Tests to determine the responsiveness of free-ranging Japanese monkeys in food-getting situations

Experiments were performed on a free-ranging Japanese monkey troop (Arashiyama-B troop) in order to study the various levels of response caused by excitement and the characteristics of each monkey's action as observed under a series of stimulating situations carried out step by step through the giving of peanuts to the monkeys in various ways. The following results were obtained: (1) Three types of responses, that is, Threat response, Fear response, and Negative response were observed. (2) In response types, fairly evident individual differences exist along side sexual and age differences. (3) Similarity of response tendencies were not readily recognizable between a mother and her children. (4) Between two sisters with a slight disparity of age, the younger showed a stronger threat response. (5) Among females more than 4 years old, the lower the rank, the stronger the fear response.     

Up-regulation of the expressions of phospholipase A2 inhibitors in the liver of a venomous snake by its own venom phospholipase A2

Venomous snakes such as Gloydius brevicaudus have three distinct types of phospholipase A₂ inhibitors (PLIα, PLIβ, and PLIγ) in their blood so as to protect themselves from their own venom phospholipases A₂ (PLA₂s). Expressions of these PLIs in G. brevicaudus liver were found to be enhanced by the intramuscular injection of its own venom. The enhancement of gene expressions of PLIα and PLIβ in the liver was also found to be induced by acidic PLA₂ contained in this venom. Furthermore, these effects of acidic PLA₂ on gene expression of PLIs were shown to be unrelated to its enzymatic activity. These results suggest that these venomous snakes have developed the self-protective system against their own venom, by which the venom components up-regulate the expression of anti-venom proteins in their liver.     

Monocytes Infiltrate the Pancreas via the MCP-1/CCR2 Pathway and Differentiate into Stellate Cells

Recent studies have shown that monocytes possess pluripotent plasticity. We previously reported that monocytes could differentiate into hepatic stellate cells. Although stellate cells are also present in the pancreas, their origin remains unclear. An accumulation of enhanced green fluorescent protein (EGFP)⁺CD45^– cells was observed in the pancreases and livers of chimeric mice, which were transplanted with a single hematopoietic stem cell isolated from EGFP-transgenic mice and treated with carbon tetrachloride (CCl₄). Because the vast majority of EGFP⁺CD45^– cells in the pancreas expressed stellate cell-associated antigens such as vimentin, desmin, glial fibrillary acidic protein, procollagen-I, and α-smooth muscle actin, they were characterized as pancreatic stellate cells (PaSCs). EGFP⁺ PaSCs were also observed in CCl₄-treated mice adoptively transferred with monocytes but not with other cell lineages isolated from EGFP-transgenic mice. The expression of monocyte chemoattractant protein-1 (MCP-1) and angiotensin II (Ang II) increased in the pancreas of CCl₄-treated mice and their respective receptors, C-C chemokine receptor 2 (CCR2) and Ang II type 1 receptor (AT1R), were expressed on Ly6C^high monocytes isolated from EGFP-transgenic mice. We examined the effect of an AT1R antagonist, irbesartan, which is also a CCR2 antagonist, on the migration of monocytes into the pancreas. Monocytes migrated toward MCP-1 but not Ang II in vitro. Irbesartan inhibited not only their in vitro chemotaxis but also in vivo migration of adoptively transferred monocytes from peripheral blood into the pancreas. Irbesartan treatment significantly reduced the numbers of EGFP⁺F4/80⁺CCR2⁺ monocytic cells and EGFP⁺ PaSCs in the pancreas of CCl₄-treated chimeric mice receiving EGFP⁺ bone marrow cells. A specific CCR2 antagonist RS504393 inhibited the occurrence of EGFP⁺ PaSCs in injured mice. We propose that CCR2⁺ monocytes migrate into the pancreas possibly via the MCP-1/CCR2 pathway and give rise to PaSCs.     

One observed case of cannibalism among wild chimpanzees of the Mahale mountains

This paper presents a detailed report on the behavior of cannibalism observed in a group of wild chimpanzees of Western Tanzania for two days of January 13 and 14, 1977. This case differs from the other ones observed so far in that the adult males killed and ate an infant of their own group. Much interesting behavior was observed in the mother whose infant was eaten and the high-ranking males who killed and ate it.     

A lone male chimpanzee in the wild: The survivor of a disintegrated unit-group

K Group, originally one of the two major study groups of chimpanzees since 1965 in the Mahale Mountains National Park, western Tanzania, was almost extinct by 1983: at most seven individuals remained in the group at the beginning of 1983. K Group continued to exist for more than four years, but in 1987 a male was left alone at the age of 15 after all the other chimpanzees of the group emigrated or disappeared. Since then he has been observed sporadically for more than five years only within the former range of K Group, without having any contact with the many resident chimpanzees of the neighboring M Group, the other major study group. The present observations reconfirm the strong philopatric tendency of adult male chimpanzees.     

The acquisition of stone-tool use in captive chimpanzees

In order to investigate the acquisition of stone-tool use to crack nuts, experiments were conducted with five captive chimpanzees, employing combinations of trial-and-error, and three types of observation learning of varied difficulty. Two adults and one sub-adult succeeded in acquiring this behavior in the tests where tool use was demonstrated by the experimenter, or by a successful chimpanzee. Analysis of their behavior patterns showed the adults' and sub-adult's process to success to be divided into three stages; these can be characterized as trial-and-error, understanding of the method, and learning the technique, respectively. A factor for distinguishing success from failure is whether or not a subject observes demonstrations with interest in the behavior itself. This interest, in turn, depends on the intensity of the desire for nuts. When released, the successful chimpanzees practiced the same behavior in a group of chimpanzees, and the behavior newly diffused to an infant. Unlike the adults, the infant did not go through the staged process but reached the solution through goal-directed trial-and-error.     

Brain Damage in Commercial Breath-Hold Divers

Background

Acute decompression illness (DCI) involving the brain (Cerebral DCI) is one of the most serious forms of diving-related injuries which may leave residual brain damage. Cerebral DCI occurs in compressed air and in breath-hold divers, likewise. We conducted this study to investigate whether long-term breath-hold divers who may be exposed to repeated symptomatic and asymptomatic brain injuries, show brain damage on magnetic resonance imaging (MRI).

Subjects and Methods

Our study subjects were 12 commercial breath-hold divers (Ama) with long histories of diving work in a district of Japan. We obtained information on their diving practices and the presence or absence of medical problems, especially DCI events. All participants were examined with MRI to determine the prevalence of brain lesions.

Results

Out of 12 Ama divers (mean age: 54.9±5.1 years), four had histories of cerebral DCI events, and 11 divers demonstrated ischemic lesions of the brain on MRI studies. The lesions were situated in the cortical and/or subcortical area (9 cases), white matters (4 cases), the basal ganglia (4 cases), and the thalamus (1 case). Subdural fluid collections were seen in 2 cases.

Conclusion

These results suggest that commercial breath-hold divers are at a risk of clinical or subclinical brain injury which may affect the long-term neuropsychological health of divers.     

Human auditory brain stem response during induced hyperthermia

A continuous monitoring of auditory brain stem response (ABR) and esophageal (Tes) and rectal temperatures (Tre) were recorded in male undergraduate subjects to investigate a relationship between the interpeak latencies (IPLs) and core temperature. The average change of Tes (36.8-39.5 degrees C) was achieved by immersing the subjects in a temperature-controlled water bath (30-42 degrees C). The IPLs became shorter with the rise in body temperature and were correlated with both Tes and Tre. The average slopes for IPL(I-III) and IPL(I-V) were significantly higher than those for IPL(III-V). The present study of humans indicated that changes of IPL(I-III) and IPL(I-V) were 0.11 and 0.16 ms, respectively, per 1 degree C change in core temperature during induced hyperthermia.