Objectives. A more direct and precise hormonal marker of the menopause has been required for some time. The aim of this study was to identify the most accurate marker of the menopause, based on analyses of inhibin A and B, FSH, LH and estradiol (E2), among 59 healthy women without hormonal treatment during the perimenopause and early postmenopause.Methods. Fifty‐nine women, aged 46–56 years (mean age 51.2 years), were examined annually for 5 years during the menopausal transition and had venous blood drawn simultaneously for later analyses of the above‐mentioned hormones.Results. Inhibin A showed a steady decline from at least 4 years before the final menstrual period (FMP) until 1 year before menopause, whereas inhibin B had a shorter lasting decline from year 3 to year 2 before menopause, concomitant with a rise in FSH and LH.Conclusion. The present study confirmed previous observations that inhibin A had a continuous decline starting before the decline of inhibin B, suggesting that an increasing part of the cycle was anovulatory. The fall in inhibin B and the increase in FSH constitute markers of ovarian aging. One year prior to menopause neither inhibin A nor inhibin B could be detected. The disappearance of these peptide hormones is an important predictor of the approaching menopause.

To assess successful implantation and early post-implantation embryonic development in assisted reproduction techniques, serum human chorionic gonadotropin (hCG) levels in early gestation in pregnancies with a singleton live birth as the outcome were evaluated. The study was performed as a prospective cohort study of patients undergoing in vitro fertilization (IVF) or artificial insemination by husband (AIH) following ovarian stimulation. Serum hCG levels on days 14, 16, 20 and 27 following ovulation induction with hCG were examined. Serum hCG values were significantly lower in early gestation in IVF compared with AIH, but no difference in hCG doubling times was observed. No difference in serum hCG values between IVF treatment with or without gonadotropin-releasing hormone agonist (GnRHa) was observed. Significantly lower hCG values but no difference in doubling times in early gestation in IVF compared with AIH may be explained by late but successful implantation in IVF. The mechanism for this assumed late implantation is not clear. Altered endometrial receptivity or factors of embryonic origin might explain the observed variation in hCG values and the assumed late implantation.

OBJECTIVE The purpose of this study was to investigate the hormonal changes during the menopausal transition in a non-clinical population. METHODS Fifty-nine healthy Norwegian women participated in a five year prospective longitudinal study during the transition from pre- to post-menopause, starting one to four years before menopause, and ending one to four years postmenopausal. None of these women were given hormone replacement therapy (HRT). Blood samples were collected every 12 months and luteinizing hormone (LH), follicle stimulating hormone (FSH), steroid hormone binding globuline (SHBG), prolactin (PRL), estradiol (E2), estrone (E1), testosterone, androstendione, dehydroepiandrostendione-sulphate (DHEA-S), and thyroid stimulating hormone (TSH) were analyzed. RESULTS The serum levels of FSH and LH, E2 and E1 profile essentially confirmed previous data obtained in cross-sectional studies. A continuous increase in serum FSH and LH and a concomitant fall in E2 and E1 were observed in all women before menopause and in the two postmenopausal years. Both androstendione and testosterone showed a decline three years before menopause. After the menopause, however, there were fluctuations in the testosterone levels. Androstendione correlated positively with both E2 and E1 and testosterone postmenopausally. Body mass index (BMI) did correlate with testosterone, but not with androstendione. BMI correlated negatively with SHBG. No correlation was found between BMI and E2, E1, FSH and LH. CONCLUSION This longitudinal prospective study of hormonal changes during the transition from pre- to postmenopause indicates that not only estrogen hormonal changes, but androgen hormonal changes as well, precedes the menopause by several years.

The Cole-Cole equation can be used to model the electrical admittance of human skin. Using a previously published two-frequency (AC excitation) three-electrode method, the admittance locus plot (ALP) in the low-frequency region (<1000 Hz) has been shown to be very well approximated by a straight line and can be described with frequency-independent parameters; phase angle απ/2, conductance at extrapolated zero frequency G0=1/R0, and ion relaxation time τ. The aim of the paper is to study characteristics of απ/2, G0 and τ in the low-frequency ALP of human palmar skin. The measured data are calculated off-line on a personal computer. Relative changes in απ/2 are small (<2%) even during a heavy physical-exercise period. G0 corresponds well with GDc obtained by the traditional DC method at excitations up to 200 mV (relative differences ≤5% during baseline registration). Based on these findings, two comparatively simpler methods using only one lock-in amplifier are suggested: either measuring simultaneously with DC and at one frequency with AC excitation, or measuring at two different frequencies successively. The low-frequency part of the ALP can then be determined. G0, α and τ estimated by these simplified methods are in good agreement with the simultaneous two-frequency method and should therefore be suited for clinical applications.

Neonatal hypothyroidism is known to induce the accumulation of substance P and serotonin in many discrete brain nuclei of the rat. In this work, we have studied the effects of p-chlorophenylalanine (PCPA), a serotonin (5-HT) depleting drug, on the regional distribution of substance P in the brains of neonatally-induced hypothyroid and euthyroid rats. PCPA injections were given 48 and 24h before sacrifice and the peptide content of discrete brain nuclei, removed by punches of frozen brain slices, was measured by radioimmunoassay. In hypothyroid animals, substance P levels were significantly increased in the n. paraventricularis, n. medialis thalami, n. arcuatus, n. mamillaris medialis, substantia nigra, area ventralis tegmenti, n. interpeduncularis, substantia grisea and n. dorsalis raphes. This hypothyroid-induced accumulation of substance P was completely abolished, and even reversed in some nuclei, by PCPA treatment. Interestingly, in normal rats, following PCPA treatment, the substance P level was increased in n. paraventricularis pars magno-cellularis, n. ventromedialis (hypothalami), n. dorsomedialis pars dorsalis (hypothalami), n. amygdaloideus centralis, area ventralis tegmenti, substantia grisea, n. medianus raphes and n. dorsalis raphes. These results lend support to the existence of a physiological relationship between both substance P and serotonergic systems.

The impedance locus plot in the complex plane has been widely used to present data from measurements of the skin electrical properties. This classical method is, however, limited to electrodermal inactive sites, time-consuming when being performed at several frequencies and inconvenient when measuring evoked responses. To overcome these difficulties we have developed a new method to estimate skin electrical admittance parameters (conductance at extrapolated zero frequency G0, phase angle (π/2)α and ion relaxation time τ) from simultaneous measurements at two different frequencies with a three-electrode lock-in amplifier measuring system. The new method can also be used to investigate the evoked responses of these parameters in psychophysiological research. The theoretical principles of the new technique are presented in the paper, and the instrumentation as well as measuring procedures are described. The results from experiments on frequency and time dependency of skin electrical admittance show that α is relatively constant or shows only moderate changes compared with G0 and τ, which change in an opposite manner during evoked responses. Changing the DC offset in the excitation voltage from −1000 to 1000 mV had very little effect upon the estimated variables: G0 and α (<4 per cent), whereas increase of the excitation alternating voltage amplitude gave a substantial increase in G0 and α, and a corresponding decrease in τ.

Measurement of electrodermal activity (EDA) has long been an important tool in psychophysiological research. Both sweat gland secretion and skin blood flow (SBF) are influenced by activity in the autonomic nervous system. In order to examine evoked responses in EDA and SBF we have developed a method to measure skin unipolar electrical admittance, skin blood flow and skin temperature simultaneously at the same skin site. With a specially designed combined probe, both conductance and capacitance (using a three electrode lock-in amplifier measuring system), blood flow (using a laser Doppler flowmetry) and temperature (using a thermistor) were recorded on a four channel chart during baseline condition and during various physiological stimuli. The combined probe and the instrumentation of this method are described. Experimental results from measurements of 12 normal adult subjects are shown. Possible applications of the method in physiological, psychological and clinical research are discussed.

To investigate a broader spectrum of responses to the activity of efferent sympathetic nerve endings in blood vessels and sweat glands of the human palmar skin, we have developed a method to measure skin potential, skin unipolar electrical admittance (conductance and capacitance), skin blood flow, and skin temperature simultaneously at the same site of human palmar skin. The electrical variables were measured with a specially designed probe and a three electrode lock-in amplifier measuring system. The aim of the paper is to evaluate this method and its potential application in clinical work. The experimental results from five subjects during 5 min of baseline condition and during repeated acoustic stimulation are presented. The skin temperature was displayed digitally. During basal condition the activities in skin electrical variables and in blood vessel vasomotion were largely independent (asynchronous), whereas efferent sympathetic discharges due to stimulation were followed by parallel evoked responses in skin admittance, skin potential and skin blood flow. Habituation to the repeated stimuli occurred differently in the four variables.

The distributions of grains and tracks per cell, as functions of the isotope content in the cell, are basic to all quantitative autoradiography. In this paper a formulation of these distributions in terms of the distribution of grains per disintegration is suggested. An empirical method for evaluating this distribution for various isotopes and various geometrical relationships between source and emulsion is described. The results are used to examine the usefulness of different techniques for double labelling autoradiography.

Marker enzymes have been used to determine the average sedimentation coefficient (s-value) of mitochondria from the ileal mucosa of guinea pigs in isotonic sucrose medium. From the determined s-value, 5590 ± 320S, a procedure has been developed allowing optimal recovery of these mitochondria by differential centrifugation. Transmission electron micrographs of the isolated mitochondria show well-preserved mitochondria. Scanning electron microscopy reveals a homogenous population with low average diameters, 0.61 ± 0.09 μm (short axis) and 0.68 ± 0.09 μm (long axis). These values are consistent with the low s-value and the low measured buoyant density, D2020=1.167 g/cm3.

The purification of guinea-pig intestinal brush borders by a rapid sucrose-gradient-centrifugation step is reported. A 29-fold increase in the maltase/DNA quotient indicates considerable purification of the brush borders from nuclei. The biological activity of the brush borders was well preserved, as demonstrated by a high recovery of human gastric-juice-mediated uptake of 57Co-labelled vitamin B-12; homogeneity and purity were confirmed by scanning electron microscopy. Both the morphological appearance and biological activity were unchanged after prolonged storage in glycerol.