A survey into the current fitness testing practices of elite male soccer practitioners: from assessment to communicating results

This study provides insight into the current fitness testing practices in elite male soccer. One hundred and two practitioners from professional soccer leagues across 24 countries completed an online survey comprising 29 questions, with five sections: a) background information, b) testing selection, c) testing implementation, d) data analysis, and e) data reporting. Frequency analysis was used to evaluate the responses to fixed response questions and thematic analysis was used for open-ended questions to generate clear and distinct themes. Strength (85%) and aerobic capacity (82%) represent the most frequently assessed physical qualities. Scientific literature (80%) is the most influential factor in testing selection and practitioners conduct fitness testing less frequently than their perceived ideal frequency per season (3.6 ± 2 vs. 4.5 ± 2). Time and competitive schedule were the greatest barriers to fitness testing administration. Practitioners mostly used a 'hybrid' approach (45%) to fitness testing, blending 'traditional' (i.e., a day dedicated to testing) and 'integrated' (i.e., testing within regular training sessions) methods. Microsoft Excel is the most used software for data analysis (95%) and visualization (79%). An equal use of the combination of best and mean scores of multiple trials (44%) and the best score (42%) was reported. Comparing a player's test performance with previous scores (89%) was the most common method for interpreting test results. However, only 38% considered measurement error. Digital displays and verbal feedback are the most common data reporting methods, with different data reporting processes for coaches and players. Practitioners can use data and findings from this study to inform their current testing practices and researchers to further identify areas for investigation, with the overarching aim of developing the field of fitness testing in elite male soccer.

Homonegativity Scores in Response to Static Same-Sex Imagery versus Observable Behavioral Change in Response to an Interactive Gay Male Target

Homonegativity research tends to focus on the identities of gay men and lesbian women through inauthentic means such as vignettes and signifiers like t-shirts with pro-gay slogans. Such research also tends to neglect sexual behavior. These issues were addressed in the present mixed-methods study. Heterosexual male (n = 196) and female (n = 219) participants were asked to complete measures of old-fashioned and modern homonegativity toward gay men and lesbian women after viewing a set of stimuli depicting gay male, lesbian female, or heterosexual couples. Participants also completed an interview with the researcher where he self-identified as a gay male and observed any changes in behavior following his disclosure. Findings indicated that male participants showed higher levels of modern homonegativity than female participants, regardless of the images viewed, and had higher odds of exhibiting negative behavioral change in response to the researcher's self-disclosure. Also, participants who viewed images of lesbian couples kissing or embracing had lower odds of showing negative behavioral change.

Affective responses to non-sexual imagery depicting gay men and lesbian women

When examining negative attitudes and behaviors directed toward gay men and lesbian women (i.e., homonegativity), researchers tend to use measures that require participants to respond to belief statements. This methodology is problematic for two reasons: 1) it focuses on the social categories "gay men" and "lesbian women" and ignores the practices of relational intimacy engaged in by gay and lesbian persons (practices that, arguably, are at the crux of homonegativity); and 2) it overlooks the affective responses that sexual minorities evoke in heterosexual people. These issues were tackled in the current study. Specifically, heterosexual participants (N = 241) were asked to report their affective state using six basic emotions while viewing photos depicting male-male, female-female, and heterosexual couples. Findings demonstrated that participants, regardless of gender, reacted most negatively to images of female-female couples engaging in everyday intimacies. Theoretical explanations for these findings are explored.

Postactivation Potentiation and Change of Direction Speed in Elite Academy Rugby Players

Marshall, J, Turner, AN, Jarvis, PT, Maloney, SJ, Cree, JA, and Bishop, CJ. Postactivation potentiation and change of direction speed in elite academy rugby players. J Strength Cond Res 33(6): 1551-1556, 2019-This study investigated the effect of preceding proagility sprints with maximal isometric squats to determine if postactivation potentiation (PAP) could be harnessed in change of direction speed. Sixteen elite under-17 rugby union players (age: 16 ± 0.41 years; body mass: 88.7 ± 12.1 kg; height: 1.83 ± 0.07 m) from an Aviva Premiership rugby club were tested. Subjects performed a change of direction specific warm-up, followed by 2 baseline proagility tests. After 10-minute recovery, 3 × 3-second maximal isometric squats with a 2-minute recovery between sets were completed as a conditioning activity (CA) on a force plate where peak force and mean rate of force development over 300 milliseconds were measured. The proagility test was repeated at set time intervals of 1, 3, 5, and 7 minutes after the CA. Overall proagility times were significantly slower (p < 0.05) at 1 minute post-CA compared with the baseline (3.3%), with no significant differences occurring at 3, 5, or 7 minutes post-CA. Therefore, it appears that performing multiple sets of maximal isometric squats do not enhance proagility performance.

"We're Disgusted With Queers, not Fearful of Them": The Interrelationships Among Disgust, Gay Men's Sexual Behavior, and Homonegativity

Using a combination of personal reflections, published literature, and original empirical research, we argue that the disgust triggered by gay men's sexual practices (specifically, anal intercourse) is a critical, though overlooked, contributor to heterosexual men and women's homonegativity (i.e., negative attitudes and behaviors directed toward men who are or are perceived to be gay). We conclude our article by articulating several directions for future inquiry that we believe will advance current understanding of prejudice and discrimination directed toward gay men.

A Systematic Review of the Psychometric Properties of Composite LGBT Prejudice and Discrimination Scales

Prejudice and discrimination against LGBT individuals is widespread and has been shown to have negative consequences for sexual and gender minority persons' physical and psychological wellbeing. A recent and problematic trend in the literature is to compositely measure prejudice toward and discrimination against LGBT persons. As such, a review of the psychometric properties of scales assessing, in a combinatory fashion, negative attitudes and/or behaviors toward LGBT persons is warranted. In the current study, 32 scales were identified, and their psychometric properties were evaluated. Most of the scales reviewed did not provide sufficient information regarding item development and refinement, scale dimensionality, scale score reliability, or validity. Properties of the reviewed scales are summarized, and recommendations for better measurement practice are articulated.

Using the Split Squat to Potentiate Bilateral and Unilateral Jump Performance

Bishop, CJ, Tarrant, J, Jarvis, PT, and Turner, AN. Using the split squat to potentiate bilateral and unilateral jump performance. J Strength Cond Res 31(8): 2216-2222, 2017-The purpose of this study was to examine if a split squat conditioning exercise with no or light loads could potentiate unilateral and bilateral jump performance. Twelve semiprofessional rugby players (age: 22.3 ± 1.4 years; height: 1.84 ± 0.05 m, mass: 92.4 ± 9.6 kg) from the English National League 1 performed a series of unilateral and bilateral countermovement jumps (CMJ) and broad jumps (BJ) over the course of 2 testing days. Both testing days involved performing baseline jumps before completing 2 sets of 10 repetitions of a split squat, this completed with either bodyweight (testing session 1) or a 30 kg weighted vest (testing session 2). A 5-minute recovery period was permitted both after the warm-up and the completion of the split squat exercise. Significantly larger bilateral jump scores were reported after completion of the bodyweight split squat: CMJ (p = 0.001, ES = 0.44, [mean difference 2.517]), BJ (p = 0.001, ES = 0.37, [mean difference 3.817]), and the weighted vest split squat; CMJ (p = 0.001, ES = 0.8, [mean difference 4.383]), BJ (p = 0.001, ES = 0.68, [mean difference 6.817]). The findings of this study demonstrate that no or light loads of a split squat conditioning exercise are able to potentiate bilateral jump performance in semiprofessional rugby players without the need for expensive weight room equipment. As such, this may provide coaches with a viable option of enhancing bilateral jump performance as part of a warm-up or on-field conditioning practice.

Do Fencers Require a Weapon-Specific Approach to Strength and Conditioning Training?

There are 3 types of weapons used in Olympic fencing: the épée, foil, and sabre. The aim of this study was to determine if fencers exhibited different physical characteristics across weapons. Seventy-nine male (n = 46) and female (n = 33) national standard fencers took part in this study. Fencers from each weapon (male and female), i.e., épée (n = 19 and 10), foil (n = 22 and 14), and sabre (n = 13 and 10), were (mean ± SD) 15.9 ± 0.7 years of age, 178.5 ± 7.9 cm tall, 67.4 ± 12.2 kg in mass and had 6.3 ± 2.3 years fencing experience; all were in regular training (∼4 times per week). Results revealed that across all performance tests (lower-body power, reactive strength index, change of direction speed, and repeat lunge ability), there was no significant main effect for weapon in male fencers (p = 0.63) or female fencers (p = 0.232), but a significant main affect for gender (p < 0.001). Pairwise comparisons revealed that male fencers scored better during the countermovement jump, change of direction speed, and repeat lunge ability test (p < 0.001). The former findings may be because of similarities in bout intensity and time, movement types (lunging and changing direction), and the need to execute competition actions as explosively as possible. Based on the findings of the present study, it could be indicated that épée, foil, and sabre fencers do not require a weapon-specific approach to strength and conditioning training. Each fencer should target the area they are weakest at, rather than an area that they feel best represents the unique demands of their weapon.

A Psychometric Review of Measures Assessing Discrimination Against Sexual Minorities

Discrimination against sexual minorities is widespread and has deleterious consequences on victims' psychological and physical wellbeing. However, a review of the psychometric properties of instruments measuring lesbian, gay, and bisexual (LGB) discrimination has not been conducted. The results of this review, which involved evaluating 162 articles, reveal that most have suboptimal psychometric properties. Specifically, myriad scales possess questionable content validity as (1) items are not created in collaboration with sexual minorities; (2) measures possess a small number of items and, thus, may not sufficiently represent the domain of interest; and (3) scales are "adapted" from measures designed to examine race- and gender-based discrimination. Additional limitations include (1) summed scores are computed, often in the absence of scale score reliability metrics; (2) summed scores operate from the questionable assumption that diverse forms of discrimination are necessarily interrelated; (3) the dimensionality of instruments presumed to consist of subscales is seldom tested; (4) tests of criterion-related validity are routinely omitted; and (5) formal tests of measures' construct validity are seldom provided, necessitating that one infer validity based on the results obtained. The absence of "gold standard" measures, the attendant difficulty in formulating a coherent picture of this body of research, and suggestions for psychometric improvements are noted.

Gene delivery polymer structure-function relationships elucidated via principal component analysis

Principal component analysis was applied to a biomaterial library of poly(beta-amino ester)s, useful for non-viral gene delivery, to elucidate chemical parameters that drive biological function. Correlative relationships and principal components were analyzed between 24 physico-chemical polymer properties and 3 cell-based functional variables in human glioblastoma cells (transfection, uptake, and viability).

The association between gay men's stereotypic beliefs about drag queens and their endorsement of hypermasculinity

To date, few researchers have investigated gay men's stereotypic beliefs about drag queens and the association between these beliefs and individual difference variables such as hypermasculinity. To address this omission, 118 men self-identifying as non-heterosexual completed an online survey consisting of an adjective checklist about drag queens and a psychometrically sound indicant of hypermasculinity. As predicted, participants who were more likely to endorse hypermasculine belief statements tended to perceive negatively valenced attributes as more characteristic of drag queens. Possible explanations for this relationship, limitations associated with the current study, and directions for future research are delineated.

A systematic review of sexual dysfunction measures for gay men: how do current measures measure up?

The measurement of subjective components of sexual functioning is of increasing importance in clinical research and practice. Differences have been reported in prevalence rates and experiences of sexual difficulties between heterosexual and gay men. The aim of this article is to identify reliable and valid measures of sexual dysfunction suitable for use with gay men. Seven measures were reviewed; details about item development, dimensionality, reliability, and validity are provided. Heteronormative and heterosexist wording were evident throughout. Several areas of concern emerged in relation to psychometric properties (e.g., questionable validity). No psychometrically robust sexual function measure was identified for use with gay populations.

Clonal replacement among 19A Streptococcus pneumoniae in Massachusetts, prior to 13 valent conjugate vaccination

As part of an ongoing study of the response of the Streptococcus pneumoniae population to conjugate vaccination, we applied multi-locus sequence typing (MLST) to 291 isolates sampled from nasopharyngeal carriage in Massachusetts children. We found 94 distinct sequence types (STs), including 19 that had not been previously recorded, and a xpt allele containing a large insertion. Comparison with a similar sample collected in 2007 revealed no significant overall difference in the ST composition (p=0.51) suggesting that the population has reached a new equilibrium following the introduction of 7 valent vaccination in 2000. Within serotypes, a large and statistically significant increase (p=0.014 Fisher's Exact test) was noted in the prevalence of the major multiresistant clone ST 320, which is apparently outcompeting ST 199 among serotype 19A strains. This sample will be used as a baseline to study the future evolution of the pneumococcal population in Massachusetts following introduction of vaccines with higher valency.

The capsule drug device: novel approach for drug delivery to the eye

Treatment of age-macular degeneration requires monthly intravitreal injections, which are costly and have serious risks. The objective of this study was to develop a novel intraocular implant for drug delivery. The capsule drug ring is a reservoir inserted in the lens capsule during cataract surgery, refillable and capable of delivering multiple drugs. Avastin was the drug of interest in this study. Prototypes were manufactured using polymethylmethacrylate sheets as the reservoir material, a semi-permeable membrane for controlled delivery and silicone check valves for refilling. The device showed near zero-order release kinetics and Avastin stability was investigated with accelerated temperature studies.

Emergence of 19A as virulent and multidrug resistant Pneumococcus in Massachusetts following universal immunization of infants with pneumococcal conjugate vaccine

BACKGROUND

The long-term effects of selective pressure from conjugate pneumococcal vaccine on the serotype distribution and antimicrobial resistance of carriage and invasive isolates of Streptococcus pneumoniae are unknown. Early changes demonstrate a reduction in vaccine serotypes and an increase in nonvaccine serotypes (NVT) among both carriage and invasive isolates. Ongoing surveillance is necessary to identify emerging invasive serotypes and antimicrobial susceptibilities.

METHODS

Enhanced surveillance of invasive pneumococcal disease in Massachusetts began in October 2001 and remains ongoing. Isolates from children less than 5 are sent to the Massachusetts Department of Public Health and subsequently to the Maxwell Finland laboratory for serotyping and determination of antimicrobial susceptibility. Annual incidence rates for vaccine serotype and NVT disease are calculated using 2000 census data.

RESULTS

NVT caused 72%-91% of invasive pneumococcal disease annually in children less than 5 years of age between 2002 and 2005. Serotype 19A has emerged as the most frequent cause of IPD in Massachusetts. A multidrug-resistant clone (ceftriaxone, amoxicillin, azithromycin and trimethoprim-sulfamethoxazole) (MLST 320) was first identified in Massachusetts in 2005.

CONCLUSIONS

Three years after the introduction of pneumococcal conjugate vaccine for universal administration to children less than 2 in Massachusetts, a significant increase in invasive disease due to serotype 19A was observed. Although MLST 199 remains the most frequent sequence type among invasive isolates (of 19A), a multidrug-resistant sequence type, not previously identified in Massachusetts, has become an important cause of invasive disease. Further surveillance of the changing ecology of S. pneumoniae is necessary as a 4-year time period is not sufficient to fully evaluate the impact of PCV of pneumococcal infections.

Aspiration of oocytes for in-vitro fertilization

An aspiration system, incorporating a regulated vacuum pump, was used to examine, in vitro, some factors that may affect oocyte collection. In an open aspiration system, as the length of the needle was increased, or the internal diameter decreased, the velocity (and flow rate) of aspirated fluid decreased. There was a difference, however, between experimental flows and those predicted by Hagen-Poiseuille's Law. Upon application of vacuum to a closed aspiration system, employing isolated bovine ovaries, there was an initial rapid increase in the collection tube vacuum to 85% of the selected pump vacuum followed by a more gradual rise to 100%. The vacuum within the needle similarly rose rapidly to approximately half the selected vacuum, while the vacuum at the needle tip was approximately 5% of selected vacuum. The vacuums throughout the system briefly equilibrated as maximum flow/velocity was reached. Flow/velocity slowed dramatically as the follicle collapsed, and stopped as the needle tip was blocked. If vacuum was maintained during the withdrawal of the needle from the follicle, there was a dramatic forward flow of fluid toward the collection tube. The morphological appearance of bovine cumulus after in-vitro aspiration was generally unaltered by vacuums commonly utilized in oocyte collection, providing the cumulus was regular, compact and refractile. The cumulus was less resistant to aspiration if it was damaged or had degenerated. These results suggest that an intact cumulus may offer protection during oocyte collection.

T lymphocytes in infectious mononucleosis; effect of IL-2 on the outgrowth of Epstein-Barr virus-infected cells

The addition of interleukin-2 (IL-2) to lymphocyte cultures from acute infectious mononucleosis (IM) donors dramatically increased the incidence of regression in such cultures and resulted in the emergence of an IL-2 dependent, CD3 Epstein-Barr virus nuclear antigen (EBNA)-negative cell population. Corresponding cultures seeded in the absence of IL-2 rarely regressed and were quickly dominated by IL-2 independent, CD3-negative, EBNA-positive cells. Lymphocyte cultures from Epstein-Barr virus (EBV) seropositive donors showed enhanced regression in the presence of IL-2 but failed to regress after the removal of the E-rosetting population. Cultures from EBV-seronegative donors showed no evidence of regression in the presence or absence of IL-2. E-rosetting cells isolated from cultures from acute IM donors that had been cultured in the presence of IL-2 lysed autologous and allogeneic lymphoblastoid cell lines.

Monoclonal antibody against a melanosomal protein in melanotic and amelanotic human melanoma cells

BALB/c mice were immunized with tyrosinase, partially purified in two stages from a human melanoma cell line. A hybridoma was obtained which produced monoclonal antibody (MoAb 1C11) reactive with 8/10 melanoma cell lines and 10/10 primary cultures of human melanocytes, neval cells, and melanomas. Immunoreactivity correlated to a certain extent with tyrosinase activity but not with melanin content. No crossreactivity was obtained with neuroblastoma, medulloblastoma, fibroblasts, keratinocytes, lymphoid cells, or murine melanomas. Purification of the antigen directly from cell lysates with a MoAb 1C11 CNBr-Sepharose affinity column gave a green-brown protein of 56 kDa with no detectable tyrosinase activity. This protein was therefore different from 60 kDa active tyrosinase, identified by enzyme activity and Western blotting with a MoAb derived previously (MoAb 5C12). Unlike 5C12, 1C11 reactivity was not destroyed by pretreatment of the antigen with periodate. Immunogold labelling showed that the 1C11-reactive antigen was associated with melanosomes, and there was close correlation between 5C12 and 1C11 reactivity in resistance to trypsin and in staining various melanocytic cell populations. MoAb 1C11 may therefore recognise a polypeptide epitope in a molecule closely linked to melanin biosynthesis.

The role of reactive oxygen metabolites in lymphocyte-mediated cytolysis

To examine the possible role of reactive oxygen metabolites in lymphocyte-mediated cytolysis, the morphology of cell death following the exposure of cells to reactive oxygen metabolites in vitro was compared with the morphology of cell-mediated killing in vitro of tumour cells by natural killer (NK) cells. Ultrastructural examination of human tumour cells that were dying following incubation for 60 min with the oxygen metabolite generating systems, xanthine-xanthine oxidase or t-butylhydroperoxide, showed that cell death in both instances was exclusively by necrosis. It was unclear which oxygen metabolites were involved in killing. Cell death was not decreased by the addition of superoxide dismutase, a scavenger of the superoxide anion, to the xanthine-xanthine oxidase mixture. Although the cells were not killed by incubation with 1 mM-hydrogen peroxide, the addition of catalase, a scavenger of hydrogen peroxide, to the xanthine-xanthine oxidase mixture significantly reduced cell death. The addition of scavengers for the hydroxyl radical to either the xanthine-xanthine oxidase mixture or t-butylhydroperoxide gave inconsistent protection. In contrast, tumour cell killing mediated by natural killer cells was by apoptosis, a morphologically distinct mode of cell death with a different basic mechanism, indicating that reactive oxygen metabolites are not directly involved in lymphocyte-mediated cytolysis.

Stimulation of neutrophil respiratory burst and iodination reaction by opsonized microfilariae of Dirofilaria immitis

It has been shown that the interaction of Dirofilaria immitis microfilariae (Mf) opsonized with sera from infected but amicrofilaraemic dogs (occult dogs) stimulated the respiratory burst and degranulation of neutrophils as measured by chemiluminescence and iodination. Sera from normal and microfilaraemic dogs gave either low level or non-significant reactions. Since the sera required were also those required for neutrophil-mediated cytotoxicity to D. immitis Mf in vitro, the results suggested that the products of oxygen reduction as well as the myeloperoxidase system could be involved in the killing of Mf by neutrophils. However, whether these pathways have a major role to play in neutrophil-mediated cytotoxicity to Mf is uncertain, as various chemical and enzymatic inhibitors of the products of the respiratory burst were unable to prevent or reduce cytotoxicity. Azide, which is a known inhibitor of the iodination reaction, also failed to reduce cytotoxicity.

T lymphocyte lines from arthritic synovial fluid: establishment and function

T lymphocyte lines have been established, with the addition of interleukin-2 (IL-2), from the synovial fluid (SF) of patients with arthritis. Characterisation of seven of these SF-derived T cell lines showed them to be T3+, T11+, and to contain a significant proportion of T8+ cells (mean 41%). The proportion of T4+ cells varied among the lines, with a mean T4+/T8+ ratio of 0.6. A significant autologous mixed lymphocyte reaction (AMLR) was observed only in one of four T cell lines assayed. Two of four lines assayed showed natural killer (NK) cell-like activity, while one line displayed a significant suppressor activity, suggesting that the T cell population in SF contained NK-like cells or suppressor cells, or both, either of which may be selected in the establishment of SF-derived T cell lines.

The ability of microfilariae to evade in vitro cell-mediated cytotoxicity

When microfilariae (Mf) of Dirofilaria immitis, both uterine and systemic, were incubated in an in vitro cytotoxicity assay with neutrophils and sera from dogs with occult infections, some Mf remained free of adherent cells and consequently evaded cytotoxicity. The ability to evade cytotoxicity could not be related to the age of the Mf, and host albumin was not detected on any Mf, either uterine or systemic. However, it was shown that some Mf failed to bind IgM, IgG and C3 when incubated with occult sera. It is suggested that the ability of some Mf to evade serum-dependent, neutrophil-mediated cytotoxicity in vitro was related to differences in their antigenicity.

Regulation of the glucose phosphotransferase system in Brochothrix thermosphacta by membrane energization

Uptake of 2-deoxyglucose, alpha-methylglucopyranoside, and glucose into intact cells of Brochothrix thermosphacta (formerly Microbacterium thermosphactum, ATCC 11509) was stimulated by KCN or CCCP. The glucose analogs were recovered almost totally as the sugar phosphates. Membrane vesicles were isolated from protoplasts and shown to be right side out by freeze fracturing and by using ATPase as a marker for the cytoplasmic membrane surface. Uptake of glucose into vesicles was dependent on the presence of phosphoenolpyruvate. NADH oxidation, K+ -diffusion gradients, and externally directed lactate gradients (pH greater than 7 initially) were used to generate transmembrane potentials across membrane vesicles. Above a threshold value of about -50 mV, uptake of glucose into membrane vesicles was reduced. Likewise, the maximum uptake of glucose and its two analogs into cells occurred when the protonmotive force was less than about -50 mV.

T lymphocytes in infectious mononucleosis. I. T cell death in vitro

A large proportion of T lymphocytes isolated from the peripheral blood of acute infectious mononucleosis (IM) patients rapidly die when cultured in vitro, with greater than 50% dying within 12-15 h of seeding and up to 80% dying within 24 h. The cells die by apoptosis, a morphologically distinct mode of cell death that occurs in circumstances where death is a regulated event such as in embryonic development and hormone-dependent atrophy. In contrast, the level of cell death remained low in cultures of lymphocytes from controls and in the T cell depleted subpopulation from acute IM patients, with less than 2% and 10% of the lymphocytes dying by apoptosis after 36 h in culture, respectively. The rapid death of acute IM T cells in vitro does not involve soluble factors (including the serum fraction) or T cell to T cell contact. It is suggested that this observation may necessitate a re-evaluation of IM T cell function in vitro.

T lymphocytes in infectious mononucleosis. II. Response in vitro to interleukin-2 and establishment of T cell lines

The addition of 20% interleukin-2 (IL-2) significantly reduced the percentage of T lymphocytes dying in vitro after being isolated from the peripheral blood of acute infectious mononucleosis (IM) patients. Moreover, the immediate addition of 20% IL-2 to freshly isolated blood allowed IM T cell lines to be readily established from the peripheral blood of acute IM patients. Characterization of seven of these IM T cell lines showed them to be T3+, T11+, T4-, T9- and generally T10-. Over half of the lines characterized were T8+. It will now be possible to re-evaluate IM T cell effector functions as previous assays of IM T cell functions may have been influenced by the presence of rapid and extensive T cell death in vitro.

Apoptosis as the mode of cell death in antibody-dependent lymphocytotoxicity

A light and electron microscopic study of antibody-dependent lymphocytotoxicity was carried out with the object of elucidating the mechanisms responsible for the cell killing, the basis for the research being the relationship that has recently been shown to exist between the morphology of cell death and its pathogenesis. Chang liver cells coated with a rabbit anti-human antibody were used as targets and normal human peripheral-blood lymphocytes as effector cells. Cytotoxicity assays using release of 51Cr demonstrated extensive K-cell killing, thus validating the suitability of the model for morphological studies. Cell death displaying the features of apoptosis correlated with K-cell activity. A small amount of cell death by classical necrosis was observed, but its extent appeared to be unrelated to the presence of lymphocytes, to pre-treatment of the target cells with antibody, or to the magnitude of 51Cr release. The results support evidence indicating that lymphocytotoxicity depends on activation of a self-destruct program within the target cell. They do not favour a mechanism involving the production of plasma membrane lesions analogous to those responsible for complement-mediated immune cytolysis.

Potentiation of anchorage-independent colony formation by sodium polyanethol sulphonate

Sodium polyanethol sulphonate (SPS) when incorporated into rat erythrocyte lysate (REL) containing semi-solid agar medium at 1 mg ml-1. markedly enhanced colony formation by a number of anchorage-independent cell lines. REL usually needed to be included for the expression of SPS induced potentiation as in its absence SPS was generally cytotoxic. Studies suggested that SPS reduced the lag prior to colony initiation resulting in the earlier appearance of colonies and in a higher cloning efficiency. The effectiveness of SPS in potentiating colony formation by responsive cell lines was markedly influenced by the species of serum and to a lesser extent by differences between individual batches. Enhancement by SPS was greater with poorer foetal calf serum (FCS) batches than with better. This effect may have been partly due to SPS interfering with the action of a growth inhibiting serum component, possibly a lipoprotein. Studies in which delipidated FCS was substituted for normal FCS suggested that SPS was also able to compensate for the lack of a growth-promoting lipid component. Binding studies showed that initially 125I-SPS bound equally well at 4 degrees C and 37 degrees C with continued labelling occurring only at 37 degrees C. Autoradiography of cells labelled at 37 degrees C for 24 h revealed the presence of intracytoplasmic 125I-SPS.

Immunological and ultrastructural aspects of the cell-mediated killing of Dirofilaria immitis microfilariae

Neutrophils in the presence of serum from dogs with occult Dirofilaria immitis infections were shown to be cytotoxic to D. immitis microfilariae recovered from the blood of microfilaraemic dogs. This cytotoxicity was correlated with the presence of IgM and IgG antibodies on the cuticular surface of microfilariae incubated in the sera from occult dogs. Such antibodies were not observed on the surface of microfilariae incubated in sera from microfilaraemic or normal dogs. The neutrophil attack was directed at the cuticular crypts, at which sites the worms appeared to be structurally most vulnerable because of the absence of the outer layer of the cuticle. The IgM antibodies were shown to be bound preferentially to these sites. Our data suggested that the neutrophil-mediated toxicity involved both hydrogen peroxide release and degranulation.

Effects of hypoxia on the kinetic and morphological characteristics of human melanoma cells grown as colonies in semi-solid agar medium

An investigation was made of the cell populations that occur in the sequential strata of human melanoma ( MM96 ) colonies. Colonies were either grown for the full duration of culture in a 'physiological' atmosphere of 5% O2 (unperturbed colonies), or grown in this atmosphere followed by a final incubation in a hypoxic atmosphere of less than 0.1% O2. Both autoradiographic and ultrastructural studies indicated that cell changes similar to those which occur successively in monolayer cultures experiencing nutritional deficiency, exist concurrently in the sequential strata of the larger unperturbed colonies. At the margin with the necrotic core, approximately half of the cells showed morphological changes associated with death by apoptosis. The other half were undergoing necrosis. Observations on colonies incubated for the final 24 or 48 h in a hypoxic (less than 0.1% O2) atmosphere showed that many of these cells, although otherwise well preserved, developed oedema complicated by cytoskeletal rupture and extrusion of areas of damaged cytoplasm within membrane-bound vesicles. Although sudden-onset hypoxia did not appear to precipitate cell death in small colonies previously lacking a necrotic core, large colonies suffered a marked reduction in the width of their viable rims. Cell death under this circumstances was by necrosis, the same mode of death as occurs with infarction. The study indicated that apoptosis was associated with sub-acute cell death as occurs with progressive nutrient depletion and catabolite accumulation, whereas necrosis was associated with acute cell death as seen in previously compromised cells subject in addition to sudden-onset hypoxia.

The role of apoptosis in atrophy of the small gut mucosa produced by repeated administration of cytosine arabinoside

Progressive atrophy of ileal crypts and villi following daily administration of cytosine arabinoside to mice was found to be the result of suppression of mitosis and marked enhancement of apoptosis in the crypt epithelium. The amount of apoptosis produced by each dose decreased as the atrophy advanced. Mucosal regeneration after cessation of administration of the drug was due to increased mitosis in the crypts, and was associated with complete restoration of susceptibility of the crypt cells to further doses. During early regeneration, the wave of increased mitosis was accompanied by a wave of mildly increased apoptosis.

The role of natural killer cells in the intravascular death of intravenously injected murine tumour cells

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The effect of dietary restriction, adrenaline, hydrocortisone and surgery on the rates of death of 125IUdR-labelled, intravenously injected tumour cells in the lungs of mice

Dietary restriction, adrenaline hydrocortisone or surgery reduced the rate at which pulmonarily arrested 125IUdR-labelled murine tumour cells were lost within 7 h of intravenous (i.v.) injection. Mice that had been adrenalectomised 10 days previously showed a normal intrapulmonary tumour cell loss rate with further surgery reducing this rate to approximately half that observed in normal mice that had been subjected to surgery. Thus, although it is likely that adrenal hormones play an important role in decreasing the rate of early intrapulmonary tumour cell loss, additional factors must be implicated. Mice subject to dietary restriction, adrenaline, hydrocortisone or surgery had reduced levels of in vitro growth inhibitor(s) in their sera. Despite this, individual surgically treated animals showed no correlation between serum in vitro-growth inhibitor levels and rate of loss of i.v. injected tumour cells from the lungs. Furthermore, the 24 h pre-incubation of tumour cells in inhibitor-rich serum did not influence the subsequent loss rate of such cells following i.v. injection into mice. Electron microscopic studies indicated that dietary restriction, adrenaline and surgery reduced the rate of intravascular tumour cell death. The decreased tumour cell death rate in mice receiving these treatments could not be related, however, to any consistent morphological change in the pulmonary vasculature. The decreased rate of intravascular tumour cell death in treated mice was followed by an increased number of lung tumours with only one of the tumour lines studied, indicating that the intravascular death rate need not be a major determinant of pulmonary tumour incidence.

Biophysical and morphological correlates of kinetic change and death in a starved human melanoma cell line

An investigation was made of the sequential biophysical and morphological changes that occur as cultured human melanoma cells (MM96) outgrow their supply of nutrient. Simultaneous buoyant-density and velocity-sedimentation fractionation experiments were used to characterize cells from 3 kinetically differing types of culture. Cells from exponential cultures were large, moderately dense and rapidly sedimenting; cells from post-exponential cultures were of intermediate size, less dense and much more slowly sedimenting; and dye-excluding cells from reproductively non-viable late post-exponential cultures were small, of widely variable though generally high density and sedimented moderately rapidly. Although reproductive viability was high in cells from both exponential and post-exponential cultures, depletion of clonogenic cells was seen at the extremes of the distribution profiles of cells fractionated by either method. This was particularly evident at the low-density extreme of the buoyant-density profiles where cells retained viability despite their loss of proliferative potential. As cells became post-exponential, nuclear size diminished in parallel with cell size, the number of microvilli declined, mitochondria condensed, cytoplasm vacuolated, the frequency of osmiophilic vacuolar inclusions rose, chromatin clumped and nucleoli became prominent. Progression to a reproductively non-viable late post-exponential state resulted in a continued parallel fall in nuclear size, increased cytoplasmic blebbing, further mitochondrial condensation, an increased proportion of cytoplasmic vacuoles containing osmiophilic material, the major part of which was melanin, and further clumping and margination of chromatin. Cells progressed rapidly from this newly described pre-apoptotic state to death by apoptosis, a process characterized by the budding and division of cells into a number of ultrastructurally well-preserved membrane-bound fragments.

The effect of 125I-5-iodo-2'-deoxyuridine labelling on murine tumour cells

Labelling with 125IUdR at radioactivity concentrations commonly employed in studied with i.v. injected tumour cells (1.0-0.1 microCi/ml) was shown to reduce considerably the in vitro reproductive viability of mastocytoma tumour cells. Velocity sedimentation cell separation studies on mastocytoma cells that had been labelled for 12 h with 0.8 microCi/ml 125IUdR yielded a population that varied markedly between fraction with respect to distribution of label and, in parallel, with respect to induced loss of reproductive viability. A similar population of mastocytoma cells that had been labelled for 36 h with 0.01 microCi/ml 125IUdR yielded fractions where distribution of label was not associated with reduced reproductive viability. Although in vivo survival (as distinct from reproductive viability) of tumour cells injected i.v. and i.p. was not significantly altered within 7 h and 30 h respectively by the commonly used concentrations of 125IUdR, it is suggested that in studies of the fate of injected tumour cells exponentially growing cells be labelled with 125IUdR for intervals well in excess of population doubling times at concentrations less than or equal to 0.025 microCi/ml.

Non-immunological cell death of intravenously injected murine tumour cells

Most DBA mastocytoma and Sarcoma 180 cells trapped in the lungs of mice after i.v. injection died within 7 h. Rates of cell death were similar for both tumour cell lines. Rates of tumour cell death were unrelated to whether the cells were allogeneic or syngeneic, induced platelet aggregation or not, had different patterns of subsequent tumour growth, or were injected in varying numbers. Cell death was by coagulative necrosis, not apoptosis. Sarcoma 180 tumour cells were quickly localized in the lung and enclosed in platelet aggregates which remained, with degranulation, until the time of tumour cell death. However, platelet aggregation did not appear to play a role in tumour cell killing. The prevention of platelet aggregation by pretreatment of mice with an anticoagulant had little effect on the rate of death of tumour cells in the lung. Mastocytoma tumour cells did not cause platelet aggregation, yet died in the lung at similar rates to Sarcoma 180 cells. The killing of tumour cells in the lung did not appear to be cell-mediated. No mononuclear cells were seen in the vicinity of tumour cells and the type of cell death was not that associated with cell-mediated killing. The tumour cells did not die within 6 h of being injected into the peritoneal cavity. It is suggested that a nonspecific non-immunological process results in the death of intravenously injected tumour cells in the lung. This process was not affected by differing oxygen levels in the inhaled gas.