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A S Griffin

Publications and source records attributed to A S Griffin.

12 recordsLinked to original sources
PubMed2004

Social learning about predators: a review and prospectus.

In comparison with social learning about food, social learning about predators has received little attention. Yet such research is of potential interest to students of animal cognition and conservation biologists. I summarize evidence for social learning about predators by fish, birds, eutherian mammals, and marsupials. I consider the proposal that this phenomenon is a case of S-S classical conditioning and suggest that evolution may have modified some of the properties of learning to accommodate for the requirements of learning socially about danger. I discuss some between-species differences in the properties of socially acquired predator avoidance and suggest that learning may be faster and more robust in species in which alarm behavior reliably predicts high predatory threat. Finally, I highlight how studies of socially acquired predator avoidance can inform the design of prerelease antipredator training programs for endangered species.

Adaptation, Psychological↗
PubMed2001

Testing Hamilton's rule with competition between relatives.

Hamilton's theory of kin selection suggests that individuals should show less aggression, and more altruism, towards closer kin. Recent theoretical work has, however, suggested that competition between relatives can counteract kin selection for altruism. Unfortunately, factors that tend to increase the average relatedness of interacting individuals--such as limited dispersal--also tend to increase the amount of competition between relatives. Therefore, in most natural systems, the conflicting influences of increased competition and increased relatedness are confounded, limiting attempts to test theory. Fig wasp taxa exhibit varying levels of aggression among non-dispersing males that show a range of average relatedness levels. Thus, across species, the effects of relatedness and competition between relatives can be separated. Here we report that--contrary to Hamilton's original prediction but in agreement with recent theory--the level of fighting between males shows no correlation with the estimated relatedness of interacting males, but is negatively correlated with future mating opportunities.

Animals↗
PubMed2001

Expectant management of prostate cancer.

OBJECTIVES: To discuss the role of expectant management in the treatment of clinically localized prostate cancer. DATA SOURCES: Published research and review articles, textbooks, and pending research publications. CONCLUSIONS: Expectant management is a viable option for the treatment of clinically localized prostate cancer in carefully selected men. IMPLICATIONS FOR NURSING PRACTICE: Nursing personnel along with physicians must work together to develop coping strategies for these men to deal with the continual uncertainty of this treatment program.

Decision Making↗
PubMed2000

Individual contributions to babysitting in a cooperative mongoose, Suricata suricatta.

Evolutionary explanations of cooperative breeding based on kin selection have predicted that the individual contributions made by different helpers to rearing young should be correlated with their degree of kinship to the litter or brood they are raising. In the cooperative mongoose or meerkat, Suricata suricatta, helpers babysit pups at the natal burrow for the first month of pup life and frequent babysitters suffer substantial weight losses over the period of babysitting. Large differences in contributions exist between helpers, which are correlated with their age, sex and weight but not with their kinship to the young they are raising. Provision of food to some group members raises the contributions of individuals to babysitting. We discuss the implications of these results for evolutionary explanations of cooperative behaviour.

Animals↗
PubMed1999

Selfish sentinels in cooperative mammals.

Like humans engaged in risky activities, group members of some animal societies take turns acting as sentinels. Explanations of the evolution of sentinel behavior have frequently relied on kin selection or reciprocal altruism, but recent models suggest that guarding may be an individual's optimal activity once its stomach is full if no other animal is on guard. This paper provides support for this last explanation by showing that, in groups of meerkats (Suricata suricatta), animals guard from safe sites, and solitary individuals as well as group members spend part of their time on guard. Though individuals seldom take successive guarding bouts, there is no regular rota, and the provision of food increases contributions to guarding and reduces the latency between bouts by the same individual.

Animals↗
PubMed1990

Frenular chordee: implications and treatment.

Twenty of 75 male children undergoing elective circumcision demonstrated a ventral glandular chordee produced by an unusually prominent frenulum. Surgical incision of this prominent band of tissue relaxed the glandular traction (chordee), more adequately exposing the ventral inner prepuce, facilitating skin incisions, and permitting an improved cosmetic and functional outcome.

Child, Preschool↗
PubMed1989

Effect of acoustic shock waves on clonogenic growth and drug sensitivity of human tumor cells in vitro.

Focused acoustic shock waves were studied for their effects on human tumor cell viability, clonogenicity, and sensitivity to chemotherapeutic agents. The elastic shock waves used in this investigation were generated with the Dornier HM3-Lithotripter by underwater spark discharge with fixed electrical parameters employing a voltage of 18 kV and a capacitance of 80 nanoFarads. These waves are characterized by a fast varying compression phase, strong asymmetrical pressure and tension phases, and a maximum amplitude of roughly 10(8) Pascal (kg.m-1 s-2). Doses as high as 2000 focused shocks showed little effect on the viability of two different cell lines. There was, however, a dose dependent inhibition of tumor cell proliferation as determined by the growth of clones in soft agarose. Each of the two cell lines showed a unique degree of colony inhibition by shock waves. It was demonstrated that shock wave effects resulted from elastic shock wave interaction with the cells and were not caused by the emission of ultraviolet light coincident with shock wave generation. Shocks were applied at a rate of 100 minute-1 in a 200 l. water bath, thereby removing the possibility for temperature changes during treatments. After treatment with shock waves it was found that tumor cells became more sensitive to growth inhibition by chemotherapeutic agents. Cisplatin, doxorubicin, and 4-hydroperoxycyclophosphamide were each more effective in blocking cell growth after the target cells had been treated with acoustic shocks. Enhanced efficacies ranged from three to 10-fold potentiation of colony inhibition. These results indicate that weak shock waves, which can be focused to a defined target region, may have utility as a cancer treatment modality either alone or in combination with cytotoxic agents.

Acoustic Stimulation↗
PubMed1989

Effects of shock waves on the rat ovary.

The studies reported in this paper were undertaken to investigate the effect of shock waves on ovarian function. In an initial study, five female Wistar rats underwent general anesthesia. One ovary was then exposed to 1500 shock waves at 20 kV using the Dornier XL-1 experimental lithotripter. One week following this treatment, the animals were sacrificed and both ovaries were step sectioned. We counted all follicles that contained both an oocyte and antrum. These follicles in turn were classified further as being healthy or atretic. No statistical difference in these counts was observed between shocked and unshocked ovaries taken from the same animal. In the definitive study, thirty-one adult female Wistar rats underwent unilateral oophorectomy. These rats were then divided into treated, sham-treated and control groups. The eleven treated animals were given general anesthesia and received 1500 shocks at 15 kV directed at their remaining ovary using the Dornier XL-1 lithotripter. The ten sham treated animals received identical anesthesia and duration of waterbath immersion as the treated group. In contrast, however, sham treated animals were positioned outside the path of the focused shock wave. The control group received no treatment. Normal estrus cycle was maintained in all groups following shock wave exposure. Two weeks after this exposure, all three groups of animals were allowed to mate. All animals in each of the three groups became pregnant. There was no statistical difference in litter size or fetal weights at three weeks gestation. No gross teratogenic effects were observed. The rat ovary appears to be structurally and functionally resistant to the shock wave energy levels used in this experiment.

Animals↗
PubMed1987

Primary leiomyosarcoma of the inferior vena cava: a case report and review of the literature.

Sixty-six cases of leiomyosarcoma of the inferior vena cava (IVC) have been reported. We present another case and review the characteristics and treatment of this rare tumor. IVC leiomyosarcomas spread by extension into adjacent tissue planes. Direct extension into the heart is known, but not into the kidneys, adrenals, or bowel. IVC leiomyosarcomas arising below the renal vein cause pain in the right-lower quadrant, back, and flank, and varying degrees of lower extremity edema; those arising in the middle caval segment cause right-upper-quadrant pain and sometimes renovascular hypertension; those arising above the hepatic vein cause varying manifestations of the Budd-Chiari syndrome. A reasonable approach to early diagnosis involves oral and intravenous contrast studies followed by computed tomography, angiography, and vena cavography. Aggressive surgical treatment is optimal in light of the tumor's slow growth pattern and relatively low malignant potential. (Metastases have been reported in fewer than 50% of cases). Tumors involving the lower IVC are most amenable to surgery; extensive collateral venous drainage of the left kidney preserves renal function during resection of middle caval tumors. Upper caval leiomyosarcomas are the least amenable to complete removal. Postoperative survival of all patients has ranged from a few weeks to eight years.

Humans↗