Autoantibodies against a 72-kDa ductal cell membrane glycoprotein in a patient affected by Sjögren's syndrome and gastric MALT lymphoma

Sjögren's syndrome is a chronic autoimmune disease affecting exocrine glands, resulting in xerostomia and xerophthalmia. Lymphocytic infiltration and fibrosis of exocrine glands as well as the presence of autoantibodies against organ-specific and non-organ-specific antigens are the hallmarks of the disease. We investigated whether some patients affected by Sjögren's syndrome might have autoantibodies directed against epithelial duct cell membrane proteins. We screened sera from patients affected by Sjögren's syndrome by indirect immunofluorescence on monkey salivary gland sections and FG-Met-2 cells (a pancreatic carcinoma cell line with ductal features) for the presence of antisalivary duct antibodies. Positive sera were employed in immunoprecipitation experiments on (35)S-methionine in vivo labeled and surface-biotinylated FG-Met-2 cells. The serum of a patient affected by Sjögren's syndrome and gastric mucosa-associated lymphoid tissue (MALT) lymphoma gave positive and distinct membrane immunostaining on FG-Met-2 cells. Immunoprecipitation with the patient's serum from (35)S-methionine-labeled cell extracts followed by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and autoradiography showed the presence of autoantibodies against a 72-kDa protein. After biotin-surface labeling of FG-Met-2 cells, a band with identical electrophoretic mobility was immunoprecipitated by the serum, demonstrating that the 72-kDa band is a membrane glycoprotein. We demonstrated by three complementary approaches, i.e., immunocytochemistry, (35)S-methionine in vivo labeling, and cell surface biotinylation, the presence of autoantibodies directed against a duct cell membrane protein of 72-kDa in a patient affected by Sjögren's syndrome and gastric MALT lymphoma. Autoantibodies directed against this novel membrane autoantigen may be an additional serological marker in some cases of Sjögren's syndrome.

Impact of coronary heart disease on world leaders

BACKGROUND

Previous studies have shown that from 1965 to 1996, coronary heart disease was a frequent natural cause of death among world leaders.

OBJECTIVE

To assess incidence of and death from coronary heart disease among world leaders and to determine the effect of this disease on office-holding ability.

DESIGN

Archive search of worldwide English-language and translated press and media reports from 1970 to 1999 for reference to coronary events.

SETTING

U.S. federal government medical analytic unit.

PARTICIPANTS

National principal decision makers in countries with populations greater than 250 000.

MEASUREMENTS

Reports of angina, heart attack, myocardial infarction, and arrhythmia attributed to coronary artery disease; use of cardiac procedures; receipt of foreign care; death; and removal from office.

RESULTS

64 leaders had initial coronary heart disease events while holding their nation's highest office. Initial event rates decreased from the 1970s to the 1990s (1.9 events per 100 person-years vs. 1.1 events per 100 person-years). Survival, use of procedures, and receipt of foreign care increased over time. Most leaders who survived an acute event continued to function in office.

CONCLUSIONS

Incidence of and death from coronary heart disease among office-holding world leaders has decreased over the past 30 years, possibly because of increased use of cardiac procedures. A coronary event in a world leader is unlikely to presage a change in government.

Heterogeneous IgG subclass distribution of islet cell antibodies

Islet cell antibodies (ICA)-IgG are the serological marker of type 1 diabetes, an organ-specific autoimmune disease. A proportion of patients also have thyro-gastric autoimmunity, implying a broader humoral autoreactivity in these cases. In order to determine whether this is also reflected within islet cell antibodies (ICA) we examined the ICA-IgG subclass distribution in type 1 diabetic patients with or without associated thyro-gastric autoantibodies. ICA-IgG subclasses were detected by two-step indirect immunofluorescence, using monoclonal antibodies against the four IgG subclasses, in sera from 51 patients with type 1 diabetes and detectable ICA; 31 had no other antibodies (group 1) and 20 had at least one associated thyroid and/or gastric autoantibody (group 2). Our results show that ICA are polyclonal and invariably IgG1. In 48% of patients with type 1 diabetes without associated thyro-gastric autoantibodies, ICA were restricted to IgG1 only. Conversely, only 10% of those with thyro-gastric antibodies had ICA-IgG1 only (P < 0.02), and a larger ICA-IgG subclass recruitment was observed in these patients (P = 0.002). These findings provide evidence of heterogeneity within ICA at the IgG subclass level, with a broader clonal recruitment within this specificity in individuals displaying features of multiple organ autoimmunity. These results support the hypothesis of heterogeneity within the pathogenetic process leading to type 1 diabetes.

Erythrocyte D-glucose transport activity in reconstituted model membranes of different lipid composition

The stereospecific influx of D-glucose into liposomes formed on sonication of different glyco- and phospholipids with transport proteins from human erythrocyte ghosts solubilized with Triton x-100 was measured as an index of their total D-glucose transport activity. Specific D-glucose transport increased when acidic phospho- and glycolipids (especially sulfatide) were added to the phosphatidylcholine bilayers of the model membranes while cholesterol strongly inhibited the process. The modulation of D-glucose transport activity and its possible correlation with the lipid composition and the chemico-physical state of the erythrocytes is discussed.

Effect of phototherapy on plasma levels of GH, LH and FSH in the newborn

Plasma levels of GH, LH and FSH were measured in 74 three-day-old newborn infants with hyperbilirubinemia before and after exposure to continuous phototherapy (PhT) for 48 h. The results obtained were compared with data observed over the same period of time in 46 newborn infants belonging to the control group having homogeneous characteristics as far as form of delivery (spontaneous), gestation age, chronological age, sex, birth weight and basal blood glucose were concerned, except hyperbilirubinemia and necessity of PhT. Hyperbilirubinemic female newborn showed higher plasma GH concentrations in comparison with hyperbilirubinemic males and with controls. Forty-eight of continuous PhT significantly reduced GH levels which, however, appeared not to be substantially different from those of normal controls of the same age. Moreover, PhT determined a slight trend to increase in FSH of females, and did not modify the physiological decline of LH in both sexes during the first five days of life. The reduction of GH following PhT from abnormal to physiological concentrations may be due to the direct effect of light and/or to continuous light-related disorders of sleep. In conclusion, 48 h of continuous exposure to light (PhT) do not impair the newborn's pituitary functions here studied.

Role of red cell sorbitol as determinant of reduced erythrocyte filtrability in insulin-dependent diabetics

Erythrocyte deformability measured as filtration index is clearly diminished in diabetics, thus possibly contributing to diabetes-associated microvascular complications. Moreover, the erythrocyte sorbitol level in IDD is clearly higher than that of non-diabetics, suggesting an alteration in the polyol pathway as possible determinant of diabetes-associated complications. Following this line of research, intracellular sorbitol as well as glucose, inositol, galactitol, mannitol and 2,3-diphosphoglycerate have been studied in 21 diabetics and in 14 controls matched for age and sex. In addition to confirming the high levels of intraerythrocytic glucose and sorbitol in diabetic subjects, statistically significant correlations have been demonstrated between sorbitol and filtration index, between plasma glucose, intracellular glucose level and glycosylated hemoglobin, suggesting a relationship between metabolic control and hemorheologic alterations in diabetes.

Effects of naloxone on prolactin, luteinizing hormone, and cortisol responses to surgical stress in humans

To evaluate the possible involvement of endogenous opioid peptides in the responses of PRL, LH, and cortisol to surgical stress, we have studied the effect of naloxone on these hormones in otherwise normal subjects of both sexes undergoing cholecystectomy for gallstones. In 24 subjects (12 males and 12 females), premedication consisted of atropine sulfate (0.007 mg/kg BW); general anesthesia (30 min later) was induced by thiopental (7 mg/kg) and maintained constant by 1% ethrane in a 70%:30% nitrous oxide-oxygen mixture. In 6 males and 6 females, naloxone (0.4 mg) was injected iv before anesthesia induction. After skin incision, a clear PRL release was observed in all subjects; this was more evident in females than in males. PRL release was significantly lower in naloxone-pretreated subjects. LH release was observed only in males and was significantly higher in naloxone-pretreated subjects. Cortisol release occurred in both sexes in a similar way and was not significantly different in naloxone-pretreated subjects. Cortisol release occurred in both sexes in a similar way and was not significantly different in naloxone-pretreated subjects. These results indicate that endogenous opioid peptides are involved in stress-induced PRL and LH release in humans.

Benserazide, a stimulator of prolactin release: a new test in the diagnosis of pituitary prolactin-secreting tumours

Benserazide, an extra-cerebral inhibitor of dopa-decarboxylase, elicits prolactin (Prl) release in normal subjects when administered po. The aims of this study were to characterize the effect of benserazide on Prl release and to evaluate benserazide as a diagnostic tool in hyperprolactinaemic patients. In normal subjects, the effect of 50 mg benserazide is reduced to a greater extent by 500 mg than by 200 mg 1-dopa, and is nullified by dopamine (DA, 50 mg iv in 180 min), which also decreases fasting plasma Prl levels. Doses of 25, 50 and 150 mg benserazide elicit Prl responses which are slightly and progressively but not significantly higher; a second dose of 50 mg, administered 150 min later, is without effect on Prl release, while TRH (200 μg iv) elicits a further Prl peak. Since it is known that consecutive doses of TRH yield progressively lower Prl responses while 5-hydroxytryptophan (the precursor of serotonin) further increases Prl release in response to benserazide, we hypothesize that, in an area involving both the hypothalamus and the pituitary gland, anti-DA drugs (benserazide), TRH, and serotonin stimulate Prl release by interacting with different kinds of receptors.

When administered to hyperprolactinaemic patients, benserazide stimulated Prl release in puerperal women and in patients with functional hyperprolactinaemias, but was totally ineffective in patients with pituitary adenomas, whatever the fasting plasma Prl levels.

In 2 patients with a normal sellar tomography in whom benserazide induced no Prl release, a second tomography or computerized axial tomography of the brain, performed respectively 3 and 6 months later, revealed a pituitary microadenoma. These results suggest that benserazide may be a valuable diagnostic tool in the differential diagnosis of hyperprolactinaemia.

The effect of histamine and H1 and H2 receptors on prolactin and luteinizing hormone release in humans: sex differences and the role of stress

The present experiments were performed to investigate the possible role of histamine and its receptors, H1 and H2, in the control of PRL and LH release in normal adult humans of both sexes. Histamine infusion (200 microgram, iv, in 15 min) induced PRL and LH release in men; in women, histamine inhibited LH release without affecting PRL release. Two H1 antagonists, dexchlorpheniramine (10 mg, iv) and promethazine (50 mg, im), reduced PRL release in both sexes, stimulated LH release in men, and inhibited LH release in women. Cimetidine, an H2 antagonist (400 mg, iv), elicited PRL release in both sexes, more consistently in females than in males, and was without effect on LH release in either sex. These data suggest that in humans, the effect of histamine on PRL release is linked to H1 and H2 receptors, which respectively stimulate and inhibit PRL release independently of sex. The effect of histamine on LH release appears to depend on sex and to be mediated only by H1 receptors. To rule out the possibility that the effects of histamine are merely due to a nonspecific stress reaction, we have evaluated PRL and LH release in otherwise normal men and women undergoing surgery for gallstones. Surgery was accompanied by PRL release in both sexes, more evident in women, and by LH release only in men. These results indicate that the effect of histamine on PRL and LH release in humans is linked to sex and H1 and H2 receptors and is not due to stress; further studies are required to clarify the possible mechanism and site of action of histamine in modifying PRL and LH release in humans.

Interaction of dopaminergic and antiserotoninergic drugs in the control of prolactin and LH release in normal women

Prolactin (Prl) release, both in the experimental animal and in man, is stimulated by serotonin (5HT) and inhibited by dopamine (DA). Data also suggest that LH release in the animal is stimulated by norepinephrine and inhibited by DA. The role of 5HT in the control of LH release is less clear. It would appear to stimulate episodic LH release and to inhibit the LH surge at the pro-oestrus in animals, but the effect of 5HT on LH release has not yet been evaluated in man. In the present paper we have studied the effect of various DA-ergic drugs (DA, iv l-dopa, po l-dopa and bromoergocriptine) and of two anti-5HT drugs, metergoline and methysergide, on Prl and LH release in normal women. DA-ergic drugs lowered plasma Prl and LH levels; anti-5HT drugs, at doses able to lower Prl levels, did not affect basal LH release nor the inhibiting effect of iv l-dopa on LH release. These data indicate that DA inhibits both LH and Prl release in normal women, and that 5HT stimulates Prl release but is not involved in the regulation of LH secretion. The fact that, at variance to all the DA-ergic drugs used, the two anti-5HT drugs did not vary LH release, suggests that metergoline and methysergide are devoid of DA-ergic activity in man, at least at the doses able to inhibit Prl release.

Effect of dihydroergocristine infusion on tolbutamide-induced insulin secretion in man

The insulinemic response to 1 g of tolbutamide i.v. is greatly enhanced (+ 145%) after a 60-min infusion of the alpha-lytic dihydrogenated ergot alkaloid, dihydroergocristine (83.3 micrograms/min, corresponding to a total dose of 5 mg) in 7 healthy subjects. No differences are observed in the glycemic responses.

Study on the reproducibility of human prolactin response to sulpiride, benserazide, insulin hypoglycaemia and arginine infusion

In order to evaluate the spontaneous variability of prolactin (PRL) release in response to various stimuli applied repeatedly on different occasions, groups of 5 to 12 subjects each underwent consecutive identical tests with one of the following stimuli applied at 3-6 days' intervals: sulpiride (100 mg im), benserazide (50 mg po), insulin hypoglycaemia (0.1 U/kg b. w. iv) and arginine infusion (25 g iv in 30 min). When repeated in the same subjects, arginine and benserazide yielded superimposable results. In contrast to this, insulin hypoglycaemia yielded significantly lower PRL release, while the PRL response to the second sulpiride test was significantly higher than to the first one. When an interval of 10 days was left between two consecutive sulpiride tests, an identical PRL release was observed. These results indicate that arginine and benserazide are reproducible tests for PRL secretion and it is possible that the decreasing effect of insulin hypoglycaemia on PRL release is due to the stressful effect of the stimulus. Finally, sulpiride probably enhances both PRL release and synthesis thus making greater amounts of PRL available to a subsequent stimulus. Since some of the above stimuli are usual tools for the study of the neuroendocrine control of PRL secretion, our findings suggest that caution appears necessary in attributing to any (neuroactive) drug an effect which might be merely due to a lack of reproducibility of the stimulus employed.