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Biomedical subjects

T C Johnson

Publications and source records attributed to T C Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1991

Identification of a cell surface component of Swiss 3T3 cells associated with an inhibition of cell division.

Polyclonal IgG, prepared to a purified bovine cell surface sialoglycopeptide (SGP) inhibitor of cell division, was used to identify an antigenically related molecule on the surface of Swiss 3T3 cells. SDS-PAGE and Western analyses showed that the anti-SGP antibody was monospecific and primarily recognized a 66-kDA protein of 3T3 cell membranes. Treatment of intact 3T3 cells or 3T3 cell membranes with either broad and phosphatidylinositol-specific phospholipase C enzymes suggested that the antigenic material most likely existed as an integral membrane molecule, or associated as a multimeric complex, and was not anchored at the cell surface by a phospholipid. The addition of anti-SGP IgG to 3T3 cell monolayer cultures was shown to promote cell division, suggesting a regulatory function for the membrane-associated molecule.

Animals↗
PubMed1991

Cell cycle arrest and cellular differentiation mediated by a cell surface sialoglycopeptide.

Cell cycling by a relatively wide variety of cell lines was shown to be reversibly inhibited by a cell surface sialoglycopeptide (SGP) isolated and purified from intact bovine cerebral cortex cells. Cell cycle arrest, mediated by the bovine SGP inhibitor, was shown to be completely reversible with mouse Swiss 3T3, mouse 1316 fibrosarcoma, mouse N2a neuroblastoma, bovine MDBK and monkey BSC-1 cells. These cell lines represented both fibroblast and epithelial-like cells, transformed and nontransformed cells, as well as their being derived from a broad array of species. In contrast to the others tested, human HL-60 leukemic cells were sensitive to the inhibitory effects of the SGP but did not reenter the mitotic cycle after the removal of the inhibitor. Instead, the mitotic arrest of HL-60 cells appeared to enhance entry into a terminal and irreversible state of cellular differentiation.

Animals↗
PubMed1991

An immune cell population that responds to beta-endorphin and is responsible for protecting nude mice from the fatal consequences of a virus infection of the central nervous system.

Reconstitution of 3- to 4-week-old BALB/c nude (nu/nu) mice with 10(7) syngeneic splenocytes, 48 h before intracerebral inoculation with a temperature-sensitive (ts) mutant of VSV (tsG31 KS5), provided protection from the fatal consequences of clinical disease in 80-90% of the infected animals. Reconstitution of animals with 10(7) splenocytes, first depleted of natural killer (NK) cells with anti-asialo GM1 and complement, also afforded protection against the infectious disease. Depletion of T-lymphocytes with anti-thy-1.2 antibody and complement, however, provided little protection with approximately 40% of the animals succumbing to the virus infection within 30 days post-infection. A single intracerebroventricular injection with 14 pM of beta-endorphin, 24 h prior to viral infection, led to an increased fatality of mice previously reconstituted with T-lymphocytes but not in animals receiving only syngeneic NK cells. The increased fatality caused by the neuropeptide was antagonized by naloxone but not beta-endorphin-(1-27). Separation of splenocyte cell populations by buoyant density centrifugation demonstrated that small race lymphocytes, and not the large granular lymphocytes, were responsible for protection of nude mice from the central nervous system infection with ts-VSV. The beta-endorphin-responsive immune cells were shown to be a minor fraction of the small race T-lymphocyte population that bear the asialo-GM1 marker.

Animals↗
PubMed1991

Physical fitness, body image, and locus of control in college women dancers and nondancers.

This study assessed the correlations among measures of physical fitness, body image and locus of control in college freshman women dancers and nondancers. 39 students enrolled in courses in modern, ballet, and jazz dance, and 120 students enrolled in an introductory personal health course were administered the Hall Physical Fitness Test Profile, the Winstead and Cash 54-item short-form Body Self-relations Questionnaire (BSRQ), and the Adult Nowicki-Strickland Locus of Control Scale. Analysis showed dancers were more physically fit, scored more positively on the BSRQ physical fitness and health domains, and were more internal in their locus of control than the nondancers. There was no significant difference between dancers and nondancers on the BSRQ appearance domain. The significant positive correlation between BSRQ health and physical fitness among dancers was not observed among nondancers. The significant positive correlation for BSRQ appearance and health was noted for nondancers but not for dancers.

Adolescent↗
PubMed1990

Beta-endorphin alters the course of central nervous system disease induced by a temperature-sensitive vesicular stomatitis virus in reconstituted nude mice.

A 100 plaque forming unit (pfu) dose of a temperature-sensitive (ts) mutant of vesicular stomatitis virus (VSV), tsG31 KS5, engendered a slowly progressive paralytic central nervous system (CNS) disease that killed all BALB/c nude mice within 28 days. Reconstitution of nude mice with 10(7) syngeneic splenocytes 24 h before intracerebral inoculation with tsG31 KS5 VSV, however, protected 92% of the animals from death. When these reconstituted animals were injected intracerebroventricularly with 14 pmol of beta-endorphin 24 h after reconstitution with splenocytes and 24 h before inoculation with tsG31 KS5 VSV, only 72% of the animals survived. Furthermore, whereas 40% of the afflicted reconstituted nude mice given intracerebroventricular injections of sterile water were able to recover from the symptoms of disease, those surviving animals which received beta-endorphin were unable to do so. A single intravenous injection of 14 pmol beta-endorphin, or repeated postinfection administration of 28 pmol of beta-endorphin intravenously into nude mice reconstituted with syngeneic splenocytes, which were pretreated with beta-endorphin, did not alter the course of CNS disease induced by tsG31 KS5 VSV. The effect induced by intracerebroventricular injection of beta-endorphin was antagonized by naloxone, but not by the neuropeptide fragment beta-endorphin-(1-27). A simultaneous intracerebroventricular injection of reconstituted nude mice with 1220 pmol of naloxone and 14 pmol of beta-endorphin resulted in a 89% survival rate, and 33% of the afflicted animals were able to overcome the symptoms of the disease induced by tsG31 KS5 VSV. Intracerebroventricular injection of reconstituted nude mice with 330 pmol of beta-endorphin-(1-27) and 14 pmol of beta-endorphin resulted in a 72% survival rate and the surviving animals were unable to improve appreciably the clinical status of their disease. Injection of reconstituted nude mice with either 1220 pmol of naloxone or 330 pmol of beta-endorphin-(1-27) alone did not alter the course of the CNS disease in any way. A single intracerebroventricular injection of 29 pmol of another psychoactive peptide, [Des-Tyr]-endorphin, 24 h after reconstitution of nude mice with splenocytes and 24 h prior to infection with virus, resulted in 74% survival; and 39% of the afflicted animals were able to recover from the clinical symptoms.

Animals↗
PubMed1990

Incentives and their influence on appointment compliance in a teenage family-planning clinic.

The purpose of this study was to ascertain whether or not the family-planning compliance patterns of indigent adolescents could be influenced by various types of incentives. From February 1988 through January 1989, 534 postpartum inner city teenagers, aged 12-19, who delivered at a large city-county public hospital, participated. Teens were randomly assigned to two treatment groups that either offered a coupon for milk for the infant or a gift for the teenage mother if they returned for their postpartum visit 4-6 weeks after delivery. A third group, which used no incentive for appointment keeping, acted as a control. Although overall compliance was low, a significant relationship was found between type of program incentive and compliance outcome. The program using milk coupons as an incentive had the best compliance rate. This incentive appeared to be most effective with black adolescents. Such incentive programs, although not without controversy, offer a potential way to enhance postpartum contraceptive appointment-keeping compliance in a high-risk population.

Adolescent↗
PubMed1990

The nucleocapsid protein of vesicular stomatitis virus isolated from the brains of nude mice is responsible for abated viral RNA synthesis at the normal body temperature of mice.

Six temperature-sensitive mutants of vesicular stomatitis virus (VSV) were isolated from the central nervous system (CNS) of athymic nude mice. The nude mice had been reconstituted with syngeneic T lymphocytes and then infected with a temperature-sensitive mutant of VSV, tsG31-KS5 VSV, for 20 days. In BHK-21 cells incubated at 38 degrees C, the normal body temperature of mice, all six CNS virus clones had diminished RNA synthesis, when compared to RNA production in BHK-21 cells incubated at 31 degrees C. In contrast, the original tsG31-KS5 VSV mutant synthesized more RNA at 38 degrees C than it did at 31 degrees C. In vitro transcription assays were exploited to discern which viral protein(s) was functionally accountable for the abated synthesis of RNA of the CNS VSV isolates. The ribonucleoprotein complexes from the CNS VSV isolates were disrupted and template (N protein and RNA) and enzyme (L and NS proteins) fractions were purified. In vitro transcription assays were performed with template fractions of the brain isolates, added to enzyme fractions either wild-type wt VSV or tsG31-KS5 VSV, or with template fractions of wt VSV or tsG31-KS5 VSV mixed with enzyme fractions of the CNS isolates. The template fraction was responsible for the decrease in RNA synthesis in all six of the brain-isolated clones. When the template fractions of wt or tsG31-KS5 VSV were mixed with enzyme fractions of all the CNS-derived VSV, except BP5A VSV, leader sequence RNA and large Mr transcripts were transcribed. One clone, BP5A VSV, did not synthesize RNA when mixed with either template or enzyme of wt VSV, and probably had more than one functional mutation that influenced viral RNA synthesis.

Animals↗
PubMed1990

Physical fitness in relation to amount of physical exercise, body image, and locus of control among college men and women.

The relations of amount of exercise, body image, and locus of control to physical fitness were investigated. The Hall Physical Fitness Test Profile, the Winstead and Cash Body Self-relations Questionnaire, and the Nowicki-Strickland Locus of Control Scale were administered to 243 freshmen. Students estimated the amount of time spent exercising on a 9-point scale ranging from no regular exercise to 10 or more hours per week for the preceding three months. Exercise included brisk walking, jogging, aerobics, and sports activities like soccer, tennis, and swimming. Increased fitness was associated with increased amounts of exercise, internal locus of control, and good body image. There was a statistically significant interaction between sex and amount of exercise. For students who exercised 2-4.9 hours per week, men were more fit than women. Fitness was comparable for men and women exercising less than two hours or at least five hours per week. Women had to exercise 5 or more hours weekly to achieve the fitness level of men who exercised 2 to 4.9 hours per week.

Adolescent↗
PubMed1989

Abrogation of the mitogenic activity of bombesin by a cell surface sialoglycopeptide growth inhibitor.

The ability of a cell surface sialoglycopeptide (SGP) growth inhibitor to abrogate the mitogenic activity of bombesin, in serum-free medium, was investigated. The SGP was shown to be a potent antagonist of bombesin-induced DNA synthesis as 2.7 nM of the inhibitor completely blocked the mitogenic activity of 5.0 nM of bombesin. Exposure of 3T3 cells to bombesin for only 10 hr was sufficient to initiate the induction of DNA synthesis 10 hr later. Kinetic studies demonstrated that the SGP was able to block bombesin-induced DNA synthesis only when added within 2 hr after exposure of the cells to the mitogen. The SGP inhibitor blocked bombesin mitogenesis at a post-receptor, intracellular, early event in the signal cascade.

Animals↗
PubMed1989

Inhibition of DNA synthesis and cell division by a cell surface sialoglycopeptide.

We have isolated and purified a cell surface sialoglycopeptide (SGP) from bovine cerebral cortex cells that previously was shown to be a potent inhibitor of cellular protein synthesis. The following studies were carried out to characterize the potential ability of the SGP to inhibit DNA synthesis and to arrest cell division. Treatment of exponentially proliferating Swiss 3T3 cells with the SGP inhibitor resulted in a marked inhibition of thymidine incorporation within 24 h. When the SGP was removed from inhibited cultures, a sharp rise in 3H-thymidine incorporation followed within 3-4 h that peaked well above that measured in exponentially growing cultures, suggesting that the inhibitory action of the SGP was reversible and that a significant proportion of the arrested cells was synchronized in the mitotic cycle. In addition to DNA synthesis, the inhibitory action of the SGP was monitored by direct measurement of cell number. Consistent with the thymidine incorporation data, the SGP completely inhibited 3T3 cell division 20 h after its addition to exponentially growing cultures. Upon reversal there was a delay of 15 h before cell division resumed, when the arrested cells quickly doubled. Most, if not all, of the growth-arrested cells appeared to have been synchronized by the SGP. The SGP inhibited DNA synthesis in a surprisingly wide variety of target cells, and the relative degree of their sensitivity to the inhibitor was remarkably similar. Cells sensitive to the SGP ranged from vertebrate to invertebrate cells, fibroblast and epitheliallike cells, primary cells and established cell cultures, as well as a wide range of transformed cell lines.

Animals↗
PubMed1989

Female child perpetrators: children who molest other children.

Little is known about sexual perpetration by females or by young children. This paper describes the sexual perpetration behavior of 13 female child perpetrators between 4 and 13 years of age. These children were treated in a specially designed program for child perpetrators, the Support Program for Abuse-Reactive Kids (SPARK) at Children's Institute International of Los Angeles, California. All of these girls used force or coercion to gain the compliance of the other child or children. Of these child perpetrators, 100% had been previously sexually abused; 31% had been physically abused; 85% were molested by family members; 77% of the girls chose a victim in their family (the other 3 girls had no available family members). The mean age of their first known perpetration was 6 years, 9 months. The average age of their victims was 4 years, 4 months. The average number of victims of these girls was 3.5 with a range of 1 to 15. The girls victimized two times more boys than girls. There was a history of sexual, physical, and substance abuse in the families of these children. Hypotheses regarding the genesis of the sexually abusive behavior in these female child perpetrators are explored.

Adolescent↗
PubMed1989

Beta-endorphin alters a viral induced central nervous system disease in normal mice but not in nude mice.

A single intracerebroventricular injection of 100 ng of beta-endorphin altered the course of the central nervous system (CNS) infection of a temperature-sensitive mutant of vesicular stomatitis virus (VSV), tsG31-KS5. When mice were administered beta-endorphin and then 24 h later infected intracerebrally with tsG31-KS5 VSV, 70% of the animals died within 8 days of infection. In comparison, less than 10% of the animals had died after 21 days when infected with tsG31-KS5 VSV alone. When mice were injected with beta-endorphin and tsG31-KS5 VSV simultaneously, or with beta-endorphin 21 days after infection, the more aggressive clinical disease was not observed. Superficially, the more lethal disease induced by beta-endorphin appeared to be a result of a mild hypothermia caused by the neuropeptide. beta-Endorphin, however, did not influence the disease in nude (nu/nu) mice even though their core temperatures were reduced to an extent similar to that of BALB/c (+/+) mice, implicating the involvement of T lymphocytes in the alteration of the course of infection in normal mice.

Animals↗
PubMed1989

Vaginal douching in teenagers attending a family planning clinic.

This study assessed the knowledge and usage patterns of vaginal douching in sexually active teenagers attending a family planning clinic. A questionnaire was administered consecutively to 94 black, 36 Hispanic, and 12 Anglo females ranging in age from 13 to 19 years. The survey showed that vaginal douching is a common practice, with almost two thirds learning about douching from their mother. The technique is primarily used for hygienic reasons with few using it to prevent pregnancy or infection. Age of first douche correlated with age of first intercourse (p less than 0.001). Almost 23% had douched within 2 days of the clinic visit, and 56% reported douching one or more times a week.

Adolescent↗
PubMed1989

Physical fitness, body image, and locus of control in college freshman men and women.

This study examined the relations among physical fitness, body image, and locus of control. The Hall-Physical Fitness Test Profile, the Winstead and Cash Body Self-relations Questionnaire (BSRQ) and the Nowicki-Strickland Locus of Control Scale were administered to 243 freshmen. Women were significantly more positive about their physical appearance than men. Men were more positive about their physical fitness than women. Men were more physically fit than women. Men and women scoring in the internal direction viewed the physical fitness domain of their body image positively. Unlike men, internally oriented women had more positive perceptions of the health aspect of their body image. Physically fit men and women had positive attitudes toward the physical fitness component of their body image. Physically fit men differed from physically fit women in that men were more internal and held more positive attitudes toward the physical health dimension of their body images.

Adolescent↗
PubMed1988

An NADP/thioredoxin system in leaves: purification and characterization of NADP-thioredoxin reductase and thioredoxin h from spinach.

An NADP/thioredoxin system, consisting of NADPH, NADP-thioredoxin reductase (NTR), and its thioredoxin, thioredoxin h, has been previously described for heterotrophic plant tissues, i.e., wheat seeds and cultured carrot cells. Until now there was no evidence for this system in green leaves. Here, we report the identification of protein components of the NADP/thioredoxin system in leaves of several species. Thioredoxin h and NTR, which were both recovered in the extrachloroplastic fraction, were purified to apparent homogeneity from spinach leaves. This represents the first time that NTR has been characterized from a plant source. Similar to that from bacterial and mammalian sources, spinach leaf NTR was a flavoprotein (Mr 68,000) composed of two subunits of identical molecular mass (Mr 33,000) that resembled Escherichia coli NTR immunologically. Spinach thioredoxin h existed in two forms (Mr of 13,500 and 12,000) and was highly specific for plant NTR. Thioredoxin h and NTR partially purified from spinach roots showed properties similar to their counterparts from leaves. Spinach cytosolic thioredoxin h differed from chloroplast thioredoxin m or f from the same source but was similar to thioredoxin h from wheat seed in immunological properties.

Amino Acids↗
PubMed1988

Child perpetrators--children who molest other children: preliminary findings.

While the seriousness of sexual abuse by adolescents is finally beginning to receive adequate attention from the professional community, the existence of child perpetrators is largely dismissed and denied. Forty-seven boys between the ages of 4 and 13 are described who have molested children younger than themselves. Coercion was involved in all of the cases included in this study. These children had been treated in a program especially designed for child perpetrators at Children's Institute International in Los Angeles. Prior to their own sexually abusive behaviors, 49% of these boys had been sexually abused and 19% physically abused. The children all knew the people who victimized them. These male child perpetrators all knew the children they molested. In 47% of the cases the sexual abuse was of a sibling. The average number of victims of these children was 2.1 with a range of 1 to 7. The mean age at the time of perpetration was 8 years, 9 months. The mean age of the victims of these children was 6 years, 9 months. There was a history of sexual and physical abuse in the majority of the families of these children, as well as a history of substance abuse. This population is compared to adolescent perpetrators.

Child↗
PubMed1988

Reconstitution with T lymphocytes protects nude mice from a central nervous system disorder induced by a temperature-sensitive vesicular stomatitis virus.

A temperature-sensitive mutant of vesicular stomatitis virus (VSV), tsG31-KS5 VSV, intracerebrally inoculated into BALB/c (+/+) or Swiss outbred mice yielded a clinically asymptomatic persistent infection of the central nervous system (CNS). BALB/c nude (nu/nu) mice infected with tsG31-KS5 VSV, however, all perished within 26 days of infection. All the nude mice were afflicted with a slowly progressing CNS disorder, with symptoms including lethargy, curvature of the spine, hind-limb paralysis and other neurological disorders, before they succumbed to the infection. Wild-type (wt) VSV infection of either normal or nude mice, on the other hand, invoked a rapidly lethal disease with all animals dying within 4 days of infection. When nude mice were reconstituted with 5 x 10(6) syngeneic T lymphocyte-enriched splenocytes, over 70% of them not only survived the tsG31-KS5 VSV infection but appeared to be free of any neurological disorders. Only 20% of these reconstituted mice infected for 20 days with tsG31-KS5 VSV endured a wt VSV challenge. In contrast, BALB/c (+/+) mice infected for 20 days with tsG31-KS5 VSV all survived a wt VSV challenge. Reconstitution of nude mice with 5 x 10(6) T lymphocytes did not elicit a vigorous secondary humoral antibody response against VSV. All the animals reconstituted with 5 x 10(7) T lymphocytes and infected with tsG31-KS5 VSV, however, had both late and early humoral responses that equalled antibody responses of BALB/c (+/+) mice. Reconstitution with either 5 x 10(6) or 5 x 10(7) T lymphocytes afforded the nude mice equivalent protection from the CNS disorder triggered by tsG31-KS5 VSV. Reconstitution with 5 x 10(6) T lymphocytes, therefore, protected nude mice from the neurological disease induced by the persistent virus without eliciting a robust humoral antibody response. Infectious, temperature-sensitive VSV was retrieved from the CNS of the nude mice that had been reconstituted with 5 x 10(6) T lymphocytes and infected for up to 30 days with tsG31-KS5 VSV. The CNS-isolated VSV was less temperature-sensitive than tsG31-KS5 VSV. When the CNS-isolated VSV was intracerebrally inoculated into Swiss outbred mice, an aggressive disease ensued with most of the mice developing a CNS disorder. In comparison, Swiss outbred mice were asymptomatically infected with tsG31-KS5 VSV. The VSV isolated from the CNS was more lethal to the mice than tsG31-KS5 VSV possibly because it was less temperature-sensitive.

Animals↗