The impact of autologous bone marrow transplantation on hematopoietic recovery after high-dose cyclophosphamide, doxorubicin and cisplatin chemotherapy for patients with gynecological malignancies

Twenty-six patients with gynecological malignancies (21 ovarian and 5 uterine malignant tumors) who were treated 42 times with high-dose cyclophosphamide, doxorubicin and cisplatin (CAP) chemotherapy with autologous bone marrow transplantation (ABMT) were assessed for the impact of predictive parameters on hematopoietic recovery. An inverse correlation was observed between the number of infused nucleated marrow cells (NMC)/kg or colony-forming units of granulocyte-macrophage (CFU-GM)/kg and the leukopenic duration < 1 x 10(3)/microliters; the correlation coefficients were r = -0.54 and -0.49, respectively (p < 0.001). The recovery time of platelet count to achieve more than 5 x 10(4)/microliters without transfusion was inversely correlated with CFU-GM/kg (r = -0.33, p < 0.05) but not with NMC/kg. Neither the episodes of fever nor the number of chemotherapy courses performed on the patients influenced the hematopoietic recovery. The numbers of infused CFU-GM and NMC were useful parameters of leukopoietic recovery after ABMT and high-dose CAP chemotherapy.

Proliferative activity of cutaneous melanocytic neoplasms defined by a proliferating cell nuclear antigen labelling index

To evaluate the proliferative activity of benign, borderline and malignant cutaneous melanocytic neoplasms, 30 cases of malignant melanoma (MM) and 41 cases of naevi were studied by immunostaining using a monoclonal antibody against proliferating cell nuclear antigen (PCNA). PCNA is a nuclear antigen expressed in the late G1 and S phase and serves as a marker of proliferating cells. Invasive MM and MM in situ showed much higher PCNA positivity rates than melanocytic naevi (invasive MM, 18.0%; MM in situ, 11.3%; ordinary melanocytic naevi, 2.6%). The PCNA positivity rate did not increase significantly with the thickness of MM. Among ordinary melanocytic naevi, junctional naevi had a higher PCNA positivity rate than compound or intradermal naevi. Mean PCNA positivity rates for Spitz's naevi and sporadic dysplastic naevi were within the range for ordinary melanocytic naevi, indicating the benign nature of both types of naevus. Contrary to some previous studies, MM in situ showed high proliferative activity, indicating that cells of MM in situ are actively proliferating. This study clearly demonstrates that MM and various types of naevi can be separated according to differences in proliferative activity defined by the PCNA labeling index.

[An adult case of intradural lumbo-sacral lipoma]

A rare case of lumbo-sacral lipoma in an adult case is reported. A 55-year-old male was admitted to the Department of Neurosurgery, Mazda Hospital, after a history of one year of urinary incontinence. Neurologically, no motor or sensory disturbance of the lower extremities was found in this patient. MRI showed a mass with high signal intensity on T2-weighted image, located between L3 to S2 vertebral segments. Metrizamide-CT scan demonstrated the outline of this hypodense mass at the same location as shown on MRI image. A L3 through L5 laminectomy was performed and the tumor was subtotally removed. Microscopic examination revealed that the tumor mass was made up of mature lipoma cells. Postoperative course of the patient was uneventful. The urinary incontinence was improved slightly. No motor or sensory deficit was found. We thought that MRI was useful for the correct diagnosis of lumbosacral lipoma. And it is best managed by operative removal of the tumor as early as possible after it is diagnosed.

Two cases of adenolipoma of the breast

Adenolipoma of the breast is a rare tumor. Two cases are described here and the literature is reviewed. Case 1 was a 52-year-old woman who had a 3-cm-long elastic hard tumor in the left breast. Case 2 was a 40-year-old woman who had a 3-cm-long elastic soft tumor in the left breast. In each case, mammography revealed well demarcated soft tissue density. Ultrasonography demonstrated well defined tumors composed of echogenic and sonolucent areas. These tumors were easily enucleated at surgery. Histologically, the tumors consisted of mammary ducts, fibrous stroma and adipose tissue, findings which are characteristic of mammary adenolipoma. An adenolipoma may still be misdiagnosed as a fibroadenoma or a fibrocystic disease. Characteristic findings of mammography and ultrasonography are emphasized.

Large-scale culture system of human CD4+ helper/killer T cells for the application to adoptive tumour immunotherapy

A simple method for the rapid expansion of human CD4+ T cells with both helper and killer functions was established. CD4+ T cells separated from peripheral blood mononuclear cells using immunomagnetic beads were stimulated with immobilised OKT-3 monoclonal antibody (mAb) plus recombinant interleukin 2 (rIL-2) in 96 well culture plates. After 6 day-culture, the CD4+ T cells were restimulated by immobilised OKT-3 mAb for an additional 24 h, then inoculated into concentrated rotary-tissue culture bag and cultured for further 9 days. This procedure yielded a 3000-fold increase in cell number (about 3-5 x 10(9) per bag). Most of the cells (over 96%) continued to express CD4+ antigen and retained their capacity to produce IL-2. The activated CD4+ T cells showed marked cytotoxicity against Fc receptor positive tumour cells in the presence of OKT-3 mAb. Moreover, we succeeded in a specific targeting of the expanded CD4+ helper/killer T cells to c-erb B-2 positive tumour cells by means of anti-CD3 x anti-c-erb B-2 bispecific antibody. These results suggested that our established simple system will be available for the expansion of large number of CD4+ helper/killer T cells which may provide an efficient strategy for adoptive tumour immunotherapy.

Immunohistochemical study of transforming growth factor beta, fibronectin, and fibronectin receptor in invasive mammary carcinomas

Thirty-one cases of mammary carcinoma were examined immunohistochemically for the expression of transforming growth factor (TGF) beta, fibronectin (FN) and fibronectin receptor (FNR) in order to clarify the reason for the reported relationship between TGF beta expression and a high incidence of lymph node metastasis. It was revealed that TGF beta expression is closely related to the expression of FN, an intercellular matrix protein, and its cellular receptor FNR, one of the integrins. The interaction between FN and FNR in a tumor is considered to form the basis of the invasive nature of carcinoma cells. Thus, it is suggested that TGF beta expression in carcinoma cells induces the interaction between FN and FNR, which may lead to carcinomatous invasion resulting in lymph nodal metastasis.

[Rapid diagnosis of tuberculous lymphadenitis by amplification of mycobacterial DNA]

In patients with cervical lymph node swelling, prompt differential diagnosis of tuberculosis leads to an appropriate treatment. A method based on DNA amplification and hybridization for the rapid detection of Mycobacterium tuberculosis was used for demonstrating its specific DNA in cervical lymph nodes biopsied from seven patients. The DNA specific for Mycobacterium tuberculosis was detected in 5 patients. Four of them were histologically diagnosed as tuberculous lymphadenitis. In another case with necrotizing lesions but without granulomatous reactions, culture method subsequently revealed a positive result. In other 2 cases, the diagnosis of tuberculosis was promptly excluded by both this method and conventional methods (histologic diagnosis/direct microscopy). The rapid detection of Mycobacterium tuberculosis by amplification of mycobacterial DNA is helpful particularly in differential diagnosis of cervical lymphadenopathy.

[Effects of steroid therapy in IgA nephropathy]

In order to estimate the effects of corticosteroid therapy in IgA nephropathy cases with daily urinary protein excretion of 1.0 g/day or more. 26 patients (8 men and 18 women, aged 32.6 +/- 14.0 years old) were subjected to this study. The results obtained were as follows: Urinary protein excretion after 1 year from the beginning of steroid therapy (1.56 +/- 1.14 g/day) was significantly (p less than 0.05) lower than that at the beginning of the therapy (4.61 +/- 6.01 g/day). In serum creatinine levels, there was no statistically significant difference with them between at the beginning (1.15 +/- 0.48 mg/dl) of steroid therapy and at the time of 1 year after (1.05 +/- 0.34 mg/dl) the therapy. As for the outcome at the end of this study setting (mean follow-up duration: 3.7 +/- 2.6 years), complete remission was attained in 7 cases, improvement in 5 cases, unchanged condition in 11 cases, increased urinary protein excretion in 2 cases and aggravated renal function in 1 case. In clinical findings at the renal biopsy, duration of the disease (3.4 +/- 1.6 months) in complete remission cases before biopsy was significantly (p less than 0.01) shorter than that in unchanged cases (65.0 +/- 40.0 months). In histological findings, rate of global sclerosing glomeruli (2.6 +/- 4.6%) in complete remission cases was significantly (p less than 0.05) lower than that (24.6 +/- 23.1%) in unchanged cases. These results suggest that steroid therapy in IgA nephropathy with persistent proteinuria of 1.0 g/day or more is beneficial, especially in cases that are in early stage of the disease with lower rate of global sclerosing glomeruli.

Distribution patterns and frequency of proliferating cells in cutaneous keratinocytic neoplasms. Immunohistochemical study with a monoclonal antibody (TOB7) used against proliferating cell nuclear antigen

BACKGROUND

Almost all markers for proliferating cells need freshly frozen tissues for evaluation; therefore retrospective study is impossible.

OBJECTIVE

In the present study, a murine monoclonal antibody (TOB7) against the proliferating cell nuclear antigen (PCNA) was used for the analysis of cell kinetics of cutaneous keratinocytic neoplasms. The antibody is applicable to formalin-fixed, paraffin-embedded tissues.

METHODS

The frequency of PCNA-positive cells and their distribution patterns were immunohistochemically investigated in various cutaneous keratinocytic neoplasms.

RESULTS

Squamous cell carcinoma and Bowen's disease showed significantly increased numbers of PCNA-positive cells when compared with other keratinocytic neoplasms. A characteristic marginal or random distribution pattern of PCNA-positive cells was observed in the lesions of each disease category.

CONCLUSION

Important information on the growth dynamics of keratinocytic neoplasms was obtained in this retrospective immunohistochemical study.

HumanC-ERBB-2 proto-oncogene product as a target for bispecific-antibody-directed adoptive tumor immunotherapy

To develop an efficient strategy for the targeting of anti-tumor effector cells, we prepared bispecific antibody (BsAb) containing anti-CD3 and an anti-c-erbB-2 proto-oncogene product. The prepared BsAb specifically reacts with both c-erbB-2-positive tumor cells and CD3+ CTL. Human CD4+ helper/killer T cells, induced from peripheral-blood mononuclear cells by activation with immobilized anti-CD3 monoclonal antibody (MAb) plus IL-2, showed no significant cytotoxicity against tumor cells. However, treatment of human CD4+ helper/killer cells with the BsAb caused the induction of specific cytotoxicity against c-erbB-2-positive tumor cells. CD4+ helper/killer cells also produced significant amounts of IL-2 during co-culture with c-erbB-2-positive tumor cells in the presence of the BsAb. Moreover, by combination with the BsAb, CD4+ helper/killer cells showed a strong in vivo anti-tumor effect against c-erbB-2 transfectant or human colon-cancer cells implanted in nude mice. Our results strongly suggest that the c-erbB-2 proto-oncogene product on human tumor cells may be a good target for BsAb-directed adoptive tumor immunotherapy.

[A study on pathogenesis of gastric mucosal lesions in hemodialysis patients, with special reference to the gastric mucosal blood flow]

Clinical characteristics of gastric mucosal lesions in hemodialysis patients were studied. The relationships between the occurrence of gastric mucosal lesions and changes of gastric mucosal blood flow were studied in normal subjects and hemodialysis patients to clarify causes of gastric mucosal lesions in them. Erosive gastritis, gastric ulcers and hemorrhagic gastritis were the main manifestations of the lesions in hemodialysis patients. The lesions were mainly localized in the gastric antrum. Hemorrhagic gastritis lesions were also found in the gastric body as well as in the gastric antrum. The gastric mucosal blood flow in the gastric body showed lower values than in healthy controls while gastric mucosal blood flow in the antrum revealed no such significant difference. Therefore, it can be considered that the low value of gastric mucosal blood flow in the gastric body may contribute to the occurrence of gastric mucosal lesions in the gastric body in hemodialysis patients. However, gastric mucosal lesions in hemodialysis patients were localized mainly in the gastric antrum, and, accordingly, the changes in the gastric mucosal blood flow are not supposed to account for the lesions in the gastric antrum. Further studies are, therefore, required to clarify the causes of gastric mucosal lesions in hemodialysis patients.

Generation propagation, and targeting of human CD4+ helper/killer T cells induced by anti-CD3 monoclonal antibody plus recombinant IL-2. An efficient strategy for adoptive tumor immunotherapy

We developed a culture system for the rapid generation of CD4+ T cells that have both helper and killer functions. CD4+ T cells isolated from human PBL did not proliferate or develop significant cytotoxicity when treated with rIL-2 because of the lack of p75 IL-2R expression. However, culture of isolated CD4+ T cells with immobilized anti-CD3 mAb plus rIL-2 resulted in a marked proliferation (500-fold increase in 14 days) of CD4+ T cells. The proliferating CD4+ T cells produced IL-2 (92 U/ml) and showed strong cytotoxicity against OKT3 hybridoma cells and Daudi, K562, and U937 tumor cells in an anti-CD3 mAb-dependent manner. The CD4+ T cells contained significant amounts of cytolytic granule-related proteins such as serine esterase and perforin. Activated CD4+ helper/killer cells can be generated from both healthy donors and tumor patients and can be propagated in vitro for 14 to 35 days by biweekly restimulation with immobilized anti-CD3 mAb plus rIL-2. This culture yielded about 20,000-fold increase in cell number after a 21-day culture. Bispecific antibody containing anti-CD3 and anti-glioma Fab components enhanced the cytotoxicity of activated CD4+ helper/killer cells against IMR32 glioma cells. Moreover, the activated CD4+ helper/killer cells showed both helper and antitumor activity in vivo and prevented growth of anti-CD3 hybridoma cells in nude mice whether or not IL-2 was administered. These results indicate that anti-CD3 mAb plus IL-2-activated CD4+ helper/killer cells may provide an effective strategy for adoptive tumor immunotherapy of cancer.

[A case of HBsAg positive liver cirrhosis who died after withdrawal of steroid]

A 42-year-old male was admitted with subarachnoidal hemorrhage. Dexamethasone 224 mg was used to reduce brain edema. His operation was successful without blood transfusion. No remarkable signs and symptoms were found except HBsAg positive and mild GPT elevation during his admission. He was discharged on the 33rd day. But 2 weeks later, he felt general fatigue and became worse day by day. He was re-admitted on the 75th day. Several therapies were given but he died of hepatic failure on the 85th day. The autopsy showed liver cirrhosis with massive necrosis. We believed that the steroid-withdrawal-phenomenon caused excessive immunological response and this process caused his hepatic failure leading to death.

Generation propagation, and targeting of human CD4+ helper/killer T cells induced by anti-CD3 monoclonal antibody plus recombinant IL-2. An efficient strategy for adoptive tumor immunotherapy

We developed a culture system for the rapid generation of CD4+ T cells that have both helper and killer functions. CD4+ T cells isolated from human PBL did not proliferate or develop significant cytotoxicity when treated with rIL-2 because of the lack of p75 IL-2R expression. However, culture of isolated CD4+ T cells with immobilized anti-CD3 mAb plus rIL-2 resulted in a marked proliferation (500-fold increase in 14 days) of CD4+ T cells. The proliferating CD4+ T cells produced IL-2 (92 U/ml) and showed strong cytotoxicity against OKT3 hybridoma cells and Daudi, K562, and U937 tumor cells in an anti-CD3 mAb-dependent manner. The CD4+ T cells contained significant amounts of cytolytic granule-related proteins such as serine esterase and perforin. Activated CD4+ helper/killer cells can be generated from both healthy donors and tumor patients and can be propagated in vitro for 14 to 35 days by biweekly restimulation with immobilized anti-CD3 mAb plus rIL-2. This culture yielded about 20,000-fold increase in cell number after a 21-day culture. Bispecific antibody containing anti-CD3 and anti-glioma Fab components enhanced the cytotoxicity of activated CD4+ helper/killer cells against IMR32 glioma cells. Moreover, the activated CD4+ helper/killer cells showed both helper and antitumor activity in vivo and prevented growth of anti-CD3 hybridoma cells in nude mice whether or not IL-2 was administered. These results indicate that anti-CD3 mAb plus IL-2-activated CD4+ helper/killer cells may provide an effective strategy for adoptive tumor immunotherapy of cancer.

Bispecific antibody-directed antitumor activity of human CD4+ helper/killer T cells induced by anti-CD3 monoclonal antibody plus interleukin 2

Freshly isolated human CD4+ T cells can not respond to recombinant interleukin 2 (rIL-2) because of their lack of p75 IL-2 receptor expression. However, we succeeded in inducing a marked proliferation of purified CD4+ T cells by activation with rIL-2 plus anti-CD3 monoclonal antibody (mAb) cross-linked to a plastic plate. The proliferated CD4+ T cells produced a significant amount of IL-2 upon stimulation with phorbol ester plus A23187. Interestingly, CD4+ T cells activated with anti-CD3 mAb plus rIL-2 revealed a strong cytotoxic activity against Fc receptor (FcR)-positive tumor cells in the presence of anti-CD3 mAb. Moreover, the CD4+ T cells could lyse FcR-negative glioma cells by targeting with bispecific mAb containing anti-CD3 mAb and anti-glioma mAb. Thus, we demonstrated that rIL-2 and immobilized anti-CD3 mAb allowed the rapid generation of human CD4+ helper/killer T cells, which may be useful for the development of a new adoptive tumor immunotherapy.

Lymphoproliferative disorders of the thyroid gland: radiological appearances

Images of lymphoproliferative disorders of the thyroid by ultrasonography (US), computed tomography (CT), 99Tcm and 67Ga scintigraphy were analysed in eight patients (two men and six women, aged 42-83 years). Seven patients were diagnosed as having primary lymphoma and one plasmacytoma. Ultrasound revealed a solid mass with homogeneous and very low echogenicity clearly distinguishable from residual thyroid tissue in five patients, diffuse hypoechoic goitre in one and multiple irregular hypoechoic nodules in both lobes in the patient with plasmacytoma (Case 8). Computed tomography demonstrated a focal low-density area in six cases of lymphoma and decreased density throughout the gland in the other two patients. 99Tcm scintigraphy showed hemilobar enlargement with decreased and uneven trapping, cold area or complete lobar defect in six patients with lymphoma and no trapping in the case of plasmacytoma. 67Ga scintigraphy demonstrated high accumulation in lymphoma and faint accumulation in the case of plasmacytoma. Radiological manifestations with a focal lesion were considered typical and diagnostic of primary thyroid lymphoma, while in one case with diffuse infiltration through the whole gland, the differential diagnosis from Hashimoto's thyroiditis could not be made. In the final case, cells infiltrated diffusely to form islands with patchy distribution among well preserved follicles, correlating with the multiple hypoechoic areas observed by US.

[Simple allergen skin test device Multi skit (tentative name)]

We have developed a device tentatively named Multi Skit (Mu), a simple allergen test device, in order to conduct the skin test safely, accurately and conveniently. The utility of this device was evaluated by determining how the results obtained by the intradermal test (In) and Mu were correlated with those obtained by IgE RAST (RA) in 65 AD patients. RA values concerning nine antigens were compared to results obtained by the In and Mu in terms of the positive and negative response coincidence rates, overall coincidence rates, and false-positive and false-negative response rates. The correlation between RA data obtained from the literature and the results of the scratch test (Sc) was also evaluated. The results of In and RAST values showed no correlation regardless of the food antigen used. Mu and RAST values showed correlation with respect to all 4 food antigens except soy-bean, resulting in overall coincidence rates of 66.2 to 87.7%, which were higher than those concerning the Sc. With respect to false-positive responses to environmental antigens, the rate obtained by Mu was higher than that by the Sc, but it was lower than that by the In. However, Mu was the most excellent test with respect to the other indices, i.e., positive and negative response coincidence rates, overall coincidence rates (73.9-89.2%) and false-negative responses. The mechanism of Mu makers it possible to minimize variations from one investigator to another, and the major drawback of all other skin tests. Mu is a safe and convenient screening skin test device which provides accurate and specific test results.

Induction of c-fos and c-myc mRNA expression by immunoglobulin G from patients with Graves' disease in thyrotrophin-dependent rat thyroid cell line (FRTL5)

The present study was conducted to evaluate effects of autoantibodies in patients with Graves' disease on induction of c-fos and c-myc mRNA expression in rat thyroid cell line (FRTL5). IgG fractions were isolated from 11 patients with Graves' disease, and six healthy subjects, with protein A-Sepharose. FRTL5 cells which had been grown to subconfluency and deprived of TSH for a week were exposed to the IgG for an hour. Expression of c-fos and c-myc mRNAs was examined by the Northern blot method using nick-translated v-fos and c-myc probes. C-fos and c-myc transcripts were induced by IgGs from two patients with Graves' disease, which displayed much higher activities in assays for TSH binding inhibitor immunoglobulins, thyroid stimulating antibodies and thyroid growth-stimulating immunoglobulins, assessed by measuring inhibition of 125I-TSH binding to the TSH-receptor, cAMP production and 3H-thymidine incorporation in FRTL5 cells, respectively, compared with those in the remaining patients. The induction of c-fos and c-myc mRNAs by IgG from a patient with Graves' disease was suppressed by preincubation with IgGs from two patients with primary myxoedema who were known to have a blocking type TSH-receptor antibody. These data suggest that the binding of the antibodies to the TSH-receptor followed by cAMP production is related to the induction of c-fos and c-myc mRNAs and, thus, to the growth of FRTL5 cells. To our knowledge, this is the first report demonstrating that autoantibodies induce proto-oncogene mRNA expression.

Macrophage-T cell interaction is essential for the induction of p75 interleukin 2 (IL-2) receptor and IL-2 responsiveness in human CD4+ T cells

Fresh human CD8+ T cells showed a strong proliferative response to a high concentration of interleukin 2 (IL-2) in the absence of macrophages. In contrast, CD4+ T cells revealed no significant IL-2 responsiveness in the absence of macrophages. However, if CD4+ T cells were cocultured with macrophages, they showed higher proliferative response to IL-2 than CD8+ T cells. In accordance with the magnitude of IL-2 responsiveness, freshly isolated CD8+ T cells expressed significant amounts of p75 IL-2 receptor, while fresh CD4+ T cells did not express p75 IL-2 receptor. The expression of p75 IL-2 receptor on CD4+ T cells was induced by coculture with macrophages. The macrophage-induced p75 IL-2 receptor acquisition was blocked by monoclonal antibody (mAb) against class II antigen. Moreover, the addition of anti-CD4 mAb or anti-class II mAb to the culture caused a great inhibition of IL-2 responsiveness of CD4+ T cells. These results strongly suggest that macrophage-T cell interaction through CD4 and/or class II molecules is essential for the expression of p75 IL-2 receptor and IL-2 responsiveness in human CD4+, but not CD8+ T cells.

Changes of brainstem auditory evoked responses (BAERs) in a brain stem ischemic model using embolization technique in cats, a preliminary study

In order to evaluate brain stem dysfunction related to ischemic process, the authors monitored the Brainstem Auditory Evoked Responses (BAERs) with time in a brain stem ischemic model. 19 adult mongrel cats were divided into two groups: embolization (n = 14) and sham operated control (n = 5). Embolization was done by injecting cylindrical silicone embolus to the right vertebral artery. Each successful embolization of the basilar artery was then confirmed by vertebral angiography. BAERs were monitored before embolization and then 5-10 min, 15 min, 30 min, 60 min, 3 hr and 6 hr after embolization. The presence of ischemic lesion caused by embolization was confirmed by injecting 2% Evans blue solution 30 min before sacrificing the animals. Leakage of the dye was observed. In embolized animals, significant (Student t test, p less than 0.05) delay of interpeak latencies of waves 1-3, 3-5, and 1-5 was observed 15 min after embolization. This delay became more significant (p less than 0.01) 30 min after embolization. These results provide evidence for the usefulness of BAERs monitoring which can be used to complement other diagnostic methods for patients with vertebrobasilar insufficiency and/or infarction.

Giant congenital capillary hemangioma of pericranium--case report

The authors report a newborn male infant with a giant congenital capillary hemangioma of the pericranium. An elastic mass, measuring 6.5 x 6.9 x 3.9 cm, was located in the parieto-occipital region. Neurological examination revealed no abnormality. Angiographically, the tumor was fed symmetrically by the bilateral superficial temporal, occipital, and middle meningeal arteries. At surgery, the encapsulated tumor appeared to have arisen from the periosteum and was removed completely. Histological diagnosis was capillary hemangioma. Capillary hemangioma is a common benign tumor in infancy and usually present as a strawberry mark or port-wine stain. However, when the tumors seat relatively deeply as in the present case, they produce little or no discoloration in the overlying skin. Angiography is then useful to differentiate capillary hemangioma from other lesions and to choose an appropriate treatment.

Fundamental study on the mechanism of DNA degradation in tissues fixed in formaldehyde

The mechanism of DNA degradation and its clinical applications were examined. When purified lambda phage and extracted liver DNA were fixed in phosphate buffered formaldehyde, the DNA did not degrade, but there was incomplete digestion with endonuclease. Rat liver tissues were fixed under various conditions and DNA extracted. Immediate fixation with buffered formaldehyde at low temperature, or the addition of EDTA to buffered formaldehyde blocked the DNA degradation. Analysis of pulsed field gel electrophoresis also showed that DNA was degraded before extraction. These results suggest that tissue nuclease has an important role in DNA degradation in tissue. Furthermore, formaldehyde fixation at low temperature, which may take time and which decreases slightly the staining capacity, is useful for the extraction of intact DNA. For clinical application, the detection of provirus was examined. Genomic DNA was extracted from a necropsy sample of adult T cell leukaemia fixed in formaldehyde; human T cell leukaemia virus type-I (HTLV-I) provirus was successfully detected by Southern blotting.