In 1958, Binford claimed the successful transmission of M. leprae into the hamster. This work has since been confirmed by Convit et al, Waters et al and Burcart et al.
Therefore, we have investigated the multiplication of M leprae in the golden hamster food-pad using materials of the passages (isolated by ourselves) and a lepromatous patient (fresh strain). Futhermore, we have tested comparison of differences in the multiplication rate, sex in the hamster and the mouse, and the enhancing effect of cortisone in the hamster alone.
The inoculum was approximately ⁴ per each foot-pad, and the experimental methods were much the same as those reported for mice. Cortisone was given intramuscularly into each hind leg of the hamsters in the daily dosage of 7.0mg for every 6 days, at the first or at 17th day and 11th week after the inoculation.
First passage in the hamster (i.e. fresh strain to hamster and mouse passage to hamster inoculation): the material examined at 5-40 week after the inoculation with fresh strain and mouse passage showed the counts of acid-fast bacilli similar to those seen in the mouse foot-pad at late stadium, but the number of M leprae in the hamster was greater than that in the mouse at an early stage (approximately 20th week) after theinoculation.
Second passage (i.e. hamster to hamster and hamster to mouse inoculation): the material examined at 24th week after the transmission with the first passage in hamster showed the counts of acid-fast bacilli similar to those of the passage. An attempt to cultivate the bacilli in Ogawa's medium gives negative result. In the case of the inoculation with M lepraemurium into the hamster foot-pad, the sites of inoculation produced the nodular swelling with the inocula of different sizes growing to a swelling of between 7.5×10⁸ and 5.0×10⁵ bacilli per foot-pad. The details are shown in Table 3.
In addition, the number of M. leprae was occasionally greater in the male mouse than in the female, while it was less in the male hamster than in the female, the resultsbeing similar to those seen in thymectomized hamster and mouse, as reported elsewhere.
The number of M. leprae in the hamster foot-pad rose to a plateau level of approximately 10⁶ bacilli. Therefore, they showed that it was in fact possible under these conditions to produce a limited multiplication resembling those in the mouse foot-pads. On the other hand, the number of bacilli in the cortisone-administered hamster rose to a plateau level at an early stage after the inoculation, the fact also being similar to that of the mouse, as described elsewhere.

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The incipient signs of 247 leprosy patients were investigated in Miyako Nanseien Leprosarium. The results were shown as four tables and they are summarized as follows:
(1) There are few lepromatous cases and many non-lepromatous cases in comparison with leprosaria in the interior of Japan.
(2) The average age of patients is younger than leprosaria in the interior of Japan.
(3) The most cases were attacked with leprosy in teens, and next many cases were suffering from leprosy under ten years old.
(4) The most incipient sign was flat, hypesthetic and hypopigmentated patch, and there were only a few cases to be attacked with lepromatous lesions as incipient signs.
(5) The incipient signs attacked on face, lower limb, upper limb, buttock and trunk in order.

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Factors affecting elongation of Myc. lepraemurium in vitro were investigated by slide culture method, and the following results were obtained:
It was reconfirmed that the most important factor influencing elongation of the bacilli in vitro was acid (pH6.0) in the culture fluid. Bovine serum was the best stimulator of elongation and glycerine as well as sucrose also enhanced elongation of the bacilli. Among the substrates of the Krebs cycle tested, 1-malic stimulated the elongation phenomenon. Among the metabolic inhibitors employed, malonate only did not inhibit elongation of the bacilli. From these results obtained, it might be presumed that the Krebs cycle would be needed for the elongation phenomenon, but probably there were some other pathways beyond the original cycle. Inhibitions of elongation by antibiotics were the same as the results of animal experiments. Finally, the log phase of elongation of the bacilli were between three and six days after incubation.

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Charcot-like changes in leprosy patient are mostly observed on foot and ankle, but rarely on other joints.
It was clinically observed that of 38 cases, 3 cases had the destruction of the whole tarsal bones, 19 cases on ankle, 4 cases on subtalar joints, 8 cases on Chopart's joint and 4 cases on Lisfranc's joint.
Charcot-like changes of ankle may be caused by repeated sprain. Clinical finding shows swelling, lateral instability and pes varus deformity of ankle.
The sclerosis, deformity of the tarsal bones and loose bodies in ankle are roentogenologically noted.
Proliferating bone changes are rare and the arthicular surface of the tibia is not damaged.
In Chopart's and subtalar joints, the condition begins with warmness and swelling without any cause.
The stability of the foot is kept well, though roentogenogram shows the destruction of navicular bone and calcaneum.
In Lisfranc's joint, the destruction of cuboid bone, caused by sprain, occurs, but may result in only pes valgus and planus deformity and stability of foot is kept well.

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Comparative observations were made of the susceptibility of various inbred mouse strains (DDD, C3H, C57BL/6, BALB/C, CF#1, CFW, RR, A, NC, SS, KK and fm) to hind foot pad infection with leprosy bacilli (N-ANETa strain, originally isolated by Shepard) under the same dietary and environmental conditions.
There were no remarkable differences, such as observed in response to subcutaneous infection with murine leprosy bacilli, in the susceptibility among these strains. Pattyn examined the multiplication of leprosy bacilli in foot pads of 5 strains of mice, and reported that some differences appeared among the experimental animals, but he interpreted that these differences were due to small differences in the original inoculum size. This claim is generally accepted in our experiments. However significant but slight differences were verified by the following results.
1) Multiplication of acid fast bacilli in the foot pads was much slower in DDD mice than in the others.
2) In KK mice the multiplication of the bacilli occurred earlier and greater yields of the bacilli were harvested from the foot pads compared with the other mice.
3) Mice of the C57BL/6 strain showed earlier multiplication but lower yields of the bacilli than the others.

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[in Japanese]

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