Insulin resistance and arteriosclerosis obliterans in patients with NIDDM

OBJECTIVE

To investigate the risk factors for arteriosclerosis obliterans (ASO) in NIDDM, we measured insulin sensitivity and other risk factors including lipoprotein(a) [Lp(a)] in NIDDM patients with and without ASO.

RESEARCH DESIGN AND METHODS

A case-control study in 100 patients with NIDDM, 35 with and 65 without ASO, was performed. Insulin sensitivity was assessed by the short insulin tolerance test's K index (KITT). Duration of diabetes, a history of smoking, prevalence of hypertension, prevalence of coronary artery disease (CAD), serum C-peptide, 24-h urinary C-peptide, serum lipids, and Lp(a) were compared in the two groups.

RESULTS

Age, BMI, HbA1c, and fasting plasma glucose were comparable in the two groups. Patients with ASO were significantly more insulin resistant than patients without ASO (KITT 2.16 +/- 0.16 vs. 3.00 +/- 0.13%/min, P < 0.0001, respectively), had a longer duration of diabetes (10.3 +/- 1.2 vs. 7.5 +/- 0.8 years, P < 0.05), included a greater number of smokers (68.6 vs. 40.0%, P < 0.01), had a higher prevalence of CAD (60.0 vs. 16.9%, P < 0.01), and had a greater percentage of insulin therapy (48.6 vs. 29.2%, P < 0.05). However, urinary and serum C-peptide levels, serum lipids, and Lp(a) levels were comparable in the two groups. Multiple logistic regression analysis indicated that a history of smoking (odds ratio 3.70, P = 0.011), insulin resistance (odds ratio 3.68, P < 0.001), and an elevated Lp(a) level (odds ratio 1.03, P = 0.020) were independently related to ASO. When patients with CAD were removed from the logistic regression analysis, insulin resistance was most strongly related to ASO (odds ratio 20.9, P < 0.001).

CONCLUSIONS

Patients with ASO were characterized by a higher prevalence of CAD, a greater percentage of smokers, a greater percentage of insulin therapy, and a higher insulin resistance than were patients without ASO. Insulin resistance, especially, may be the most powerfully related to ASO. Lp(a) may play a minor role in the development of ASO.

Bacterial pneumonia causes augmented expression of the secretory leukoprotease inhibitor gene in the murine lung

The cDNA of murine secretory leukoprotease inhibitor (SLPI) was cloned from a mouse lung cDNA library. The amino acid sequence deduced from the cDNA showed 58 and 51% homology with those of human and porcine SLPI, respectively. A two-domain structure with similar amino acid sequences, four intradomain disulfide bonds, and high proline content, which are characteristics common to human and porcine SLPI, was also found in the mouse protein. The amino acid residues for the signal sequence and active site are also conserved in mouse SLPI. RNase protection assay showed the expression of the SLPI gene in liver, intestine, spleen, and epididymis, suggesting the distribution of SLPI in tissues other than lung and seminal vesicles. In the lung infected with Streptococcus pneumoniae strain FP1284, 10 h after inoculation of bacteria the number of SLPI mRNA transcripts was three times higher than baseline. The increased level of expression remained constant for at least 48 h. This result clearly contrasts to that obtained for spleen, in which the SLPI mRNA transcript level was mostly unchanged during the course of pneumonia. These facts suggested the local regulation of the SLPI gene expression in vivo in response to inflammatory stimuli at the site of inflammation.

Glucose tolerance, insulin secretion, and insulin sensitivity in nonobese and obese Japanese subjects

OBJECTIVE

To investigate the relative contributions of insulin secretion and insulin resistance to the development of glucose intolerance in Japanese subjects.

RESEARCH DESIGN AND METHODS

A cross-sectional study of 756 Japanese subjects (530 nonobese, 226 obese) was performed. A 75-g oral glucose tolerance test (OGTT) was given, and subjects were classified according to the World Health Organization (WHO) criteria (normal glucose tolerance [NGT], impaired glucose tolerance [IGT], and diabetes). Early-phase insulin secretion was assessed by the insulinogenic index (the ratio of the increment of insulin to that of plasma glucose [PG] 30 min after a glucose load [delta IRI0-30 min/delta PG0-30 min]). Total insulin secretion was assessed by mean immunoreactive insulin (IRI) during the OGTT, and insulin resistance was assessed by use of the homeostasis model [HOMA(R)].

RESULTS

Early-phase insulin secretion was significantly decreased in IGT, compared with patients with NGT, in both the nonobese and obese subjects (0.70 +/- 0.05 vs. 0.37 +/- 0.03, P < 0.01 and 1.36 +/- 0.19 vs. 0.73 +/- 0.08, P < 0.01, respectively). However, mean IRI and HOMA(R) in both nonobese and obese subjects with IGT and NGT were not statistically different. Subjects with diabetes showed a significant decline in early-phase and total insulin secretion and a significantly higher level of insulin resistance than did subjects with IGT. When the fasting glucose (FPG) exceeded 100 mg/dl, early-phase insulin decreased progressively. The graphed relationship between FPG and mean IRI did not show an inverted U-shape, and mean IRI decreased progressively when FPG exceeded 100-130 mg/dl. The pattern of changes in insulin secretion and insulin resistance associated with the progression of glucose intolerance was similar in both the nonobese and obese subjects.

CONCLUSIONS

The worsening from NGT to IGT in Japanese subjects may be associated with a decrease in early-phase insulin secretion in nonobese as well as in obese subjects. Hyperinsulinemia in IGT is not common. We suggest that impaired early-phase insulin secretion may be the initial abnormality in the development of glucose intolerance in Japanese people. Insulin resistance may be a consequence of hyperglycemia and/or obesity.

CD8 cytotoxic T-cell clone rapidly transfers autoimmune diabetes in very young NOD and MHC class I-compatible scid mice

A CD8 T-cell clone (YNK1.3) generated from acutely diabetic NOD mouse islets, showed proliferation and cytotoxicity when challenged with NOD and BALB/c islet cells and NOD-derived insulinoma cells. When 1-2 x 10(7) YNK1.3 cells were administered to 7-10-day-old NOD mice, the cells transferred overt diabetes very rapidly in each of the 16 recipients within 4 days of cell transfer. However, of 14 recipients receiving YNK 1.3 cells above 14 days of age none became diabetic. Fluorescent dye-labelled YNK1.3 cells extensively accumulated in the islets by 36 h after transfer in 7-day-old NOD recipients, while no significant insulitis was seen in 21-day-old recipients. Over half of NOD-scid recipients (5/9) rapidly became diabetic within 5 days after transfer of 1-2 x 10(7) YNK1.3 cells at 7 days of age, whereas only one of 12 recipients over 14 days of age became diabetic. Furthermore, YNK1.3 cells also transferred diabetes to H-2Kd-matched very young BALB/c-scid and CB17-scid mice, but not to C57BL/6-scid mice. Thus, optimally activated islet-specific CD8 T-cell clones are able to rapidly transfer diabetes to NOD and MHC class I compatible scid mice when a large enough number is administered at 7 days of age. Administration of monoclonal antibodies against adhesion molecules involved in the trafficking of lymphocytes from the circulation into the inflammatory tissues, could not prevent the cellular infiltration of YNK1.3 cells into the islets in 7-day-old NOD recipients. The results indicate that islet cells in the mouse around 7 days of age are generally susceptible to cytotoxic CD8 T cells, suggesting, therefore, that CD8 T cells may play an important role in the initiation of autoimmune diabetes in NOD mice.

A large right coronary artery-left ventricle fistula with mild volume overload on the left ventricle owing to its capacitive action--pulsed Doppler and cineangiographic analyses in a patient

A 54-year-old woman was admitted to our hospital because of a heart murmur without subjective symptoms. Angiography disclosed an enlarged right coronary artery and flow drainage into the left ventricle, ie, a large right coronary artery-left ventricle fistula. Analysis of pulsed Doppler studies and cineangiograms indicated considerable capacitance of this fistula owing to Windkessel action, which attenuated volume overload on the left ventricle. The features in this case suggest that evaluation of fistula hemodynamics is important in determining the overload on the ventricle through the fistula.

Expression of IFN-inducible protein-10 in chronic hepatitis

Chemokines such as IFN-inducible protein-10 (IP-10) and JE/monocyte chemotactic protein-1 (MCP-1) are induced in the murine liver in a tissue-specific manner. We examined whether IP-10 and MCP-1 are pathologically involved in chronic hepatitis. Whereas the serum levels of IP-10 and MCP-1 in patients with chronic persistent hepatitis C were elevated compared with those in normal volunteers, both chemokine levels were further significantly higher in patients with the active form (chronic active hepatitis (CAH)). The elevated IP-10 level was not a general phenomenon of inflammation, because it was not seen in patients with rheumatoid arthritis, whereas MCP-1 levels were elevated to the same extent in both patient groups. Better responsiveness to IFN therapy in CAH was related to lesser grades of necroinflammatory activity and was predicted by the lower IP-10 and higher MCP-1 levels. IP-10 levels in patients cured by IFN therapy decreased to the levels in normal volunteers, while the MCP-1 levels only slightly decreased. Serum levels of both chemokines in patients who were not cured remained unchanged after IFN therapy. In situ hybridization analysis of CAH revealed that IP-10 mRNA was expressed mainly in hepatocytes around intralobular focal and periportal piecemeal necrosis, while some MCP-1 mRNA was expressed in some sinusoidal cells. These results suggested that IP-10 plays a specific role in the intralobular accumulation of mononuclear cells and/or the death of hepatocytes in chronic hepatitis.

Expression of IFN-inducible protein-10 in chronic hepatitis

Chemokines such as IFN-inducible protein-10 (IP-10) and JE/monocyte chemotactic protein-1 (MCP-1) are induced in the murine liver in a tissue-specific manner. We examined whether IP-10 and MCP-1 are pathologically involved in chronic hepatitis. Whereas the serum levels of IP-10 and MCP-1 in patients with chronic persistent hepatitis C were elevated compared with those in normal volunteers, both chemokine levels were further significantly higher in patients with the active form (chronic active hepatitis (CAH)). The elevated IP-10 level was not a general phenomenon of inflammation, because it was not seen in patients with rheumatoid arthritis, whereas MCP-1 levels were elevated to the same extent in both patient groups. Better responsiveness to IFN therapy in CAH was related to lesser grades of necroinflammatory activity and was predicted by the lower IP-10 and higher MCP-1 levels. IP-10 levels in patients cured by IFN therapy decreased to the levels in normal volunteers, while the MCP-1 levels only slightly decreased. Serum levels of both chemokines in patients who were not cured remained unchanged after IFN therapy. In situ hybridization analysis of CAH revealed that IP-10 mRNA was expressed mainly in hepatocytes around intralobular focal and periportal piecemeal necrosis, while some MCP-1 mRNA was expressed in some sinusoidal cells. These results suggested that IP-10 plays a specific role in the intralobular accumulation of mononuclear cells and/or the death of hepatocytes in chronic hepatitis.

Telomerase elevation in pancreatic ductal carcinoma compared to nonmalignant pathological states

Telomerase activity was measured in surgically resected tissues of 20 human pancreatic ductal carcinomas, 12 adenomas, 5 pancreatitis tissues, 14 normal pancreatic ducts, and 13 normal pancreatic tissues (primarily made up of acinar cells) using a PCR-based telomerase assay. Relative telomerase activity was expressed as the equivalent telomerase intensity of the number of cells of a human pancreatic cancer cell line, MIA PaCa-2, per microgram of protein in the tissue samples. The median value (25th percentile, 75th percentile) of relative telomerase activity in pancreatic carcinomas was 13.2 (3.58, 244), which was significantly higher relative to normal tissues, normal ducts, pancreatitis tissues, and adenomas (P < 0.0001). When the cutoff value of relative telomerase activity was set at 1.00 and 3.00, the positivity rates of telomerase activity in pancreatic ductal carcinomas were 100 and 80%, respectively. Some of the adenoma samples displayed a weak telomerase ladder. However, when semiquantitatively analyzed, the relative telomerase activity of all adenoma tissues was less than 1.00 equivalent cells per microgram protein of the tissues, which was equivalent to the values encountered in normal ducts. Thus, our results indicate that reactivation of telomerase may occur at a late stage of pancreatic ductal carcinogenesis. Therefore, telomerase may be a specific marker for distinguishing pancreatic cancer from pancreatitis and adenomas.

Histopathology, pathophysiology, and indications for surgical treatment of renal hyperparathyroidism

Morphological changes in the parathyroid glands evidently occur early during renal failure. Histopathological investigations have suggested that parathyroid cells initially increase diffusely with a normal lobular structure (diffuse hyperplasia). The parathyroid glands then become hyperplastic with some nodules (nodular hyperplasia). Cells in nodules grow monoclonally and proliferate aggressively, possibly induced by some kind of genetic abnormality. Pathophysiologically, in cells consisting of hyperplastic nodules, suppression of parathyroid hormone (PTH) secretion under the influence of excess extracellular calcium is more deranged, possibly due to a reduction of calcium-sensing receptors. Vitamin D receptor density decreases more severely in these cells, possibly causing abnormal PTH synthesis, PTH secretion, and even parathyroid cell proliferation. According to histopathological and pathophysiological findings, patients with nodular hyperplasia during renal hyperparathyroidism may be refractory to medical treatments, including calcitriol pulse therapy, and parathyroidectomy will become necessary. There is a relationship between the pattern of parathyroid hyperplasia and glandular weight in which glands weighing more than 500 mg may be pathognomonic of nodular hyperplasia. Glandular volume, estimated by ultrasonography, is one of several important criteria indicating parathyroidectomy. In order to prevent a recurrence of hyperparathyroidism, all nodular hyperplastic tissue should be extirpated.

Alkylation-induced apoptosis of embryonic stem cells in which the gene for DNA-repair, methyltransferase, had been disrupted by gene targeting

An enzyme O6-methylguanine-DNA methyltransferase (MGMT) catalyzes transfer of a methyl group from O6-methylguanine and O4-methylthymine of alkylated DNA to its own molecule, thereby repairing the pre-mutagenic lesions in a single step reaction. Making use of gene targeting, we developed mouse embryonic stem (ES) cell lines deficient in the methyltransferase. Quantitative immunoblot analysis and enzyme assay revealed that MGMT-/- cells, in which both alleles were disrupted, contained no methyltransferase protein while cells with one intact allele (MGMT+/-) contained about half the amount of protein carried by the parental MGMT+/+ cells. MGMT-/- cells have an extremely high degree of sensitivity to simple alkylating agents, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-methyl-N-nitrosourea (MNU), whereas MGMT+/- cells are slightly more sensitive to these agents, as compared with findings from normal cells. A high frequency of mutation was induced in MGMT-/- cells on exposure to a relatively low dose of MNNG. Electrophoretic analyses of the DNAs as well as fluorochrome staining of the cells revealed that MGMT-/- cells treated with MNNG undergo apoptotic death, which occurs after G2-M arrest in the second cycle of cell proliferation.

Use of serum creatine kinase MM isoforms for predicting the progression of left ventricular dilation in patients with hypertrophic cardiomyopathy

Serum creatine kinase (CK) isoforms were examined to detect the progression of left ventricular (LV) enlargement with reduced motion, resembling dilated cardiomyopathy (DCM), in hypertrophic cardiomyopathy (HCM). Changes in LV indices were determined annually by echocardiography in 51 patients until serum measurements (first follow-up period, 6.5 +/- 2.2 years). Serum creatine isoforms (CKMM1, CKMM2 and CKMM3) were measured with high-voltage electrophoresis in 35 of these patients from 1991 to 1992, and the data for these latter patients are reported here. Serum total CK, CKMB, lactate dehydrogenase and its isoenzyme LDH1 were also measured. The changes in LV indices were further monitored until January, 1995 (second follow-up). During the 2 follow-up periods, the patients in the on-going group showed a reduction in the LV ejection fraction (LVEF) to < 55% with LV end-diastolic dimension (LVDd) < 55 mm, and those in the DCM-like group showed a reduction in LVEF to < 55% and an increase in LVDd to > 55 mm. During the first follow-up period, LVEF and LVDd remained at > or = 55% and < 55 mm, respectively, in 26 patients (nonprogressive-disease group), while 3 patients entered the on-going group and 6 entered the DCM-like group. The CKMM3/CKMM1 ratios in the on-going and DCM-like groups were significantly higher than those in the control and nonprogressive-disease groups. The CKMM3/CKMM1 ratio was significantly correlated with the annual rate of change for the LV end-systolic dimension (LVDs), LVDd, and LVEF, with the closest correlation observed for the annual change in LVDs. Moreover, 5 patients in the nonprogressive-disease group with elevation of the CKMM3/CKMM1 ratio to > + 2SD above the mean for the controls had an elevated annual change in LVDs within +/- 1SD of the mean in the DCM-like group. These results indicate that the ratio of CKMM3 to CKMM1 can be used to predict the progression of LV enlargement in HCM.

Renal transplantation and secondary hyperparathyroidism

Secondary hyperparathyroidism (2'HPT) improves after renal transplantation (RTx) along with recovered function of the renal allograft. However, normal renal function does not last long due to rejection, drug-induced nephrotoxic nepthropathy, or recurrence of post-transplant glomerulonephritis. Therefore, improved calcium and phosphate metabolism, and parathyroid function after RTx fluctuate in accordance with the function of the renal allograft. In cases with severe 2'HPT, parathyroidectomy should be performed before RTx because hypercalcemia due to secondary or tertiary hyperparathyroidism aggravates the renal allograft function. In the follow-up of mild 2'HPT after RTx, hypercalcemia and vascular calcification should be monitored carefully by serum parathyroid hormone, calcium and phosphate concentrations, alkaline phosphatase activity, and bone X-ray film. If serum calcium level exceeds 12 mg/dl, parathyroidectomy (PTx) should be performed to prevent the acceleration of vascular calcification. Total PTx with forearm allograft is a preferred surgical procedure for 2'HPT even after RTx.

Surgical treatment of renal hyperparathyroidism

Advanced secondary (renal) hyperparathyroidism induced by chronic renal disturbance is one of the most serious complications for long-term hemodialysis patients. Parathyroidectomy is indicated in patients with severely advanced renal hyperparathyroidism refractory to medical treatment (including calcitriol pulse therapy) and the clinical effect of parathyroidectomy is striking. However, skeletal deformity, vessel calcification, and remarkable reduction of bone content is irreversible, and it is important to perform parathyroidectomy at right time. Based on histopathological and pathophysiological investigations, nodular hyperplasia is monoclonal neoplasia with abnormal parathyroid hormone (PTH) response to extracellular calcium and vitamin D. When parathyroid hyperplasia progresses to nodular hyperplasia, parathyroidectomy should be required. Total parathyroidectomy with forearm autograft is the preferable procedure for renal hyperparathyroidism, especially for patients who need to continue hemodialysis treatment after parathyroidectomy. Removal of all parathyroid glands, including supernumerary glands, at the initial operation, and proper choice of adequate parathyroid tissue for autograft, are important to prevent persistent and recurrent hyperparathyroidism. Preoperative image diagnosis is useful for localization, and routine resection of thymic tissue is necessary to remove supernumerary glands. In our series of 548 patients, graft-dependent recurrent hyperparathyroidism was not negligible and the incidence was about 20% at the 5th year postoperatively. Enlarged autografts of parathyroid tissue could be removed from forearm under local anesthesia with fewer invasions. The function of autografted parathyroid tissue is nearly satisfactory and no re-transplantation of cryopreserved parathyroid tissue was necessary. To avoid adynamic bone disease, relatively high PTH level is required-over-suppression of PTH by excess of vitamin D and calcium salts should be avoided. In our experience, total parathyroidectomy with forearm autograft is very effective and adequate treatment for advanced renal hyperparathyroidism, and parathyroid function can be controlled after parathyroidectomy.

Parathyroid function and bone metabolic markers in primary and secondary hyperparathyroidism

Remarkable changes of parathyroid function immediately after parathyroidectomy were evaluated in primary (PHPT) and secondary (RHPT) hyperparathyroidism. Bone metabolism was also evaluated by new specific markers of bone formation and resorption. A rapid decline into the undetectable range, and a rapid recovery of serum bioactive parathyroid hormone (PTH) concentrations were observed after parathyroidectomy in PHPT. Since the function of the remnant parathyroid glands was not clear, we investigated the transcription of PTH mRNA. Despite the suppression of PTH secretion in the remnant parathyroid glands, no significant difference was found in the amount of PTH mRNA present in an adenoma as compared to a remnant gland when evaluated by cytoplasmic dot hybridization and in situ hybridization. Although measurement of serum PTH concentration by assays of inactive fragment was available for the longterm follow-up of PTH function in RHPT, parathyroid function should be evaluated by biologically active intact PTH immediately after operation. The PTH gradient also was successfully evaluated by the measurement of intact PTH. A discrepancy was observed between bone resorption evaluated by type I collagen cross-linked N-telopeptide as compared to bone formation evaluated by osteocalcin immediately after operation. This discrepancy will improve and bone mineral density will increase in the first 6 months after parathyroidectomy.

Surgery for renal hyperparathyroidism--experience of 640 cases

Our experience in the field of surgery for renal hyperparathyroidism, gained from 640 cases, the largest number in the world, was reviewed. Additional comments were made on the relation between renal transplantation and renal hyperparathyroidism.

Histopathology, pathophysiology, and indications for surgical treatment of renal hyperparathyroidism

Morphological changes in the parathyroid glands evidently occur early during renal failure. Histopathological investigations have suggested that parathyroid cells initially increase diffusely with a normal lobular structure (diffuse hyperplasia). The parathyroid glands then become hyperplastic with some nodules (nodular hyperplasia). Cells in nodules grow monoclonally and proliferate aggressively, possibly induced by some kind of genetic abnormality. Pathophysiologically, in cells consisting of hyperplastic nodules, suppression of parathyroid hormone (PTH) secretion under the influence of excess extracellular calcium is more deranged, possibly due to a reduction of calcium-sensing receptors. Vitamin D receptor density decreases more severely in these cells, possibly causing abnormal PTH synthesis, PTH secretion, and even parathyroid cell proliferation. According to histopathological and pathophysiological findings, patients with nodular hyperplasia during renal hyperparathyroidism may be refractory to medical treatments, including calcitriol pulse therapy, and parathyroidectomy will become necessary. There is a relationship between the pattern of parathyroid hyperplasia and glandular weight in which glands weighing more than 500 mg may be pathognomonic of nodular hyperplasia. Glandular volume, estimated by ultrasonography, is one of several important criteria indicating parathyroidectomy. In order to prevent a recurrence of hyperparathyroidism, all nodular hyperplastic tissue should be extirpated.

Surgical treatment of renal hyperparathyroidism

Advanced secondary (renal) hyperparathyroidism induced by chronic renal disturbance is one of the most serious complications for long-term hemodialysis patients. Parathyroidectomy is indicated in patients with severely advanced renal hyperparathyroidism refractory to medical treatment (including calcitriol pulse therapy) and the clinical effect of parathyroidectomy is striking. However, skeletal deformity, vessel calcification, and remarkable reduction of bone content is irreversible, and it is important to perform parathyroidectomy at right time. Based on histopathological and pathophysiological investigations, nodular hyperplasia is monoclonal neoplasia with abnormal parathyroid hormone (PTH) response to extracellular calcium and vitamin D. When parathyroid hyperplasia progresses to nodular hyperplasia, parathyroidectomy should be required. Total parathyroidectomy with forearm autograft is the preferable procedure for renal hyperparathyroidism, especially for patients who need to continue hemodialysis treatment after parathyroidectomy. Removal of all parathyroid glands, including supernumerary glands, at the initial operation, and proper choice of adequate parathyroid tissue for autograft, are important to prevent persistent and recurrent hyperparathyroidism. Preoperative image diagnosis is useful for localization, and routine resection of thymic tissue is necessary to remove supernumerary glands. In our series of 548 patients, graft-dependent recurrent hyperparathyroidism was not negligible and the incidence was about 20% at the 5th year postoperatively. Enlarged autografts of parathyroid tissue could be removed from forearm under local anesthesia with fewer invasions. The function of autografted parathyroid tissue is nearly satisfactory and no re-transplantation of cryopreserved parathyroid tissue was necessary. To avoid adynamic bone disease, relatively high PTH level is required-over-suppression of PTH by excess of vitamin D and calcium salts should be avoided. In our experience, total parathyroidectomy with forearm autograft is very effective and adequate treatment for advanced renal hyperparathyroidism, and parathyroid function can be controlled after parathyroidectomy.

Possible participation of cyclooxygenase-2 in the recurrence of allergic inflammation in rats

In the recurrence of allergic inflammation in a rat air pouch model, pouch fluid volume, prostaglandin E2 concentration in the pouch fluid, leukocyte infiltration into the pouch fluid, and granulation tissue weight were markedly increased by the antigen challenge. To clarify the role of cyclooxygenase-2 in the recurrence of allergic inflammation, the time-course of changes in protein levels of cyclooxygenase-1 and cyclooxygenase-2 in the granulation tissue and in the infiltrated leukocytes was examined by Western blot analysis. It was shown that cyclooxygenase-1 levels in the granulation tissue and in the infiltrated leukocytes were not changed by the antigen challenge, but cyclooxygenase-2 levels were increased. Furthermore, treatment with the selective cyclooxygenase-2 inhibitor, NS-398 ([N-2(cyclohexyloxy-4-nitrophenyl]-methanesulfonamide), suppressed the recurrence of allergic inflammation as did the non-selective cyclooxygenase-1/cyclooxygenase-2 inhibitor, indomethacin. The steroidal anti-inflammatory drug, dexamethasone, inhibited the induction of cyclooxygenase-2, and suppressed the allergic inflammation. These findings strongly suggested that cyclooxygenase-2 induced by the antigen challenge plays a role in the recurrence of inflammation induced by the allergic mechanism.

Organization and expression of the mouse MTH1 gene for preventing transversion mutation

An enzyme, 8-oxo-7,8-dihydrodeoxyguanosine triphosphatase (8-oxo-dGTPase), is present in various organisms and plays an important role in the control of spontaneous mutagenesis. The enzyme hydrolyzes 8-oxo-dGTP, an oxidized form of dGTP, to 8-oxo-dGMP, thereby preventing the occurrence of A:T to C:G transversion, caused by misincorporation. We isolated the mouse genomic sequence encoding the enzyme and elucidated its structure. The gene, named MTH1 for mutT homologue 1, is composed of at least five exons and spans approximately 9 kilobase pairs. A genomic region containing the pseudogene was also isolated. The promoter region for the gene is GC-rich, contains many AP-1 and AP-2 recognition sequences, and lacks a typical TATA box. Primer extension and S1 mapping analyses revealed the existence of multiple transcription initiation sites, among which a major site was defined as +1. The putative promoter region was placed upstream of the chloramphenicol acetyltransferase reporter gene, and control of expression of the gene was examined by introducing the construct into mouse NIH 3T3 cells. Deletion analysis indicated that a sequence from -321 to +9 carries the basic promoter activity while an adjacent region, spanning from +352 to +525 stimulates the frequency of transcription.

A unique enzyme from Saccharothrix sp. catalyzing D-amino acid transfer

A newly isolated actinomycete belonging to Saccharothrix sp. was found to produce a unique enzyme catalyzing D-amino acid transfer. The enzyme, which was tentatively named D-amino acid transferase, was purified 2600-fold to electrophoretic homogeneity and the molecular mass was 41 kDa. The enzyme was D-configuration specific and recognized aromatic D-amino acid esters to form oligo D-amino acid esters. D-Phenylalanine ester was favored as substrate over other D-amino acid esters. The optimum conditions for oligo D-phenylalanine ester formation by D-amino acid transferase were pH 7.0 and 40 degrees C. The enzyme was inhibited by DAN, EPNP and DFP.

Semi-quantitative analysis of telomerase in pancreatic ductal adenocarcinoma

Using a polymerase chain reaction-based amplification assay, we measured telomerase activity in surgically resected pancreatic ductal carcinomas (n = 16 cases) and normal ducts (n = 6), comparing findings with the telomerase activity of a human pancreatic cancer cell line, MIA PaCa-2, as a standard, i.e., relative telomerase activity was determined. Telomerase activity was expressed as the equivalent telomerase intensity of the number of cells of MIA PaCa-2 per microgram protein of tissue samples. The median value for telomerase activity in normal pancreatic ducts was 0.13 and the 25th and 75th percentile were 0.01 and 0.76. The median value for telomerase activity in pancreatic ductal adenocarcinoma was 34.7 (25th percentile, 4.98; and 75th percentile, 296), significantly higher than that of normal ducts (P < 0.001). When the cut-off value was set at 1.0 and 3.0, the telomerase positivity rate of pancreatic ductal adenocarcinomas was 100% and 81.3%, respectively. Telomerase may be specific marker for pancreatic ductal carcinomas.