Opioid peptides do not modulate atrial natriuretic peptide or aldosterone release under basal conditions in man

The effect of two analogues of [Met]-enkephalin, [D-Ala2,N-Phe4,Met(0)-ol5]-enkephalin and its guanyl derivative, on plasma concentrations of atrial natriuretic peptide (ANP) and serum aldosterone in six normal subjects was investigated. All subjects were given a 1 litre water load to inhibit vasopressin release. Both analogues, when injected i.v. at a dose of 100 micrograms, stimulated release of prolactin and GH and inhibited serum cortisol; there was no significant change in blood pressure, pulse rate or urine output. Neither plasma concentrations of ANP nor serum aldosterone levels changed significantly after injection of either analogue at a low or high dose. Naloxone, given i.v. as an 8 mg bolus, also failed to alter concentrations of either ANP or aldosterone, while it significantly stimulated the release of serum LH and cortisol. It was concluded that under basal conditions opiate receptors are unable to modulate plasma ANP or serum aldosterone concentrations.

The effect of alpha adrenergic manipulation on the 24 hour pattern of cortisol secretion in man

We have studied the role of central alpha-1 adrenoceptor mechanisms which stimulate cortisol secretion throughout the 24 h period in man. Six normal subjects were given 24 h i.v. infusions of the alpha-1 adrenoceptor agonist methoxamine, the alpha-1 antagonist thymoxamine, and saline under double-blind conditions. The only cardiovascular effects of these adrenergic manipulations was a slight bradycardia accompanying the methoxamine infusion. The methoxamine infusion was accompanied by higher concentrations of cortisol than the saline infusion during waking hours and the food related secretory surges were exaggerated, while the converse held with thymoxamine. In contrast, the nocturnal surge of cortisol secretion was unaffected by these adrenergic manipulations. These findings suggest that an alpha-1 adrenoceptor mechanism contributes to the maintenance of cortisol secretion during waking hours, but not at night.

Effect of adrenaline on basal and ovine corticotrophin-releasing factor-stimulated ACTH secretion in man

Six normal male subjects were given, in single blind random order on six separate occasions, i.v. bolus doses of synthetic ovine corticotrophin-releasing factor-41 (oCRF-41; 25 and 50 micrograms) with and without adrenaline (3 micrograms/min) i.v. for 150 min, the adrenaline infusions alone and saline placebo. The adrenaline infusions resulted in plasma adrenaline concentrations of 4.33 +/- 0.82 (S.E.M.) nmol/l and were associated with an increase in blood glucose, heart rate and systolic blood pressure and a reduction of diastolic blood pressure. Despite these evident biological effects at several sites, there was no stimulation of plasma ACTH or cortisol by adrenaline in comparison with the effect of saline, and no enhancement of the stimulatory effect of either dose of oCRF-41 on ACTH or cortisol secretion. The ACTH response to 50 micrograms oCRF-41 was greater than that to 25 micrograms, indicating that the 25 micrograms dose of oCRF-41 was submaximal and capable of further enhancement. As the plasma adrenaline concentrations during the adrenaline infusions reached the upper limit of the physiological range of plasma adrenaline in man, yet failed to enhance the ACTH or cortisol responses to a submaximal dose of oCRF-41, we conclude that circulating adrenaline neither exerts a direct stimulatory effect on pituitary corticotrophs nor enhances the effect of CRF under physiological circumstances. The adrenaline infusions attenuated the ACTH and cortisol responses to oCRF-41 and were associated with a transient reduction of basal concentrations of both hormones.

Alpha-adrenergic stimulation of corticotropin secretion by a specific central mechanism in man

In a double-blind study in normal subjects, methoxamine, a highly selective agonist at alpha-1-adrenoceptors, significantly increased circulating ACTH and cortisol. The stimulant effect of methoxamine on cortisol secretion was dose dependent in the range 3.5-7 micrograms/kg/min, was abolished by concomitant administration of the strong alpha-1-adrenergic (and weak H1) antagonist thymoxamine but unaffected by the antihistamine, chlorpheniramine. In order to test whether the action of methoxamine on ACTH secretion was exerted centrally or peripherally, the effects of norepinephrine (NE), an alpha-1-agonist that does not cross the blood-brain barrier, were studied. Doses of NE (1-12 micrograms/min) that increased systolic blood pressure by amounts similar to the changes produced by methoxamine, did not result in any rise in plasma cortisol in normal subjects. The effect of methoxamine, which is more lipid soluble than NE, on plasma ACTH and cortisol, appears to be exerted on the CNS and not at the pituitary or via nonspecific peripheral mechanisms. In addition to its water solubility, NE differs from methoxamine in its beta-1-, beta-2- and alpha-2-agonist actions. However, prenalterol (2 mg) and salbutamol (250 micrograms), respectively beta-1- and beta-2-adrenergic agonist drugs, had no effect on the secretion of ACTH or cortisol and the alpha-2-antagonist yohimbine in an effective dose did not unmask a stimulant effect of intravenous NE on plasma cortisol. At high infusion rates, NE significantly inhibited cortisol secretion. Stimulation of central alpha-1-adrenergic mechanisms results in secretion of ACTH in man, presumably by increased release of a corticotropin-releasing factor.

Diagnosis and management of ACTH-dependent Cushing's syndrome: comparison of the features in ectopic and pituitary ACTH production

The clinical features, diagnosis and management of 16 consecutive patients with ectopic ACTH production are described and biochemical data are compared with those of 48 consecutive patients with pituitary-dependent Cushing's disease. In 10 cases the ectopic ACTH secreting tumour was completely occult to routine clinical and radiological investigation, and no basal or dynamic investigation of adrenal-pituitary function was able clearly to differentiate these patients from those with Cushing's disease. High dose dexamethasone suppression testing assessed by plasma cortisol was usually helpful but unexpected responses were seen in both diagnostic groups; the metyrapone test yielded no useful information and should now be abandoned. Hypokalaemia was seen in all patients with ectopic ACTH production but in only 10% of those with Cushing's disease who were not on diuretics at presentation. Successful diagnosis and tumour localization was most frequently achieved by a combination of CT scanning of the chest and abdomen and venous catheter sampling for ACTH. All patients in whom the ectopic ACTH-secreting tumour was obvious at presentation died of their primary tumour within 8 months, whereas seven of the 10 patients with occult tumours at presentation are alive 1.5-16.5 years later, and appear cured. Occult ectopic ACTH secretion may be impossible to distinguish from pituitary Cushing's disease. Multiple and repeated investigations are often required to make this differential diagnosis, essential for appropriate therapy.

Maternal oestriol levels reflect placental function rather than foetal function

We have examined the relationship between foetal levels of E3 and DHEA-SO4 and the birthweight of the child. Levels of these steroids do not relate to birthweight--although the concentration of DHEA-SO4 was marginally but not significantly higher in infants of lower birthweight. These findings suggest that the placental conversion of foetal precursors, and not the level of the precursors themselves, determines the concentration of E3 in the mother. Measurement of E3 as a clinical test reflects the function of both the foetus and the placenta.

The relationship between prolactin, dehydroepiandrosterone sulphate and testosterone in normally menstruating females

Circulating levels of prolactin, dehydroepiandrosterone sulphate (DHEAS) and testosterone (T) were measured in single blood samples from 115 normal women throughout the menstrual cycle. There was an inverse relationship between prolactin and both DHEAS and T. Subjects with high serum prolactin levels had significantly lower levels of DHEAS and T.

Interpretation of single progesterone measurement in diagnosis of anovulation and defective luteal phase: observations on analysis of the normal range

Single serum progesterone determinations were made in 79 apparently normal women with a regular menstrual cycle. A normal range (40 subjects) was derived from the concentrations in the follicular phase and used to define an "anovular" range for luteal phase values (nine out of 39 subjects). The remaining luteal phase values were used to construct an "ovular" range for the luteal phase and, within this range, to define a group of values (less than the 20th centile) which could be described as a "defective luteal phase." The cut off limits between ovular and anovular and between normal and defective luteal phases were respectively two and four times the follicular phase median. It is proposed that the numerical findings of this study may be used as a rule of thumb for defining normality and abnormality from a single serum progesterone determination.

Corticotrophin releasing factor: responses in normal subjects and patients with disorders of the hypothalamus and pituitary

Synthetic CRF-41 has been given to 43 patients with hypothalamic, pituitary or adrenal diseases and contrasted with the responses in 20 normal subjects. In the normal subjects the mean increment in serum cortisol (+/- SE) was 276 +/- 38 nmol/l; the increments showed a significant negative correlation with the basal serum cortisol levels (r = -0.56; P less than 0.02). The mean peak serum cortisol was 662 +/- 34 nmol/l and the mean peak corticosterone was 28.6 +/- 3.8 nmol/l. There was a significant positive correlation between the peak serum corticosterone and cortisol concentrations (r = 0.84; P less than 0.0001). Dexamethasone pretreatment abolished the rise in cortisol in response to CRF-41. The peak serum cortisol following CRF-41 was not significantly different between the normal subjects and those patients with pituitary disease who had normal cortisol responses to insulin-induced hypoglycaemia. However, in individual patients the peak cortisol levels induced by hypoglycaemia were greater than, but significantly correlated with, those induced by 100 micrograms of CRF-41. Seven patients were ACTH deficient in response to hypoglycaemia, and of these six responded normally to CRF-41. Only one of these patients had a lesion clearly originating in the hypothalamus; four had pituitary tumours with suprasellar extensions and the remaining patient had idiopathic GH and ACTH deficiency. Our data suggest that these patients have a functional defect of ACTH secretion due to the failure of CRF to reach the corticotroph. Of the four patients with pituitary-dependent Cushing's disease who were on no treatment at the time of testing, three showed an exaggerated and one a normal response to CRF-41. These normal or enhanced responses of hypercortisolaemic patients with Cushing's syndrome contrast with the complete inhibition of the responses to CRF-41 in normal subjects given dexamethasone. In the treated patients with Cushing's syndrome and normal serum cortisol levels, those with pituitary-dependent disease showed an enhanced ACTH response to CRF-41 as compared with the ectopic ACTH group, but there was some overlap between the two groups. Acromegalic patients did not show a GH response to CRF-41. We conclude that administration of CRF-41 is a safe new method for investigating disorders of the hypothalamo-pituitary axis.

Acne conglobata responding to buserelin, a gonadotrophin-releasing hormone analogue

A 65-year-old man who had had acne conglabata since early adult life was treated with buserelin for advanced prostatic cancer. Within 1 month of starting therapy, the inflammatory acne had completely resolved and this coincided with remission of the carcinoma. Gonadotrophin-releasing hormone analogues may be useful in the treatment of resistant acne.

Generation of a monoclonal antibody (Epenl) which binds selectively to murine ependymal cells

In order to define surface antigens unique to ependymal cells, spleen cells from C57/B16 mice immunized with a suspension of 70-80% purified isolated ependymal cells from syngeneic animals were fused with NS-1 myeloma cells. Five hybridomas were found which secrete monoclonal antibodies that recognize ependymal cells both by indirect immunofluorescence and radioimmunoassay. One of them, Epenl, appears to be a relatively specific surface marker of murine and rat ependymal cells, whereas the 4 others also recognize neurons, astrocytes, and/or oligodendrocytes. Absorption of Epenl with murine cerebral cortex did not affect its binding, whereas absorption with ependymal cells abolished it. Labeling of in vivo sections with Epenl demonstrates prominent binding to ependymal cells lining ventricular cavities. Epenl does not bind to neurons or astrocytes in culture, and binds only minimally to isolated oligodendrocytes. It does, however, recognize an antigenic determinant present in lung tissue.

Chlamydia trachomatis has penicillin-binding proteins but not detectable muramic acid

Chlamydia trachomatis LGV-434 was grown in HeLa 229 cells. Benzylpenicillin completely inhibited the formation of infectious elementary bodies (EBs) at a concentration of 19 pmol/ml or higher and produced abnormally large reticulate bodies (RBs) in the inclusions at 30 pmol/ml or higher. The possible targets for penicillin in C. trachomatis were three penicillin-binding proteins (PBPs) which were identified in the Sarkosyl-soluble fractions of both RBs and EBs. The apparent subunit molecular weights were 88,000 (PBP 1), 61,000 (BPB 2), and 36,000 (PBP 3). The 50% binding concentrations of [3H]penicillin for PBPs 1 to 3 in EBs and RBs were between 7 and 70 pmol/ml. Such high susceptibility to penicillin was shown by an organism that did not have detectable muramic acid (less than 0.02% by weight) in preparations of either whole cells or sodium dodecyl sulfate-insoluble residues.

Cellular origin and interactions involved in gamma-interferon production induced by OKt3 monoclonal antibody

OKT3 monoclonal antibody, a human T cell mitogen, induced interferon production by cultured mononuclear cells at 10(-11) M concentrations. Interferon was secreted only under conditions wherein OKT3 was mitogenic, and production was correlated with cell proliferation. Thus, like mitogenesis, interferon secretion reached a peak 3 days after OKT3 stimulation, was inhibited by a factor(s) in human serum, and required 1000 times higher concentrations of Fab and F(ab')2 fragments of OKT3 for induction. The interferon was most likely of "gamma" (immune) type, because pH 2 and 56 degrees C treatments denatured it, whereas anti-alpha or -beta interferon antibodies did not. Mononuclear cells were fractionated into subpopulations that contained OKT4+ cells (helper/inducer T cells), OKT8+ cells (cytotoxic/suppressor T cells), and OKM1+ cells (monocytes) by combining sheep red blood cell rosetting and complement-mediated lysis using monoclonal antibodies against specific cell types. Both OKT4+ and OKT8+ cells proliferated upon OKT3 stimulation with the absolute requirement of OKM1+ cells. However, OKT4+ cells plus OKM1+ cells were necessary for the secretion of interferon. Studies with selective pretreatments with mitomycin C suggested that gamma-interferon was secreted by the OKT4+ cells and that the OKM1+ population subserved an accessory function.

Cellular origin and interactions involved in gamma-interferon production induced by OKt3 monoclonal antibody

OKT3 monoclonal antibody, a human T cell mitogen, induced interferon production by cultured mononuclear cells at 10(-11) M concentrations. Interferon was secreted only under conditions wherein OKT3 was mitogenic, and production was correlated with cell proliferation. Thus, like mitogenesis, interferon secretion reached a peak 3 days after OKT3 stimulation, was inhibited by a factor(s) in human serum, and required 1000 times higher concentrations of Fab and F(ab')2 fragments of OKT3 for induction. The interferon was most likely of "gamma" (immune) type, because pH 2 and 56 degrees C treatments denatured it, whereas anti-alpha or -beta interferon antibodies did not. Mononuclear cells were fractionated into subpopulations that contained OKT4+ cells (helper/inducer T cells), OKT8+ cells (cytotoxic/suppressor T cells), and OKM1+ cells (monocytes) by combining sheep red blood cell rosetting and complement-mediated lysis using monoclonal antibodies against specific cell types. Both OKT4+ and OKT8+ cells proliferated upon OKT3 stimulation with the absolute requirement of OKM1+ cells. However, OKT4+ cells plus OKM1+ cells were necessary for the secretion of interferon. Studies with selective pretreatments with mitomycin C suggested that gamma-interferon was secreted by the OKT4+ cells and that the OKM1+ population subserved an accessory function.