Biochemistry of Cervical Mucus**Supported by the United States Public Health Service Grants HD 02682 and HD 03696 and in part by the Ford Foundation. Presented at the 26th Annual Meeting of the American Fertility Society, Washington, D. C. March 18–21, 1970

Manipulation of metabolism to improve liquid preservation of mammalian spermatozoa

Reproductive success in mammals hinges on the ability of sperm to generate sufficient energy through cellular metabolism to perform the energy-intensive processes required for fertilisation, including motility, maturation, and oocyte interactions. It is now widely accepted that sperm exhibit metabolic flexibility, utilising a combination of glycolysis and oxidative phosphorylation (supported by the Krebs cycle and other complementary pathways) to meet their energy demands. However, the preferred pathway for energy production varies significantly among species, making it challenging to map species-specific metabolic strategies, particularly in species with high metabolic flexibility, like the ram. Additionally, differences in methodologies used to measure metabolism have led to biased interpretations of species' metabolic strategies, complicating the development of liquid storage methods aimed at preserving spermatozoa by manipulating energy generation based on species-specific requirements. This review examines sperm energy requirements, current methods for assessing metabolic capacity, and the current research on species-specific metabolism. Future research should focus on establishing a standardised approach for determining metabolic preferences to accurately map species-specific strategies, a critical step before developing effective liquid preservation methods. By identifying species-specific regulatory points, strategies can be designed to temporarily inhibit metabolic pathways, conserving resources and reducing the accumulation of metabolic by-products. Alternatively, supplementation with depleted metabolites can be guided by understanding areas of excessive consumption during prolonged metabolism. Applying this knowledge to develop tailored preservation techniques will help minimise sperm damage and improve survival during in vitro processing and liquid storage, ultimately enhancing the success of artificial breeding programs.

Nanoparticle-based vaginal drug delivery systems for HIV prevention

IMPORTANCE OF THE FIELD

Several strategies are being investigated for the prevention of heterosexual transmission of HIV. Of these, topical vaginal drug delivery systems, microbicides, are being actively pursued. HIV prevention by means of a topical microbicide has several drug delivery challenges. These challenges include the vaginal mucosal barriers and potential degradation of the drugs in the vaginal lumen due to pH and enzymes present. Also, new drugs being evaluated as microbicides have specific mechanisms of action, which in some cases require drug targeting to a specific site of action. Nanoparticles provide a delivery strategy for targeted or controlled delivery to the vagina which can be applied in the field of HIV prevention.

AREAS COVERED IN THE REVIEW

This review summarizes nanoparticulate systems and their use in mucosal delivery to date. The sexual transmission of HIV along with the various targets to prevent transmission are discussed as well as the potential opportunities, challenges and advantages in using a nanoparticle-based approach for microbicidal drug delivery.

WHAT THE READER WILL GAIN

This review provides a general understanding of vaginal drug delivery, its challenges, and nanoparticulate delivery systems. Additionally, insight will be gained as to the limited existing application of this technology to the field of HIV prevention.

TAKE HOME MESSAGE

To date, few studies have been published that exploit nanoparticle-based microbicidal delivery to the vagina. The use of nanoparticles for vaginal drug delivery provides an approach to overcome the existing barriers to success.

Vaginal drug delivery systems for HIV prevention

Microbicides have become a principal focus for HIV prevention strategies. The successful design of drug delivery systems for vaginal microbicide drug candidates brings with it a multitude of challenges. It is imperative that the chemical and physical characteristics of the drug candidate and its mechanism of action be clearly understood and considered to successfully deliver and target drug candidates efficiently. In addition, an understanding of the dynamic nature of the vaginal environment, the tissue and innate barriers present, as well as patient preferences are critical considerations in the design of effective microbicide products. Although the majority of drug candidates clinically evaluated to date have been delivered using conventional semisolid aqueous-based gel dosage forms, drug delivery system design has recently been extended to include advanced delivery systems such as vaginal rings, quick-dissolve films, and tablets. Ultimately, it may be necessary to develop multiple dosage platforms for a single active agent to provide users with options that can be used within the constraints of their social environment, personal choice, and environmental conditions.

Early Pregnancy Factor in Cervical Mucus of Pregnant Women

PROBLEM

This study was carried out to determine the presence of early pregnancy factor (EPF) activity in cervical mucus of pregnant women and explore the relationship between EPF activity in sera suggested it and in cervical mucus.

METHOD OF STUDY

Cervical mucus and sera were collected from 60 pregnant women in different terms and 25 non-pregnant women, respectively. EPF activity was detected by rosette inhibition assay.

RESULTS

EPF activity did exist in cervical mucus of pregnant women and was similar both in cervical mucus and sera.

CONCLUSIONS

We report here for the first time the EPF activity in cervical mucus of pregnant women. The parallel change observed in sera suggested it might be another useful index in evaluating embryo viability.

Chemical properties of bovine cervical mucus during normal estrus and estrus induced by progesterone and/or PGF2alpha

Ninety-two Friesian cows were used to determine the chemical properties of cervical mucus during normal estrus and estrus induced by progesterone (P4)-releasing intravaginal devices (PRID) and/or prostaglandin F2alpha. The animals were assigned to 4 groups (no treatment, a PRID for 12 days plus injection of 1000 IU PMSG at the removal of PRID, a double i.m. injection of PGF2alpha 11 days apart, or PRID for 7 days plus an im injection of PGF2alpha 24 h before the removal of PRID). A number of cows with normal estrus exhibited three consecutive estrous cycles after delivery. Cows that had not shown estrus for 3 months after delivery had their ovaries palpated twice at 10-day intervals, to determine their ovarian activity. Then PRID and/or PGF2alpha was administered in cows that had a palpable corpus luteum in one of the two palpations (cyclic cows). A double artificial insemination (AI) was performed to the cows of the three induced-estrus groups, while the cows with normal estrus received only one AI. Cervical mucus samples were collected from all cows 5 to 30 min before the first AI. Additionally, samples of cervical mucus were collected from 20 cows during their first estrus after the induced one. The results are summarized as follows: 1) The biochemical properties of cervical mucus in the first three estrus periods after delivery were similar. 2) These properties were similar both in normal estrus after delivery and in the first estrus after an induced one. 3) Glucose and fructose concentrations for normal estrus were similar to those for induced estrus groups. 4) Total protein and cholesterol concentrations were significantly lower (P < 0.001) in normal than in induced estrus, while no difference was found among the induced estrus groups. 5) Pregnancy rates of the cows did not differ significantly among the normal and the induced-estrus groups. 6) The percentages of cows in the induced-estrus groups that produced cervical mucus with total protein and cholesterol concentrations similar to those for the normal estrus groups was very low.

Physical properties of bovine cervical mucus during normal and induced (progesterone and/or PGF2alpha) estrus

Ninety two Friesian cows were used to determine physical properties of cervical mucus collected during normal estrus and estrus induced. Estrus was induced using either progesterone (P4) releasing intravaginal devices (PRID) and/or prostaglandin F2alpha (PGF2alpha). The animals were assigned to 4 groups (no treatment, a PRID for 12 days plus an injection of 1000 IU PMSG at the removal of the PRID, a double injection of 3 mL PGF2alpha 11 days apart, and a PRID for 7 days plus an injection of PGF2alpha 24 h before the removal of PRID). A number of cows with normal estrus exhibited three consecutive estrus cycles after calving. Cows that had not shown estrus for three months after calving had their reproductive system palpated twice at 10-day intervals, to determine their ovarian activity. Then PRID and/or PGF2alpha was administered to cows that were found to have a palpable corpus luteum in one of two palpations (cycling cows). The cows of the three induced estrous groups were artificially inseminated (AI) twice, while those with normal estrus received only a single AI. Cervical mucus samples were collected from all cows 5 to 30 min before the first AI. Additionally, samples of cervical mucus were collected from 20 cows at their first estrus after the induced estrus. The results are summarized as follows: 1) The physical properties of cervical mucus were similar in the first three normal consecutive estrus cycles after calving. 2) The physical properties of cervical mucus in normal estrus after calving were similar to those in the first estrus after an induced estrus. 3) The pH values for normal estrus were similar to those for induced estrus. 4) Viscosity of cervical mucus in the normal estrous group was significantly lower than that in the induced estrus. Furthermore, significant differences were noticed among the three induced estrous groups. 5) Spinnbarkeit, crystallization and receptivity of cervical mucus (penetration test) were significantly higher in the normal estrous group than in the induced estrous groups, while no difference was detected among induced estrus groups. 6) Pregnancy rates in the normal estrus group were the same as in the induced estrus groups. 7) The percentages of cows in the induced estrous groups that produced cervical mucus with similar viscosity, spinnbarkeit and receptivity (penetration test) characteristics as the normal estrus group, was very low.

Ultrastructural evidence of mucus in human conjunctival epithelial cultures

PURPOSE

To demonstrate by ultrastructural techniques that human conjunctival epithelium cells in vitro can produce mucin-like secretion.

METHODS

Primary cultures of human conjunctival epithelial cells were grown in different culture media. Cultures were allowed to grow and were processed after 5 days and 1, 2, 3, 4, or 5 weeks for transmission and scanning electron microscopy, according to the method of Nichols et al. modified in our laboratory.

RESULTS

Marked differences were seen between primary cultures grown with or without hydrocortisone. A thick tannic acid-stained layer was observed when hydrocortisone was present in the culture medium; however, that layer was virtually absent in cultures grown with hydrocortisone-free media. Scanning electron microscopy revealed a dense deposit showing a network-like structure. Moreover, the age of the cultures clearly influenced the thickness of the tannic acid-stained deposit, which thickened as the cultures aged.

CONCLUSIONS

These results strongly suggest that the layer growing in the presence of hydrocortisone is mucus. The fact that this material became more abundant as the cultures aged indicates that mucus is actively produced and secreted by conjunctival epithelial cells in vitro. This study might contribute to the knowledge of mucus-deficient pathologies of the ocular surface.

Cyclic changes in the concentration of glucose and fructose in human cervical mucus

OBJECTIVE

To determine a possible cyclic change in the concentration of glucose and fructose in the aqueous phase of human cervical mucus (CM).

DESIGN

Concentrations of glucose and fructose were longitudinally determined in the aqueous phase of CM of normal cycling women using enzymatic techniques, modified for small quantities.

SETTING

Patients visiting a fertility clinic were selected.

PATIENTS

Nine healthy women with regular menstrual cycles of 28 +/- 3 days that appeared to be ovulatory, demonstrated by sonographic follicle immaging and serum progesterone (P) measurements.

INTERVENTIONS

Cervical mucus samples were longitudinally collected preovulatory, postovulatory, and premenstrual in ovulatory cycles, monitored by ultrasound and blood estradiol and P measurements.

MAIN OUTCOME MEASURES

The study was designed to measure glucose and fructose longitudinally on three different points during one cycle.

RESULTS

The preovulatory glucose concentrations in CM were lower than postovulatory and premenstrual. The preovulatory fructose concentrations were lower than premenstrual. The glucose concentration correlated with the blood P level.

CONCLUSION

There is a consistent change in the glucose concentration measured in human CM in three phases of the menstrual cycle. The preovulatory and premenstrual fructose concentrations differ significantly. Knowledge of the carbohydrate metabolism in human cervical mucus may contribute in illuminating the possible role of the carbohydrate metabolism in sperm migration at midcycle and implantation in the luteal phase.

Lectin binding sites on human endocervix: a comparison with secretory and proliferative endometrium

Endocervix and corresponding endometrium of women of reproductive age were studied histochemically with 13 fluorescein isothiocyanate-labeled lectins to delineate the differences between the epithelial cells in two anatomical sites. Lectin from Maclura pomifera (MPA), Ulex europaeus (UEA-I), Glycine max (SBA), and Vicia villosa (VVA) bound only to endocervical epithelium and were the only four lectins that distinguished endocervical from endometrial epithelium. These differences were independent of menstrual cyclic changes and blood group antigen secretion. These data show that lectins can be used to histochemically distinguish endocervical from endometrial glands.

Hormonal control of oviductal ciliary activity: effect of prostaglandins

Prostaglandins have been shown to exist in the walls of the oviduct and to effect strongly oviductal muscle contractions and egg transport. Our observations, using laser light-scattering spectroscopy, indicate that the "natural" prostaglandins F2 alpha, E1, and E2 can stimulate ciliary activity in cultures of ciliated epithelium of the rabbit oviduct. These findings suggest a new alternative to explain the effect of prostaglandins on oviductal egg transport.

The presence of complement in human cervical mucus and its possible relevance to infertility in women with complement-dependent sperm-immobilizing antibodies

Full-complement component lytic activity was measured in human midcycle cervical mucus, using a sensitive 51Cr release hemolytic assay. The level measured was 11.5% of the activity of complement in an equal volume of undiluted human serum. The relevance of this level of complement to complement-dependent sperm-immobilizing antibody activity was studied. After 1 hour's incubation with mucus levels of complement, immobilization of about 50% of spermatozoa occurred and after 3 hours' incubation, immobilization of about 70% of spermatozoa occurred.

Immunoglobulins, proteinase inhibitors, albumin, and lysozyme in human cervical mucus. I. Communication: hormonal profiles and cervical mucus changes--methods and results

The serum levels of luteinizing hormone (LH), estradiol-17beta, and progesterone were determined simultaneously with the concentrations of immunoglobulin (Ig) G, IgA, C'3, alpha1-antitrypsin, inter-alpha-trypsin inhibitor, alpha1x-antichymotrypsin, albumin, and lysozyme in cervical mucus during nine ovulatory cycles. Spinnbarkeit and ferning were also assessed, and the basal body temperature was measured and recorded during these cycles. The profiles were synchronized according to the LH peak. The midcycle period, characterized by the rapid increase and decline of estrogen and the beginning rise of progesterone, shows a prounced minimum of immunoglobulins, C'3, proteinase inhibitors, albumin, and lysozyme in cervical mucus, which is known to be most receptive to sperm penetration at this time. Although the variation of cervical mucus values is considerable during the early proliferative and the luteal phases, the midcycle values appear to be constantly low, showing slight differences among the profiles of the different parameters. The statistical evaluation and the assessment of the significance of parameters for ovulation detection and the assessment of the fertile period as well as the correlation of these parameters with basal body temperature will be the subject of the second communication of this series.

The frequency of Y chromatin-positive spermatozoa during in vitro penetration tests under various experimental conditions

Complete analysis were carried out on the semen of 55 subjects. The semen was then investigated by using the fluorescent microscopic technique to determine the percentage proportion of Y chromatin-bearing spermatozoa. After staining with quinacrine mustard, an average Y chromatin frequency of 48.2% +/- 2.9% was recorded. With this spermatozoal material, 139 in vitro penetration tests were carried out with cervical mucus. After penetration there was a small, but statistically significant, increase in the percentage of Y spermatozoa (to 52.7% +/- 3.8%). The figures thus recorded were then correlated under variable experimental conditions in addition to variable semen parameters. The ratio of X:Y spermatozoa was related to the duration of the penetration tests, varying temperatures during the penetration, varying acid values of semen and cervical secretion, and also to the value of sperm motility in the semen analysis and to cervical factors. None of the above variables had any measurable influence on the percentage distribution of X and Y spermatozoa during in vitro penetration.

Gamma globulins in the mice vaginal fluids: cyclic and experimental variations

The study of the gamma globulins in the vaginal fluids reveals that the lowest values were found in mice at estrus and in castrated mice 8 days after the estrogen treatment. We suggest that the variation of gamma globulins in the vaginal fluids is influenced both under physiological and experimental conditions by estrogens.

Quantitative analysis of immunoglobulins and albumin in secretion of female reproductive tract

Total protein, IgG, secretory IgA (SIgA), IgA, IgM, and albumin were quantitatively analyzed in 115 cervical fluid specimens from healthy, adult women. Although albumin was the most predominant protein among those that were analyzed (17.2% of total protein), IgG was the major immunoglobulin in this secretion (8.7%). A highly significant correlation between the levels of IgG and albumin and a mean IgG-albumin ratio similar to that of serum suggest that both proteins originate from the circulation. Although the main type of IgA was of the secretory type (4.4%), serum type IgA (smaller than 1.0%) was close to 2. The mean levels of IgG and albumin (but not of SIgA) of the postpartum group were significantly higher than those of the normal subjects. The number of children, the current method of contraception, and present and past local infections had no effect on the immunoglobulins and albumin in this secretion when the mean levels of these components were analyzed and compared with the "normal" values.