摘要:

SUMMARYMass spectrometry is now established as a viable method for determing the sequence of amino acids in proteins. The approach involves chemical and enzymic digestion of the protein (as in classical methods) to small peptides (ten residues) which are then chemically modified to increase their volatility. The chemical modifications are (i) acetylation of basic nitrogen sites and (ii) Permethylation. The derivatives so obtained may be sequenced in the mass spectrometer as mixtures of several peptides. This is achieved by a temperature gradient in the mass spectrometer source, which effects partial, or total separation of the derivatized peptides according to their volatilities. In this way, much tedious separation work (sometimes the rate‐determining factor in classical approaches) may be avoided. The sequencing process is carried out from the N‐terminal residue, utilizing the preferential cleavage of the ionized petide at the amide bonds; each amino acid is associated with a characteristic mass increment and thus the sequence can be determined. Mass spectrometry is especially useful in the detection and characterization of novel amino acids which might otherwise be difficult to identify. Although almost all work to date has used electron impact mass spectrometery, in the future it is possible that newer methods of ionization, such as field desorption and chemical ionization, might be profitably u

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03811.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYIn a case of subacute de Quervain thyroiditis characterized by a period of pronouced hypermetabolism followed by hypometabolism, levels of T4, T3 and the TSH response to TRH were repeatedly measured.As expected, the response to TRH was absent or low during the hypermetabolic phase, high during the hypometabolic phase and returned to normal with recovery. However, at the beginning and at the end of the hypometabolic phase, while circulating levels of T3 and T4 both lay in the subnormal range, two periods of inadequate response to TRH could be demonstrated. During the first period, the response to TRH was zero or very small; during the second period, stimulation by TRH was exaggerated.The response to TRH thus depends not only on the level of circulating thyroid hormones but on other factors such as the previous state of pituitary stimulation or inhibition.

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03798.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe role of calcium as an intracellular messenger in the activation of eukaryotic cells is discussed. Particular emphasis is devoted to: (1) the interrelationship between cell activation by chemical stimuli and alterations in intracellular calicum metabolism, and (2) the interrelated roles of calcium and the cyclic nucleotides, cyclic AMP and cyclic GMP, in achieving the final intergrated, co‐ordinated cellular respons

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03812.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe results of intermittent GH treatment of 3‐7½ years duration in seven patients with isolated GH deficiency (IGHD) and five patients with multiple pituitary hormone deficiencies (MPHD) are presented.This therapeutic schedule was found to be comparably effective to those using a continuous‐administration schedule. In contradistinction to the findings obtained with the latter, there was no progressive decline in growth velocity. The patients with IGHD were found to respond better than the patients with MPHD both in the first course as well as in consequent courses. In the intervals between courses, the growth velocity was less than in the pretreatment period in both groups.It is concluded that optimal results can be obtained by instituting an initial course of continuous treatment of 1 year's duration for the IGHD patients and of 2 years' duration for the MPHD patients, followed by an intermittent therapeutic schedule. This regime not only leads to the same growth achievement obtained with long‐term continuous administration of GH but allows conservation of supplies of this very scarce h

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03799.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYTo monitor the effect of LHRH treatment on hypothalamo‐pituitary‐gonadal function, women with functional amenorrhoea were investigated by standardized LHRH and repeated clomiphene tests before and after LHRH therapy. The actual pituitary gonadotrophin reserve was defined by Human Pituitary Gonadotrophin Index (HPGI). Clomiphene response served as hypothalamic function test, plasma oestradiol and progesterone concentrations were measured for assessement of the gonadal function.LHRH treatment as performed in this study did not change basal gonadotrophin levels or the pituitary responsiveness in our standardized LHRH test. Plasma oestradiol concentrations remained unaltered at the lower limit of the early follicular phase values of a normal menstrual cycle. The inability to respond to clomiphene was changed to clomiphene responsiveness during therapy in eighteen out of twenty‐nine women with anovulation. The majority of the responders had HPG‐Indices of R 2. Patients with hyperprolactinaemic anovulation did not convert. The possibility of an ultrashort feedback action of LHRH on its own production in the human is di

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03800.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe mode of action is discussed of the peptide hormones which trigger neosynthesis of a specific product in their target cells without being involved in any release step. Particular attention is paid to the early events elicited by ACTH in isolated adrenocortical cells. It is shown that extracellular calcium ions at physiological concentrations can serve as first messenger activating steroidogenesis if the isolated cells are pretreated in an appropriate ionic environment. Among other factors the extracellular calcium/phosphate ratio seems to be of importance. A model is proposed where calcium serves as direct messenger in the physiological activation by ACTH, cyclic AMP being a subserving factor maintaining full steroidogenesis.

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03813.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYPlasma cortisol was monitored repeatedly after oral administration of cortisol and cortisone (cortisone acetate) to seven adrenalectomized patients with pituitary‐dependent Cushing's syndrome. The amount of glucocorticoid administered was 25 mg cortisol or 33 mg cortisone/g urine creatinine/24 h. Peak plasma cortisol levels were within recommended values in all patients after cortisone and in three of the patients after cortisol. The remaining four patients had elevated peak plasma cortisol levels after cortisol. Transcortin binding capacity in plasma was normal.It is concluded that cortisol as well as cortisone is suitable for oral glucocorticoid substitution therapy in patients with normal liver function, but that cortisone apparently gives a marginally smoother plasma cortisol curve. However, it is essential to monitor plasma cortisol after institution of glucocorticoid maintenance therapy, since different and unpredictable plasma cortisol levels may exist after a given amount of glucocorticoid, although the dose required correlates reasonably well with creatinine excretion in urin

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03801.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe purpose of this investigation was to elucidate the biological significance of lysine11and of the tripeptide sequence ‐Lys‐Pro‐Val‐NH2for the biological activity of α‐melanocyte‐stimulating hormone. To this end thein vitromelanotropic activities of twenty‐four synthetic peptides related to the hormone were determined. Extension or reduction of the length of the lysine11side chain results in a marked decrease of the melanotropic potency of the respective analogue. The C‐terminal tripeptide (11‐13), the tetrapeptide (10‐13), and the pentapeptide (9‐13) were found to be hormonally active in the same order of magnitude as the central hexapeptide (5‐10). The following conclusion was drawn: α‐MSH possesses (in contrast to ACTH) two message sequences (active sites), (i) ‐Glu‐His‐Phe‐Arg‐Trp‐, and (ii) ‐Gly‐Lys‐Pro‐Val‐NH2which are capable of independently triggering the hormone receptor responsible for melanin dispersion. Thus, despite the close structural similarity of the two hormones, α‐MSH and ACTH appear to react with their respective target cell receptors by quite different chemica

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03814.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SUMMARYTotal body potassium has been measured in chromatin positive males (Klinefelter's syndrome) and males with a 47,XYY karyotype. In patients with an extra X chromosome the level of potassium was very significantly less than in normal males. Its concentration referred to lean body mass, estimated from the patient's height and weight, was also greatly reduced and not significantly different from values found in normal women.In 47, XYY males individual values were low but there was no reduction in the mean value for the group if allowance was made for the obesity of some XYY subjects. The significance of these findings, however, is difficult to assess as ther height frequently exceeded that of the controls on which the predicted potassium values were based.From these findings it would seem taht when characteristics which are normally associated with the female sex occur in males, as in Klinefelter's syndrome, there is also a reduction in body potassium either in the total content or the lean tissue concentration, or in both.By comparison, 47, XYY males appear to be more normal in these respects but further normal data is requird in order to interpret the results.The possibility that abnormal androgen production in the chromatin positive men may be influencing the potassium levels is the subject of further investigation.

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03802.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0300-0664    

DOI:10.1111/j.1365-2265.1976.tb03815.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY