Establishment of a multi-species biofilm model to evaluate chlorhexidine efficacy.

BACKGROUND: Chronic infections, for example, diabetic foot ulcers, have a large impact in terms of patient morbidity and mortality. These wounds are characterized by complex polymicrobial communities of bacteria, which may include a number of difficult-to-eradicate multidrug-resistant pathogens. AIM: To establish a multi-species biofilm model to test the efficacy of chlorhexidine and chlorhexidine-containing formulas in eradication of polymicrobial biofilms. METHODS: A Centers for Disease Control and Prevention bioreactor was used to establish a multi-species biofilm incorporating Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis with equal numbers of each pathogen. This model was used to test the effectiveness of chlorhexidine at controlling the pre-formed biofilm. FINDINGS: Chlorhexidine digluconate (CHD) was added to the bioreactor at a range of concentrations. K. pneumoniae and P. aeruginosa survived within multi-species biofilms, up to and including 4% CHD, whereas S. aureus was reduced to below the level of detection at 1%. Wiping the biofilm-containing coupons from the bioreactor with chlorhexidine-containing medical wipes resulted in >3 to <4log10 reduction after 24h, for all species. When the coupons were embedded in a simulated wound bed, formed in an agar plate, CHD-containing medical dressings completely eliminated S. aureus (>8log10 reduction), but had minimal effect (<3log10) against the other species tested. CONCLUSION: The study demonstrates that the effectiveness of chlorhexidine may be limited in settings where it is required to act on multi-species biofilms. This may compromise the ability of chlorhexidine to control the infection and spread of these pathogens.

Dynamics of prolactin in amniotic fluid and extraembryonic coelomic fluid in early human pregnancy.

Concentrations of prolactin were measured by an immunoradiometric assay in 26 matched samples of amniotic fluid, extraembryonic coelomic fluid and maternal serum from 9 to 12 weeks of pregnancy and in a further 131 amniotic fluid samples from 9 to 20 weeks. Low levels of prolactin (median 40 MU/l) were present in amniotic fluid from 9 to 12 weeks. Levels in the coelomic fluid were higher (median level 371 MU/l; P < 0.0001) than in amniotic fluid. From 13 weeks, there was a rapid rise in amniotic fluid prolactin to reach a peak at 19 weeks (median level 99,850 MU/l). The pattern of increase of prolactin in amniotic fluid is similar to, but occurs 2 weeks later than that for insulin-like growth factor-binding protein-1, another major decidual product.

The usefulness of serum thyroglobulin in the follow-up of differentiated thyroid carcinoma in children.

Serum thyroglobulin has been measured serially in ten children aged 5-17 years presenting with differentiated thyroid carcinoma. At presentation 4 had intra-thyroidal disease, 3 had lymph node metastases, and 3 had lung metastases. During follow-up for a median of 37.0 months (range 21-108) 3 patients have been disease-free, 4 have had a local relapse, and 3 have had persistent disease. Seventy-seven separate serum thyroglobulin measurements have been performed; 36 on and 41 off thyroid replacement therapy. A level of thyroglobulin of less than 5 ng/ml was taken as indicative of absence of disease, and compared against combined clinical examination and 131I scanning. Overall sensitivity of thyroglobulin measurement was 36/37 (97%), and although specificity was 30/40 (75%), this rose to 30/32 (94%) if raised thyroglobulin levels noted within 3 months of 131I therapy in otherwise asymptomatic patients (n = 4) or in subjects with intact thyroid tissue (n = 4) were excluded. Concordance with clinical status was 30/31 (97%) in measurements taken on, and 31/32 (94%) in those taken off, thyroid replacement. These data indicate that thyroglobulin measurement is a sensitive and specific means of detecting residual, recurrent, and metastatic thyroid carcinoma in children.

Acute and long-term effects of once-daily oral bromocriptine and a new long-acting non-ergot dopamine agonist, quinagolide, in the treatment of hyperprolactinemia: a double-blind study.

Quinagolide (CV 205-502, Sandoz), an octahydrobenzo (g) quinoline, is a new non-ergot dopamine agonist which has specific D2 receptor activity and a long half-life, making it suitable for once-daily treatment. Recent uncontrolled reports have suggested that quinagolide may be successfully used for the clinical management of hyperprolactinemia with fewer adverse reactions than bromocriptine. This study is the first to compare quinagolide in a double-blind manner with bromocriptine, given only once-daily instead of the usual multidose regimen. In the first phase we compared, in 7 hyperprolactinemic patients, the effects over 24 h of a single oral dose of 0.05 mg quinagolide with 2.5 mg bromocriptine. Compared with placebo, both bromocriptine and quinagolide showed potent PRL-inhibiting and GH-releasing effects, with comparable effects at 24 h; no significant changes were observed in TSH, LH, FSH or cortisol. Twelve hyperprolactinemic patients were then randomized to receive either once-daily bromocriptine or quinagolide in incremental doses for a period of six months. Both drugs were found to be equally effective, and no differences were seen either in adverse reactions or PRL levels during repeated diurnal sampling. We therefore conclude that quinagolide and bromocriptine are therapeutically equivalent in long-term use, and both are equally effective when given once a day. However, some patients intolerant of bromocriptine may respond better to quinagolide, and vice versa.

Megavoltage pituitary irradiation in the management of prolactinomas: long-term follow-up.

OBJECTIVE To determine the long-term effects of external beam megavoltage radiotherapy (RT: 4500 cGy via three portals at 180 cGy or less total daily dose) on endocrine function in prolactinomas. DESIGN Longitudinal study following radiotherapy with periodic re-assessment at regular intervals, at least 2 months off dopamine agonist therapy. PATIENTS Thirty-six female patients, age range 19-50 years, with either macroprolactinomas (12 patients) or microprolactinomas (24 patients), but without significant suprasellar extensions. MEASUREMENTS Clinical appraisal, and anterior and posterior pituitary assessment: basal levels at yearly intervals or less, with dynamic screening with TRH, LHRH and hypoglycaemic stimulation every 2-3 years. RESULTS Before RT, serum prolactin (PRL) levels ranged from 1150 to 34,000 mU/l; after RT (mean 8.5 years, range 3-14), serum PRL fell to normal (i.e. less than 360 mU/l) in 18 of the 36 patients (50%), and to just above the normal range (378-780 mU/l) in a further 10 (28%). Two patients had PRL levels at their last follow-up higher than those at presentation, with one patient showing evidence of tumour recurrence on CT scan. A total of eight of the 36 patients (23%) developed post-RT gonadal deficiency by the end of follow-up at 8 +/- 3.1 years (+/- SD, range 3-11), but six were aged over 40 years at that time. GH deficiency was frequent, occurring in 94% of patients, usually from 2 to 3 years post-RT, while TSH deficiency and reduced ACTH reserve was uncommon (each 14%), and occurred later. In the subgroup of 12 patients with macroprolactinomas, results were broadly comparable. CONCLUSIONS Megavoltage RT produces a progressive fall in serum prolactin in the great majority of patients with prolactinomas, with a relatively low incidence of TSH or ACTH deficiency. As it is now clear that dopamine agonist therapy alone provides sufficient management for microprolactinomas, RT may be used for the long-term control of macroprolactinomas, together with interim dopamine agonist therapy. It allows pregnancy to be safely undertaken but, in view of the delayed onset of gonadal deficiency, its administration should be timed with respect to the desired onset of conception in women.

The effects on anterior pituitary hormone secretion of salmon calcitonin in healthy volunteers.

The reports of the effect of calcitonin on pituitary function are confusing and often refer to uncontrolled studies. We have now carried out a double-blind placebo-controlled trial of intravenous and subcutaneous salmon calcitonin on anterior pituitary function in 17 healthy volunteers. Visual analogue scores for the nausea and vomiting seen after salmon calcitonin correlated with the rise in ACTH and, secondarily, cortisol. Calcitonin had no effect on growth hormone, prolactin, thyrotrophin, luteinizing hormone or follicle stimulating hormone. It is concluded that the stimulation of ACTH secretion following a single dose of salmon calcitonin is probably the result of the stress of nausea rather than a direct effect on the pituitary.

Subcutaneous growth hormone-releasing hormone augments pulsatile nocturnal GH release in GH-insufficient children, but may also raise basal GH secretion.

Growth hormone-releasing hormone (GHRH) when given s.c. to GH-insufficient children either as pulses, or once or twice daily, promotes linear growth. These treatment regimens, however, are not ideal as they require frequent drug administration and a significant proportion of patients do not show improved growth. We have now investigated the GH response to a nocturnal s.c. infusion of GHRH (1-29)NH2, at two dosages, 5 and 10 micrograms/kg/h, in a group of five GH-insufficient children. The s.c. infusion of GHRH between 2100 h and 0600 h augmented nocturnal pulsatile GH release in all five children. There was a dose-dependent response for the GH area under the curve (AUC), and mean total GH concentration. The AUC for GH was significantly greater after the 10 than 5 micrograms/kg/h GHRH which in turn was greater than that after placebo; mean (SD) AUC: 14816 (3978), 8125 (1931), 3032 (1582) mU min/l respectively (P less than 0.01 and P less than 0.05). There was no significant change in the number of GH pulses during the 9-h infusions when the subjects were infused with GHRH 10 or 5 micrograms/kg/h compared to placebo, and they occurred at similar times although the number of pulses tended to be greater after GHRH; the mean (SD) numbers of GH pulses were 5.0 (0.7), 3.8 (0.8), 3.2 (0.8), respectively. There was however a significant rise in the mean baseline GH concentration in all patients during the infusion of GHRH 10 micrograms/kg/h compared to placebo, but not with 5 micrograms/kg/h. Thus, GHRH(1-29)NH2 given s.c. augmented nocturnal pulsatile GH release in GH-insufficient children but it also increased baseline GH secretion. These results suggest that a sustained release preparation of GHRH could be a potential treatment for GH-insufficient children, and that a dose of 5 micrograms/kg/h would promote pulsatile GH release, but that at higher dosage it may also raise basal GH secretion.

Pyridostigmine, an Acetylcholinesterase Inhibitor, Stimulates Growth Hormone Release, but has no Effect on Basal Thyrotrophin or Adrenocorticotrophin Levels, or the Thyrotrophin Response to Thyrotrophin-Releasing Hormone.

Abstract Pyridostigmine, an acetylcholinesterase inhibitor, stimulates growth hormone (GH) release and is thought to act by inhibiting hypothalamic somatostatin release. There are few data concerning the effect of pyridostigmine on other pituitary hormones apart from GH. We have studied the effect of pyridostigmine on basal GH, thyrotrophin (TSH), prolactin, adrenocorticotrophin and cortisol release, and thyrotrophin-releasing hormone (TRH)-stimulated TSH and prolactin release, in two studies involving nine healthy male subjects. Pyridostigmine stimulated GH release in all subjects but had no effect on adrenocortocotrophin or cortisol levels, or basal or TRH-stimulated TSH and prolactin levels. There are some data to suggest that somatostatin inhibits TRH-stimulated TSH release. Our findings, however, suggest that either endogenous somatostatin tone has little effect on the TSH response to TRH compared to its effects on GH or pyridostigmine acts through a mechanism other than altering somatostatin tone. Pyridostigmine did not alter adrenocorticotrophin or cortisol levels in the presence of a clear action on GH release, providing further evidence that the previously reported effects of cholinergic drugs on cortisol release are stress-related.

Long-term effects of radiotherapy for acromegaly on circulating prolactin.

In 61 acromegalic patients, serum PRL was assessed (off medical treatment) before and 2 to 12 (mean 6.4) years after external beam radiotherapy. Before radiotherapy elevated PRL levels were present in 22 of 35 males (63%) and 12 of 26 females (46%) and were above 1000 mU/l in 11 males and 5 females. When studied for up to 5 years after radiotherapy, 22 of 23 (96%) patients who had not had surgery and who had normal PRL pre-radiotherapy showed an increased PRL level and this was also seen in 17 of 27 (63%) who had been hyperprolactinaemic initially. In contrast, 10 of 27 patients (37%) who had elevated pre-radiotherapy levels (all greater than 1000 mU/l) had a reduction in PRL values after radiotherapy. In all 11 patients who underwent surgery before radiotherapy, an increase in PRL was seen after radiotherapy. In the 21 patients followed for 10-12 years, the peak PRL value occurred 1-6 years after radiotherapy. After this, a progressive reduction of PRL to normal was seen. Normal levels were reached 4 to 10 years after radiotherapy. No correlation was found between pretreatment PRL values and final GH values in the whole group, nor between changes in PRL and the development of impaired ACTH or TSH secretion. Thus, different patterns of PRL behaviour suggest that radiotherapy treatment may either produce hyperprolactinemia from mild hypothalamic damage or ablate PRL secreting cells if they were present in the tumour before treatment. These changes do not predict final GH results or the development of hypopituitarism after radiotherapy.

Anterior and posterior pituitary function in brain-stem-dead donors. A possible role for hormonal replacement therapy.

Blood samples were obtained, at the time of organ donation, from 31 consecutive brain-stem-dead (BSD) donors referred to one transplant coordinator during a 9-month period. Twenty-four cases (77%) had clinical diabetes insipidus (DI), which was poorly controlled with marked dehydration in a majority of cases (serum osmolality range 268-357; median 302 mOSM/kg). Serum triiodothyronine (T3) was subnormal in 25 (81%); all had normal or high serum reverse T3; and the serum free thyroxine (T4) index was subnormal in 9 (29%), and TSH was subnormal in 7 (23%). In no case were T4 and TSH both subnormal and results were typical of the sick euthyroid syndrome rather than TSH deficiency. Of 21 cases not receiving corticosteroids, 5 (24%) had a serum cortisol above 550 nmol/L (20 micrograms/dl), excluding ACTH deficiency, and only 1 had undetectable cortisol levels. Those with severe hypotension did not have significantly lower serum cortisol (mean 354 vs. 416; P greater than 0.5). Levels of prolactin, growth hormone, gonadotrophins, and gonadal steroids were variable, but only a minority were frankly deficient in these hormones. BSD donors frequently have DI, which is often managed poorly by nonspecialists and requires appropriate replacement therapy. In contrast most patients are not totally deficient in anterior pituitary hormones. Routine hormonal therapy with cortisol and T3 cannot, therefore, be justified on endocrinological grounds. Widespread introduction of such treatment should only follow controlled trials that clearly demonstrate clinically significant improvement in the transplanted organ function, without detriment to the donor.

Prolactinomas presenting as primary amenorrhoea and delayed or arrested puberty: response to medical therapy.

Fourteen patients presented with arrested pubertal development associated with prolactin-secreting pituitary tumours; serum prolactin ranged from 4000-104,300 mU/l in the ten females and 920-68,000 in four males. Skull X-ray showed a markedly expanded pituitary fossa in eight patients. CT scan and/or air encephalography showed macroadenomas in nine, of whom seven had large suprasellar extensions to their tumours, yet only five had complained of headache and only two had visual field defects. All were treated with bromocriptine (7.5-60 mg/day) which lowered prolactin substantially in all and into the normal range in 11 (range less than 60-3090, median 105 mU/l). Puberty thereafter progressed spontaneously in 13, but in one patient, whose prolactin did not suppress completely, menarche could be induced only with clomiphene. Anterior pituitary function improved on bromocriptine. In seven patients with macroadenomas, tumour shrinkage into the pituitary fossa was complete and in two others incomplete shrinkage was followed by transsphenoidal hypophysectomy. Seven patients received pituitary irradiation, six after bromocriptine-induced shrinkage and one after transsphenoidal surgery. At follow-up 6 months to 10 years (median 5 years) after presentation, ten remain on bromocriptine with a suppressed serum prolactin, one has a normal prolactin after surgery, and three are off bromocriptine with residual hyperprolactinaemia (418-4680 mU/l). To date, four females have become pregnant and one male has fathered two children. Prolactinomas are an important, albeit rare, cause of arrested puberty and should therefore be sought. Most patients respond well to bromocriptine, with or without pituitary irradiation.

Immunoreactive human chorionic gonadotrophin from the cyst fluid and CSF of patients with craniopharyngioma.

A specific radioimmunoassay for the beta-chain of human chorionic gonadotrophin irHCG beta has demonstrated HCG-like material to be present in craniopharyngioma cyst fluid in nine consecutive patients with craniopharyngioma. There was no detectable LH/HCG bioactivity as assessed using testosterone production from isolated Leydig cells from rat testis in seven samples tested. One patient was also found to have measurable irHCG beta in the cerebrospinal fluid (CSF), which fell to undetectable levels following surgery; in this patient, there was clinical evidence that the cyst fluid had leaked into the CSF pre-operatively. Immunocytochemical staining for HCG beta and intact HCG was positive in five of the tumours. irHCG beta was not measurable in the serum of any of the patients.

Modulation of the actions of tyrosine by alpha 2-adrenoceptor blockade.

1. Eight normal subjects were given, in double-blind, random order L-tyrosine 50, 250 and 500 mg kg-1 and placebo orally. Plasma tyrosine concentrations rose in a dose-dependent manner, without affecting the concentrations of the other large neutral amino acids. Tyrosine stimulated the secretion of prolactin and thyrotrophin (TSH) but had no effect on the plasma concentrations of adrenocorticotrophic hormone (ACTH), cortisol, growth hormone or the gonadotrophins. 2. The lack of a stimulant effect of tyrosine on ACTH secretion was presumed to be due to activation of one of the negative feedback mechanisms that control the rate of synthesis and release of the catecholamines, and this hypothesis was tested by examining the effects of the alpha 2-adrenoceptor antagonist idazoxan on the actions of tyrosine. 3. Seven normal males were given on 6 separate occasions tyrosine 250 and 500 mg kg-1 and placebo orally following pretreatment with saline and idazoxan (0.1 mg kg-1 i.v.). Following pretreatment with idazoxan, tyrosine stimulated the secretion of ACTH and noradrenaline in a dose-dependent manner, although neither tyrosine nor idazoxan on their own had any effect on the secretion of either substance. 4. The lack of effect of tyrosine when given on its own appears to be due, to partly, to activation of alpha 2-adrenoceptors, which inhibit the release of noradrenaline. Idazoxan caused a small increase in systolic blood pressure, both when given on its own and in combination with tyrosine. Neither tyrosine nor idazoxan had any significant effect on the state of behavioural arousal, as measured by visual analogue scales, or on the secretion of growth hormone or the gonadotrophins.

Terguride--a new dopamine agonist drug: a comparison of its neuroendocrine and side effect profile with bromocriptine.

Terguride, the C9-10 dihydrogenated derivative of lisuride, is a new drug which inhibits pituitary prolactin (PRL) secretion. It has mixed dopaminergic-antidopaminergic and alpha 2-antiadrenergic activity, and has proved useful in the clinical management of hyperprolactinemia. However, no trial comparing its use with the standard dopamine agonist bromocriptine has been reported. We have therefore compared three doses of terguride with bromocriptine 2.5 mg and placebo in a randomized double-blind crossover trial in eight normal volunteers. Terguride showed a potent dose-dependent PRL-inhibiting and growth hormone (GH)-releasing effect, while no significant changes were observed in thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), or luteinizing hormone (LH) in comparison to placebo. The neuroendocrine profile of terguride 1 mg was identical to that of bromocriptine, with a significant reduction in PRL still evident at 24 hours. However, in this small group of normal subjects, the side effects experienced at any dose of terguride were significantly less than with bromocriptine. Terguride 1 mg was always preferred to bromocriptine, while the lower doses were indistinguishable from placebo. Terguride is therefore likely to play an important role in the treatment of hyperprolactinemia.

GH feedback occurs through modulation of hypothalamic somatostatin under cholinergic control: studies with pyridostigmine and GHRH.

We have studied the effect of increased cholinergic tone on the GH response to growth hormone-releasing hormone (GHRH) and on GH feedback, using pyridostigmine, an acetylcholinesterase inhibitor. In six healthy male adult volunteers 120 mg oral pyridostigmine increased basal GH secretion compared to placebo and augmented the GH response to 100 micrograms i.v. GHRH (1-29) NH2; the effect was more than the additive effect of pyridostigmine and GHRH when each was given alone. Pretreatment with 2 IU methionyl-hGH given i.v. abolished the serum GH response to GHRH given 3 h later, demonstrating a negative feedback loop of GH on the response to GHRH; this inhibited response to GHRH was restored in subjects given pyridostigmine as well as methionyl-hGH. The data demonstrate that enhanced cholinergic tone releases GH, augments the serum GH response to GHRH and unblocks the negative feedback effect of methionyl-hGH pretreatment on the GH response to GHRH. These results suggest that GH negative feedback effects on its own secretion occur predominantly through increased hypothalamic somatostatin secretion; this somatostatin secretion is under inhibitory cholinergic control.

Hyperprolactinaemia and microadenomas in primary hypothyroidism.

The presence at presentation of hyperprolactinaemia and abnormalities on high resolution computed tomographic (CT) scanning of the pituitary gland have been documented in 19 patients with primary hypothyroidism. The changes on thyroid hormone replacement were followed for up to 28 months after presentation. At presentation serum PRL was elevated in 12 subjects (454 to 2612 mU/l); after stabilization of thyroid replacement PRL remained raised in 9 patients (525 to 1888 mU/l) despite 10-18 months of treatment. Pretreatment CT scans showed enlarged pituitaries in 11 patients with suprasellar extension in five. In 11 patients there was initially an area of low attenuation suggesting a microadenoma and on rescanning this appearance remained in five patients. Hyperprolactinaemia in hypothyroid patients does not always return to normal with thyroid hormone replacement.