Dose-response study of the inhibiting effect of somatostatin on growth hormone and insulin secretion in normal subjects and acromegalic patients.

A dose-response study of the effect of somatostatin on plasma growth hormone (GH) and immunoreactive insulin (IRI) levels was performed in normal subjects and acromegalic patients. In normal subjects 150 mug of somatostatin completly suppressed GH and IRI responses to arginine, while with 75 and 37.5 mug only a partial suppression was usually observed. Basal levels of plasma IRI were significantly lowered within 15 min from the start of somatostatin injection at each of the three dose levels. In three acromegalics the doses of 150 and 75 mug of somatostatin were effective in lowering both GH and IRI levels; the dose of 37.5 mug was still effective in lowering plasma IRI levels, while GH levels were not significantly modified. A dose of somatostatin inhibiting GH secretion without affecting insulin secretion has not been found either in acromegalics and in normals. It was concluded that the effects of somatostatin on GH and IRI secretion cannot be easily dissociated.     

Hypokalemic rhabdomyolysis without watery diarrhea: an unexpected presentation of a pancreatic neuro-endocrine tumor

Pancreatic polypeptide (PP) islet cell tumors are usually not associated with a distinct clinical syndrome, although some reports suggest that they can cause a watery diarrhea syndrome similar to vasoactive intestinal polypeptide (VIP) cell tumors. We report the case of a young woman with an unusual presentation of a pancreatic neuroendocrine tumor mainly secreting PP. The patient developed a reversible hypokalemic rhabdomyolysis very likely secondary to the presence of the tumor. The myopathy resolved following the restoration of normokaliemia using potassium supplementation and a partial laparoscopic pancreasectomy. Isolated cases of hypokalemic rhabdomyolysis induced by intestinal diseases have been described in literature but these did not include gastroenteropancreatic neoplasms. We suggest that pancreatic neuroendocrine tumors should be added to the list of intestinal diseases capable of producing hypokalemic myopathy.     

Defective granulocyte chemotaxis and natural killer activity in a patient with recurrent infections

A 25-year-old male with a history of recurrent infections presented with fever, severe aplastic anaemia, splenomegaly and retroperitoneal node enlargement. Lympho-histiocytic granulomas were found in spleen, liver and lymph nodes. Granulocyte studies revealed normal morphology, severely impaired random migration and complete absence of directed locomotion. Whereas phagocytosis was slightly reduced, candidacidal activity and nitroblue tetrazolium reduction were normal. Basal granulocyte cyclic GMP levels were within the normal range while a 5-fold increase of cyclic AMP levels was observed. Numerous abnormalities were also found in the patient's lymphocytes: lack of delayed hypersensitivity, reduced response to mitogens, low OKT4/OKT8 ratio, absence of natural killer (NK) activity with normal number of cells recognized by NK-specific monoclonal antibodies. These observations describe a distinct clinico-pathologic entity and suggest the possibility of a common defect in granulocytes and in NK cells.     

Plasma cyclic nucleotide levels in patients with refractory anaemia with excess of blasts

Summary To verify the clinical usefulness of extracellular cyclic nucleotide determinations as tumour markers in preneoplastic syndromes, plasma cyclic AMP (cAMP) and cyclic GMP (cGMP) levels were monitored in 47 patients with refractory anaemia with excess of blasts (35 RAEB and 12 RAEBt), 20 of whom progressed to acute leukaemia during the observation period. The control group consisted of 45 healthy subjects matched for age and sex. In all groups of patients plasma cAMP levels were within the normal range, whereas plasma cGMP levels were significantly higher than those of normal subjects in both RAEB and RAEBt patients, and increased further when progression to acute leukaemia occurred. These data suggest that serial determinations of plasma cGMP may be useful to monitor the progression of the disease, though there is no evidence that cGMP values at diagnosis may have a prognostic significance.