Aron Johnson - Academia.edu (original) (raw)

Papers by Aron Johnson

Research paper thumbnail of Functional Tests of Spermatozoa

Urologic Clinics of North America, 1987

Research paper thumbnail of The Optimized Sperm Penetration Assay

The Journal of Urology, 1987

Vasoactive intracavernous pharrnacotherapy (VIP) using papaverine and phentolamine is attracting ... more Vasoactive intracavernous pharrnacotherapy (VIP) using papaverine and phentolamine is attracting wide interest and gaining increasing acceptance. However, details on the methodology of this therapy, such as drug preparations and dosagesi injection techniques, patient education, complications, and follow-up, are still not well known.

Research paper thumbnail of Sperm Penetration Bioassay to Evaluate Semen Obtained from Electroejaculated Patients

The Journal of Urology, 1987

Research paper thumbnail of Effect of aging and cold temperature storage of hamster ova as assessed in the sperm penetration assay

Fertility and Sterility, 1985

The penetration of zona pellucida-free hamster ova by human spermatozoa has been used to quantita... more The penetration of zona pellucida-free hamster ova by human spermatozoa has been used to quantitate sperm penetration potential. However, since mammalian eggs in vitro have limited viability, the effect of in vitro aging on the ability of hamster ova to be penetrated by human spermatozoa was examined. Zona-free ova maintained at room temperature (25°C) lost their ability to be subsequently penetrated with a halflife of 50.1 ± 8.8 minutes. This was partly the result of removing the zona pellucida by trypsin digestion, since zona-free oocytes in the presence of trypsin inhibitor or zona pellucida-intact oocytes had half-lives of 99.1 ± 15.2 and 120.5 ± 17.4 minutes, respectively. Reduction in penetration rates associated with ovum aging did not appear to be due to loss of viability and could be completely prevented by maintaining the ova on ice (4°C). In the presence of TEST-yolk buffer at 4°C, ova retained (100%) their ability to be penetrated for up to 24 hours and were morphologically indistinguishable from fresh ova. These observations show that ovum aging in vitro at 25°C is much greater than previously anticipated. This may result in artifactually low and variable scores in the penetration bioassay. Fertil Steril43:766, 1985

Research paper thumbnail of Conditions influencing human sperm capacitation and penetration of zona-free hamster ova

Fertility and Sterility, 1984

The ability of human spermatozoa to penetrate zona-free hamster ova was examined following low-te... more The ability of human spermatozoa to penetrate zona-free hamster ova was examined following low-temperature capacitation (4 degrees C) in TES-Tris (TEST)-yolk buffer for periods of up to 66 hours. Results obtained from 66 individuals demonstrated that the number of penetrations per ova were increased by an average of 2.5-fold when spermatozoa were capacitated for 42 hours, as compared with 18 hours. Furthermore sperm with extremely poor penetration rates after 18-hour capacitation was often improved by longer capacitation periods. Patients from our infertility clinic with less than 20 X 10(6) spermatozoa/ml of ejaculate had significantly lower penetration rates when compared with patients and donors with greater than 20 X 10(6) spermatozoa/ml (P less than or equal to 0.001). The observed effects of TEST-yolk buffer appear to be related to its ability to preserve sperm motility over prolonged periods, during which increased capacitation of the total sperm population is achieved.

Research paper thumbnail of A quality control system for the optimized sperm penetration assay

Fertility and Sterility, 1995

Objective: To develop a quality control system for the optimized sperm penetration assay (SPA) an... more Objective: To develop a quality control system for the optimized sperm penetration assay (SPA) and to use this system to monitor interassay variability and stability over time. Design: Four semen donors were tested consecutively for a period of weeks (7 to 139 weeks) with the SPA. Their average semen analyses and SPA scores were evaluated to monitor natural biologic variation. Intra-assay variation was obtained by dividing 11 semen samples into three aliquots and testing each separately in the SPA. A single ejaculate from seven individuals was aliquoted and frozen to be used as a control. They were tested on different assay days in 1986 and subsequently in 1991 to evaluate the assay stability over time. Main Outcome Measures: Results were expressed as a sperm capacitation index (mean number of sperm penetrations per ovum). Results: Consecutive weekly semen analyses and SPAs on donors exhibited coefficients of variation ranging from 20% to >40%. In contrast, these variations were much greater than intra-assay variability. Analysis offrozen semen specimens tested in several SPAs also displayed a low coefficient of variation. When aliquots of these frozen samples were tested in the SPA 5 years later, there were no differences in the observed values, showing the remarkable stability of this assay over time. The lower limit of the normal fertile range did not change over a period of 2 years. Conclusions: Results show that using fresh semen samples as a positive control in the SPA is inadequate. This deficiency has been overcome with the use of frozen semen controls. With frozen semen for quality control, the optimized SPA developed in this laboratory is a highly reproducible assay that meets the strict criteria required for clinical laboratory certification.

Research paper thumbnail of Humster Testing and Egg Yolk

Fertility and Sterility, 1991

must be established before proceeding to D and C. Unfortunately, they do not share our confidence... more must be established before proceeding to D and C. Unfortunately, they do not share our confidence in the algorithm. We have now screened nearly 5,000 first-trimester patients with serum progesterone. No viable pregnancies have been identified in association with a serum progesterone < 5.0 ng/mL. We therefore are comfortable with this viability cutoff value. With a progesterone value of ~5.0 ng/mL, but <25 ng/mL, the patient is followed utilizing a combination of serial human chorionic gonadotropin (hCG) titers and transvaginal ultrasound. Only 1.5% of the EPs in our series are associated with a serum progesterone ~ 25 ng/mL, and, in our experience, all of these have been associated with a normal rise in hCG titers but are visible as ectopic gestations on transvaginal scanning. 2 They are correct in stating that not all viable pregnancies have an hCG titer which rises ~50% in 48 hours. It should be noted, however, that the hCG titer in those patients they cite is usually in excess of 10,000 mlU /mL, 3,4 a level at which an intrauterine pregnancy is easily visible on transabdominal or transvaginal scanning. At our center, a viable intrauterine pregnancy is always visible on transvaginal scanning at an hCG titer of ~2,000 mlU /mL (First International Reference). It is therefore not, as their letter would suggest, progesterone alone or serial hCG alone, but both in conjunction with sensitive transvaginal ultrasonography that allows us to correctly diagnose an EP. Weare confident that our data show that neither are we interrupting viable intrauterine pregnancies nor are we missing EPs. Each center must establish its own criteria for D and C in a patient with a suspected EP. This decision should be based on clinical acumen, the availability of reliable hCG and progesterone testing, as well as expert transvaginal scanning. Each laboratory must identify critical hCG and progesterone levels relative to ultrasonographic sensitivity. We believe that our published algorithm, when applied properly does what it claims to do, i.e., allows us to identify EPs without the use of laparoscopy.

Research paper thumbnail of Studies on human spermatozoa with round head syndrome

Fertility and Sterility, 1984

Research paper thumbnail of Rapid method for quantitation of androgen binding protein in sertoli cell cultures and its use for measurement of binding kinetics

Journal of Steroid Biochemistry, 1985

The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli... more The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli cell specific protein, androgen binding protein (ABP), has been frustrated by the extremely rapid rate of dissociation of the ABP-dihydrotestosterone complex. We describe a rapid and highly sensitive assay suitable for ABP quantitation which utilizes DEAE Bio-Gel and [3H]dihydrotestosterone. The assay has been used to accurately measure the rate of dissociation (8.25 X 10(-4) s-1, t1/2 14 min) and the rate of association (2.04 X 10(5) M s-1) of the binding of [3H]dihydrotestosterone to rat ABP. The ratio of these rate constants is in perfect agreement with the equilibrium dissociation constant determined by Scatchard analysis (4.0 nM). This multipoint assay is extremely rapid such that binding can be measured at equilibrium, it has high precision (coefficient of variation 3%), and is particularly useful at low protein concentrations (50 ng/ml); furthermore, the assay background of nonspecific 3H-binding is extremely low (0.2%). Since at such low protein concentrations a 10 point Scatchard analysis can be performed on 1 ml culture medium containing as little as 3 fmol ABP, the assay is suitable for monitoring changes in ABP secretion resulting from manipulations of cells in culture. The assay which utilizes DEAE Bio-Gel A is compared to five alternative methods: the standard method of steady state gel electrophoresis, Dextran-coated charcoal assay, hydroxylapatite assay, DEAE filter assay, and radioimmunoassay. The DEAE Bio-Gel assay has advantages over all of these alternative methods. In summary, this new assay is particularly useful for monitoring temporal changes in the secretion of ABP, and the method is equally effective in quantitating ABP in rat, rabbit and hamster Sertoli cell cultures.

Research paper thumbnail of Specialized Sperm Testing

Contemporary Endocrinology

Infertility is traditionally defined as the inability of a couple to conceive following 1 yr of u... more Infertility is traditionally defined as the inability of a couple to conceive following 1 yr of unprotected intercourse. It is not an uncommon problem, with nearly 15% of couples failing to establish a pregnancy without medical intervention. In those couples who seek evaluation from a reproductive specialist, 30 to 40% of males have an abnormality that significantly contributes to their

Research paper thumbnail of Functional Tests of Spermatozoa

Urologic Clinics of North America, 1987

Research paper thumbnail of The Optimized Sperm Penetration Assay

The Journal of Urology, 1987

Vasoactive intracavernous pharrnacotherapy (VIP) using papaverine and phentolamine is attracting ... more Vasoactive intracavernous pharrnacotherapy (VIP) using papaverine and phentolamine is attracting wide interest and gaining increasing acceptance. However, details on the methodology of this therapy, such as drug preparations and dosagesi injection techniques, patient education, complications, and follow-up, are still not well known.

Research paper thumbnail of Sperm Penetration Bioassay to Evaluate Semen Obtained from Electroejaculated Patients

The Journal of Urology, 1987

Research paper thumbnail of Effect of aging and cold temperature storage of hamster ova as assessed in the sperm penetration assay

Fertility and Sterility, 1985

The penetration of zona pellucida-free hamster ova by human spermatozoa has been used to quantita... more The penetration of zona pellucida-free hamster ova by human spermatozoa has been used to quantitate sperm penetration potential. However, since mammalian eggs in vitro have limited viability, the effect of in vitro aging on the ability of hamster ova to be penetrated by human spermatozoa was examined. Zona-free ova maintained at room temperature (25°C) lost their ability to be subsequently penetrated with a halflife of 50.1 ± 8.8 minutes. This was partly the result of removing the zona pellucida by trypsin digestion, since zona-free oocytes in the presence of trypsin inhibitor or zona pellucida-intact oocytes had half-lives of 99.1 ± 15.2 and 120.5 ± 17.4 minutes, respectively. Reduction in penetration rates associated with ovum aging did not appear to be due to loss of viability and could be completely prevented by maintaining the ova on ice (4°C). In the presence of TEST-yolk buffer at 4°C, ova retained (100%) their ability to be penetrated for up to 24 hours and were morphologically indistinguishable from fresh ova. These observations show that ovum aging in vitro at 25°C is much greater than previously anticipated. This may result in artifactually low and variable scores in the penetration bioassay. Fertil Steril43:766, 1985

Research paper thumbnail of Conditions influencing human sperm capacitation and penetration of zona-free hamster ova

Fertility and Sterility, 1984

The ability of human spermatozoa to penetrate zona-free hamster ova was examined following low-te... more The ability of human spermatozoa to penetrate zona-free hamster ova was examined following low-temperature capacitation (4 degrees C) in TES-Tris (TEST)-yolk buffer for periods of up to 66 hours. Results obtained from 66 individuals demonstrated that the number of penetrations per ova were increased by an average of 2.5-fold when spermatozoa were capacitated for 42 hours, as compared with 18 hours. Furthermore sperm with extremely poor penetration rates after 18-hour capacitation was often improved by longer capacitation periods. Patients from our infertility clinic with less than 20 X 10(6) spermatozoa/ml of ejaculate had significantly lower penetration rates when compared with patients and donors with greater than 20 X 10(6) spermatozoa/ml (P less than or equal to 0.001). The observed effects of TEST-yolk buffer appear to be related to its ability to preserve sperm motility over prolonged periods, during which increased capacitation of the total sperm population is achieved.

Research paper thumbnail of A quality control system for the optimized sperm penetration assay

Fertility and Sterility, 1995

Objective: To develop a quality control system for the optimized sperm penetration assay (SPA) an... more Objective: To develop a quality control system for the optimized sperm penetration assay (SPA) and to use this system to monitor interassay variability and stability over time. Design: Four semen donors were tested consecutively for a period of weeks (7 to 139 weeks) with the SPA. Their average semen analyses and SPA scores were evaluated to monitor natural biologic variation. Intra-assay variation was obtained by dividing 11 semen samples into three aliquots and testing each separately in the SPA. A single ejaculate from seven individuals was aliquoted and frozen to be used as a control. They were tested on different assay days in 1986 and subsequently in 1991 to evaluate the assay stability over time. Main Outcome Measures: Results were expressed as a sperm capacitation index (mean number of sperm penetrations per ovum). Results: Consecutive weekly semen analyses and SPAs on donors exhibited coefficients of variation ranging from 20% to >40%. In contrast, these variations were much greater than intra-assay variability. Analysis offrozen semen specimens tested in several SPAs also displayed a low coefficient of variation. When aliquots of these frozen samples were tested in the SPA 5 years later, there were no differences in the observed values, showing the remarkable stability of this assay over time. The lower limit of the normal fertile range did not change over a period of 2 years. Conclusions: Results show that using fresh semen samples as a positive control in the SPA is inadequate. This deficiency has been overcome with the use of frozen semen controls. With frozen semen for quality control, the optimized SPA developed in this laboratory is a highly reproducible assay that meets the strict criteria required for clinical laboratory certification.

Research paper thumbnail of Humster Testing and Egg Yolk

Fertility and Sterility, 1991

must be established before proceeding to D and C. Unfortunately, they do not share our confidence... more must be established before proceeding to D and C. Unfortunately, they do not share our confidence in the algorithm. We have now screened nearly 5,000 first-trimester patients with serum progesterone. No viable pregnancies have been identified in association with a serum progesterone < 5.0 ng/mL. We therefore are comfortable with this viability cutoff value. With a progesterone value of ~5.0 ng/mL, but <25 ng/mL, the patient is followed utilizing a combination of serial human chorionic gonadotropin (hCG) titers and transvaginal ultrasound. Only 1.5% of the EPs in our series are associated with a serum progesterone ~ 25 ng/mL, and, in our experience, all of these have been associated with a normal rise in hCG titers but are visible as ectopic gestations on transvaginal scanning. 2 They are correct in stating that not all viable pregnancies have an hCG titer which rises ~50% in 48 hours. It should be noted, however, that the hCG titer in those patients they cite is usually in excess of 10,000 mlU /mL, 3,4 a level at which an intrauterine pregnancy is easily visible on transabdominal or transvaginal scanning. At our center, a viable intrauterine pregnancy is always visible on transvaginal scanning at an hCG titer of ~2,000 mlU /mL (First International Reference). It is therefore not, as their letter would suggest, progesterone alone or serial hCG alone, but both in conjunction with sensitive transvaginal ultrasonography that allows us to correctly diagnose an EP. Weare confident that our data show that neither are we interrupting viable intrauterine pregnancies nor are we missing EPs. Each center must establish its own criteria for D and C in a patient with a suspected EP. This decision should be based on clinical acumen, the availability of reliable hCG and progesterone testing, as well as expert transvaginal scanning. Each laboratory must identify critical hCG and progesterone levels relative to ultrasonographic sensitivity. We believe that our published algorithm, when applied properly does what it claims to do, i.e., allows us to identify EPs without the use of laparoscopy.

Research paper thumbnail of Studies on human spermatozoa with round head syndrome

Fertility and Sterility, 1984

Research paper thumbnail of Rapid method for quantitation of androgen binding protein in sertoli cell cultures and its use for measurement of binding kinetics

Journal of Steroid Biochemistry, 1985

The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli... more The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli cell specific protein, androgen binding protein (ABP), has been frustrated by the extremely rapid rate of dissociation of the ABP-dihydrotestosterone complex. We describe a rapid and highly sensitive assay suitable for ABP quantitation which utilizes DEAE Bio-Gel and [3H]dihydrotestosterone. The assay has been used to accurately measure the rate of dissociation (8.25 X 10(-4) s-1, t1/2 14 min) and the rate of association (2.04 X 10(5) M s-1) of the binding of [3H]dihydrotestosterone to rat ABP. The ratio of these rate constants is in perfect agreement with the equilibrium dissociation constant determined by Scatchard analysis (4.0 nM). This multipoint assay is extremely rapid such that binding can be measured at equilibrium, it has high precision (coefficient of variation 3%), and is particularly useful at low protein concentrations (50 ng/ml); furthermore, the assay background of nonspecific 3H-binding is extremely low (0.2%). Since at such low protein concentrations a 10 point Scatchard analysis can be performed on 1 ml culture medium containing as little as 3 fmol ABP, the assay is suitable for monitoring changes in ABP secretion resulting from manipulations of cells in culture. The assay which utilizes DEAE Bio-Gel A is compared to five alternative methods: the standard method of steady state gel electrophoresis, Dextran-coated charcoal assay, hydroxylapatite assay, DEAE filter assay, and radioimmunoassay. The DEAE Bio-Gel assay has advantages over all of these alternative methods. In summary, this new assay is particularly useful for monitoring temporal changes in the secretion of ABP, and the method is equally effective in quantitating ABP in rat, rabbit and hamster Sertoli cell cultures.

Research paper thumbnail of Specialized Sperm Testing

Contemporary Endocrinology

Infertility is traditionally defined as the inability of a couple to conceive following 1 yr of u... more Infertility is traditionally defined as the inability of a couple to conceive following 1 yr of unprotected intercourse. It is not an uncommon problem, with nearly 15% of couples failing to establish a pregnancy without medical intervention. In those couples who seek evaluation from a reproductive specialist, 30 to 40% of males have an abnormality that significantly contributes to their