Histopathological changes in digits of dairy cows affected with sole ulcers

Forty-eight digits of 8 dairy cows, which had been diagnosed as sole ulcers in one or two hooves, were examined histopathologically and classified into 5 grades on the basis of the severity of the circulatory disturbances and of keratogenesis. All the cows had significantly higher grades than normal cows. Although hind lateral digits were most severely damaged, there were no significant differences in the grades among claw positions except hind lateral digits. From these results, it is suggested that the cows affected with sole ulcers had some systemic factors predisposing all the digits to digital disorders.

Construction of high-resolution physical maps from yeast artificial chromosomes using restriction landmark genomic scanning (RLGS)

We have established a new system for chromosome-specific yeast artificial chromosome (YAC) contig construction using restriction landmark genomic scanning (RLGS-based YAC contig mapper). RLGS is a powerful tool for detecting more than 1000 restriction landmarks distributed on an entire genome in one procedure. In this system, RLGS is applied to sorted chromosomes to cover the target chromosome. Using these landmarks as guideposts, chromosome-specific YAC clones are then ordered. In this paper, we report the construction of a map for a human chromosome 21 YAC contig spanning q22.1 using this new approach. Applying RLGS to sorted chromosomes 21 enables detection of approximately 1400 spots (equivalent of 1050 PacI landmarks), covering the entire region of this chromosome. We constructed the 2.5-Mb YAC contig encompassing 21q22.1 with 66 spots (equivalent of 50 PacI landmarks). With this contig map, we could detect two deleted regions and chimerism in the YAC insert DNA. Our results demonstrated the usefulness of this approach for finding DNA alterations of YACs, such as deletions and chimerism.

Amitriptyline inhibits the G protein and K+ channel in the cloned thyroid cell line

We have reported that thyroid K+ channel is activated by extracellular application of the thyroid-stimulating hormone (TSH) using single channel recording method performed on cloned normal rat thyroid cell (FRTL-5) membrane. Treatment of dibutyryladenosine cyclic monophosphate (Bt2 cAMP) also activated the TSH-dependent K+ channel. These findings indicate that the thyroid K+ channel is activated through the TSH-adenosine cyclic monophosphate (cAMP)-protein kinase A system. We examined the effects of amitriptyline on TSH-guanosine triphosphate binding protein (G protein)-adenylate cyclase-cAMP-K+ channel system in the cloned normal rat thyroid cell line FRTL-5. Amitriptyline inhibited the cAMP production induced by TSH. Amitriptyline also inhibited the cAMP production induced by cholera toxin, indicating that amitriptyline inhibited the thyroid G protein. Amitriptyline had no effect on TSH-receptor binding and cAMP production by forskolin (adenylate cyclase stimulator). Amitriptyline inhibited the K+ channel activation by cAMP, indicating that the suppressing mechanism is not the inhibition of TSH receptor or G protein but the direct suppression of K+ channel. It was concluded that amitriptyline inhibited the thyroid G protein and K+ channel.

Antitumor activity of natural-type human tumor necrosis factor on experimental brain tumors in rats

The effects of intralesional injection of newly synthesized natural-type human tumor necrosis factor (nh-TNF) on experimental brain tumors in rats were investigated. The repeated injection of 5,000 U of nh-TNF into the tumor resulted in the prolongation of the survival time of the rats. More than half of the nh-TNF treated tumors were red, and were characterized by histopathological features of marked congestion of tumor vessels. Fibrin formations were also found in the tumor vessels. These histological findings were not observed in the control tumors. Furthermore, coagulative necrosis was observed in the center of some reddish tumors. Leukocytes adhering to vascular endothelium and infiltration of the leukocytes were also observed in the tumors of nh-TNF treated rats. In the immunohistochemical examination, these infiltrated cells were primarily polymorphonuclear leukocytes and macrophages. Expression of intercellular adhesion molecule-1 (ICAM-1) increased on the tumor endothelial cells after the administration of nh-TNF. These results suggest that repeated injection of nh-TNF has a therapeutic effect on brain tumors through its extensive influences on tumor vasculature.

[Two cases of pseudomyxoma peritonei that responded to intraperitoneal administrations of a combined CDDP, 5-FU and MMC therapy]

Pseudomyxoma peritonei, which is the seeding of the peritoneum by mucin-secreting metastatic deposits and the filling of the peritoneal cavity by these secretions, is a malignancy that even after excision of the metastatic areas has a poor prognosis, since no effective therapy has yet been established. Herein, we report two cases of pseudomyxoma peritonei that responded to a combined postsurgical therapy consisting of CDDP, 5-FU and MMC. Case 1 involved a 56-year-old woman who underwent an appendectomy, a bilateral ovariectomy, and an omentectomy, due to pseudomyxoma peritonei. Further, a subcutaneous implant-type reservoir was sited intraperitoneally for postoperative chemotherapy. At 30 days after surgery, therapy commenced, consisting of 100 mg of CDDP and 20 mg of MMC administered intraperitoneally and 1,000 mg of 5-FU continuously infused by intravenous drip. This combined therapy was given for 5 days and repeated 8 times. As a result, the serum CEA value, which had elevated postoperatively, fell within the respective normal range, and at 4 years postoperatively, this patient remains alive. Case 2 concerns a 59-year-old woman who underwent an appendectomy, a right ovariectomy, and an omentectomy due to pseudomyxoma peritonei, and was postoperatively given 50 mg intraperitoneal administration of CDDP. She received 2 courses of postoperative chemotherapy similar to that given case 1 but with the addition of a 500 mg 5-FU intraperitoneally. At 8 months postoperatively, she is alive and disease-free. Given the above results, intraperitoneal administrations of this combined CDDP-5-FU-MMC therapy may be effective for patients with pseudomyxoma peritonei.

Syringomyelia and hydrocephalus in a dog

A 7-year-old spayed female Pomeranian with a 6-month history of progressive paraparesis was determined to have syringomyelia accompanied with hydrocephalus. Magnetic resonance imaging clearly revealed severe syringomyelia in the cervical portion of the spinal cord, which was directly connected to the marked dilated fourth ventricle. Acetazolamide was prescribed for 3 weeks, but the neurologic deficits progressed. Laminectomy of the first and second vertebrae, which is one method of treating this type of syringomyelia in human beings, was performed, and then, acetazolamide was continued. The dog had partial amelioration, and further deterioration was not evident in the 12 months after surgery.

[Congenital cholesteatomas in Japanese--forty from our experience and fifty-five from a survey of the Japanese literature]

To determine the locations of congenital cholesteatomas and to elucidate the relationship between ossicular anomalies and congenital cholesteatomas, cholesteatomas from our patients and those reported in the Japanese literature were investigated. We analyzed 40 ears with congenital cholesteatomas (38 patients) experienced by us during the past 9 years. Our criteria of congenital cholesteatoma were as follows: 1. The tympanic membrane manifests neither retraction, perforation, nor granulation, 2. There is no continuity between the tympanic membrane and the matrix of a cholesteatoma. Twenty patients with past histories of otitis media were included. Thirty-three patients (87%) were males and 2 had bilateral congenital cholesteatomas. The ages of the patients ranged from 2 to 46 years (mean: 10.7). A survey of the Japanese literature revealed 55 additional cases of congenital cholesteatoma reported by others.

Elongation mechanism of collagen fibrils and force-strain relations of tendon at each level of structural hierarchy

Tension-induced structural changes in bovine Achilles tendon collagen at each level of the hierarchy structure were investigated by means of the X-ray diffraction method. In order to estimate the straining mechanism in a collagen fibril, three elementary models for molecular elongation and rearrangement of collagen fibril were proposed on the basis of the Hodge-Petruska model: [1] molecular elongation, [2] increase in gap region and [3] relative slippage of laterally adjoining molecules. The characteristic 67 nm D-period of a collagen fibril increases with applied force. A Hookean-type force-strain curve was obtained for the D-period while the force-strain relation for the tendon was non-Hookean. The relative intensity of third-order reflection of the D-period to that of the second-order one, I3/I2, decreased with the applied force. This decrease in I3/I2 indicates a decrease in the ratio of the overlap region of collagen fibril to the D-period, O/D, which was analyzed on the basis of the Hodge-Petruska model. Decomposition of the observed strain in the D-period, epsilon(D), into these three deforming modes revealed that the major contribution to epsilon(D) originated from mode [1], molecular elongation. It was deduced that a fibril is mechanically composed of molecules connected serially to each other.

Five candidate genes for hamster cardiomyopathy did not map to the cardiomyopathy locus by FISH analysis

The Syrian cardiomyopathic hamster (BIO14.6), that develops both muscular dystrophy and progressive cardiomyopathy, is widely used as an animal model of autosomal recessive cardiomyopathy mimicking human hypertrophic cardiomyopathy, and five genes have been proposed as strong candidates for the cause of cardiomyopathy. We recently mapped the cardiomyopathy locus of the hamster to the centromeric region of chromosome 9qa2.1-b1 by construction of a genetic linkage map of the Syrian hamster. Thus, we analyzed the loci of the five candidate genes, alpha tropomyosin, cardiac troponin T, adhalin, calpain 3 and cardiac myosin binding protein-C, by the FISH method, and found that these genes were mapped on the distal portion of chromosome 12qa5 and 4pa2 and the proximal portion of chromosomes 9qb7, 1qc1.1 and 1qb3, respectively. These results provide strong evidence that the five candidate genes previously proposed are not related to the hamster cardiomyopathy.

Prognosis of malignant mammary tumor in 53 cats

Medical records of fifty-three cats diagnosed as malignant mammary tumor from 1982 to 1993 were reviewed. The mean age of the cats at diagnosis was 11.1 years, and Japanese domestic and Siamese breeds were predominant. Survival rates after 1 and 2 years of diagnosis were 31.8% and 17.7%, respectively, suggesting poor prognosis of this malignancy. The survival time was significantly associated with tumor size or WHO clinical stage, but not with breed, age, or gender. Twenty-nine cats with pulmonary metastasis died within 5 months following metastatic detection. Postoperative prognosis was significantly related to the tumor size at surgery, but not with type of surgery and adjuvant chemotherapy using cyclophosphamide and/or vincristine.

[Assay of specific anti-Chlamydia pneumoniae antibodies by ELISA method. 2. studies on clinical usefulness and serological diagnostic standards]

We measured anti-Chlamydia pneumoniae (C. pneumoniae) specific antibody titers by means of a newly-developed enzyme-linked immunosorbent assay (ELISA) method using an anti-C. pneumoniae specific antibody detection reagent. The clinical usefulness of this method was hereby evaluated. The IgG, IgA and IgM titers in 418 serum specimens obtained from patients with respiratory tract infections were measured by this new ELISA method, and the results were compared with the titers determined for the same specimens with the micro immunofluorescence (Micro-IF) method. The results showed good correlation coefficients for IgG, IgA and IgM. The two assay methods showed high agreement rates for positivity and for negativity. Specimens which did not yield the same results with the ELISA method and the Micro-IF method were subjected to analysis by the Western blot method, and the rates of agreement with the ELISA results were high. In addition, the child (0 approximately 15 yrs old; n = 122) and adult (16 approximately 90 yrs old; n = 133) cases were classified on the basis of being antigen-positive or antigen-negative at the initial examination, and their antibody-positive rates were determined. The adults showed no statistically significant differences in the antibody-positive rates for either IgG or IgA antibodies as a function of the pretreatment antigen status. However, the children showed statistically significant (p < 0.001) differences in the antibody-positive rates for both IgG and IgA antibodies as a function of the antigen status in the antigen-positive group compared with the rates in the antigen-negative group. Furthermore, the IgM-positive rates for the children were high in the antigen-positive group compared with the rates in the antigen-negative group, and the difference was statistically significant (p < 0.001). The IgM-positive rates in the adults were also significantly (p < 0.05) different between the antigen-positive group and the antigen-negative group. The Micro-IF method was applied to 34 specimens from antigen-positive patients, and 22 specimens were found to show an IgG titer of > or = 512 or an IgM titer of > or = 16. The diagnoses of these patients were acute respiratory disease in sixteen, pneumonia in four. Application of the ELISA-method to those 22 specimens showed all of them to exhibit IgG absorbance of > or = 0.6 and IgA absorbance of 0.2. The results described above indicate the clinical usefulness of our new ELISA method for the detection of antibodies specific for C. pneumoniae. The significance of this ELISA method for serological diagnosis of C. pneumoniae infections and the criteria for diagnosis of acute infections were also discussed.

Dysfunction of the Orleans reeler gene arising from exon skipping due to transposition of a full-length copy of an active L1 sequence into the skipped exon

We examined the genomic structure of the reeler gene in Orleans reeler mouse mutant. Exon skipping of the reeler gene caused a 220 bp deletion in the transcript, resulting in a frame shift of the reeler gene which disrupts the 8th EGF-like motif of the reeler product. Surprisingly, the skipped exon was inserted by the 7104 bp L1 element which carried the full-length stretch of the mouse L1 sequence, consisting of a 212 bp F-type tandem repeat, open reading frame 1 (ORF1), ORF2, the polyadenylation signal and a poly A stretch. The transposed L1 sequence was flanked by 13 bp of the target sequence at both ends. ORF1 and ORF2 of this L1 repeat element are thought to encode a component of the RNP particle and the reverse transcriptase, respectively. Orleans reeler was originally established by spontaneous mutation caused by L1 insertion, and this L1 sequence is considered to be potentially active for transposition in mouse genome.

[A case of Nothnagel syndrome]

A 72-year-old woman developed a sudden onset of bilateral ptosis, diplopia and gait disturbance. Neurological examination revealed bilateral oculomotor palsies, truncal ataxia, and transient slight weakness in the right upper extremity. She was diagnosed to have Nothnagel syndrome. T2-weighted MRI disclosed a high signal intensity lesion at the left paracentral portion of the upper midbrain in addition to the bilateral medial thalamic lesions, while brain CT showed only the thalamic lesions. Brain MRI was useful for detecting the small midbrain lesion.

Mechanism of nonlinear responses of taste cells to mixed tastes

Coupling between ionic flows through different kinds of channels affects essentially the responses of multisensitive taste cells to single- and mixed-taste stimuli. The mechanism of taste transduction is studied by using a realistic model of the multisensitive cells of the rat. The transduction pathways considered are amiloride-sensitive Na+ channels for NaCl and HCl and adenosine 3',5'-cyclic monophosphate-mediating K+ channels for sucrose. Contributions of paracellular pathways and taste-insensitive ionic channels are also studied. The calculated responses of various multisensitive cells induced by single stimuli of NaCl, HCl, or sucrose reproduce experimentally observed responses as well. The two main conclusions are as follows. 1) Whether the response of a cell to a binary mixture becomes synergetic or antagonistic can be estimated from the individual responses of the cell to each component of the mixture. 2) Whether the response is enhanced or suppressed by addition of a new taste to the original taste can be determined, for most receptive cells, from a viewpoint of linear superposition of the individual responses.

Peripheral cortisol levels throughout gestation in the cow: effect of stage of gestation and foetal number

This study characterized the peripheral plasma cortisol profile throughout gestation and examined the effect of stage of gestation and foetal number in Holstein cows after non-surgical embryo transfer. Cows (n = 10) were divided into two groups: Group 1 = single embryo recipient cows (n = 5); and group 2 = twin-embryo recipient cows (n = 5). Mean plasma cortisol concentrations remained basal (2-4 ng ml-1) in both groups up to 2 days prepartum increased significantly (P < 0.05) to peak at parturition day, and then declined rapidly 1 day post-partum. Twin-bearing cows had significantly (P < 0.01) higher mean plasma cortisol concentration on the day of parturition than in the singleton cows. There was no effect of the stage of gestation on cortisol levels in either group (P > 0.1), except in the last 48 h prior to parturition. A single cow giving birth prematurely had 100% higher plasma cortisol levels on the day of parturition and 1 day post-partum than cows giving birth at term.

Effects of 20 alpha-hydroxysteroid dehydrogenase and its inhibitors on canine osteosarcoma cell growth in vitro

Cytotoxic effect of progesterone on the neoplastic cells was investigated using POS cells, a cell line established from a spontaneous osteosarcoma in a dog. The 20 alpha-HSD activity of POS cells was 0.85 +/- 0.26 NADPH nmol/min mg protein, demonstrating that a considerable activity was present in this tumor cell. When progesterone was added to the medium and cultured for 48 hr, progesterone dose-dependently inhibited the cell growth, showing that progesterone was cytotoxic on this osteosarcoma cells in vitro. In order to assure the role of 20 alpha-HSD on the cell growth, various concentrations of four types of steroid derivatives, STZ 20, 23, 25, and 26, potent inhibitors of 20 alpha-HSD, were added to the medium with 0.1 microM progesterone. Then, the POS cell growth was more strongly inhibited, which may suggest that the cytotoxicity of progesterone was enhanced by inactivation of 20 alpha-HSD by STZs. From these results, POS osteosarcoma cells have 20 alpha-HSD, which might play an important role in tumor cell growth against the cell toxicity of progesterone.

Plasma bovine placental lactogen concentration throughout pregnancy in the cow; relationship to stage of pregnancy, fetal mass, number and postpartum milk yield

This study characterized the peripheral plasma placental lactogen (bPL) profile throughout gestation and examined the relationship between the stage of gestation, fetal mass, number, and postpartum lactation with circulating levels of bPL in Holstein cows after nonsurgical embryo transfer. Cows (n = 12) were divided into two groups: Group 1 = single embryo recipient cows (n = 5); Group 2 = twin embryo recipient cows (n = 7). Blood was collected about every third day from Day 0 (Day 0 was defined as the first day of standing estrus), then daily for the last 10 d of gestation, and sampling was stopped 1 d postpartum. The cows were milked twice daily at 0800 and 1800 hr. Two twin-embryo recipient cows had abnormal pregnancies; therefore, their data were excluded from that of the group and reported separately. The time trend concentrations of plasma bPL were significantly affected by the stage of gestation (P < 0.01) but not fetal number (P < 0.21). In both groups bPL levels remained low during the first two trimesters, then increased rapidly (P < 0.01) to peak concentrations between Days 200 and 220, and stabilized at this elevated level until parturition. Postpartum milk yields were indistinguishable between the singleton and twin bearing cows. Calf birth weight and postpartum lactation were both correlated (P < 0.01) to peripheral bPL concentration in singleton cows, however, this relationship decreased with a subsequent increase in fetal number. Cows giving birth prematurely to stillborn calves or to a schistosomus reflexus calf exhibited a deviating pBL profile. These results indicate that peripheral bPL levels are positively associated with the stage of gestation but not with fetal number. Otherwise, the peripheral pattern of bPL is a valuable index for predicting feto-placental viability.

Postparturient change in endotoxin levels of ruminal fluid and serum in dairy cows

The changes in the endotoxin levels of ruminal fluid and serum in postparturient cows were evaluated. Five cows were fed hay and concentrates on an individual basis (farm A) and the other 5 cows were given complete feed ad libitum (farm B) after parturition. Ruminal pH levels decreased in both groups after parturition. Subsequently, the ruminal endotoxin levels increased with the declining pH on both of the farms. The ruminal endotoxin levels were slightly higher in cows of farm B than those of farm A. Serum endotoxin levels also showed episodic fluctuations, however, there were no parallel changes between the endotoxin levels of the ruminal fluid and sera.

A case of varicella-zoster myelopathy

INTRODUCTION

Early diagnosis of neurological complications of varicella-zoster virus (VZV) is important because of its treatability. We performed polymerase chain reaction (PCR) to detect VZV-DNA from the cerebrospinal fluid (CSF) of a patient with myelopathy.

PATIENT & METHODS

A 69-year-old man developed sensory disturbances in the lower extremities and bladder-bowel disturbances, followed by cutaneous zoster on his left arm. Polymerase chain reaction was applied to identify the viral DNA in CSF.

RESULTS

The increased antibody index of VZV and herpes simplex virus (HSV) in the CSF suggested intrathecal synthesis of IgG antibodies to these viruses. VZV-DNA was detected in the CSF by nested PCR, but neither HSV-1 nor HSV-2 DNA was detected in CSF. He was successfully treated with acyclovir and prednisolone.

CONCLUSION

PCR may be a useful tool for the diagnosis of VZV myelopathy.

Histological progression of follicular lymphoma associated with p53 mutation and rearrangement of the C-MYC gene

Follicular lymphoma is a low grade malignant lymphoma. However, some follicular lymphomas undergo histological transformation into higher grade malignant lymphomas. We recently encountered a diffuse large cell lymphoma which seemed to have progressed from a follicular lymphoma and which finally transformed into a small non-cleaved lymphoma. Each stage of the histological transformation was accompanied by increasing clinical grades of malignancy. It was suspected that in our patient a follicular lymphoma initially developed due to rearrangement of the BCL2 gene, and then underwent histological transformation into a diffuse large cell lymphoma, which was associated with p53 mutation. Subsequent rearrangement of C-MYC promoted the histological transformation of this diffuse large cell lymphoma into a small non-cleaved lymphoma. Our findings indicate that p53 mutation and rearrangement of C-MYC are involved in the histological transformation of follicular lymphomas into more advanced lymphomas.

[Aging brains and the dementias]

Dementia has been defined generally as an acquired persistent impairment of intellectual function caused by organic brain diseases. The rapidly increasing incidence of dementias has been claimed on the basis of epidemic studies in Japan as well as in Western developed countries. These observations are justified by the facts that most dementias are found in people over the age of 65 years, and that the elderly population is increasing rapidly resulting in both absolute numbers and percentage of the population. In Japan, it is estimated that 1.5 million of demented persons are present. The purpose of this paper is to describe clinical manifestations and morphological alterations of aged and demented individuals, diagnostic process to differential diagnosis to provide knowledgeable approach to management, and adequate care of the demented individuals. In aged brain, there are a variety of morphological changes. Some of these are usually observed in aged brains; atrophy of the brains, loss of neurons, accumulations of lipofuscin. Others observed in pathologically aged brains, or accelerated aging brains are Alzheimer's neurofibrillary tangles, senile plaques, and granulovacuolar degeneration. Psychiatric manifestations associated with aging and dementing diseases are described. It should be realized that clinical manifestations of the demented reflect primarily the topography of the organic lesions in the brain, and functional alterations, and are influenced by psychological and socio-environmental factors.

Prolongation of lung xenograft survival in rats with a short course of deoxyspergualin and cyclosporin A

The efficacy of 15-deoxyspergualin (DSG), cyclosporin A (CyA), and splenectomy--alone or in combination--in prolonging the survival of concordant lung xenotransplants was studied in the hamster-to-rat model. In the untreated group, rejection occurred within 3 days, with an elevation of lymphocytotoxic antibody titers. The rejected lung revealed that ED1 + cells were more prevalent than MRC OX8 + cells in the perivascular infiltrates. In the DSG group, the antibody response was suppressed and median survival increased to 7.5 days. The rejected lungs demonstrated a highly significant depression in ED1 + cellular infiltration and a moderate MRC OX8 + cellular infiltration. When maintenance CyA was combined with a short course of DSG, survival dramatically increased to beyond 100 days. There were no deposits of IgM, IgG, or C3 or of any cell infiltrate in the grafts of two animals sacrificed 107 and 119 days post-transplantation. We conclude that initial treatment with DSG combined with continuous CyA can suppress acute rejection in the hamster-to-rat lung xenograft model, resulting in long-term graft survival.

A genetic linkage map of the Syrian hamster and localization of cardiomyopathy locus on chromosome 9qa2.1-b1 using RLGS spot-mapping

The Syrian cardiomyopathic hamster (BIO14.6) has an inherited form of progressive myocardial necrosis and congestive heart failure. Although widely studied as an animal model for human hypertrophic cardiomyopathy, further genetic analysis has been limited by a scarcity of DNA markers. Until now, only six autosomal linkage groups have been described and the number of polymorphic loci was extremely limited. In this study, we applied the restriction landmark genome scanning (RLGS) spot-mapping method to construct a genetic map of the Syrian hamster (Mesocricetus auratus) using 72 back-cross progeny. Although the polymorphic rate is very low (3-7%) between the strains, 531 polymorphic spots/loci were mapped, showing the power of this approach and reasonable applicability to other organisms lacking a well-defined genetic map. Further, the spot markers which flank the cardiomyopathy (cm) locus were cloned to determine the chromosomal location of cm by fluorescent in situ hybridization (FISH) analysis, resulting in the assignment of the locus to the centromeric region of hamster chromosome 9qa2.1-b1. Several candidate genes responsible for hypertrophic cardiomyopathy in humans have been excluded.

Stress-strain curve and Young's modulus of a collagen molecule as determined by the X-ray diffraction technique

The purpose of the work described in this paper was to make a stress-strain curve for a collagen molecule and estimate Young's modulus of a molecule along the molecular axis. X-ray diffractometry was performed on bovine Achilles tendon in order to measure strain in the collagen molecule along the molecular axis as a response to a macroscopically applied force. By geometrical calculations and experiments, cross-sectional areas of a molecule and molecules in a tendon collagen fiber were determined. The applied force was translated to the stress and the stress-strain curve of the collagen molecule was constructed, which was found to be almost linear. Young's modulus of the molecule was determined to be slightly smaller than when determined by dynamic mechanical methods. The difference was considered to suggest the existence of a viscoelastic component within the molecule as well as the difference in the mechanical properties of collagen in different tissues. The expected viscoelasticity was speculated to be related to the hydrogen bond network in the collagen molecule.