[Bell's facial paralysis. Study with magnetic resonance and gadolinium]

The facial never was investigated by gadolinium-enhanced MR in 7 patients diagnosed as Bell's Palsy. All cases showed complete facial paralysis, and were studied on the acute phase of the disease. Most Bell's palsy patients demonstrate facial nerve enhancement, usually in the tympanic and labyrinthine segments. No gadolinium enhancement on the opposite facial never was seen in this serie. Because Gad-MR does not appear to influence the therapeutic decision, it may not be necessary in the management of Bell's Palsy.

[Bronchiolitis obliterans associated with organizing pneumonia. Clinico-pathological study of 6 cases]

Over the last three years six patients diagnosed of bronchiolitis obliterans with organizing pneumonia were studied. Diagnosis was established by open lung biopsy in 4 and by transbronchial lung biopsy in 2. The initiation of the symptoms was subacute although one patient evolved to respiratory failure requiring mechanical ventilation. The mean age of presentation was 68 years with male predominance over females of 5:1. The most frequent symptoms were fever and general malaise in 6 patients, cough and dyspnea in 4, respectively and weight loss in 2 patients. Functional respiratory tests showed restrictive ventilation disturbances in 4 out of 5 patients, mixed in 1 and a reduction in diffusion capacity in the 5 patients in whom it was determined. The radiologic pattern of multifocal alveolar infiltration was present in 6 cases. Interstitial involvement was also associated in 3 patients with pleural effusion in 2. Histologic findings of intraluminal polypoid masses affecting the bronchiols and alveolar conducts (bronchiolitis obliterants) with extension to the alveoli forming conjunctive Masson polyps (organizing pneumonia) was found in the 4 patients who underwent open lung biopsy and in 1 diagnosed by transbronchial biopsy although there were quantitative differences in the degree of alveolar involvement. Response to treatment with steroids was favorable in 5 out of 6 patients while the remaining patients spontaneously improved following thoracotomy.

[Moyamoya syndrome. Diagnosis with angio-MRI]

We present a case of Moya-Moya syndrome in a 28-year-old female patient with an unusual debut in the form of mirror-image writing. The patient was studied by CAT, conventional cerebral angiography, MRI and angio-MRI. The results obtained show a very good correlation between the images of conventional angiography and those obtained by angio-MRI. Angio-MRI requires no contrast, is noninvasive and rapid, promising to be a first class alternative in the diagnosis and follow-up of Moya-Moya syndrome.

Computerized tomography versus magnetic resonance imaging: a comparative study in hypothalamic-pituitary and parasellar pathology

OBJECTIVE

We wished to analyse the relative value of computerized tomography and magnetic resonance in patients referred for evaluation of pituitary and parasellar lesions.

DESIGN

We performed a separate evaluation by two independent neuroradiologists of computerized tomography and magnetic resonance images ordered numerically and anonymously, with no clinical data available.

PATIENTS

We studied 40 patients submitted for hypothalamic-pituitary study; 31 were carried out preoperatively, of which histological confirmation later became available in 14. The remaining nine patients were evaluated postoperatively.

MEASUREMENTS

Over 40 parameters relating to the bony margins, cavernous sinuses, carotid arteries, optic chiasm, suprasellar cisterns, pituitary, pituitary stalk and extension of the lesion were evaluated. These reports were compared with the initial ones offered when the scans were ordered, and with the final diagnosis.

RESULTS

Concordance between initial computerized tomography and magnetic resonance was observed in 27 cases (67.5%); among the discordant cases computerized tomography showed the lesion in two, magnetic resonance in 10, while in the remaining case reported to harbour a microadenoma on computerized tomography the differential diagnosis between a true TSH-secreting microadenoma and pituitary resistance to thyroid hormones is still unclear. Both neuroradiologists coincided in their reports in 32 patients (80%); when the initial report was compared with those of the neuroradiologists, concordance was observed with at least one of them in 34 instances (85%). Discordant results were observed principally in microadenomas secreting ACTH or PRL and in delayed puberty. In the eight patients with Cushing's disease (histologically confirmed in six) magnetic resonance was positive in five and computerized tomography in two; the abnormal image correctly identified the side of the lesion at surgery.

CONCLUSIONS

In patients referred for evaluation of Cushing's syndrome or hyperprolactinaemia (due to microadenomas) or after surgery, magnetic resonance is clearly preferable to computerized tomography. In macroadenomas both scans are equally diagnostic but magnetic resonance offers more information on pituitary morphology and neighbouring structures. Nevertheless, there are cases in which the results of computerized tomography and magnetic resonance will complement each other, since different parameters are analysed with each examination and discordant results are encountered.

Autoimmune insulin syndrome in a patient with progressive systemic sclerosis receiving penicillamine

The case of a patient with progressive systemic sclerosis, who developed hypoglycaemia and insulin autoantibodies, is described. Repeated blood glucose measurements showed levels less than 2.8 mmol/l. High immunoreactive insulin levels, with undetectable free insulin, led to the discovery of anti-insulin antibodies in the patient's serum. He had no history of exogenous insulin use and was receiving penicillamine treatment. A double mechanism for the autoimmune insulin syndrome in this case is proposed: acting in a patient with increased humoral immunoresponsiveness, penicillamine might have induced the development of insulin autoantibodies.

Effect of recombinant human growth hormone in a postpediatric hemodialysis patient with delayed growth

We present an 18-year-old patient who has been on renal replacement therapy since the age of 11. He had growth retardation and delayed puberty, with a bone age of 13.6 years. Treatment with human recombinant growth hormone (rhGH) resulted in a clearcut increase in height and lean body mass. We emphasize that rhGH treatment could be tried even at a postpediatric age, provided bone radiology suggests that further growth is possible.

Muscle insulin resistance in uremic humans: glucose transport, glucose transporters, and insulin receptors

To determine the cellular basis for insulin resistance observed in patients with uremia, we investigated insulin action in vivo and in vitro using skeletal muscle obtained from patients with chronic renal failure. Uremic subjects had significantly reduced rates of insulin-stimulated glucose disposal, as determined by a 3-h intravenous glucose tolerance test and using the hyperinsulinemic euglycemic clamp technique. Hepatic glucose production was similar before (control, 76.2 +/- 6.3 vs. uremic, 74.2 +/- 6.9 mg.kg-1.min-1) and during insulin infusion at 40 mU.m-2.min-1 (control, -60.9 +/- 6.6 vs. uremic, -53.9 +/- 6.3 mg.kg-1.min-1). In incubated human skeletal muscle fiber strips, basal 2-deoxy-D-glucose transport was unchanged in uremic subjects compared with controls. However, the increase in insulin-stimulated glucose transport was significantly reduced by 50% in muscles from uremic patients (P = 0.012). In partially purified insulin receptors prepared from skeletal muscle, 125I-labeled insulin binding, beta-subunit receptor autophosphorylation, and tyrosine kinase activity were all unchanged in uremic subjects. The abundance of insulin-sensitive (muscle/fat, GLUT-4) glucose transporter protein measured by Western blot using Mab 1F8 or polyclonal antisera was similar in muscles of control and uremic patients. These findings suggest that the insulin resistance observed in skeletal muscle of uremic patients cannot be attributed to defects in insulin receptor function or depletion of the GLUT-4 glucose transporter protein. An alternative step in insulin-dependent activation of the glucose transport process may be involved.

Mutagenesis of lysine 460 in the human insulin receptor. Effects upon receptor recycling and cooperative interactions among binding sites

Mutations in the insulin receptor gene can cause insulin resistance. Previously, we have identified a mutation substituting glutamic acid for lysine at position 460 in the alpha-subunit of the insulin receptor in a patient with a genetic form of insulin resistance. In the present work, we have investigated the effect upon receptor function of amino acid substitutions at position 460. Decreasing the pH from 8.0 to 5.5 caused a progressive acceleration of the dissociation of 125I-insulin from the wild-type insulin receptor. Substitution of acidic amino acids (Glu or Asp) for Lys460 decreased the ability of acid pH to accelerate dissociation of 125I-insulin. In contrast, substitution of Arg or neutral amino acids (Val, Met, Thr, or Gln) had no effect upon the sensitivity to acid pH. Correlated with decreased sensitivity to acid pH, substitution of Glu or Asp at position 460 retarded the dissociation of 125I-insulin from intracellular receptors subsequent to receptor-mediated endocytosis. Furthermore, retardation of dissociation of 125I-insulin from the internalized receptor was associated with a decreased half-life of the receptor. In summary, the Glu460 mutation appears to cause insulin resistance by accelerating receptor degradation and, thereby, decreasing the number of insulin receptors on the cell surface. Additional studies suggested that Lys460 may provide the amino groups whereby disuccinimidyl suberate cross-links the two alpha-subunits to each other. Consistent with the hypothesis that Lys460 is located at the interface between adjacent alpha-subunits, substitutions at position 460 impair cooperative interactions among insulin binding sites. The Glu460 mutation decreases positively cooperative binding interactions; the Arg460 mutation impairs negative cooperativity. Mutations at position 460 in the alpha-subunit did not decrease the ability of insulin to stimulate receptor tyrosine kinase.

Increased glucose transporter (GLUT4) protein expression in hyperthyroidism

We have studied skeletal muscle glucose uptake by perfused hindquarter preparations from rats treated with thyroxine. Basal glucose uptake (in the absence of insulin) was approximately 2 fold higher in muscle of hyperthyroid rats compared to controls. Insulin (10(-7) M) stimulated glucose uptake 4.0 and 6.8 fold in the 10 day and 30 day controls rats, respectively. Maximal glucose uptake (10(-7) M insulin) was not different in control and hyperthyroid rats and thus insulin responsiveness in the hyperthyroid animals was reduced to 2.5 fold stimulation. The abundance of the insulin-sensitive glucose transporter protein (muscle/fat, GLUT-4), measured by Western blot analysis using polyclonal antisera, was higher in skeletal muscle from both groups of hyperthyroid rats. These studies indicate that thyroid hormones increase basal glucose uptake in skeletal muscle and this is due, at least in part, to an increment of GLUT-4 isoform. Increased expression of muscle glucose transporter proteins may be responsible for the increased peripheral glucose utilization seen in hyperthyroidism.

Standard breakfast test: an alternative to glucagon testing for C-peptide reserve?

We measured C-peptide after glucagon and breakfast tests to compare the effectiveness of both tests in evaluating residual beta cell function in normal and diabetic subjects. A significantly higher C-peptide response was elicited after standard breakfast in patients with insulin-dependent diabetes mellitus of less than two years' evolution, ranging from 0.12 +/- 0.07 to 0.83 +/- 0.18 ng/ml (P less than 0.05). In nonobese noninsulin-dependent diabetes mellitus the response ranged from 0.86 +/- 0.02 to 1.89 +/- 0.48 ng/ml (P less than 0.0025); in obese NIDDM from 1.02 +/- 0.37 to 1.55 +/- 0.46 ng/ml (P less than 0.05), and in normal subjects from 0.77 +/- 0.23 to 2.11 +/- 1.22 ng/ml (P less than 0.0025). We conclude that the standard breakfast test is a useful and practical approach to the study of residual beta cell function.

[Computerized tomography findings in annular pancreas in an adult]

We present a case of annular pancreas in an adult female studied by computerized tomography. CT demonstrated an enlarged pancreatic head in the center of which was visualized the contrast-filled duodenal lumen. We consider these findings to be sufficiently characteristic of annular pancreas to permit differential diagnosis with neoplastic processes of the pancreatic head without having to resort to more invasive diagnostic methods like endoscopic retrograde cholangiography.

Diazoxide-induced long-term hyperglycemia. II. Slackening of proinsulin conversion

The rate of glucose-stimulated insulin release was found to be increased but that of proinsulin conversion decreased in islets removed from diazoxide-treated rats. This coincided with an elevated islet proinsulin/insulin ratio. The defect in proinsulin conversion was not corrected by preincubating the islets, at high glucose concentration, in the presence of either urokinase or rat serum. Likewise, the administration of kallikrein inhibitor in vivo did not affect the rate of proinsulin conversion as measured in vitro. Since these results fail to document a role for exocytosis-coupled endocytotic uptake of circulating factors in the efficiency of proinsulin conversion, it is speculated that the slackening of the latter process in islets removed from diazoxide-treated rats could be somehow linked to sustained inhibition of insulin release.

Carbohydrate metabolism and plasma levels of insulin and glucagon in patients with atherosclerotic vascular disease

In non-obese, non-diabetic patients suffering acute myocardial infarction, angina pectoris, previous myocardial infarction and peripheral vascular disease, the plasma levels of glucose, insulin, C-peptide and glucagon were determined in basal condition and during an intravenous glucose tolerance test. In the four groups there was a high frequency of glucose intolerance. Basal hyperinsulinism was present in all groups; in groups; in those which maintained normal glucose tolerance there was a high B-cell response to the sugar. Basal hyperglucagonemia was found in the early stage of acute ischemic heart disease, in patients with previous myocardial infarction and in those with peripheral vascular disease. The elevated plasma glucagon levels may play a role in the complex disturbance of carbohydrate metabolism present in patients with atherosclerotic vascular disease.

Plasma glucose, insulin, proinsulin, C-peptide and glucagon before and after a carbohydrate-rich meal in hyperthyroid patients

The function of the pancreatic B- and A- cell during a carbohydrate-rich meal was investigated in hyperthyroid patients, since these patients frequently present an altered handling of glucose. In basal conditions the plasma levels of glucose, immunoreactive insulin (IRI), C-peptide (CPR), proinsulin were higher in hyperthyroid patients than in normal subjects, whereas plasma glucagon was similar in the two groups. Hyperthyroid patients had high post-breakfast incremental areas of glucose and IRI and those of CPR and glucagon were normal. In post-breakfast plasma, the hyperthyroid patients had high proinsulin and normal insulin levels. The molar ratio between CPR and IRI was low throughout the test in the hyperthyroid group. In conclusion, in the hyperthyroid group the plasma levels of proinsulin were high and those of glucagon were normal; in response to the standard breakfast the levels of insulin and C-peptide were normal. These findings do not explain the altered glucose handling present in these patients.

Anomeric specificity of glucose-induced insulin release in normal and diabetic subjects

The alpha- and beta-anomer of D-glucose (3.5 or 5.0 g) were injected intravenously in 15 normal subjects and 13 non-insulin-dependent diabetic patients with mild fasting hyperglycaemia. In the normal subjects, alpha-D-glucose increased more than beta-D-glucose the plasma insulin concentration. Thus, 2 min after injection of D-glucose, the concentration of insulin relative to paired basal value was 61% higher in response to alpha- than beta-D-glucose (p less than 0.05). In 8 diabetic subjects, the secretory response to D-glucose was insufficient to allow characterization of its anomeric specificity. In the remaining 5 diabetic patients, a preferential response to alpha-D-glucose was observed in 3 cases, but not so in the other 2 cases. These results indicate that glucose-stimulated insulin release is alpha-stereospecific in normal subjects. A possible perturbation of such a stereospecificity in certain diabetic subjects warrants more extensive investigation on its precise incidence and etiopathogenic significance.