Prolactin is a protein hormone of the anterior pituitary gland that was originally named for its ability to promote lactation in response to the suckling stimulus of hungry young mammals. We now know that prolactin is not as simple as originally described. Indeed, chemically, prolactin appears in a multiplicity of posttranslational forms ranging from size variants to chemical modifications such as phosphorylation or glycosylation. It is not only synthesized in the pituitary gland, as originally described, but also within the central nervous system, the immune system, the uterus and its associated tissues of conception, and even the mammary gland itself. Moreover, its biological actions are not limited solely to reproduction because it has been shown to control a variety of behaviors and even play a role in homeostasis. Prolactin-releasing stimuli not only include the nursing stimulus, but light, audition, olfaction, and stress can serve a stimulatory role. Finally, although it is well known that dopamine of hypothalamic origin provides inhibitory control over the secretion of prolactin, other factors within the brain, pituitary gland, and peripheral organs have been shown to inhibit or stimulate prolactin secretion as well. It is the purpose of this review to provide a comprehensive survey of our current understanding of prolactin's function and its regulation and to expose some of the controversies still existing.

/pdf/prolactin-structure-function-and-regulation-of-secretion-3w4x6fqbg3.pdf

Prolactin: Structure, Function, and Regulation of Secretion

I. Introduction IN THE adult ovary, folliculogenesis starts when follicles leave the pool of resting follicles (RF) to enter the growth phase. From there, the early growing follicle undergoes a developmental process including a dramatic course of cellular proliferation and differentiation. In primates, only one follicle commonly reaches the preovulatory stage every cycle; most follicles fail to complete this maturation scheme, dying in the process termed atresia. In recent years, a picture has emerged depicting the classic endocrine control of ovarian function by LH and FSH, entangled in a maze of regulatory systems hinging on cell-cell interactions between follicular cells, via action of a variety of molecules (1–3). Different types of cell-cell interactions have been described. In paracrine regulations, a molecule synthesized by one cellular type is released into the interstitial milieu to act directly on another cellular type. In autocrine regulations, molecules synthesized by one cellular type are rel...

/pdf/regulation-of-ovarian-follicular-development-in-primates-4srrm0fi7f.pdf

Regulation of ovarian follicular development in primates: facts and hypotheses.

The techniques of optical trapping and manipulation of neutral particles by lasers provide unique means to control the dynamics of small particles. These new experimental methods have played a revolutionary role in areas of the physical and biological sciences. This paper reviews the early developments in the field leading to the demonstration of cooling and trapping of neutral atoms in atomic physics and to the first use of optical tweezers traps in biology. Some further major achievements of these rapidly developing methods also are considered.

/pdf/optical-trapping-and-manipulation-of-neutral-particles-using-4qf0uymz6l.pdf

Optical trapping and manipulation of neutral particles using lasers

We review recent advances in laser cell surgery, and investigate the working mechanisms of femtosecond laser nanoprocessing in biomaterials with oscillator pulses of 80-MHz repetition rate and with amplified pulses of 1-kHz repetition rate. Plasma formation in water, the evolution of the temperature distribution, thermoelastic stress generation, and stress-induced bubble formation are numerically simulated for NA=1.3, and the outcome is compared to experimental results. Mechanisms and the spatial resolution of femtosecond laser surgery are then compared to the features of continuous-wave (cw) microbeams. We find that free electrons are produced in a fairly large irradiance range below the optical breakdown threshold, with a deterministic relationship between free-electron density and irradiance. This provides a large ‘tuning range’ for the creation of spatially extremely confined chemical, thermal, and mechanical effects via free-electron generation. Dissection at 80-MHz repetition rate is performed in the low-density plasma regime at pulse energies well below the optical breakdown threshold and only slightly higher than used for nonlinear imaging. It is mediated by free-electron-induced chemical decomposition (bond breaking) in conjunction with multiphoton-induced chemistry, and hardly related to heating or thermoelastic stresses. When the energy is raised, accumulative heating occurs and long-lasting bubbles are produced by tissue dissociation into volatile fragments, which is usually unwanted. By contrast, dissection at 1-kHz repetition rate is performed using more than 10-fold larger pulse energies and relies on thermoelastically induced formation of minute transient cavities with lifetimes <100 ns. Both modes of femtosecond laser nanoprocessing can achieve a 2–3 fold better precision than cell surgery using cw irradiation, and enable manipulation at arbitrary locations.

Mechanisms of femtosecond laser nanosurgery of cells and tissues

One substantial benefit of sexual reproduction could be that it allows animals (including humans) to react rapidly to a continuously changing environmental selection pressure such as coevolving parasites. This counteraction would be most efficient if the females were able to provide their progeny with certain allele combinations for loci which may be crucial in the parasite-host arms race, for example the MHC (major histocompatibility complex). Here we show that the MHC influences both body odours and body odour preferences in humans, and that the women's preferences depend on their hormonal status. Female and male students were typed for their HLA-A, -B and -DR. Each male student wore a T-shirt for two consecutive nights. The next day, each female student was asked to rate the odours of six T-shirts. They scored male body odours as more pleasant when they differed from the men in their MHC than when they were more similar. This difference in odour assessment was reversed when the women rating the odours were taking oral contraceptives. Furthermore, the odours of MHC-dissimilar men remind the test women more often of their own actual or former mates than do the odours of MHC-similar men. This suggests that the MHC or linked genes influence human mate choice today.

/pdf/mhc-dependent-mate-preferences-in-humans-1og0pyy44l.pdf

MHC-dependent mate preferences in humans

Conventional methods of semen preparation for IVF, such as swim-up sedimentation, regular Percoll gradients, are not very effective in the treatment of severe oligoasthenozoospermia (total motile count less than 5 X 10(6)). For these cases, a new method of sperm preparation consisting of a reduced volume of a discontinuous Percoll gradient (mini-Percoll) has been utilized. The results obtained were analysed by comparing mini-Percoll versus resuspension in two groups of patients with severe male factor infertility. In the mini-Percoll group, a statistically significant improvement (P less than 0.001) was obtained in the post-treatment seminal parameters of motility, progression and proportion of normal forms. In the resuspension group (n = 12), only eight of 108 oocytes inseminated were fertilized (7%), while in the mini-Percoll group (n = 29), 124 out of 336 oocytes were fertilized (40%) (P less than 0.001). Furthermore, in the mini-Percoll group, a higher pregnancy rate (25 versus 7%) and low abortion rate (22 versus 33%) were observed. Although more studies are necessary to confirm these preliminary data, mini-Percoll seems to be a valid laboratory tool for semen samples of extremely poor quality.

Mini-Percoll: a new method of semen preparation for IVF in severe male factor infertility

Previous experiences in subjects with other forms of third space fluid accumulation have shown that albumin is efficacious in preventing and correcting haemodynamic instability. Using a similar approach in an effort to increase the serum oncotic pressure and to reverse the leakage of fluids from the intravascular space, high risk subjects for severe ovarian hyperstimulation syndrome (SOHS) were treated with albumin. In a recent large study two high risk factors were identified, i.e. the number of oocytes and levels of serum oestradiol. Thirty-six women undergoing assisted reproductive techniques who presented both these factors, received intravenous albumin at a dose of 5% in Ringers lactate in doses of 500 ml during oocyte retrieval and 500 ml immediately thereafter in the recovery room. Daily measurements of urine output, serum and urine electrolytes, weight, abdominal girth, and haematocrit prior to and after oocyte retrieval revealed normal serum and urine electrolyte levels, and no signs of haemoconcentration. No patient in this study developed SOHS, and of course none had to be hospitalized. Vaginal ultrasound performed in the majority of the subjects revealed < or = 100 ml of peritoneal fluid 48-72 h after oocyte retrieval. The only complication from the use of intravenous albumin was the appearance of a 'flu-like condition' (low grade temperature, nausea and muscle pains) developed by 12 women between days 3 and 5 after oocyte collection. Intravenous albumin had thus prevented the development of severe ovarian hyperstimulation syndrome in an assisted reproduction programme.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of intravenous albumin in patients at high risk for severe ovarian hyperstimulation syndrome.

https://dergipark.org.tr/tr/download/article-file/2636

High fecundity of amenorrhoeic women in embryo-transfer programmes

Various microsurgical procedures at the cellular and subcellular levels using laser non-touch techniques are presented and reviewed. In these procedures, the beams of light, varying in their wavelength (range: 14 ns to continuous wave), were directed via microscopes towards the target area. Micromanipulation of human spermatozoa with a laser-generated optical trap enabled the assessment of possible effects on sperm motility and measurements of the relative force generated by each single spermatozoon. Furthermore, the optical trap also provides a new approach to the measurements of intracellular forces without physically touching the cell or its organelles, and inducing chromosome movement during cell division is also possible. Laser beams in a specific configuration are able to induce minimal superficial damage to the zona pellucida of oocytes from various species. This manipulation is aimed at increasing the fertilization rate following insemination with low-quality spermatozoa. Another intracellular application of the laser beams is the destruction of extra pronuclei in polyspermic fertilized human oocytes. These procedures require special equipment which is not commonly available. However, simpler devices may be developed if the advantages of this novel technology are demonstrated.

R.H. Asch

Papers

Mini-Percoll: a new method of semen preparation for IVF in severe male factor infertility

The use of intravenous albumin in patients at high risk for severe ovarian hyperstimulation syndrome.

High fecundity of amenorrhoeic women in embryo-transfer programmes

Micromanipulation of gametes using laser microbeams.

New treatment for infertility due to congenital absence of vas deferens.