (0-20). Her arthritis resolved promptly following the withdrawal of propylthiouracil and the anti-MPO titres declined over 16 months to 66.8 RU/mL. While she did not develop the life-threatening renal or respiratory tract complications, there was a delay in establishing the correct diagnosis with its attendant morbidity. This case highlights the need for greater awareness of this relatively rare adverse effect of antithyroid medications so as to allow its early detection, leading to the prompt cessation of the offending medication.

Development of ipsilateral adrenocortical carcinoma sixteen years after resection of an adrenal tumour causing Cushing's syndrome

INTRODUCTION

At times, it may be difficult to differentiate early stage, low-grade adrenocortical carcinoma from benign adrenal adenoma.

CLINICAL PICTURE

A 53-year-old lady underwent right adrenalectomy for a 4-cm adrenocortical tumour causing Cushing's syndrome. Histology revealed an adrenocortical adenoma. Sixteen years later, she presented with a 14-cm adrenal tumour, again on the right side.

TREATMENT

She underwent surgical removal of the tumour. Histology confirmed adrenocortical carcinoma.

OUTCOME

She died of metastatic disease 17 months later.

CONCLUSIONS

This case highlights the importance of long-term, systematic follow-up of patients treated for benign adrenal adenomas, especially if the tumour size exceeds 4 cm.

Does growth hormone prevent aging in the healthy elderly with low serum insulin-like growth factor-I ?

Aging is associated with a gradual decline in the function of a number of endocrine glands. While there are phenotypic similarities seen in the changes of aging with some endocrine hormone deficiency states, the relationship between the decline in growth hormone (GH) secretion, and the decrease in serum insulin-like growth factor-I (IGF-I), with these body composition changes is far from clear. The decline in serum IGF-I, unlike that of thyroxine and estradiol, is not accompanied by an increase in pituitary GH secretion. The recent enthusiastic recommendation for GH 'replacement' in the aging population with low serum IGF-I remains highly controversial. The evidence is still unclear on any significant beneficial effect of such replacement in healthy fit elderly men and women. There is some early evidence of beneficial effects of such replacement in the frail elderly. There are no studies that have investigated the effect of GH on longevity in humans, but results from animal studies on caloric restriction and longevity do not suggest that GH administration will increase life span. There is still insufficient evidence that treatment with exogenous GH in the healthy elderly that attains serum IGF-I levels similar to that of young adults is beneficial or safe.

Anaplastic thyroid carcinoma with destructive thyrotoxicosis in a patient with preexisting multinodular goiter

Presentation of anaplastic thyroid carcinoma with thyrotoxicosis is extremely rare and its occurrence in a patient with Wegener's granulomatosis has not been reported previously. We describe an elderly lady with Wegener's granulomatosis who developed a rapidly growing anaplastic thyroid carcinoma in a preexisting multinodular goiter and discuss the mechanism of thyrotoxicosis in this patient.

Is ovarian and adrenal venous catheterization and sampling helpful in the investigation of hyperandrogenic women?

OBJECTIVE

To audit our practice of performing ovarian and adrenal venous catheterization and sampling in hyperandrogenic women who fail to suppress their elevated androgen levels following a 48-h low-dose dexamethasone suppression test (LDDST). We considered the technical success rate of catheterization, the extra information obtained in addition to the standard biochemical tests and imaging findings, and the impact of sampling on management decisions.

DESIGN

A retrospective analysis of the results of all ovarian and adrenal venous catheterizations performed at St Bartholomew's Hospital, London, in the years 1980-1996.

PATIENTS AND METHODS

Baseline ovarian and adrenal androgens were measured in all women presenting with symptoms and signs of hyperandrogenism. Those patients who failed to suppress their elevated testosterone (T), androstenedione (A4) and/or dehydroepiandrosterone-sulphate (DHEAS) levels following a LDDST to within the normal range or to less than 50% of the baseline value were investigated further with adrenal computed tomography (CT), ovarian ultrasound, and ovarian and adrenal venous catheterization and sampling.

RESULTS

Results were available in 38 patients. The overall catheterization success rate was: all four veins in 27%, three veins in 65%, two veins in 87%. The success rate for each individual vein was: right adrenal vein (RAV) 50%, right ovarian vein (ROV) 42%, left adrenal vein (LAV) 87% and left ovarian vein (LOV) 73%. Eight patients were found to have tumours by means of imaging (adrenal CT and ovarian ultrasound), three adrenal and five ovarian, seven of which underwent operation. In six of these patients the clinical presentation was suggestive of the presence of a tumour; in addition, the combination of imaging findings allowed the detection of suspicious adrenal and ovarian masses in all eight cases. The five patients with ovarian tumours had serum testosterone levels > 4.5 nmol/l. In a further eight patients, laparotomy was performed based on a combination of diagnostic and therapeutic indications; in two of these patients the catheterization results were suggestive of an ovarian tumour. All these eight patients were shown histologically to have polycystic ovarian syndrome (PCOS), and no occult ovarian tumour was identified. None of the patients with nontumourous hyperandrogenism had a baseline testosterone level in excess of 7 nmol/l (median 4.4 nmol/l, range 2.5-7 nmol/l).

CONCLUSIONS

Our results suggest that ovarian and adrenal venous catheterization and sampling should not be performed routinely in women presenting with symptoms and signs of hyperandrogenism, even if they fail to suppress their elevated androgen levels to a formal 48-h LDDST. All patients presenting with symptoms and signs of hyperandrogenism and elevated androgen levels, and where the suspicion of an androgen-secreting tumour is high, should have adrenal CT and ovarian ultrasound imaging to detect such a tumour. Venous catheterization and sampling should be reserved for patients in whom uncertainty remains, as the presence of a small ovarian tumour cannot be excluded on biochemical and imaging studies used in this series alone. Its use should be restricted to units with expertise in this area.

Treatment of advanced neuroendocrine tumours using combination chemotherapy with lomustine and 5-fluorouracil

OBJECTIVE

Combination chemotherapy with the two agents streptozotocin (SZT), which is a nitrosurea, and 5-fluorouracil (5-FU), an alkylating agent, has a long-established role in the treatment of neuroendocrine tumours; however, it is often accompanied by considerable toxicity, and it has not been assessed in a comparative manner with other current chemotherapy regimens. In order to assess the therapeutic response and adverse effects using an alternative nitrosurea, lomustine (CCNU), which has a different side-effect profile, in combination with 5-FU, we have reviewed all patients with neuroendocrine tumours who received this form of treatment in our department.

DESIGN

Retrospective analysis of the case notes of patients with metastatic neuroendocrine tumours who received treatment with the combination of CCNU and 5-FU, and who were followed up according to a defined protocol in a given time frame.

PATIENTS

Thirty-one patients with metastatic neuroendocrine tumours (18 with carcinoid tumours, five islet-cell tumours, five chromaffin-cell tumours and three medullary carcinoma of the thyroid) treated with the combination of CCNU and 5-FU, and when necessary additional therapy, over a 22-year period, were included in this analysis.

MEASUREMENTS

The symptomatic, hormonal and tumoural responses before and after chemotherapy with the combination of CCNU and 5-FU over a median follow-up duration of 25 months (range 9-348 months) were recorded. Of the 31 patients (16 males; median age 52 years, range 20-86 years), eight (four males; median age 61 years, range 30-74 years) were treated with the combination of CCNU and 5-FU alone (Group 1), whereas the other 23 patients (12 males; median age 47 years, range 20-86 years) received additional therapy with other chemotherapeutic regimens, somatostatin analogues, alpha-interferon or radiolabelled meta-iodobenzylguanidine (131I-MIBG) therapy (Group 2).

RESULTS

A total of 121 therapeutic cycles was administered (mean 3.9, range 1-14 cycles). None of the patients obtained a complete tumour response. A partial tumour response (not a complete but a 50% or greater reduction of all measurable tumour) was seen in six out of the 29 patients (21%) (four out of eight in Group 1 and two out of 21 in Group 2, respectively). There was no tumour progression in eight out of the 29 patients (27.5%) (one out of eight in Group 1 and seven out of 21 in Group 2, respectively). The median survival over the period of the study was 48 months (95% confidence interval, CI, 22-74 months). The overall 5-year survival rate was 42% (95% CI, 17-67%) for all patients and 50% (95% CI, 18-83%) for the carcinoid group alone, according to Kaplan-Meier analysis. A complete or partial symptomatic response was obtained in 12 out of 27 (44%) patients who presented with symptoms (four out of eight in Group 1 and eight out 19 in Group 2, respectively) and a complete or partial hormonal response in eight out of 19 patients (42.1%) who presented with hormonally active disease (two out of four in Group 1 and six out of 15 in Group 2, respectively). Nine out of the 15 (60%) patients with carcinoid tumours who presented with symptoms obtained a symptomatic response, five out of 10 patients (50%) a hormonal response, and four out of 16 (25%) patients a partial tumoural response, respectively. The combination of CCNU and 5-FU was safe and well tolerated. Serious side-effects necessitating the termination of CCNU and 5-FU were seen only in two patients, and mainly consisted of reversible bone marrow suppression. No chemotherapy-related death was recorded.

CONCLUSIONS

Chemotherapy with CCNU and 5-FU, either alone or in combination with other therapeutic modalities, produces considerable symptomatic and hormonal improvement and moderate tumour regression/stabilization according to currently accepted WHO criteria, particularly in patients with metastatic gastroenteropancreatic neuroendocrine tumours with minimal adverse effects. However, long-term survival was still relatively poor. It may therefore be a valuable additional therapl was still relatively poor. It may therefore be a valuable additional therapeutic option, particularly for well-differentiated carcinoid and islet-cell tumours, but mainly reserved for when there is no response or progression of the disease after currently available first-line treatment with somatostatin analogues or radiopharmaceuticals.

The value of radiolabelled MIBG and octreotide in the diagnosis and management of neuroendocrine tumours

Neuroendocrine tumours have a particular tendency to express functional receptors and/or uptake mechanisms. Radionuclides, such as 123I-MIBG, which is taken up by a specific uptake mechanism, and 111In-pentetreotide, which binds to somatostatin receptors, present an imaging modality based on these physiological characteristics rather on purely anatomical alterations. They have been successfully utilised for both the diagnosis and staging of neuroendocrine tumours, as they can identify lesions beyond the diagnostic sensitivity of conventional imaging modalities. Scintigraphy with 111In-pentetreotide is in general more sensitive but scintigraphy with 123I-MIBG may occasionally demonstrate lesions not evident with 111In-pentetreotide. Although both are effective in identifying hepatic metastases there may be quantitative and qualitative differences in the pattern of uptake. 131I-MIBG therapy, based on a positive 123I-MIBG scan, produces symptomatic and hormonal improvement and moderate tumour regression/stabilisation in many patients with metastatic neuroendocrine tumours with minimal adverse effects. It may be a valuable alternative or additional therapeutic option to the currently available conventional treatment modalities. Although experience with 90Y-DOTA-D-Phe1-Tyr3-octreotide therapy is still limited, preliminary studies have demonstrated useful activity in tumours with positive 111In-pentetreotide scans, and yet other radionuclide analogues may become available. However, treatment with the combination of both radionuclides is another therapeutic possibility.

Comparing fasting plasma glucose against two-hour post-load glucose concentrations for the diagnosis of diabetes mellitus and glucose intolerance in Singaporean hospital patients

INTRODUCTION

Several studies have assessed the impact of the 1997 American Diabetes Association (ADA) recommendation, of using fasting plasma glucose (FPG) concentration, to diagnose diabetes mellitus in population-based cohorts. However, data concerning the impact of this recommendation in the hospital setting are limited. As the performance characteristics of diagnostic tests vary depending on the prevalence of diabetes in the population studied, we have examined the clinical impact of adopting the ADA recommendations in comparison to the traditional 2-hour post-load glucose (2HPG) concentration used by the World Health Organisation (WHO) in diagnosing diabetes and other categories of glucose intolerance in Singaporean hospital patients.

MATERIALS AND METHODS

We analysed the results of the standard 75 g oral glucose tolerance test (OGTT) performed on 625 patients in our hospital from 1994 to 1999.

RESULTS

The prevalence of diabetes amongst these 625 patients was 36.8% (230) based on the ADA recommendation of using FPG, 42.8% (263) on using the 2HPG and 52.0% (325) on using the full 1998 WHO criteria. The degree of agreement (kappa) in establishing the diagnosis of diabetes between the FPG and 2HPG cut-offs was 0.48. Ninety-five (15.2%) individuals had diabetes based on the 2HPG alone, 62 (9.9%) based on the FPG alone and 168 (26.9%) based on both the FPG and 2HPG. Eighty-six (13.8%) individuals had impaired fasting glucose (IFG) and 123 (19.7%) had impaired glucose tolerance (IGT). The kappa-value between IFG and IGT was 0.08.

CONCLUSION

Fasting plasma glucose concentration was an inadequate parameter in diagnosing diabetes and intermediate categories of glucose intolerance in our cohort of subjects. Our findings suggest that the OGTT remains an important diagnostic tool for classifying glucose tolerance in our hospital patients.

Panhypopituitarism due to pituitary cyst of Rathke's cleft origin--two case reports

INTRODUCTION

Rathke's cleft cysts are cystic sellar and suprasellar lesions, characteristically lined by a single layer of ciliated cuboidal or columnar epithelium.

CLINICAL PICTURE

We report 2 patients who presented with gastrointestinal symptoms and were initially investigated for dyspepsia. However, attention was subsequently drawn to persistent hyponatraemia that led to the diagnosis of panhypopituitarism due to Rathke's cleft cyst.

TREATMENT

Transsphenoidal surgery followed by drainage of the cyst and partial excision of the cyst wall in both patients.

OUTCOME

No recurrence of the lesions over a mean follow-up of 16 months. There has been an improvement of the hypothalamo-pituitary-adrenal axis in 1 patient and the hypothalamo-pituitary-thyroid axis and visual fields in the other.

CONCLUSION

Symptomatic Rathke's cleft cysts are rare and can occasionally cause panhypopituitarism. Ideal management of these cysts is unclear, but aspiration followed by partial excision of the cyst wall seems the best initial option.

The role of spiral computed tomogram in the diagnosis of acute pulmonary embolism

Acute pulmonary embolism is associated with considerable morbidity and mortality. Early diagnosis and prompt treatment is essential. A number of non-invasive diagnostic tools are available for its detection. However, each one of these tests has its limitations and the invasive pulmonary angiography remains the gold standard. We describe the use of spiral volumetric computerised tomogram in the diagnosis of acute pulmonary embolism in six patients in our centre where ventilation-perfusion scan facility is not available. This safe, simple and non-invasive test has an excellent sensitivity and specificity for the detection of central and segmental pulmonary embolism and may replace the conventional invasive pulmonary angiography for the diagnosis of pulmonary embolism.

Treatment of metastatic carcinoid tumours, phaeochromocytoma, paraganglioma and medullary carcinoma of the thyroid with (131)I-meta-iodobenzylguanidine [(131)I-mIBG]

OBJECTIVE

Meta-iodo-benzyl-guanidine labelled with 131-iodine [(131)I-mIBG] has been used extensively for imaging tumours originating from the neural crest but experience with its therapeutic use is limited, particularly for non-catecholamine secreting tumours. In order to assess the therapeutic response and potential adverse effects of the therapeutic administration of (131)I-mIBG, we have reviewed all patients who had received this form of treatment in our department.

DESIGN

Retrospective analysis of the case notes of patients with neuroendocrine tumours who received treatment with (131)I-mIBG and were followed-up according to a defined protocol in a given time frame.

PATIENTS

Thirty-seven patients (18 with metastatic carcinoid tumours, 8 metastatic phaeochromocytoma, 7 metastatic paraganglioma and 4 metastatic medullary carcinoma of the thyroid) treated with (131)I-mIBG over a 15-year period were included in this analysis.

MEASUREMENTS

The symptomatic, hormonal and tumoural responses before and after (131)I-mIBG therapy over a median follow-up duration of 32 months (range 5-180 months) were recorded. Of the 37 patients (22 males; median age 51 years, range 18-81 years), 15 were treated with (131)I-mIBG alone whereas the other 22 received additional therapy.

RESULTS

A total of 116 therapeutic (131)I-mIBG doses were administered [mean cumulative dose 592 mCi (21.9 GBq); range 200-1592 mCi (7.4-58.9 GBq)]. None of the patients showed a complete tumour response. However, 82% of patients treated with (131)I-mIBG alone and 84% who received additional therapy showed stable disease over the period of follow-up. Overall survival during the period of the study was 71%. The overall 5-year survival rate was 85% (95% confidence interval, 72-99%) for all patients and 78% (95% confidence interval, 55-100%) for the carcinoid group alone, according to Kaplan-Meier analysis. Symptomatic control was achieved in all the patients treated with (131)I-mIBG alone, and in 72% of those receiving additional therapy. Hormonal control was noted in 50% and 57% of patients, respectively. (131)I-mIBG therapy was safe and well tolerated. Serious side-effects necessitating the termination of (131)I-mIBG therapy were seen in only 2 of our patients.

CONCLUSIONS

(131)I-mIBG therapy produces symptomatic and hormonal improvement and moderate tumour regression/stabilization in patients with metastatic neuroendocrine tumours with minimal adverse effects. It may be a valuable alternative or additional therapeutic option to the currently available conventional treatment modalities.

A rare cause of syncope in a patient with diabetes mellitus--a case report

INTRODUCTION

Hypoglycaemic episodes in patients with diabetes mellitus are mostly due to excess doses of exogenous insulin or oral hypoglycaemic agents, coupled with poor caloric intake and excessive unplanned physical exertion. Hypoglycaemia as a result of endogenous hyperinsulinaemia due to an insulinoma is extremely rare in such patients.

CLINICAL PICTURE

This patient with type 2 diabetes mellitus presented with episodes of syncope. Investigations confirmed recurrent hypoglycaemia from endogenous hyperinsulinaemia, with localisation of a tumour in the tail of the pancreas.

TREATMENT

Distal pancreatectomy and splenectomy. Histology confirmed an insulinoma.

OUTCOME

No further hypoglycaemic episodes were noted. The patient returned to his diabetic state with rather poor glycaemic control.

CONCLUSIONS

Repeated hypoglycaemic episodes in a patient with diabetes mellitus despite complete withdrawal of hypoglycaemic agents should lead one to consider other causes of hypoglycaemia.

Comparison of somatostatin analog and meta-iodobenzylguanidine radionuclides in the diagnosis and localization of advanced neuroendocrine tumors

A comparison has been made of [(123)I]meta-iodobenzylguanidine ([(123)I]MIBG) and [(111)In]pentetreotide scintigraphy in 54 patients with a variety of neuroendocrine tumors of whom 46 patients had metastatic disease. [(111)In]Pentetreotide scintigraphy was more sensitive in detecting metastatic lesions, as demonstrated on computed tomography and/or magnetic resonance scanning, than [(123)I]MIBG: 67% vs. 50% for carcinoid tumors (n = 24), 91% vs. 9% for pancreatic islet cell tumors (n = 12), 100% vs. 60% for medullary thyroid carcinomas (n = 5), and 75% vs. 100% for pheochromocytomas/paragangliomas (n = 4). In only 2 patients were lesions seen with [(123)I]MIBG scanning that were not apparent with [(111)In]pentetreotide. With the exception of pancreatic islet cell tumors, both radionuclides exhibited a similar sensitivity in detecting hepatic metastases, whereas in three patients the two radionuclides exerted a complementary role as different deposits exhibited uptake to only 1 or the other radionuclide. Hepatic metastases were the most important clinical predictor of a positive scan for both radionuclides. Neither elevated 5-hydroxyindoleacetic acid levels nor any other hormonal marker was predictive of a positive scan. In 8 patients with clinical and/or hormonal evidence of a neuroendocrine tumor but negative conventional radiology, [(111)In]pentetreotide scintigraphy was more sensitive than [(123)I]MIBG (37.5% vs. 12.5%) in detecting lesions. In conclusion, scintigraphy with [(111)In]pentetreotide detects more metastatic lesions than [(123)I]MIBG in patients with carcinoid and pancreatic islet cell tumors and medullary thyroid carcinomas; [(123)I]MIBG scintigraphy may be more sensitive for sympathoadrenomedullary tumors. The radionuclides may exert a complementary role in the detection and treatment of neuroendocrine tumors in occasional patients, as areas of different pattern of uptake were identified within the same patient. These data have implications not only for staging such tumors, but also for identifying patients who might benefit from treatment using either [(131)I]MIBG or radioactive somatostatin analogs.

Placental alkaline phosphatase, insulin, and adenine nucleotides or adenosine synergistically promote long-term survival of serum-starved mouse embryo and human fetus fibroblasts

Earlier we showed that in serum-starved fibroblasts placental alkaline phosphatase (PALP) can exert growth factor-like effects. Here we report that in mouse embryo (NIH 3T3) and human fetus (HTB-157) fibroblasts, PALP (200 nM) alone provided full protection against serum starvation-induced cell death for 5 days. After 12 days, substantial effects of PALP on cell survival required the copresence of insulin (500 nM) and ATP or adenosine (100 microM). In serum-starved NIH 3T3 cells, PALP induced activating phosphorylation of p42/p44 mitogen-activated protein (MAP) kinases; insulin, but not ATP, had small additional effects. PALP also stimulated the expression of various cyclins; ATP both prolonged and enhanced PALP-induced expression of cyclins A and E. Finally, ATP/adenosine enhanced activation of Akt kinase by insulin. The results suggest that PALP may be a regulator of growth and remodeling of fetal tissues during the second and third trimester of pregnancy when it is expressed.

alpha(1)-antitrypsin can increase insulin-induced mitogenesis in various fibroblast and epithelial cell lines

alpha(1)-Antitrypsin (AT), the archetypal member of the superfamily of serine proteinase inhibitors, inhibits leukocyte elastase activity and thereby can prevent lung damage. Here we show that in fibroblasts from human fetal lung and mouse embryo as well as in certain epithelial cells AT can also enhance the stimulatory effects of insulin on DNA synthesis and cell proliferation. Warming of AT at a moderate (41 degrees C) temperature for a longer time (21 h) or at a higher (65 degrees C) temperature for 30 min before treatment increased its stimulatory effects on both DNA synthesis and activating phosphorylation of p42/p44 mitogen-activated protein kinases. The results suggest that AT may promote regeneration of damaged tissues under pathophysiological conditions which are associated with fever.

Expression of human choline kinase in NIH 3T3 fibroblasts increases the mitogenic potential of insulin and insulin-like growth factor I

In mammalian cells, growth factors, oncogenes, and carcinogens stimulate phosphocholine (PCho) synthesis by choline kinase (CK), suggesting that PCho may regulate cell growth. To validate the role of PCho in mitogenesis, we determined the effects of insulin, insulin-like growth factor I (IGF-I), and other growth factors on DNA synthesis in NIH 3T3 fibroblast sublines highly expressing human choline kinase (CK) without increasing phosphatidylcholine synthesis. In serum-starved CK expressor cells, insulin and IGF-I stimulated DNA synthesis, p70 S6 kinase (p70 S6K) activity, phosphatidylinositol 3-kinase (PI3K) activity, and activating phosphorylation of p42/p44 mitogen-activated protein kinases (MAPK) to greater extents than in the corresponding vector control cells. Furthermore, the CK inhibitor hemicholinium-3 (HC-3) inhibited insulin- and IGF-I-induced DNA synthesis in the CK overexpressors, but not in the vector control cells. The results indicate that high cellular levels of PCho potentiate insulin- and IGF-I-induced DNA synthesis by MAPK- and p70 S6K-regulated mechanisms.

Growth factor-like effects of placental alkaline phosphatase in human fetus and mouse embryo fibroblasts

Human placental alkaline phosphatase (PALP) is synthesized in the placenta during pregnancy and is also expressed in many cancer patients; however, its physiological role is unknown. Here we show that in human fetus fibroblasts as well as normal and H-ras-transformed mouse embryo fibroblasts PALP stimulates DNA synthesis and cell proliferation in synergism with insulin, zinc and calcium. The mitogenic effects of PALP are associated with the activation of c-Raf-1, p42/p44 mitogen-activated protein kinases, p70 S6 kinase, Akt/PKB kinase and phosphatidylinositol 3'-kinase. The results suggest that in vivo PALP may promote fetus development as well as the growth of cancer cells which express oncogenic Ras.

Extracellular calcium stimulates DNA synthesis in synergism with zinc, insulin and insulin-like growth factor I in fibroblasts

In serum-starved mouse NIH 3T3 fibroblasts cultured in 1.8 mM Ca2+-containing medium, addition of 0.75-2 mM extra Ca2+ stimulated DNA synthesis in synergism with zinc (15-60 microM), insulin and insulin-like growth factor I. Extra Ca2+ stimulated phosphorylation/activation of p42/p44 mitogen-activated protein kinases by an initially (10 min) zinc-independent mechanism; however, insulin, and particularly zinc, significantly prolonged Ca2+-induced mitogen-activated protein kinase phosphorylation. In addition, extra Ca2+ activated p70 S6 kinase by a zinc-dependent mechanism and enhanced the stimulatory effect of zinc on choline kinase activity. Insulin and insulin-like growth factor I also commonly increased both p70 S6 kinase and choline kinase activities. In support of the role of the choline kinase product phosphocholine in the mediation of mitogenic Ca2+ effects, cotreatments with the choline kinase substrate choline (250 microM) and the choline kinase inhibitor hemicholinium-3 (2 mM) enhanced and inhibited, respectively, the combined stimulatory effect of extra Ca2+ (3.8 mM total) and zinc on DNA synthesis. In various human skin fibroblast lines, 1-2 mM extra Ca2+ also stimulated DNA synthesis in synergism with zinc and insulin. The results show that in various fibroblast cultures, high concentrations of extracellular Ca2+ can collaborate with zinc and certain growth factors to stimulate DNA synthesis. Considering the high concentration of extracellular Ca2+ in the dermal layer, Ca2+ may promote fibroblast growth during wound healing in concert with zinc, insulin growth factor-I insulin, and perhaps other growth factors.

The possible mechanism of synergistic effects of ethanol, zinc and insulin on DNA synthesis in NIH 3T3 fibroblasts

In serum-starved NIH 3T3 fibroblast cultures, zinc (15-40 microM) enhanced both the individual and combined stimulatory effects of insulin and ethanol (EtOH) on DNA synthesis. Zinc, but not EtOH, also promoted the stimulatory effects of insulin on activating phosphorylation of p42/p44 mitogen-activated protein (MAP) kinases. In the presence of zinc, insulin induced premature expression of cyclin E during early G1 phase; EtOH partially restored the normal timing (late G1 phase) of cyclin E expression. The results suggest that zinc and EtOH promote insulin-induced DNA synthesis by different mechanisms; while zinc acts by enhancing the effects of insulin on MAP kinase activation, EtOH may act by ensuring timely zinc-dependent insulin-induced expression of cyclin E.

Menstrual irregularity in women with acromegaly

Menstrual irregularity is common in women with acromegaly, occurring in 40-84%. Although it has been attributed to gonadotropin deficiency and/or PRL excess, it has not been evaluated in detail, and its pathogenesis is not well understood. To explore the various possible pathogenic mechanisms, we have analyzed the clinical, endocrinological, and radiological characteristics of 47 women with active acromegaly within the reproductive age range (15-41 yr) with respect to their menstrual pattern; 9 patients (19%) had normal cycles, 7 (15%) had oligomenorrhea, 29 (62%) had amenorrhea, and 2 (4%) had polymenorrhea. Compared to patients with normal cycles (n = 9), patients with menstrual irregularity (oligo/polymenorrhea or amenorrhea; n = 38) were more hirsute, had lower serum estradiol (normal: median, 76.5 pmol/L; range, 20-570; menstrual irregularity: median, 283; range, 140-431; P < 0.01), and sex hormone-binding globulin (SHBG; normal: median, 19.6 nmol/L; range, 5-52; menstrual irregularity: median, 48; range, 18-60; P < 0.01), but similar testosterone levels; in addition, patients with amenorrhea had higher serum GH (normal: median, 100 mU/L; range, 8.8-400; amenorrhea: median, 30; range, 10.7-120; P < 0.05). PRL levels in excess of 1000 mU/L were found in 16 of the 38 patients with menstrual irregularity compared to only 1 of the 9 patients with normal cycles. Patients with menstrual irregularity had a greater impairment of anterior pituitary function than patients with normal cycles. Acromegalic patients who were defined as estrogen sufficient (estradiol, >140 pmol/L) had clinical baseline endocrine profiles and LH responses to GnRH stimulation similar to those in patients with polycystic ovarian disease. There was a positive correlation between GH levels and tumor size (r = 0.35; P < 0.05) and an independent inverse correlation between GH and SHBG levels (r = -0.6; P < 0.01), which persisted even in patients who were estrogen sufficient, but there was no correlation between GH and estradiol levels; in addition, there was a negative correlation between estradiol levels and tumor size (r = -0.42; P < 0.05). Thirty-five of the patients with menstrual irregularity had meso- or macroadenomas and 3 had microadenoma, whereas 6 of the 9 patients with normal cycles had microadenomas. In conclusion, menstrual irregularity is common in women with acromegaly (81% of our patients). Amenorrheic patients have higher GH levels, are mainly estrogen deficient, and tend to have larger tumors than patients with normal cycles. However, the independent negative correlation between GH and SHBG levels suggests that GH may, directly or indirectly, lead to a fall in SHBG, possibly determined by the hyperinsulinemia known to occur in acromegaly. Low SHBG levels may contribute to the menstrual disturbance seen in acromegaly in addition to any gonadotropin deficiency or hyperprolactinemia and may account for hirsutism in the presence of normal testosterone levels.

Ethanol potentiates the mitogenic effects of sphingosine 1-phosphate by a zinc- and calcium-dependent mechanism in fibroblasts

In mouse embryo NIH 3T3 fibroblasts, ethanol (60-80 mM) was found to enhance the stimulatory effects of sphingosine 1-phosphate (S1P) on both DNA synthesis and cell proliferation. Well-detectable potentiating effects of ethanol on S1P-induced mitogenesis required the presence of calcium (>1 mM) and zinc (20-40 microM) in the incubation medium. The amphibian tetrapeptide bombesin, which is known to mobilize intracellular calcium in fibroblasts, had no effect alone, but it approximately doubled the combined stimulatory effects of ethanol and S1P on DNA synthesis. The synergistic mitogenic effects of ethanol and S1P were also slightly enhanced, rather than inhibited, by the alcohol dehydrogenase inhibitor 4-methylpyrazole (5 mM). Of the various growth regulatory enzymes examined, ethanol detectably enhanced the stimulatory effects of S1P on the phosphosphorylation (activation) of p42/p44 mitogen-activated protein (MAP) kinases, but not of p38 MAP kinase. Cotreatment of fibroblasts with ethanol for 10 min also enhanced the stimulatory effects of S1P on the activities of c-Raf-1 kinase and p70 S6 kinase, but neither S1P nor ethanol had effects on phosphatidylinositol 3'-kinase and Akt/PKB kinase activities. Ethanol-plus-S1P-induced DNA synthesis was partially inhibited by both PD 98059 (50 microM) and rapamycin (10 nM), inhibitors of p42/p44 MAP kinase kinase and mTOR/p70 S6 kinases, respectively. The results indicate that in NIH 3T3 fibroblasts, ethanol can enhance the mitogenic effects of S1P by a zinc- and calcium-dependent mechanism involving both the rapamycin-sensitive p70 S6 kinase-dependent and the c-Raf-1/MAP kinase-dependent growth regulatory pathways.

Bombesin promotes synergistic stimulation of DNA synthesis by ethanol and insulin in fibroblasts

In NIH 3T3 fibroblasts and several other cellular systems, ethanol (50-80 mM) was previously shown to greatly enhance the mitogenic effects of insulin particularly in the presence of zinc. Here we report that in NIH 3T3 fibroblasts the combined stimulatory effects of ethanol and insulin on DNA synthesis can be further increased by bombesin both in the absence and presence of zinc. Bombesin also enhanced insulin-plus-ethanol-induced DNA synthesis in mouse Swiss 3T3 and Balb/c 3T3 fibroblasts, but in these cells bombesin was effective only in the presence of zinc. In NIH 3T3 fibroblasts, the potentiating effects of ethanol on insulin-induced DNA synthesis by the zinc-dependent and bombesin-dependent mechanisms were additive. Wortmannin, an inhibitor of phosphatidylinositol 3'-kinase (PI3K), prevented the comitogenic effect of ethanol in the presence of bombesin but not in the presence of zinc. Furthermore, bombesin, but not ethanol, was found to enhance the stimulatory effect of insulin on PI3K activity. Rapamycin, an indirect inhibitor of p70 S6 kinase actions, inhibited the comitogenic effects of ethanol in the presence of both zinc and bombesin. However, only ethanol, but not bombesin, enhanced the stimulatory effect of insulin on p70 S6 kinase activity; this effect of ethanol was zinc-dependent. Neither ethanol nor bombesin enhanced the stimulatory effects of insulin on the phosphorylation (activation) of p38/p42/p44 mitogen-activated protein kinases. The results suggest that in mouse fibroblasts maximal stimulation of DNA synthesis by physiologically relevant concentrations of ethanol occurs if both PI3K and p70 S6 kinase are activated. These data suggest a mechanism by which ethanol may affect growth in affected human tissues during its tumor promoting actions.

The role of cytotoxic chemotherapy in the management of aggressive and malignant pituitary tumors

Pituitary tumors are mostly benign lesions, although 5-35% are locally invasive. A small number exhibit a more aggressive course, infiltrating dura, bone and sinuses, and are designated highly aggressive. However, the presence of metastases separate from the pituitary in the central nervous system or at a distance is necessary to designate pituitary tumors as carcinomas, i.e. truly malignant. When conventional therapeutic modalities fail, systemic chemotherapy remains the last option. We report seven such patients, three with highly aggressive and four with malignant pituitary tumors (n=4) four women; median age, 32 yr; range, 23-48 yr), who received one or more courses of chemotherapy with lomustine and 5-fluorouracil (median, two courses; range, one to six courses). Three patients with systemic metastatic disease had a shorter survival (median, 5 months; range, 1-14 months) than the one patient with central nervous system metastases alone (10 yr). A patient with an aggressive nonmetastatic prolactinoma who initially responded to chemotherapy died from another nondisease-associated cause. Two patients, one with an aggressive and one with a metastatic tumor, achieved symptomatic improvement with a median duration of 6 months. A hormonal reduction greater than 50% was observed in two of seven patients; only one patient who had an aggressive tumor obtained an objective tumor response. The median survival from the time of initiation of chemotherapy in patients with malignant tumors ranged from 3-65 months. Two patients with malignant tumors developed disease progression while receiving chemotherapy; no patient with extracranial metastases showed a response. Treatment was well tolerated, with minimal individual side-effects. Three patients with no response to initial treatment received different chemotherapeutic regimens with no additional response. All patients with metastatic malignant tumors eventually died. Treatment with cytotoxic chemotherapy is noncurative, and current experience is limited. Until another more specific form of treatment is available, chemotherapy may still be of some value in patients with highly aggressive and malignant pituitary tumors, at least in achieving a temporary remission or delay in progression. The combination of lomustine/5-fluorouracil proved easy to administer with minimal toxicity, although the response rate was only 14%. Until a more specific treatment is found, an optimal chemotherapeutic regimen needs to be established.

Carcinoid tumours presenting as breast cancer: the utility of radionuclide imaging with 123I-MIBG and 111In-DTPA pentetreotide

Secondary tumours of any type in the breast are rare. A review of the literature demonstrated only 23 cases of carcinoid tumours with associated breast metastasis, as distinct from primary carcinoid tumours of the breast. Distant metastases from carcinoid tumours are correlated with poor prognosis and survival. Although both primary and metastatic mammary carcinoid tumours are uncommon, the recognition of the true origin of the tumours may be of importance owing to the different clinical management and prognosis of the two conditions. Recently, radionuclide-labelled imaging techniques have been applied to the localization of such lesions, based on isotope uptake by receptors present in these neuroendocrine tumours. We report two new cases of carcinoid tumours with breast metastases, the primaries being in the ileocaecal valve and the bronchus, respectively. The diagnosis of a carcinoid tumour was based on the clinical, biochemical, histopathological and immunostaining features. Furthermore, these patients had both 123I-MIBG and 111In pentetreotide scintigraphy performed. These radionuclides play a useful role in the localization and potentially in the management of carcinoid tumours and their distant metastases.

Phosphorylation of ethanolamine, methylethanolamine, and dimethylethanolamine by overexpressed ethanolamine kinase in NIH 3T3 cells decreases the co-mitogenic effects of ethanolamines and promotes cell survival

Ethanolamine (Etn), as well as its N-methyl (MeEtn) and N,N-dimethyl (Me2Etn) analogues, were recently shown to potentiate the stimulatory effect of insulin on DNA synthesis in serum-starved NIH 3T3 fibroblasts. In the present work we assessed the impact of the co-mitogenic effects of Etn and its methyl analogues on cell proliferation and cell survival, and examined whether the cell growth regulatory effects of these ethanolamines involve an Etn-kinase-mediated phosphorylation step. For this purpose, NIH 3T3 sublines highly overexpressing Drosophila Etn kinase and an appropriate vector control line were utilized and the effects of Etn, MeEtn, Me2Etn, methylamine (MeNH2), and dimethylamine (Me2NH) were studied. 31P-NMR analysis of the water-soluble cell metabolites revealed that both MeEtn and Me2Etn, but not choline, are excellent substrates for the expressed Etn kinase. The methylated ethanolamines (MeEtn and Me2Etn) and methylamines (MeNH2, Me2NH) were used as Etn models that can or cannot be phosphorylated, respectively. In serum-starved vector control cells, both MeNH2 (1 mM) and Me2NH (1 mM) were more effective than Etn in enhancing insulin-induced DNA synthesis, and both were almost as effective as MeEtn and Me2Etn. However, in the Etn kinase overexpressor cells the potentiating effects of Etn, MeEtn and Me2Etn, but not those of MeNH2 and Me2NH, were significantly reduced. Moreover, in the overexpressor cells, lower concentrations of Etn (50-200 microM) inhibited the combined mitogenic effects of Me2NH (1 mM) and insulin. These data are consistent with a mechanism in which the phosphorylated and non-phosphorylated ethanolamines are negative and positive regulators of insulin-induced mitogenesis, respectively. After incubating the cells for 13 days in serum-free medium in 96-well microplates, there was a steady decrease in cell numbers in both cell lines. However, between 6-13 days, 0.1-1 mM MeEtn and, particularly, Me2Etn provided significant protection against cell death in the Etn kinase overexpressor cells. In vector control cells, only Me2Etn in combination with insulin had similar effects on cell survival. The data suggest that phosphorylated ethanolamines may function as promoters of cell survival.

Ethanol potentiates the stimulatory effects of insulin and phosphocholine on mitogenesis by a zinc-dependent and rapamycin-sensitive mechanism in fibroblasts and JB6 cells

In most cellular systems ethanol inhibits growth factor-induced cell growth. Here we examined the effects of ethanol on DNA synthesis and cell proliferation induced by insulin and phosphocholine (PCho) in NIH3T3 fibroblasts, Swiss 3T3 fibroblasts and mouse epidermal JB6 cells. In serum-starved low (12-18) passage NIH3T3 fibroblasts, 60 mM ethanol enhanced the mitogenic effect of insulin in the absence or presence of 25 microM zinc about 2- or 12-fold, respectively. In contrast, in serum-starved high (30-47) passage NIH3T3 cells 60 mM ethanol had large (20-40-fold) potentiating effects on insulin-induced DNA synthesis even in the absence of zinc. Furthermore, ethanol also enhanced the effects of PCho on DNA synthesis in both the absence and presence of insulin. The potentiating effects of ethanol on insulin- and PCho-induced DNA synthesis were associated with 1.2-1.3-fold stimulation of cell proliferation. Rapamycin, an inhibitor of p70 S6 kinase action, strongly inhibited the potentiating effects of ethanol on insulin- and PCho-induced mitogenesis. Unexpectedly, ethanol inhibited synergistic activation of p42/p44 mitogen-activated protein kinases by insulin and PCho. In both Swiss 3T3 and JB6 cells, ethanol potentiated insulin-induced DNA synthesis only in the presence of zinc. In these cells, ethanol also increased the effects of PCho on both DNA synthesis and cell proliferation in the co-presence of either insulin or ATP. The results indicate that in various cell lines physiologically relevant concentrations of ethanol can increase the ability of insulin and PCho to induce DNA synthesis and, to smaller extents, cell proliferation. In low passage NIH3T3 cells as well as in Swiss 3T3 and JB6 cells potentiation of insulin-induced DNA synthesis by ethanol requires the presence of zinc.

Ethanolamine, but not phosphoethanolamine, potentiates the effects of insulin, phosphocholine, and ATP on DNA synthesis in NIH 3T3 cells--role of mitogen-activated protein-kinase-dependent and protein-kinase-independent mechanisms

NIH 3T3 fibroblasts express a phospholipase D activity hydrolyzing phosphatidylethanolamine (PtdEtn) which produces ethanolamine (Etn) in response to a variety of growth regulating agents. The main objective of this work was to evaluate the effects of Etn on mitogenesis and to determine whether these effects require its metabolism to phosphoethanolamine (PEtn) or PtdEtn. To increase conversion of Etn to PEtn, an Etn-specific kinase derived from Drosophila was highly expressed in NIH 3T3 cells. Overexpression of this Etn kinase resulted in large (10-12.5-fold) increases in PEtn formation, but only in modest (1.2-1.7-fold) increases in PtdEtn synthesis. In both vector control and Etn kinase overexpressor cells, Etn had biphasic effects on insulin-induced DNA synthesis with maximal (approximately 2-fold) potentiating effects being observed at 0.5-1 mM concentrations, followed by an inhibitory phase at higher Etn concentrations. In the Etn kinase overexpressor lines, the inhibitory phase was elicited by lower Etn concentrations and it was partially blocked by 5 mM choline due to decreased formation of PEtn. In both vector control and Etn kinase overexpressor cells, phosphocholine (PCho) and insulin synergistically stimulated DNA synthesis; their effects were further enhanced by physiologically relevant (5-60 microM) concentrations of Etn by a mechanism independent of mitogen-activated protein (MAP) kinase. Concentrations of Etn >50 microM also enhanced the effects of both PCho and the synergistic effects of PCho plus ATP; however, in the latter case 20 microM Etn was inhibitory. The magnitude of both the potentiating and inhibitory effects of Etn on PCho-induced as well as PCho + ATP-induced DNA synthesis were similar in the vector control and Etn kinase overexpressor cells; they were associated with stimulation and inhibition, respectively, of p42 MAP kinase activity. The results indicate that in NIH 3T3 cells Etn exerts significant effects on DNA synthesis which, except inhibition of insulin-induced DNA synthesis by higher concentrations of Etn, do not correlate with the metabolism of Etn to PEtn or PtdEtn.

Phosphocholine and sphingosine-1-phosphate synergistically stimulate DNA synthesis by a MAP kinase-dependent mechanism

We have previously shown that in NIH 3T3 fibroblasts phosphocholine (PCho) potentiates sphingosine-1-phosphate (S1P)-induced mitogenesis. Here we report that PCho and S1P also synergistically stimulate DNA synthesis in mouse Swiss 3T3 fibroblasts and in mouse JB6 epidermal cells. The combined actions of PCho and S1P on DNA synthesis were associated with synergistic activation of the p42/p44 mitogen-activated protein (MAP) kinases. Ethanolamine (50-100 microM) further enhanced the synergistic effects of PCho and SIP on DNA synthesis but not on MAP kinase activity. The results indicate that the synergistic mitogenic effects of PCho and S1P (i) are not restricted to NIH 3T3 fibroblasts, (ii) are predominantly mediated by the MAP kinase-dependent signal transduction pathway, and (iii) are enhanced by ethanolamine via a MAP kinase-independent mechanism.

Clinical, radiological and pathological features of patients with Rathke's cleft cysts: tumors that may recur

Rathke's cleft cysts are cystic sellar and suprasellar lesions, characteristically lined by a single layer of ciliated cuboidal or columnar epithelium. In contrast, craniopharyngiomass, which are also cystic sellar and suprasellar lesions, are characteristically lined by stratified squamous epithelium with keratinization on a layer of connective tissue. The usual management recommended for Rathke's cleft cysts is simple surgical drainage with partial excision of the cyst wall. Recurrences of these cysts reportedly have been very rare. This retrospective study presents the details of 12 patients (6 females; median age 30 yr, range 21-58 yr) with Rathke's cleft cyst, referred to our department over a 15-yr period (1981-1996), an unusual feature being the recurrence of 4 (33%) of these lesions. Clinical, endocrine, radiological, surgical (10 transsphenoidal; 2 transcranial), and pathological details were recorded. Nine out of 12 patients (75%) were symptomatic; visual symptoms were the commonest, and 8 had visual field defects. The median duration of symptoms was 12 months (range 3-24 months). Three patients (25%) had panhypopituitarism, 2 of whom also had diabetes insipidus (17%). The cysts varied in size from 6 mm to 50 mm, 1 being entirely suprasellar. There were no pathognomonic clinical or radiological features to differentiate them from other pituitary lesions, although the presence of diabetes insipidus in 2 patients suggested that the lesion was not a pituitary adenoma. A definite histological diagnosis was possible in 8 patients; in 4, the diagnosis was presumptive. The median duration of follow-up was 30 months (1-168 months). Four patients (33%) showed reexpansion at 3, 6, 48, and 48 months after initial surgery, 3 of whom were symptomatic and required repeat surgery. Two of these patients were given postoperative external beam pituitary radiotherapy. Apparent recurrence of Rathke's cleft cysts after initially successful surgery in our series was higher than suggested by previous reports, and thus, long-term follow-up with pituitary imaging and neuroophthalmological assessment is essential. There are no specific characteristics of the cyst that predict recurrence. Ideal management of these cysts is unclear, but aspiration, followed by extensive excision of the cyst wall when possible, seems to be the best initial option. For recurrent symptomatic tumors, surgical resection is the treatment of choice. Considering the high recurrence rate with residual structural and functional dysfunction, the role of radiotherapy in preventing recurrence of these cysts needs careful evaluation with a larger study with a longer follow-up period.

A comparison of the insulin tolerance/glucagon test with the short ACTH stimulation test in the assessment of the hypothalamo-pituitary-adrenal axis in the early post-operative period after hypophysectomy

OBJECTIVE

The insulin tolerance test (ITT) is the established reference test for assessing the hypothalamo-pituitary-adrenal (HPA) axis. Various authorities, however, have suggested that the 250 microgram short ACTH stimulation test may be used to assess the HPA axis in place of the ITT in suspected hypopituitarism, although a number of other studies have suggested that the test may be unreliable in this setting. In this study, the ITT (or glucagon test) has been compared with the 250 microgram short ACTH stimulation test in patients with pituitary tumours pre-operatively and within 2 weeks of trans-sphenoidal hypophysectomy.

DESIGN

An ITT, or a glucagon test when the ITT was contraindicated, and the 250 micrograms short ACTH stimulation test, were performed in all the patients before (an ITT in 18 and a glucagon test in three patients) and within 2 weeks after trans-sphenoidal hypophysectomy (an ITT in 16 and a glucagon test in five patients).

PATIENTS

Twenty-one patients with pituitary disorders (15 with acromegaly, one with a prolactinoma and five with non-functioning tumours) were studied; four had a microadenoma, two a mesoadenoma and 15 a macroadenoma.

MEASUREMENTS

Serum cortisol was measured by radioimmunoassay. A normal response was defined as a rise in serum cortisol to 580 nmol/l or above for all the tests.

RESULTS

Before surgery, three of 18 patients (17%) had a discrepancy between the ITT and the 30 minute short ACTH stimulation test and one of three between the glucagon test and the 30 minute short ACTH stimulation test. Combined together, pre-operatively, four of 21 patients (19%) had discrepant results. In the early post-operative period, the discrepancy between ITT and the 30 minute short ACTH stimulation test was higher with four of 16 patients (25%) showing discordant results; one of the five patients tested had a discrepancy between the glucagon test and the 30 minute short ACTH stimulation test. On combining the tests, the post-operative discrepancy was five of 21 patients (24%).

CONCLUSIONS

The 250 microgram short ACTH stimulation test produces discordant results from the ITT in a clinically significant proportion of affected patients when assessing the HPA axis, although the rate of discordance varies according to the criteria used for normality for both the tests. We suggest that the ITT should remain the preferred test for assessing ACTH secretory capacity compared with the standard 250 microgram short ACTH stimulation test, both in the preoperative and in the early post-trans-sphenoidal hypophysectomy period.

ATP-dependent choline phosphate-induced mitogenesis in fibroblasts involves activation of pp70 S6 kinase and phosphatidylinositol 3'-kinase through an extracellular site. Synergistic mitogenic effects of choline phosphate and sphingosine 1-phosphate

In serum-starved NIH 3T3 clone 7 fibroblasts, choline phosphate (ChoP) (0.5-1 mM) and insulin synergistically stimulate DNA synthesis. Here we report that ATP also greatly enhanced the mitogenic effects of ChoP (0.1-1 mM) both in the absence and presence of insulin; maximal potentiating effects required 50-100 microM ATP. The co-mitogenic effects of ATP were mimicked by adenosine 5'-O-(3-thiotriphosphate), adenosine 5'-O-(2-thiodiphosphate), ADP, and UTP, but not by AMP or adenosine, indicating the mediatory role of a purinergic P2 receptor. Externally added ChoP acted on DNA synthesis without its detectable uptake into fibroblasts, indicating that ChoP can be a mitogen only if it is released from cells. Extracellular ATP (10-100 microM) induced extensive release of ChoP from fibroblasts. ChoP had negligible effects, even in the presence of ATP or insulin, on the activity state of p42/p44 mitogen-activated protein kinases, while in combination these agents stimulated the activity of phosphatidylinositol 3'-kinase (PI 3'-kinase). Expression of a dominant negative mutant of the p85 subunit of PI 3'-kinase or treatments with the PI 3'-kinase inhibitor wortmannin only partially (approximately 40-50%) reduced the combined effects of ChoP, ATP, and insulin on DNA synthesis; in contrast, the pp70 S6 kinase inhibitor rapamycin almost completely inhibited these effects. ATP and insulin also potentiated, while rapamycin strongly inhibited, the mitogenic effects of sphingosine 1-phosphate (S1P). Furthermore, even maximally effective concentrations of ChoP and S1P synergistically stimulated DNA synthesis. The results indicate that in the presence of extracellular ATP and/or S1P, ChoP induces mitogenesis through an extracellular site by mechanisms involving the activation of pp70 S6 kinase and, to a lesser extent, PI 3'-kinase.

Pheochromocytoma: effect of nonionic contrast medium in CT on circulating catecholamine levels

PURPOSE

To study the catecholamine-releasing effect of peripheral intravenous administration of the nonionic contrast medium iohexol in patients with pheochromocytomas.

MATERIALS AND METHODS

Ten patients (eight women, two men; mean age, 44 years; age range, 25-70 years) with pheochromocytomas and related tumors and six healthy volunteers (five men, one woman; mean age, 31 years; age range, 27-35 years) were examined. Plasma catecholamine levels were measured at intervals for 60 minutes after the injection of 0.9% saline or iohexol on 2 separate days. All 10 patients intravenously received the specific alpha-adrenergic blocker phenoxybenzamine hydrochloride (0.5 mg/kg in 250 mL of 5% dextrose infused over 2 hours) 24 hours before iohexol-enhanced computed tomography.

RESULTS

There was no statistically significant increase in epinephrine or norepinephrine levels in the patients or the control subjects.

CONCLUSION

While it may be prudent to administer oral alpha- and beta-adrenoceptor antagonists in all patients with a biochemically proved pheochromocytoma to control their symptoms and to prevent a spontaneous adrenergic crisis, specific blockade may not be required before contrast medium-enhanced scanning with iohexol. Although the sample size of this study is relatively small, the results do suggest that in an incidentally detected, clinically silent adrenal mass that may or may not be hypersecreting, the nonionic contrast medium iohexol may be used for scanning without blockade.

Protein kinase Calpha is a major mediator of the stimulatory effect of phorbol ester on phospholipase D-mediated hydrolysis of phosphatidylethanolamine

Stimulation of phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PtdCho) by phorbol 12-myristate 13-acetate (PMA) has been shown to be mediated by the alpha- and betaI-isoforms of protein kinase C (PKC). To determine the role of various PKC isozymes in the regulation of PLD-mediated phosphatidylethanolamine (PtdEtn) hydrolysis, MCF-7 human breast carcinoma cells overexpressing the alpha- and theta-isoforms, and R6 rat fibroblasts overexpressing the alpha-, betaI-, and epsilon-isoforms were used. In the vector control MCF-7 cells, which contain low levels of PKC-alpha, PMA (100 nM) had only small effects on the hydrolysis of PtdEtn (1.1-1.35-fold) and PtdCho (1.15-1.6-fold). Stable expression of PKC-alpha in MCF-7 cells, which was accompanied by increased levels of the betaI- and theta-isoforms as well, greatly enhanced both PMA-induced PLD-mediated formation of phosphatidylethanol (approximately 5-fold) and the hydrolysis of PtdEtn (2.5-2.9-fold) and PtdCho (5.5-7.2-fold). The effects of PMA on the hydrolysis of PtdEtn (and PtdCho) in MCF-7/PKC-alpha cells were significantly inhibited by 0.5-3 microM concentrations of Gö 6976, a selective inhibitor of the conventional PKC subfamily. Stable expression of PKC-alpha in R6 fibroblasts enhanced, at a shorter (10 min) incubation time, the effects of PMA on the hydrolysis of both PtdEtn and, to a lesser extent, PtdCho. In contrast, stable expression of PKC-betaI in R6 fibroblasts, which originally did not contain this enzyme, enhanced the effects of PMA only on PtdCho, but not PtdEtn, hydrolysis. Overexpression of either PKC-theta in MCF-7 cells or PKC-epsilon in R6 and NIH 3T3 fibroblasts had no detectable effects on PMA-induced hydrolysis of PtdEtn. Collectively, the results suggest that PKC-alpha has a major role in the mediation of phorbol ester action on PtdEtn hydrolysis, while PtdCho hydrolysis may be regulated by both the alpha and betaI isoforms.

A lump in the chest. A common problem in an unusual setting

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Purification, characterization and modulation of a microsomal carboxylesterase in rat liver for the hydrolysis of acyl-CoA

A carboxylesterase containing long-chain acyl-CoA hydrolase activity was purified to apparent homogeneity from rat liver microsomes. Palmitoyl-CoA was the most preferred substrate, followed by stearoyl-CoA and oleoyl-CoA. Arachidonoyl-CoA, linoleoyl-CoA and acetyl-CoA were not hydrolysed by the enzyme. The purified enzyme had no activity on the hydrolysis of phospholipids and neutral lipids. The molecular mass of the enzyme was found to be 56 kDa by SDS/PAGE and 64 kDa by gel-filtration chromatography. On isoelectric focusing, the purified enzyme behaved like the ES-4 type, with a pI of 6.15. Determination of the amino acid sequence revealed that its N-terminal sequence is 100% homologous with the only other known N-terminal sequence for a rat carboxylesterase isoenzyme (ES-10). Enzyme activity was inhibited by lysophosphatidic acid and activated by lysophosphatidylcholine. The modulation of enzyme activity by these lysophospholipids might represent a plausible mechanism for the physiological control of acyl-CoA concentrations.