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Biomedical subjects

L A Johnson

Publications and source records attributed to L A Johnson.

At least 217 records · Page 12Linked to original sources
PubMed1971

Herpesvirus type 2 isolated from cervical tumor cells grown in tissue culture.

A herpesvirus has been isolated from spontaneously degenerating cultures of cervical tumor cells grown in vitro. The virus was identified as a type 2 herpesvirus on the basis of biologic properties, including plaque morphology and microtubule formation in infected HEp-2 cells, and of immunologic specificity as determined by neutralization. Herpesvirus antigens and virus particles were not seen in duplicate cultures of viable cervical tumor cells.

Antigens, Viral↗
PubMedDate not supplied

Immunocytochemical localization of acrosin on both acrosomal membranes and in the acrosomal matrix of porcine spermatozoa.

Immunocytochemical techniques were employed to determine, at the ultrastructural level, the location of acrosin in porcine spermatozoa. Antisera to highly purified porcine acrosin was produced in rabbits. The (Fab')2 fragments of the immunoglobulins were purified and conjugated with horseradish peroxidase (HRP). Washed, formaldehyde-fixed spermatozoa were reacted with the labeled antiacrosin immunoglobulins, utilizing a direct staining technique. Electron microscopy revealed that the peroxidase reaction product of HRP-antiporcine acrosin was distributed evenly over the outer acrosomal membrane of spermatozoa with intact acrosomes. The labeled antibody was also distributed evenly over the inner acrosomal membrane of cells when the overlying acrosomal structures were absent. In some spermatozoa, labeling was noted throughout the acrosomal matrix. No significant labeling was observed in control specimens when spermatozoa were exposed to HRP-antiporcine acrosin immunoglobulins that had been adsorbed previously with excess purified acrosin or exposed to HRP-conjugated rabbit antiporcine immunoglobulins. This pattern of labeling is consistent with the hypothesis that acrosin may function as a zona lysin. The observation that the outer acrosomal membrane and acrosomal matrix are labeled suggests that acrosin is not exclusively located on the inner acrosomal membrane and, thus, could participate in physiologic events other than zona penetration.

Acrosin↗
PubMedDate not supplied

The predetermination of embryonic sex using flow cytometrically separated X and Y spermatozoa.

A review is given of the predetermination of sex in various domestic animals and in the human using sperm samples enriched for X- or Y-chromosome bearing spermatozoa obtained by flow cytometry and cell sorting. A comparison of other putative methods of sperm separation is made. In separating human X and Y spermatozoa, measurements of the DNA content in each individual gamete using the Hoechst fluorochrome 33342 remains the only validated method. The difference in DNA content between human X and Y spermatozoa is approximately 2.8%, and cell sorters have been adapted to take account of this and the asymmetrical nature of the sperm head. DNA analyses and PCR have been used to validate the method for animal spermatozoa. In the human, fluorescence in-situ hybridization (FISH) has confirmed sorting accuracy. Many correctly-diagnosed normal offspring have been born in various animal species and any potential mutagenic or cytotoxic effects are being closely monitored as are the cost and efficiency of the technology.

Animals↗