Retinol to retinol-binding protein (RBP) is low in obese adults due to elevated apo-RBP

Elevated serum retinol-binding protein (RBP) concentration has been associated with obesity and insulin resistance, but accompanying retinol values have not been reported. Assessment of retinol is required to discriminate between apo-RBP, which may act as an adipokine, and holo-RBP, which transports vitamin A. The relations between serum RBP, retinol, retinyl esters, BMI, and measures of insulin resistance were determined in obese adults. Fasting blood (> or =8 h) was collected from obese men and women (n = 76) and blood chemistries were obtained. Retinol and retinyl esters were quantified by HPLC and RBP by ELISA. RBP and retinol were determined in age and sex-matched, nonobese individuals (n = 41) for comparison. Serum apo-RBP was two-fold higher in obese (0.90 +/- 0.62 microM) than nonobese subjects (0.44 +/- 0.56 microM) (P < 0.001). The retinol to RBP ratio (retinol:RBP) was significantly lower in obese (0.73 +/- 0.13) than nonobese subjects (0.90 +/- 0.22) (P < 0.001) and RBP was strongly associated with retinol in both groups (r = 0.71 and 0.90, respectively, P < 0.0001). In obese subjects, RBP was associated with insulin (r = 0.26, P < 0.05), homeostatic model assessment of insulin resistance (r = 0.29, P < 0.05), and quantitative insulin sensitivity check index (r = -0.27, P < 0.05). RBP was associated with BMI only when obese and nonobese subjects were combined (r = 0.25, P < 0.01). Elevated serum RBP, derived in part from apo-RBP, was more strongly associated with retinol than with BMI or measures of insulin resistance in obese adults. Investigations into the role of RBP in obesity and insulin resistance should include retinol to facilitate the measurement of apo-RBP and retinol:RBP. When evaluating the therapeutic potential of lowering serum RBP, consideration of the consequences of vitamin A metabolism is paramount.     

Ureaplasmas in the marmoset (Callithrix jacchus): transmission and elimination.

All adult marmosets tested had ureaplasmas in their throats but not in the lower respiratory tract, and rarely in the genital tract. Ureaplasmas persisted in the throat of a marmoset separated from the colony for 44 days. They could not be recovered from the animals for at least nine weeks after a course of minocycline. Airborne reinfection did not occur when these animals were surrounded by, but separate from, infected marmosets. It occurred when the minocycline-treated animals were caged with the infected marmosets or were inoculated. The genital tract was more difficult to infect than the oropharynx.     

Biosurfactants from thermophilic dairy streptococci and their potential role in the fouling control of heat exchanger plates

Recent work on biosurfactant release by thermophilic dairy streptococci is reviewed. There is a suggestion thatStreptococcus thermophilus isolates may release biosurfactants that stimulate detachment of already-adhering cells and leave an anti-adhesive coating on a substratum. A previously published rapid screening method is described for the identification of biosurfactant-releasing microorganisms, and growth medium supplements to enhance biosurfactant release by thermophilic dairy streptococci are reported. New experimental work described includes the isolation and purification of biosurfactants from dairy isolates by thin layer chromatography. Many compounds isolated were extremely surface-active and reduced the water surface tension to values around 30 mJ m^–2 at a concentration of 10 mg ml^–1. Most importantly, the thin layer chromatograms of various isolates resembled each other, and an adsorbed purified compound from one isolate retarded the deposition to glass of another isolate by a factor of two. Provided our findings implicate that these biosurfactants could also be adsorbed to heat exchanger plates in pasteurizers and thereby retard colonization by thermophilic streptococci, these compounds may have major economic implications. Further work is required, however.     

A new extra long acting depot preparation of the LHRH analogue Zoladex®. First endocrinological and pharmacokinetic data in patients with advanced prostate cancer

A new depot formulation of the LHRH analogue Zoladex® (goserelin acetate) has been developed which releases the drug over a period of at least 3 months as judged by measurement of drug content in depots at intervals after insertion in male rats and by the suppression of oestrogen secretion and oestrus in female rats. This formulation is based on the lactide/glycolide polymer system used for the standard 1-month Zoladex® depot, but the dose has been increased to 10.8 mg and the characteristics have been modified to enable a longer release of drug to be achieved.

Thirty-eight patients with histologically proven, locally advanced (stage T3 or T4) and/or metastatic prostate cancer were treated with this new longer acting LHRH analogue depot formulation containing 10.8 mg Zoladex®. After initial increase of serum testosterone in the first week of therapy, castration levels were reached in all patients after 4 weeks and this was maintained for more than 14 weeks. At the time of depot exhaustion, when escape from castration levels of androgen occurred, all patients received a single injection of a standard 1-month depot containing 3.6 mg Zoladex® which restored castration levels of androgen thus showing that the pituitary gland was again suppressed. The tolerance and acceptability of the longer-acting depot is high and comparable to the 1-month depot. Taking into account social and psychological factors, patients with advanced prostate carcinoma will soon be able to be treated with a longer acting LHRH depot formulation every 3 months an alternative of the 1-month depot now widely used clinically.     

Serological evidence that chlamydiae and mycoplasmas are involved in infertility of women

Women with a history of infertility for 2 or more years were examined by hysterosalpingography (HSG) and antibodies against Chlamydia trachomatis, Mycoplasma hominis and M. genitalium were measured by a microimmunofluorescence technique in sera obtained immediately before HSG. Of 45 women with abnormal HSG findings, 15 (33%) had antibodies to C. trachomatis and 16 (35.5%) to M. hominis. In contrast, of 61 women with normal HSG findings, only 8 (13%) and 7 (11.5%) had antibodies to these micro-organisms, respectively. Antibody against M. genitalium was found in 26 of the patients (20% abnormal HSG and 28% normal HSG), indicating the need for further investigation of the significance of this mycoplasma in female infertility. The present results do confirm, however, that C. trachomatis is an important cause of infertility in women and suggest strongly that M. hominis is implicated.     

Potent agonist and antagonist analogues of luliberin containing an azaglycine residue in position 10.

Potent agonist and antagonist analogues of luliberin containing an azaglycine residue in position 10 were synthesised and tested in androgen-sterilised constant-oestrus rats. The agonist, [D-Ser(Bu^t)⁶, Azgly¹⁰]-luliberin, induced ovulation at a dose of 6ng/rat i.v., 10μg/rat p.o. and was at least five times as potent as [D-Ser(Bu^t)⁶, des-Gly-NH₂¹⁰, Pro-ethylamide⁹]-luliberin. [D-Ser(Bu^t)⁶, Azgly¹⁰]-luliberin (1μg/rat) also prevented HCG-induced increases in ovarian and uterine weight in immature rats and was a highly potent antitumour agent when given to rats bearing DMBA-induced mammary tumours. The antagonist, [D-Phe², D-Phe⁶, Azgly¹⁰]-luliberin at a dose of 15μg/rat completely inhibited ovulation induced by luliberin (0.5μg/rat), whereas [D-Phe², D-Phe⁶]-luliberin lost activity below 125μg/rat.     

Interaction of silver nitrate with readily identifiable groups: relationship to the antibacterialaction of silver ions

Microbiologically it was demonstrated that amino acids, e.g. cysteine (CySH), and othercompounds, e.g. sodium thioglycollate, containing thiol groups neutralized the activity of silvernitrate against Pseudomonas aeruginosa PAOl. Amino acids with disulphide bonds wereinactive, with the exception of l -cystine dimethyl ester, as were all amino acids with nosulphur groups. Iodoacetamide reacted with CySH to produce a CyS–acetamide complex thatwas unable to quench the activity of Ag⁺. Chemical analyses using cyclic voltammetrydemonstrated that high coordination numbers (3·1) were obtained with thiol-containingamino acids and low numbers (0·28–0·4) with other amino acids. Bothmicrobiologically and chemically, the results imply that interaction of Ag⁺ with thiolgroups plays an essential role in bacterial inactivation.