TPC NEWS Vol.15, No.2 Winter (Whole Number 26)

( English Summary)

Page- 3  Message from the director of the Tsukuba Primate Center for Medical Science(TPC) : Top-down and bottom-up    

                                                   Yasuhiro YOSHIKAWA

  For these three years, I have led a project funded by the Science and Technology Agency, “ Development of a system for behavior analysis of  nonhuman  primates using a neuro-computer,” (See, TPC NEWS  Vol. 14, No.24).  This project team consisted of  three different groups, a technological and physical group, which mainly developed hard and software for computers;  a human science group, which made behavioral and psychological analyses; and a biomedical group, which will use the system.

  Free discussion meetings were held once a month in Tsukuba to enable smooth communication and exchange information.  Twenty four meetings in total and three mini-symposia have been held so far.  Looking back, I can not help admiring the participants from such different fields for their enthusiastic discussions.  This is an advantage of being in Tsukuba, a science city where many scientists of various fields live.

Hot discussions on the strategy for system development always resulted in a competition between the methods of top-down and bottom-up processing.  It is natural that biologists use top-down processing instinctively.  On the contrary, the method of processing utilized in physical and technological fields,  particularly in the development of computer processing, is bottom-up.  In other words, the biologicals generalize from specific answers (deductive method), and the techno-physics extract from general answers (inductive method).

During the development of this system, great differences in the characteristics of humans and computers appeared.  As for information processing, humans, or rather living things, have adopted easy methods as much as possible during their evolution.  This is a primal strategy for them to survive and react in real time to surroundings being full of information.  This is the root of top-down thinking.  When humans, as well as animals, extract the characteristics of the subjects, they instinctively evaluate the characteristics.  For example, when we see another person’s face, we usually pay attention to the movements of the eyes and mouth, but don’t care about those of the nose, ears and hair.  On the other hand, since computers have no sense of evaluation like this, all movements or even all pixels have equal weight.

Information processing on pictures and images, which is processed mainly in our right brain, may not match today’s computers which are an extension of the algorithm of our left brain.  These three years made me realize how difficult it is to transfer what humans do naturally to computers, and that the bottom-up strategy needs much more time and effort than the top-down does.

Six years have passed since I became the director of the Tsukuba Primate Center.

I realize that I have applied both methods of  bottom-up and top-down to run this Center smoothly and to tackle the budget bureaucrats in Kasumigaseki, Tokyo.

I think the bottom-up method is democratic, and enables us to get the consensus of many people, although it takes much time.  However, it is impossible to get the agreement of all people, some complaints have to be ignored, and this method involves some risks of ending in a deadlock.  While, the top-down method needs no time, and progresses speedily, it tend to be one-sided or to fall in self-righteousness. The policy, “ Make people obey without giving them any information,” is one of the typical top-down methods.  This method would be bogged down when the leaders evade their responsibility and when information on the results is not open to the public.  It is essential when using the top-down method that results be made available to the public to enable feedback, and that the person in charge of the decision truly undertake truly his/her responsibility.

I think, the bottom-up method is, in general, suitable for ordinary times, on the contrary, the top-down is effective in emergencies.

Page-4  Research Project at the TPC: Nonhuman primate models for senile diseases

     V   A simple method for detecting visual function in cynomolgus monkeys

                                                           Michihiro SUZUKI

  A simple method for judging visual function in the cynomolgus monkey was designed.  The principle of this method is to examine whether a monkey watches the eyes of two observers who wear a face hood covered with a sheet of neutral density filter paper.   Thirty-eight normal monkeys and 6 monkeys with pathological findings in the optical system were examined by this method.   It was demonstrated that this simple method was very useful for a routine examination of visual function in the cynomolgus monkeys kept in a cage individually.

Page-9 

    VI   Studies of senile plaques in nonhuman primates

            Shinichiro NAKAMURA

  Senile plaques (SPs) and cerebral amyloid angiopathy (CAA), which are histopathological hallmarks in Alzheimer's disease (AD), were histopathologically examined in aged cynomolgus monkeys.  The SPs were classified into mature (neuritic) plaques and diffuse ones, being consistent with humans.  Mature plaques were more predominant than diffuse plaques.  They were often adjacent to capillary-CAA.  The mature plaques were frequently localized in the temporal lobes.  Immunohistochemically, SPs and CAA consisted of amyloid b protein (Ab).  All SPs were comprised of Ab42(43) and one-third of mature plaques consisted of Ab40.  On the other hand, capillary-CAA was mainly made of Ab42(43) and meningeal-CAA was made predominantly of Ab40.  Both SPs and CAA contained apolipoprotein E (apoE), alpha-1-antichymotripsin (aACT), but apoE was contained in half of the diffuse plaques, and no, aACT was detected in diffuse plaques. Swollen neurites of the mature plaques were contained with amyloid precursor protein, ubiquitin, and microtubule-associated protein-2.   Furthermore, astroglias and their processes rather than microglias reacted with the mature plaques.  Tau protein was not detected in either the SPs nor CAA.  Almost all the features resembled those of humans, but immunoreactivity to apoE, aACT and tau differed from that of humans.  Since not only Ab but also several co-factors may be important for the formation of SP and CAA, it is necessary to further study on differences between the co-factors in monkeys and humans.  This animal model will contribute to the pathogenesis of AD and cerebral amyloid deposition.

Page-13  Laboratory Tests: Western blot technique for detecting antibody to              simian retrovirus type D (SRV/D)

                                                         Koji FUJIMOTO

  Western blot is, in general, a more specific test for detection of antibody than enzyme-linked immunosorbent assay or indirect immunofluorescence test (IFA).  In this report, Western blot was used to test for serum antibody to SRV/D which is a causative agent of the simian acquired immunodeficiency syndrome (SAIDS).  The usefulness of this technique as a serological screening test for the virus infection was then evaluated. 

Positive control serum showed reactivity to viral proteins representing gag related p10-14, p22, p24, p27 and env related gp70 (Fig. 1).  The sera reacted to more than two distinct virus-related bands were judged as positive.

Of nine IFA positive macaque sera tested by the Western blot, two were positive, one was equivocal and six were negative (Fig. 2).  The six negative sera reacted with proteins of molecular weight exceeding 100kd which are thought to be contanimated cellular proteins during the process of virus purification. 

From this result, we have introduced the Western blot in the serological screening test for SRV/D infection in the macaque colony at the Tsukuba Primate Center.

Page-15  Case Report: Squamous cell carcinoma in the oral cavity in an infant cynomolgus monkey

                                                          Ippei SAKAKIBARA

Although a few cases of squamous cell carcinoma in the oral cavity have been reported in primates, this case report seems to be the first one involving a young cynomolgus monkey.

Case:

A male colony-bred cynomolgus monkey ( 1 year-old, born on June 10, 1994 ).

Swelling was seen in the left cheek and mandibuloar lymph node.

                                                          (June 9, 1995)

Biopsy on the gingival area indicated that carcinoma cells metastated in the lymph node.                                                      ( August 18, 1995)

Tumor mass in the left lower gingiva and inside the zygomatic arch was    exterpated .                                            (October 5, 1995)

Swelling was noticed again in the cheek.              ( November 20, 1995)

The animal was sacrificed.                           ( December 22,1996 )

                      *(See, Clinography, in the TPC NEWS Vol.15, No.2 )

Autopsy findings: The left eye protruded, the left cheek was very swollen.  A large block of squamous cell carcinoma infiltrated subcutaneous tissues of the cheek and  gingiva.  Osteolytic destruction was observed in the left side of the skull (Fig.1)

Histopathological findings: Squamous cell carcinoma in the subcutaneous tissue of the cheek is shown in Fig. 2.  Carcinoma cells proliferated in the dermis.  Intercellular bridge was seen evidently.  Cytoplasm dyed darkly.  Nuclei are round or egg shape, some of them were large and divided.  Nucleoli were evident.  Dysplasia was strong.  Cornification and cancer pearl were not seen (Fig.3).

The marginal and medullary sinuses in the mandibular lymph node were filled with metastatic carcinoma cells (Fig. 4).

According to immuno-histological staining (ABC method following the microwave pretreatment), keratins were seen but no vimentins.    

Page-16  Clinography:  Diarrhea in cynomolgus monkeys

                                                       Fumiko ONO

  Diarrhea is one of the most important problems when maintain cynomolgus  monkey colonies.

  At the TPC, diarrhea observed in cynomolgus monkeys is more frequent  and serious than that in squirrel and African green monkeys.   From July 1995 to June 1996, 24% of death in the cynomolgus monkeys were caused directly or indirectly by diarrhea.

  Fig. 1 shows the total number of cynomolgus monkeys with diarrhea by month.   The numbers increased around May when temperature and humidity become unstable.  At present, we have about 1,760 cynomolgus monkeys,  of which 52 monkeys (3%) on average, are suffering from diarrhea everyday.   Although many cases usually recover spontaneously within a few days, some  cases are chronic.  Treatment procedure for diarrhea at the TPC is as follows.

  We observe physical conditions of the monkeys every morning, inputting  the individual's findings into the computer database.  The monkeys suffering  continuously from diarrhea for more than 3 days and those under treatment for the past one month are picked up, and their data shown in a card form ( Table 1).

  Treatment courses are decided according to the data, treatment history, and  results of bacteriological and protozoological examination of the feces.  As a matter of course, infant and juvenile monkeys should be treated soon after the onset of diarrhea.  Usually we administrate mixed medicines containing bisumus nitrite, albumin tannate, pancreatin, yeast, lactobacillus, berberine, and aluminium silicate, etc. to the monkeys in the early stage of diarrhea.  In cases where there is no sign of recovery, the feces are re-examined, so that specific antibiotic therapy can be carried out.  However, in some cases causative pathogens still have not been identified.

  Campylobacter causes serious diarrhea in juvenile monkeys.  When diarrhea resulting from Campilobacter is found in group feeding monkeys, all monkeys in the same cage should undergo treatment.

  We are taking care to use low generation  anitibiotics to prevent the appearance of antibiotic-resistant bacteria.

Treatment of chronic diarrhea is difficult, however, we have to eliminate deaths from diarrhea by controlling the fecal conditions and utilizing the individual database, as well as searching for the causes.

Page-18  Topics: Prion diseases---Bovine spongiform encephalopathy (BSE)

   In these pages, Dr. Yoshikawa describes prion diseases, focusing on bovine spongiform encephalopathy (BSE).  He outlined the history of BSE outbreaks, background of the recent epidemics in the U. K, countermeasures taken by the British government, clinical and pathological characteristics, as well as the characteristics of BSE ‘s pathogens.

Page-21  Transmission of scrapie prion to squirrel monkeys

                                                               Fumiko ONO

   Four squirrel monkeys were exposed to scrapie prion protein isolated from the brain of the sheep that had developed spongiform encephalopathy in Japan.

   Supernatant of brain homogenate taken from sheep with scrapies was inoculated into two squirrel monkeys.  After four years, these squirrel monkeys hardly demonstrated significant alterations in behavior and showed neurological evidence of disease.

  On the other hand, evidence of disease was seen in two squirrel monkeys inoculated with brain homogenate from mice that had been inoculated with sheep scrapie.  Progressive neurological deterioration was observed, which included tremors, myoclonus and ataxia.  Behavioral deterioration in movement and feeding behavior were also observed approximately 33 months post inoculation.

   EEG analysis demonstrated, such as multiple abnormalities.  These included multiple spikes or flattened profiles to background activity.   Auditory brain stem responses (ABR) were slightly prolonged.  Visual evoked potentials (VEP) were indistinct or of low amplitude.

   On necropsy, histopathology revealed spongiform degeneration and glial reactions throughout the CNS.  Prion proteins could be identified in the brain by immunohistochemistry and by the Western blot analysis.  Our data suggests that the behavioral and neurological deterioration of the animals in this study were due to prion infection.  This model system will be useful for the study of the pathogenesis of prion disease. 

Page-24  Topics: Ebola-Reston virus infection among newly-imported cynomolgus monkeys in the U.S.A.

   Dr. Takasaka reports about the recent outbreak of Ebola-Reston virus infection among newly-imported cynomolgus monkeys in the USA, presenting the record of the outbreak by time.

Page- 25  Dual X-ray absorptiometry (DXA) demonstration in two monkey facilities in the Philippines

   Mr. Hiyaoka, reports on his visit to the Philippines to demonstrate how to use a dual X-ray absorptiometry (DXA). 

Page-27  Report of the Seminar ’96 by the Corporation for Production and Research of Laboratory Primates (CPRLP)

   Mr. Narita reports about the Seminar ’96 by the CPRLP, held on February 8, 1996, in Tsukuba.  Its theme was B virus.

Page-27  From: Primate Forum on PC-net

    The titles of an on-line series lecture on the TPC’s Primate Forum, “Zoonoses,” by Dr. Kazuya YAMANOUCHI are listed.  Fifty lectures have been up-loaded so far.