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Biomedical subjects

D F Katz

Publications and source records attributed to D F Katz.

90 records · Page 5Linked to original sources
PubMed1978

The movement of human spermatozoa in cervical mucus.

Movement characteristics of freely swimming spermatozoa were studied with high-speed cinemicrography. At 21 degrees C, flagellar beat frequency was higher in midcycle human cervical mucus than in native semen or Tyrode's solution; the beat shape differed, possessing diminished amplitude and wavelength. Although the spermatozoa swam straighter in the mucus, the progressive swimming speeds did not differ in the three media. Swimming speed and beat frequency were linearly related in semen and in Tyrode, but in mucus the linearity was less certain. In midcycle cervical mucus at 37 degrees C, beat frequencies and swimming speeds were greater than at 21 degrees C, but the trajectories were equally straight, and the distances swum per beat (kinetic efficiencies) did not differ.

Cervix Mucus↗
PubMed1978

A microliter oxygen electrode system for sperm suspensions.

A new polarographic oxygen electrode system is described which can accept sperm suspensions with volumes as low as 50 microliters. In this configuration, the electrode tip forms the base of the suspension reaction chamber, and there is no stirring. Consequently, structured fluids such as cervical mucus can be applied. Measurements can be performed in as little time as 10 minutes. The system reliably measures oxygen consumption rates as low as 0.1 mm Hg/minute, so that mammalian sperm suspensions with concentrations of the order 1 X 10(6)viable cells/ml can be applied. Sample experiments, comparing the oxygen uptake of human spermatozoa in semen and in Tyrode's solution, are described.

Adult↗
PubMed1976

Improved motility recovery of human spermatozoa after freeze preservation via a new approach.

A new sperm isolation technique was studied in conjunction with the short-term freeze preservation of human spermatozoa. The isolation procedure yielded subpopulations of spermatozoa with very high percentage motility and progressive motility score, and which were virtually free of seminal debris. For 24 semen samples from 13 donors, the mean prefreeze values of percentage motility and motility score were 53% (2.8), 73% (3.1), and 88% (3.5) for the parent semen, 7.5% BSA (middle) fractions, and 17.5% BSA (bottom) fractions, respectively. These samples were used without a priori constraint on semen quality. Eleven samples were preselected on the basis of good motility in the semen. These yielded prefreeze motility values of 66% (3.2), 70% (3.4), and 87% (3.9) for the semen and two fractions, respectively. Sperm motility in the middle fractions was thus intermediate to that in the semen and in the bottom fractions, although closer to the former in these 11 cases. The sperm freeze preservation procedure involved dilution of the semen samples and separated sperm fractions with a cryoprotective semen extender, and freezing and thawing in a conventional manner. Post-thaw percentage motility, motility score, and percentage survival were substantially higher for the separated fractions than for the parent semen. For the 24 cases, the bottom fractions yielded mean values of 57% motility, 3.0 motility score, and 70% survival, in comparison with the respective values of 20%, 2.3, and 34% for the semen. In the 11 preselected cases, the bottom fractions yielded post-thaw mean values of 60% motility, 3.3 motility score, and 72% survival; the middle fractions yielded respective values of 45%, 3.1, and 64%; and the parent semen yielded respective values of 27%, 2.3, and 41%. It was concluded that the major factor in improving post-thaw motility recovery was the separation process as a whole, rather than the degree of separation.

Cell Separation↗
PubMed1975

Methods of measuring swimming speed of spermatozoa.

Three basic approaches for determining the mean swimming speed of a suspension of microorganisms were compared, using bull and ram spermatozoa. Number fluctuation counting was performed automatically on a Quantimet 720 image analysing computer, the mean speed being obtained using 'probability after' statistics. The other two approaches were photomicrographic: number flux counting was performed on single photomicrographs; on the same photomicrographs, the mean speed was estimated from measurement of 'whole' and 'half' track lengths. These results were compared with each other and with the Quantimet results. The 'probability after' method was also compared, on additional samples, with cine-photomicrographic tracking. The mean speeds predicted by the 'probability after' method compared favourably with the other methods (range 68 mum/sec to 162 mum/sec). The results also suggested that, on single photomicrographs, measurement of 'half' track lengths or number flux counting were generally preferable to measurement of whole track lengths.

Animals↗
PubMedDate not supplied

Morphometric analysis of spermatozoa in the assessment of human male fertility.

A videomicrographic system was developed for measurement of morphometric parameters of human spermatozoa. Contours of the images of spermatozoa on a video monitor are digitized by manually tracing them with the cursor of an electromagnetic digitizer integrated to a microcomputer. The accuracy and precision of the methodology were evaluated. A comparison of human sperm heads in shallow wet preparations and in dried, stained preparations indicated that the latter were smaller in length, width, projected area, and circumference, but that the ratio length/width was not different. An analysis was made of 457 ejaculates from 16 fertile donors. The variation between ejaculates within donors was similar in magnitude to the variation between donors. A study was performed comparing seminal sperm morphometry in single specimens from 30 fertile and 30 infertile men. The sperm head length/width ratio was the parameter that differed the most between these two groups. Moreover, it was the per-ejaculate variability of this parameter, rather than the central tendency, that maximized the difference.

Cytological Techniques↗
PubMedDate not supplied

Automatic analysis of human sperm motion.

A new computerized methodology is described in which sperm movement characteristics are analyzed automatically. Video fields containing images of spermatozoa are electronically digitized, and the centroid position of each sperm head is determined. Over time, strings of centroids identify the swimming paths of individual spermatozoa. Details of path acquisition are described for human spermatozoa in semen, and include a discussion of how individual cells are identified and distinguished from each other. A diversified set of movement characteristics is computed for each spermatozoon, including two new measures of path shape based on the instantaneous turning angle. The traditional and the new measures of vigor and swimming pattern are evaluated and compared for consistency and redundancy. Analysis of data from human semen indicates that the new angular measures may be particularly useful in discriminating between spermatozoa exhibiting widely different patterns of motion.

Humans↗
PubMedDate not supplied

The relationship between the motility and morphology of spermatozoa in human semen.

High-speed videomicrography was used to assess simultaneously the morphology and motility of seminal spermatozoa from 10 fertile donors and 10 patients being evaluated for infertility. In both donors and patients, morphologically normal spermatozoa were more likely to be motile and had significantly higher straight line velocity, greater rolling frequency and flagellar beat frequency than abnormally shaped cells. For donors and patients there were highly significant, linear correlations (R = 0.7 to R = 0.98) between the movement characteristics of morphologically normal and abnormal spermatozoa within an ejaculate. A greater percentage of normal donor spermatozoa were motile than were the normal spermatozoa from patients (56% vs. 28%, respectively, P less than 0.005) and normal donor spermatozoa also swam faster than normal patient spermatozoa (49.1 +/- 3.2 microns/sec vs. 37.4 +/- 4.3 microns/sec, mean +/- sem, respectively, P less than 0.05). Overall, a multivariate analysis of variance, including straight line velocity, rolling frequency, beat frequency, and flagellar beat amplitude, demonstrated that these movement characteristics were significantly greater for the normal cells from donors than for the normal spermatozoa from patients. These biologic distinctions notwithstanding, the discrimination between semen from donors and patients was not improved when only morphologically normal cells were analyzed for motility.

Humans↗
PubMedDate not supplied

Swimming of spermatozoa in a linear viscoelastic fluid.

A modified resistive force theory is developed for a spermatozoon swimming in a general linear viscoelastic fluid. The theory is based on a Fourier decomposition of the flagellar velocity, which leads to solving the Stokes flow equations with a complex viscosity. We use a model spermatozoon with a spherical head which propagates small amplitude sinusoidal waves along its flagellum. Results are obtained for the velocity of propulsion and the rate of working for a free swimming spermatozoon and the thrust on a fixed spermatozoon. There is no change in propulsive velocity for a viscoelastic fluid compared to a Newtonian fluid. The rate of working does change however, decreasing with increasing elasticity of the fluid, for a Maxwell fluid. Thus the theory predicts that a spermatozoon can swim faster in a Maxwell fluid with the same expenditure of energy for a Newtonian fluid.

Animals↗
PubMedDate not supplied

Assessment of reproductive disorders and birth defects in communities near hazardous chemical sites. III. Guidelines for field studies of male reproductive disorders.

Exposures to environmental toxicants can have detrimental effects on several aspects of human male reproduction: fertility, sexual function, hormone status, and pregnancy/birth outcomes. However, no simple prescreening methods are available for reliably identifying potential hazards; questionnaires alone are relatively imprecise and inefficient in the absence of field data. Multidisciplinary field studies are required that include detailed exposure information, health and reproductive histories, physical examinations, semen analyses, and possibly, hormone analyses. Semen analysis is a critical component of field studies for evaluating two aspects of male reproduction: 1) changes in sperm or seminal content, which may be indicative of adverse effects on the male reproductive system with possible implications for fertility potential; and 2) defects in sperm DNA or chromosomes, which may be associated with subsequent changes in viability during embryonic development and health risks to the offspring. Semen analyses may be tiered: 1) initially, each semen study may include conventional semen assays (concentration, motility, and morphology) as well as specific biomarkers indicated by the health effect of concern in the study cohort: and 2) archived samples (i.e., frozen, videotaped, or smeared) may be utilized in later second-tier analyses to further characterize specific findings. Before initiating any field study, it is cost effective to critically evaluate the suitability of the cohort by confirming exposure and determining that there are adequate numbers of male participants in each exposure category. Such evaluations must be based on the statistical sensitivities of the specific tissue biomarkers and health endpoints for detecting changes. This article summarizes the components of the ideal field study and identifies research needs for improving field studies of male effects and for understanding the mechanisms of male reproductive toxicity. Several promising semen methods currently under development are also discussed.

Adult↗
PubMedDate not supplied

Analysis of pre-ovulatory changes in cervical mucus hydration and sperm penetrability.

Changes in cervical mucus occur during the proliferative phase of the menstrual cycle and are known to correlate with receptivity to sperm and to the endocrine milieu. Prior studies, however, have often lacked biological incisiveness and technical objectivity and precision. This study analyzed daily changes in mucus water content (hydration) prior to the LH surge (LH+0) in normal women, in relation to daily levels of serum LH, FSH, estradiol and progesterone, and to daily tests of sperm penetration of the mucus. Cervical mucus was studied for 12 cycles in 10 ovulating women. Three to ten mucus specimens were collected per cycle, over the days LH-8 to LH+0. Each specimen was subjected to measurement of both water content (hydration) and penetration by spermatozoa from fresh specimens of normal human semen. For the latter, a new microscale assay was developed and applied, which was amenable to very small volumes of mucus. The new technique determines objective measures of both the numbers of penetrating sperm (motile and non-motile) and the distance penetrated by the forward most vanguard sperm. In these experiments, variations in semen quality were controlled by performing a companion penetration assay in an artificial 1.5% polyacrylamide gel. The patterns of change in mucus hydration varied quantitatively among women, with preovulatory baseline levels ranging from 93.8-96.5%. All normal cycles (as defined by endocrine profiles) displayed a significant increase in hydration over a one-day period occurring 3-4 days before the LH peak. The magnitude of this shift varied among women between 2 and 3% (absolute hydration), a distinction well within the precision of the hydration assay. This quantum increase in hydration was more pronounced than the corresponding increase in serum estradiol on the same day. The change in mucus hydration, and the associated increase in sperm penetrability, were more consistent among cycles than the changes in reproductive hormones. There was a strong but non-linear correlation between mucus hydration and sperm penetrability. Once the value of hydration rose above approximately 97.5%, there was a substantial increase in penetrability. This 'cut-off point' in sperm penetrability was in the middle of the range of hydration values (across women) which preceded the quantum jump in hydration-which, itself, preceded the surge of LH. Hydration began to increase approximately 2 days before measurable increases in sperm penetration of the mucus in vitro. These results demonstrate that mucus hydration may be a valuable marker of the approach to ovulation and delineation of the fertile period. They also provide new methods for assessing sperm penetration into both large peri-ovulatory and very small samples of collected mucus.

Body Water↗
PubMedDate not supplied

Incidence and implications of altered semen quality on family planning.

Alterations in the expression of the human genome, or interference with its products, can be induced in the male reproductive system by chemicals mimicking or antagonizing naturally occurring hormones. Opportunities exist for disruption at the hypothalamus, pituitary and testis levels. Recent concerns generated by the increased incidence of testicular cancer, congenital anomalies of the male genitalia and possible alterations in human semen quality have been linked to the environment. The report by Carlsen in 1992 [1] suggested that semen quality has deteriorated over the past six decades. More recent reports suggest that the decline may be globally non-uniform and regional in nature. The effects of any such declines upon overall pregnancy rates are generally unknown, although some studies have attempted to address them. A preliminary review of the impact of a small decrease in sperm concentrations suggests that a directly measurable reduction in fecundity does not occur, but that future problems could be anticipated. Decrements in semen quality will alter the epidemiological probabilities of pregnancy due to coitus on different cycle days and may thereby change the duration of the fertile time. Current understanding of the implications of altered semen quality on relative fertility is not sufficient to change our current teaching and practice of NFP.

Family Planning Services↗
PubMedDate not supplied

Standardization and comparability of CASA instruments.

Thirty human semen specimens were analyzed using a standard manual method, then videotaped and reanalyzed using two different computer-aided sperm analysis (CASA) instruments (the HTM system, Hamilton-Thorn Research, Danvers, MA, and the CTS system, Motion Analysis Corp., Santa Rosa, CA). Videotaped specimens were analyzed by CASA for 5 frames for sperm concentration (CON) and percent motility (MOT), and for 15 frames for kinematic variables (straight-line velocity, VSL; curvilinear velocity, VCL; linearity, LIN; and amplitude of lateral head displacement, ALH). Machine parameter settings for the two instruments were matched as closely as possible. CASA values were compared with each other for all measures and with manual results for sperm count and the percentage of motile sperm. Results show: 1) HTM and CTS average values for CON are not different from manual measures for the 5- or 15-frame analysis, but slight differences are seen between CTS and HTM; 2) average values for MOT for the 5-frame analysis are higher than the 15-frame analysis for both instruments, but the average manual measurement for percent motility is much higher than any CASA value; 3) average VSL and LIN are slightly higher for HTM than CTS, but pair-wise comparison shows a high degree of concordance between the instruments; and 4) the mean values for VCL and ALH are equal for the two instruments, and there is a close concordance for the pair-wise comparison for VCL; however, pair-wise comparison of ALH reveals significant differences between the instruments. Overall, the differences seen between these instruments are slight, and are probably not biologically or clinically significant.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

New measures of sperm motion. I. Adaptive smoothing and harmonic analysis.

Several kinematic measures from computer-aided sperm analysis (CASA) instruments depend critically upon the computation of the spatially averaged path of a sperm's curvilinear swimming trajectory. Presently available instruments compute the average path by smoothing the curvilinear trajectory using a fixed-length running average. We demonstrate that this method significantly distorts the spatially averaged path for irregularly swimming sperm, both within and between trajectories, resulting in inaccurate calculations for the velocity of the average path (VAP), amplitude of lateral head displacement (ALH), beat-cross frequency (BCF), wobble of the curvilinear trajectory (WOB), and straightness of the curvilinear trajectory (STR). The authors introduce an alternative approach, based on engineering signal processing techniques, where the width of the running average is adapted to the changing wavelengths of the major spatial oscillations of each curvilinear trajectory. How this adaptive method results in less distortion of the average path and produces more accurate characterizations of the above measures is shown. This method is implemented in a computer program developed by the authors, called PathTool. It is also demonstrated that the simple methods used to characterize the frequency and amplitude of the major oscillation in a sperm's curvilinear trajectory (ie, BCF and ALH) are only accurate for the most periodic, progressive, and symmetrical trajectories. Three new measures are introduced, based on mathematical harmonic analysis, that are more robust alternatives to the present methods. These new methods and measures are initially evaluated using prototypical sperm trajectories from human semen. Results suggest that adaptive smoothing and harmonic analysis produce more accurate estimates of the frequency and magnitude of oscillations in sperm trajectories than the method based on fixed-length smoothing, BCF, and ALH.

Animals↗
PubMedDate not supplied

Operational standards for CASA instruments.

Computer-aided sperm analysis (CASA) technology is 7 years old. Over 120 papers have been written that verify the technology or apply it in basic and clinical studies. Most of the technical problems with CASA, such as the dependence of velocity on video frame rate, inaccuracy of count and percent motility for low- and high-concentration specimens, parameter dependence on the number of frames analyzed, sensitivity of the subjective threshold setting, confusion over the presence of debris, and different implementations of algorithms across instruments, still persist. A critical review of the literature reveals that no standard practices are followed within or across instruments. Moreover, no standards have been embraced or recommended by professional societies. Despite its potential to provide objective measurements of specimen and individual sperm parameters, and to automate the laboratory semen analysis, the promise of CASA has not been fulfilled. Unless laboratory medicine defines instrument performance and laboratory standards and co-operates with industry to achieve these goals, CASA technology may remain a research curiosity. This outcome is especially worrisome in the context of increasing requirements for laboratory accuracy, precision, standardization, and accreditation under the Clinical Laboratory Improvement Act of 1988.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Sampling factors influencing accuracy of sperm kinematic analysis.

Sampling conditions that influence the accuracy of experimental measurement of sperm head kinematics were studied by computer simulation methods. Several archetypal sperm trajectories were studied. First, mathematical models of typical flagellar beats were input to hydrodynamic equations of sperm motion. The instantaneous swimming velocities of such sperm were computed over sequences of flagellar beat cycles, from which the resulting trajectories were determined. In a second, idealized approach, direct mathematical models of trajectories were utilized, based upon similarities to the previous hydrodynamic constructs. In general, it was found that analyses of sampling factors produced similar results for the hydrodynamic and idealized trajectories. A number of experimental sampling factors were studied, including the number of sperm head positions measured per flagellar beat, and the time interval over which these measurements are taken. It was found that when one flagellar beat is sampled, values of amplitude of lateral head displacement (ALH) and linearity (LIN) approached their actual values when five or more sample points per beat were taken. Mean angular displacement (MAD) values, however, remained sensitive to sampling rate even when large sampling rates were used. Values of MAD were also much more sensitive to the initial starting point of the sampling procedure than were ALH or LIN. On the basis of these analyses of measurement accuracy for individual sperm, simulations were then performed of cumulative effects when studying entire populations of motile cells. It was found that substantial (double digit) errors occurred in the mean values of curvilinear velocity (VCL), LIN, and MAD under the conditions of 30 video frames per second and 0.5 seconds of analysis time. Increasing the analysis interval to 1 second did not appreciably improve the results. However, increasing the analysis rate to 60 frames per second significantly reduced the errors. These findings thus suggest that computer-aided sperm analysis (CASA) application at 60 frames per second will significantly improve the accuracy of kinematic analysis in most applications to human and other mammalian sperm.

Computer Simulation↗
PubMedDate not supplied

Effects of psychological stress on human semen quality.

We investigated the relationship between psychological stress and sperm concentration, motility, and morphometry in a prospective study of 157 volunteers who were enrolled in a prepaid health plan. We measured psychological job stress and life-event stress by telephone interview. Sperm-kinematic and nuclear-morphometric variables were measured using computer-assisted image analyses. Sperm concentration, percent motility, and semen volume were determined by objective visual methods. We performed multiple linear regression for each semen variable to examine its relationship to stress, controlling for potential confounders. Stress at work and total number of life events were not related to differences in semen quality. However, the recent death of a close family member was associated with a reduction in straight-line velocity (P = 0.002) and percent of progressively motile sperm (P = 0.02); it was also marginally associated with an increase in the fraction of sperm with larger and more tapered nuclei. These findings suggest that the fecundity of men experiencing the stress of a family member's death might be temporarily diminished.

Adult↗