Asok K. Bhattacharyya

Semen quality and age-specific changes: a study between two decades on 3,729 male partners of couples with normal sperm count and attending an andrology laboratory for infertility-related problems in an Indian city

OBJECTIVE To compare the semen quality and age-specific changes in men between the 1980s and 2000s. DESIGN Prospective study. SETTING Andrology laboratory, University of Calcutta, India. PATIENT(S) A semen sample was obtained from 3729 men presenting for infertility problems in two distinct decades, that is, between 1981-85 and 2000-2006. INTERVENTION(S) Subjects with sperm count >20 x 10(6)/mL without any extreme pathological disorders were selected. Samples having a major liquefaction problem were excluded. MAIN OUTCOME MEASURE(S) A standard World Health Organization procedure for semen analysis was performed that included assessment of volume, sperm concentration, and percentage motility. The motility parameters were further classified into forward progressive motility and nonprogressive motility. RESULT(S) The present large-scale study confirms a significant decline in the sperm motility parameters and seminal volume in the present decade. However, no change in overall sperm concentration was noted. A decline was seen in sperm motility with increasing age in both decades. CONCLUSION(S) There are significant changes in sperm motility and volume between the two decades, and the age-related changes in semen parameters are also different in the two decades.

Emerging technologies for the molecular study of infertility, and potential clinical applications

The techniques currently used to treat infertility cases are quite limited in their capabilities, due to an incomplete understanding of the molecular activities of germ cells. Fortunately, several technologies are presently being researched that should aid the understanding of the various molecular causes of germ cell pathologies. This review discusses microarray technology, proteomics, metabolic profiling, the PolScope, atomic force microscopy and microfluidics. These technologies have all seen success in preliminary studies, and promise directly or indirectly to improve the low success rates of IVF and other related therapies. However, their widespread use in laboratories and clinics may not be seen until preliminary studies confirming their safety and effectiveness are published, and until standardized protocols for their utilization are established.

The in vitro effect of benzo[a]pyrene on human sperm hyperactivation and acrosome reaction

OBJECTIVE To evaluate the in vitro effect of benzo[a]pyrene on sperm hyperactivation and acrosome status in normozoospermic semen samples of nonsmokers analyzed by computer-assisted semen analysis (CASA). DESIGN Experimental in vitro study. SETTING Andrology laboratory. PATIENT(S) Thirteen proven fertile, normozoospermic, and nonsmoking men. INTERVENTION(S) Spermatozoa were washed free of seminal plasma and were treated with different concentrations of benzo[a]pyrene and compared with controls treated with medium alone. The benzo[a]pyrene concentrations were: 100, 50, 25, and 12.5 microg/mL. MAIN OUTCOME MEASURE(S) Effect of varying concentrations of benzo[a]pyrene on sperm hyperactivation and acrosomal reaction. RESULT(S) A statistically significant increase in sperm hyperactivation was observed in presence of benzo[a]pyrene at concentrations of >or=50 microg/mL. The result of the acrosome halo test showed that concentrations of benzo[a]pyrene >or=25 microg/mL statistically significantly decreased the percentage of halo formation, indicating an inappropriate (false) acrosome reaction. CONCLUSION(S) Benzo[a]pyrene statistically significantly affected sperm functional competence as evidenced by increased hyperactivation as well as premature acrosomal reaction.

Assessment of sperm functional competence and sperm-egg interaction.

A precise understanding in the functional competence of mammalian sperm is essential to generate clinical advances for the treatment of infertility and novel contraceptive strategies. The fundamental knowledge on the controlling parameters for spermatozoal activation process will help in the identifying the causes in fertilization failure due to male factor as well as in developing male contraceptive methodologies. The defects in the sperm-egg interaction seem to be one of the controlling mechanisms, however, none of the presently available methods for the evaluation of the fertilizing ability of sperm precisely indicates the reason for the failure or the success of sperm entry into egg. Adequate number of motile spermatozoa with normal morphology and timely occurrence of acrosome reaction are presumably the major prerequisites for the penetration through the egg investments. The present communication briefly reviews some of the main features of mammalian sperm which control the success or the failure of fertilization and existing clinical methods indicating the lack of fundamental knowledge on the sub-cellular and molecular aspects of this unique and species-specific cell-cell interaction.

Human seminal antiliquefying agents — A potential approach towards vaginal contraception

One-hundred-one natural and synthetic enzyme inhibitors or inactivators were screened in vitro against the liquefaction property of human ejaculates with a view to develop antiliquefying agents for vaginal contraception. Of those compounds, 27 demonstrated no effect, 36 quickened and 20 delayed the process of liquefaction, while 18 agents stopped it completely. The highly effective antiliquefying agents also showed spermicidal property and were found to coagulate even the liquid ejaculates. Compounds having antiliquefying property, together with coagulating and spermicidal activities, will offer a highly promising approach towards vaginal contraception.

Purification of human seminal acrosin inhibitor and its kinetics

A low molecular mass, naturally occurring acrosin inhibitor has been identified and purified (490-7-fold) from human semen, and kinetic studies have been performed on the association characteristics as well as for the determination of affinity constants (Ki values). The results show thatKi value (3.34 × 10−2) of the inhibitor towards human acrosin is almost three times lower than that of pancreatic trypsin, indicating a much higher specificity and inhibitory property for acrosin. The purified human seminal acrosin inhibitor has a molecular mass of 5.5 kDa and shows a single band using 10–20% gradient SDS PAGE. The work is of great significance for the development of more specific, nontoxic and irreversible inhibitors for human acrosin.

A Method of Obtaining Dead-beat Response of Third-order Servo Systems

ABSTRACT This paper presents a method for obtaining dead-beat response of third-order servo systems. It has been shown that among the three state variables, viz. error, error rate and error acceleration of a third-order system following a step input signal, the last two reach simultaneously zero values at intervals of one time period of damped osecillation if the real part of the complex root be equal to the real root of the closed-loop characteristic equation. Dead-beat response can be obtained on reducing the finite value of error to zero, when the above condition is achieved for the first time, by processing the input signal and applying the same with the help of a switching circuit. The results of simulator study of a proposed third-order system have also been given.

Third-order Feedback Control Systems—Their Sign Patterns and Controllability†

ABSTRACT A new approach to finding all possible responses of a linear third-order control system subjected to step input commands is suggested in the present paper. Two terms sign pattern and sign code of the state variables of the system dynamics are introduced. A simple method of control by signal processing for lightly damped third-order systems is discussed and the method is illustrated by an example.

Dead-beat Control of Third-order Servo-systems†

ABSTRACT In this paper a method of obtaining dead-beat response of third-order servo systems is described. It is shown that among the three state variables of the system, e.g. error, output velocity and output acceleration, the first two, following a step signal input, attain zero values simultaneously—for an instant for certain combinations in the system parameters. For such an initial adjustment of the parameters, the system response can be made dead-beat if the parameters are suitably controlled in a discrete manner from an instant of very small value of the error. A switching circuit is described for achieving the discrete control. Results of studies of a proposed third system simulated on the analogue computer are also given.

The effect of temperature and the duration of cryopreservation on human sperm chromatin

Objective: The present study was carried out to assess the effect of different freezing temperatures and duration of freezing on human sperm chromatin integrity. Design: Prospective study Materials and Methods: Semen samples were obtained from 93 randomly selected men attending the University Clinic, specimens from 5 proven fertile volunteers served as the controls. After preliminary semen analysis, each sample was divided in five aliquots and mixed with commercially available cryopreservation medium (Tardigrade, IMV, France). One aliquot (A) was used for the pre-freeze study of chromatin integrity, two other aliquots (B1, B2) were frozen in a mechanical freezer at -80oC and the last two aliquots (C1, C2) were frozen in liquid nitrogen (-196oC). The duration of cryopreservation for aliquots B1 and C1 was 1 week, and 3 months for aliquots B2 and C2. Chromatin cryoinjury was examined under fluorescent microscope using acridine orange. Results: The mean percentage of spermatozoa with intact chromatin in pre-freeze samples (aliquot A) was 90.1 ± 5.9%, it showed no difference from that of whole semen without a cryopreservative. After 1 week of freezing, chromatin integrity reduced to 76.5 ± 7.7% and 81.6 ± 8.1% in aliquots B1 & C1, respectively. It dropped to 69.6 ± 8.6% and 76.3 ± 7.1% for aliquots B2 & C2 respectively upon prolonged freezing for 3 months. Conclusion: The process of freeze-thawing has an adverse effect on human sperm chromatin. The loss of chromatin integrity is more prominent in case of mechanical freezing at -80oC than with liquid nitrogen, both at 1 week as well as after prolonged preservation for three months. Therefore, cryopreservation in liquid nitrogen should be recommended for freezing of semen specimens used for assisted reproduction. Support: Indian Council of Medical Research. Author Disclosure Block: S. Pal, None; A. Varghese, None; A. Agarwal, None; A.K. Bhattacharyya, None.