[An autopsy case of thymic carcinoma producing various tumor markers and the examination of 222 autopsy cases of thymic malignant tumor in Japan]

The autopsy of a 76-year-old Japanese female patient, which revealed thymic carcinoma with various tumor markers such as NSE, CYFRA, and CA-125, is presented. The patient died from hepatic failure because the liver was overtaken by the tumors. At autopsy, the thymic carcinoma was found to have metastased only in the liver. From microscopical analyses and electron microscopical findings, we diagnosed poorly differenciated squamous cell carcinoma of thymic origin. In the histochemical analyses, the tumor cells were positively stained in CA 125, CA 19-9, EMA, NSE, AE 1, AE 3, CEA, S-100, glimerius and Bcl-2. These date suggest that the tumor cells produced various tumor markers. In 222 autopsy cases of thymic malignant tumor observed in Japan over a period of 4 years, the dominant pathohistological image was squamous cell carcinoma. It is interesting that the greatest number of combined malignant tumors with thymic malignancies were thyroid papillary carcinomas.

Macrophage-derived transforming growth factor-beta1 induces hepatocellular injury via apoptosis in rat severe acute pancreatitis

BACKGROUND

The mechanism of acute pancreatitis-induced hepatocellular injury is unclear. We have observed hepatocyte apoptosis in rat acute necrotizing pancreatitis. These studies were designed to determine the mediator(s) responsible for hepatocyte apoptosis and to clarify the significance of macrophages as its source.

METHODS

A rat sodium deoxycholate-induced pancreatitis model was used. Immunohistochemical studies for apoptosis-inducing mediators on hepatocytes were examined in the liver and on the peritoneal macrophages. The levels of transforming growth factor-beta1 (TGF-beta1) were also evaluated quantitatively with an enzyme-linked immunosorbent assay. Induction of apoptosis on the hepatocytes was evaluated by in situ nick-end labeling and tissue DNA fragmentation enzyme-linked immunosorbent assay. Finally, the effects of TGF-beta1 neutralization and macrophage depletion were examined.

RESULTS

In the liver and the peritoneal macrophages, strong expression of TGF-beta1 was detected early in the course of pancreatitis. In sodium deoxycholate-induced pancreatitis, the levels of TGF-beta1 were also elevated in the plasma (9.2 +/- 0.8 ng/mL), in the pancreatitis-associated ascitic fluid (11.5 +/- 0.6 ng/mL), and in the liver homogenate (2.8 +/- 0.3 ng/g of liver tissue). Moreover, the amount of fragmented DNA of the liver with pancreatitis was 290% +/- 20% of that with a sham operation and serum alanine aminotransferase levels elevated to 248.2 +/- 67.0 IU/L. TGF-beta1 neutralization partly blocked the positive labeling on the nuclei of the hepatocytes, the elevation of the amounts of fragmented DNA (205% +/- 10% of sham operation), and the serum alanine aminotransferase level (144.2 +/- 14.9 IU/L). On the other hand, the macrophage depletion caused a marked decrease in the TGF-beta1 protein level in the plasma (4.8 +/- 1.2 ng/mL) or in the pancreatitis-associated ascitic fluid (8.0 +/- 1.0 ng/mL). Moreover, the macrophage depletion completely inhibited the elevation of the TGF-beta1 protein level in the liver homogenate (1.5 +/- 0.4 ng/g of liver tissue), and thereafter decreased the amounts of the positive labeling on the nuclei of the hepatocytes and decreased the amount of fragmented DNA (120% +/- 18% of sham operation) and the serum alanine aminotransferase elevation (119.2 +/- 24.2 IU/L).

CONCLUSIONS

In a model of sodium deoxycholate-induced pancreatitis, macrophages are responsible for pancreatitis-induced hepatocellular injury by means of apoptosis, and macrophage-derived TGF-beta1 is one of the major factors inducing the hepatocyte apoptosis.

[An autopsy case of chronic thromboembolic pulmonary hypertension with long-term progressive dyspnea]

A 71-year-old man who had been suffering from slowly progressive dyspnea on exertion for 16 years was admitted because of hemoptysis and severe dyspnea in 1997. His medical history included respiratory failure in 1986. At that time, chest X-ray films showed cardiomegaly and striking enlargement of hilar pulmonary arteries, while a lung perfusion scan revealed segmental defects. A diagnosis of chronic thromboembolic pulmonary hypertension (CTPH) was made on the basis of multiple filling defects detected by pulmonary angiography and marked pulmonary hypertension (104/29 mmHg) measured by right heart catheterization. The patient died unexpectedly 1 month later. Autopsy revealed a large new thrombotic lesion straddling the organizing thrombotic lesion in the right pulmonary artery. It is important to keep CTPH in mind when examining and treating patients with unexplained dyspnea. In this respect, our case was considered of value to an understanding of the natural course of CTPH.

Survivin promotes cell proliferation in human hepatocellular carcinoma

Survivin is a recently described inhibitor of apoptosis. Because suppression of apoptosis is important for carcinogenesis and tumor growth, we investigated the expression and function of survivin in human hepatocellular carcinomas (HCCs). We have shown that 4 HCC cell lines and 7 out of 8 human HCC tissues expressed survivin messenger RNA (mRNA), whereas expression of survivin mRNA was not detected in normal liver and nontumor areas of these tissues using the reverse transcription polymerase chain reaction. Survivin was detected primarily in the nucleus by immunofluorescence staining of HCC cells. In addition, 14 of 20 (70%) HCC tissues showed positive nuclear staining for survivin, whereas nontumor tissues showed little detectable staining by immunohistochemistry. Survivin expression strongly correlated with the proliferation index but not significantly with the apoptosis index in HCC tissues. Therefore, we performed cell cycle analysis after survivin transfection and showed that overexpression of survivin resulted in a decrease in the G(0)/G(1) phase and an increase in the S phase in all 4 HCC cell lines. Furthermore, we have found that survivin interacted with cyclin-dependent kinase 4 (Cdk4) and overexpression of survivin released p21(WAF1/Cip1) (p21) from Cdk4. From these results, we conclude that survivin promotes cell proliferation by interacting with Cdk4 and releasing p21 from Cdk4. This may play an important role in carcinogenesis and progression of human HCCs.

Reduced expression of ICE/caspase1 and CPP32/caspase3 in human hepatocellular carcinoma

The interleukin-1(-converting enzymes (ICE)/caspase1 and the CPP32/caspase3, cysteine proteases, play an important role in the maintenance of homeostasis by inducing apoptosis. Since human hepatocellular carcinomas (HCCs) demonstrate strong resistance to apoptosis, we investigated the expression of ICE and CPP32 in human HCCs. Reverse transcription PCR analysis revealed that one out of five HCC tissues showed no band of ICE mRNA and two out of five HCC tissues showed no band of CPP32 mRNA. An immunohistochemical study of 20 cases of HCC tissues and non-tumor parts revealed that immunoreactivity of ICE and CPP32 was preferentially observed in the cytoplasm, appearing as a diffuse and homogeneous pattern. Some nuclei also stained with anti-ICE antibody or anti-CPP32 antibody and demonstrated apoptotic features. Overall, the expression of ICE and CPP32 were significantly down-regulated in the HCCs compared to nontumor cells. In situ nick end labeling method (TUNEL) labeling index significantly decreased according to the decreasing staining intensity of CPP32. However, there was no tendency for the TUNEL labeling index to decrease with decreasing ICE staining intensity. Our results suggested that the expression of ICE and CPP32 were down-regulated and that especially reduced expression of CPP32 may contribute to resistance against apoptosis in human HCCs.

C-ERBB-2 gene amplification as a prognostic marker in human bladder cancer

OBJECTIVES

To evaluate c-erbB-2 gene amplification and its prognostic significance in transitional cell carcinoma of the bladder.

METHODS

Alterations in the gene copy number of c-erbB-2 were detected in 57 bladder tumor samples using a method based on the polymerase chain reaction.

RESULTS

Eighteen tumors (32%) showed gene amplification of c-erbB-2, which correlated with tumor grade and stage. A strong association of c-erbB-2 amplification with patient survival was also found. The amplification resulted in a significantly poorer prognosis among the patients with high-grade and/or invasive tumors. Multivariate analysis revealed that c-erbB-2 amplification and tumor grade were independent prognostic factors.

CONCLUSIONS

Our data indicate a possible role of the c-erbB-2 gene in the development of aggressive behavior in bladder tumors. Moreover, the use of c-erbB-2 gene amplification, together with tumor grade and stage, could provide an accurate basis for determining the prognosis of bladder cancer.

Clinico-epidemiology of hepatitis B viral infection in Northeastern Thailand

Hepatitis B viral (HBV) infection is a common disease world wide. A study of clinico-epidemiology of HBV infection was conducted in 381 patients who seropositive for hepatitis B surface antigen (HBsAg) in Srinagarind Hospital, Khon Kaen University, Northeastern Thailand, during August 1997 to December 1998. 293 males, 88 females and their mean age was 30.96 +/- 12.78 years with a range from 15 to 77 years. The clinical features of acute hepatitis, chronic hepatitis, liver cirrhosis, hepatocellular carcinoma (HCC) and asymptomatic carrier were 2.36, 34.12, 4.99, 1.05 and 57.48% of cases. Possible routes for HBV transmission were family history of hepatitis, tattooing, intravenous drug addict and blood transfusion in 20.3, 11.3, 8.2 and 6.9% of cases, respectively. Signs of chronic liver disease were common in liver cirrhosis and HCC. Acute fulminating hepatitis was not found in this study.

Relationship between the pixel value in digital subtraction angiography and iodine concentration: study in high iodine concentration with original phantom

Quantitative digital subtraction angiography (DSA) image analysis based on densitometry is widely accepted and used. For the densitometoric DSA image analysis, it is required that there is a linear relationships between the pixel values on DSA images (DSA values) and contrast medium iodine concentration or the thickness of the vessels or the chambers filled with contrast material. We studied on relationship between the DSA value and iodine concentration especially in high iodine concentration. As for the relationship between DSA values and iodine concentration on the DSA images at low concentration, DSA phantom had a good linear relationship. However, the relationship at the high iodine concentration, DSA phantom sometimes lost this linear relationship. Our results suggested that it was necessary to identify relationship between DSA values and iodine concentration in each DSA system, especially in high iodine concentration setting, for densitometoric DSA image analysis.

Evaluation of intracranial pressure by transcranial Doppler ultrasonography in dogs with intracranial hypertension

Transcranial Doppler ultrasonography (TCD) has been used to confirm changes in cerebral hemodynamics. In this study, we investigated whether the parameters for the basilar artery measured by TCD were correlated with the intracranial and cerebral perfusion pressures in extreme intracranial hypertension. An intracranial hypertension model was produced in seven dogs by inflating a balloon inserted into the epidural space. The resistance index was compared with the corresponding intracranial pressure and cerebral perfusion pressure values during intracranial hypertension. A significant correlation was recognized between the resistance index and cerebral perfusion pressure. Therefore, measurement of the basilar artery by TCD in the dog with intracranial hypertension is useful in estimating the intracranial circulation in cases where the measurement of intracranial pressure is not available or not indicated.

Non-invasive diagnosis of ischemic brain damage after cardiopulmonary resuscitation in dogs by using transcranial Doppler ultrasonography

We have attempted to identify whether it is possible to utilize transcranial Doppler ultrasonography to evaluate the brain damage that occurs after resuscitation from 3 min (control group) and 12 min (damage group) of cardiac arrest in dogs. In this study we used transcranial Doppler ultrasonography to follow the basilar arterial flow and middle cerebral arterial flow for 180 min following the induction of cardiac arrests. Two abnormal waveform patterns (the "to-and-fro" and "diastolic no-flow" patterns) were found in all dogs in the damage group whereas abnormal waveforms were not detected in the control group. Pathological diagnosis revealed that, compared with the control group, the damage group recognized ischemic alteration at the level of the hippocampus and caudate nucleus. In conclusion, this study shows that the basilar arterial flow of observed with transcranial Doppler ultrasonography may be use for the prediction of outcome and the diagnosis of brain damage in the dog.

Cell death and cell-cycle arrest induced by incorporation of [3H]thymidine into human haemopoietic cell lines

PURPOSE

To investigate the influence of [methyl-3H]thymidine ([3H]Tdr) incorporated into human haemopoietic cell lines.

MATERIALS AND METHODS

HL-60, Molt-4, Jurkat, Raji and SKW6-CL4 cells were incubated in the presence of [3H]Tdr. Cell proliferation, cell viability, DNA fragmentation and expression of caspase-3 and Bcl-2 families were examined. The cell-cycle of HL-60 was analysed using flow cytometry.

RESULTS

In HL-60, Molt-4 and Jurkat, cell death was accompanied by DNA nucleosomal fragmentation and activation of caspase-3. In Raji and SKW6-CL4, it was accompanied by neither. Protein levels of Bcl-2 and Bad in HL-60 and Molt-4 did not significantly change, and that of Bax was decreased after a 3-day incubation. HL-60 incubated in the presence of 74 or 185 kBq/ml [3H]Tdr arrested at G2/M phase, and then underwent apoptosis. In 7.4 kBq/ml, the cell-cycle progressed after the delay in S-phase.

CONCLUSIONS

Two different modes of cell death were observed when [3H]Tdr was incorporated into the human haemopoietic cell lines. Incorporation into HL-60 cells resulted in delay of S-phase progression, arrest at G2/M and apoptosis.

Purification, crystallization and preliminary X-ray crystallographic study of alpha-amylase from Bacillus stearothermophilus

A recombinant alpha-amylase from Bacillus stearothermophilus was found to be produced as several isoforms arising from different N--terminal processing. Some of those isoforms were purified to homogeneity and crystallized at 293 K using the hanging-drop vapour-diffusion method under the following conditions: 35 mM sodium acetate (pH 4.6), 6.25%(v/v) 2-propanol, in the presence of 1.23%(w/v) acarbose (a pseudo-oligosaccharide inhibitor) in the drop. The crystals diffracted beyond 2.0 A resolution using synchrotron radiation at the Photon Factory, Tsukuba. They belong to the monoclinic space group P2(1), with unit-cell parameters a = 53.7 (2), b = 92.9 (4), c = 53.2 (2) A, beta = 109.4 (1) degrees.

Stability of the molten globule state of a domain-exchanged chimeric protein between human and bovine alpha-lactalbumins

A domain-exchanged chimeric alpha-lactalbumin (alpha-LA), which consisted of the alpha-domain of human alpha-LA and the beta-domain of bovine alpha-LA, was constructed. Like native alpha-LA, the chimeric protein was in a molten globule state in the absence of Ca(2+) at neutral pH and low salt concentration. The stability of the molten globule state of the constructed chimeric protein was identical to that of the recombinant human protein and was higher than that of the recombinant bovine protein. The stability of the molten globule state of alpha-LA is defined by the stability of the alpha-domain.

Apoptotic cell death of hepatocytes in rat experimental severe acute pancreatitis

BACKGROUND

Apoptosis of hepatocytes has been reported to be involved in liver failure complicated with systemic manifestations such as endotoxemia. We hypothesized that hepatocyte apoptosis occurs in severe acute pancreatitis.

METHODS

Induction of apoptosis was evaluated in the liver from rats with necrotizing pancreatitis. Apoptosis-inducing activity of the pancreatitis-associated ascitic fluid on hepatocytes was evaluated in vivo by intraperitoneal injection of the ascitic fluid and in vitro using rat primary hepatocyte culture.

RESULTS

Apoptosis was detected in hepatocytes in the rats both with severe acute pancreatitis and with the intraperitoneal injection of the ascitic fluid by in situ nick-end labeling and DNA fragmentation. Apoptotic change and hepatic injury were ameliorated by administration of an interleukin-1 beta-converting enzyme inhibitor. The ascitic fluid exhibited cytocidal activity in rat primary hepatocyte culture via apoptosis, which was confirmed by DNA fragmentation, by cell cycle analysis, and by nuclear fragmentation. The neutralizing antibody for transforming growth factor-beta 1 partially blocked the apoptosis induction but the antibody to tumor necrosis factor-alpha had no effect.

CONCLUSIONS

Apoptotic cell death occurs in hepatocytes in severe acute pancreatitis partially via transforming growth factor-beta 1 in the pancreatitis-associated ascitic fluid.

[Renal cell carcinoma in a horseshoe kidney with abdominal aortic aneurysm: a case report]

We herein report a case of renal cell carcinoma in a horseshoe kidney with an abdominal aortic aneurysm in a 69-year-old man. Radiological examinations showed a left renal tumor, horseshoe kidney and abdominal aortic aneurysm. We performed a left radical nephrectomy with the division of the isthmus and artificial graft through an abdominal transperitoneal approach. Histological findings revealed clear cell type renal cell carcinoma without invasion of the capsule or renal pelvis. Only 31 cases of renal cell carcinoma in a horseshoe kidney have been reported in Japan, and our case is the 32nd. No case with abdominal aortic aneurysm has been reported previously. We assume that abdominal aortic aneurysm was associated with renal cell carcinoma by chance in the horseshoe kidney in this case. The arterial and venous supplies vary from case to case. We emphasize that arteriography and venography are very important preoperative procedures.

Hepatocyte growth factor increases in injured organs and functions as an organotrophic factor in rats with experimental acute pancreatitis

We previously reported that serum hepatocyte growth factor (HGF) levels are elevated in patients with acute pancreatitis and that pancreatitis-associated ascitic fluid (PAAF) contains cytotoxic factor(s) inducing apoptosis on Madin-Darby canine kidney (MDCK) cells. In this study, plasma HGF levels and HGF tissue distribution were investigated in rats with experimental acute pancreatitis, and the effects of HGF on the cytotoxic activity and apoptosis-inducing activity of PAAF also were examined. Plasma HGF levels were elevated in rats with two experimental pancreatitis models of different grades of severity. The degree of its elevation was correlated with the severity and the organ dysfunctions. In rats with severe pancreatitis, HGF protein and messenger RNA (mRNA) levels significantly increased in liver, kidney, and lung, which were injured organs. When anti-HGF neutralizing antibody was administered in severe pancreatitis, liver dysfunction worsened, and apoptotic cells increased in kidney. Recombinant HGF inhibited the cytocidal activity of PAAF on MDCK cells in a dose-dependent manner. Moreover, recombinant HGF prevented the apoptotic cell death (DNA fragmentation, nuclear fragmentation, and caspase-3 activation) induced by PAAF. These results suggest that HGF is produced in injured organs and may function as an organotrophic and antiapoptotic factor against the organ injuries in acute pancreatitis.

The comparison between the cerebral blood flow directly measures and cerebral blood flow velocity in the middle and basilar cerebral arteries measured by transcranial Doppler ultrasonography

Transcranial Doppler ultrasonography (TCD) may be useful for determining alterations in cerebral blood flow (CBF) during excessive hemodynamic changes by non-invasive measurement of the CBF velocity. The purpose of this study was to measure the correlation between CBF and the middle cerebral artery (MCA) and basilar artery (BA) flow velocities, as measured by TCD during excessive hemodynamic changes produced by hypertension and hypotension in adult dogs. The peak, diastolic, and mean flow velocities were measured by TCD. Arterial hypertension was induced by administration of dopamine at 5 and 15 microg/kg/min, and hypotension was induced by hemorrhage. During the hemodynamic changes, the BA velocity correlated more closely with the alteration in the CBF than the MCA velocity. In terms of percentages of the values during anesthesia, there was good correlation between CBF and the MCA and BA velocities. In conclusion, our findings indicate that MCA and BA velocity measurements, as a percentage of the values during anesthesia, both give an equally accurate indication of alterations in CBF during excessive hemodynamic changes.

Expression of functional CD40 in human hepatocellular carcinoma

CD40, a member of the tumor necrosis factor receptor (TNFR) family, plays a crucial role in the survival, proliferation, and differentiation in B cells. However, the expression of CD40 other than in B cells has not been well studied. Therefore, we investigated the expression and function of CD40 in hepatocellular carcinomas (HCCs). Expression of CD40 mRNA in 6 established HCC cell lines was analyzed by reverse-transcription polymerase chain reaction (RT-PCR) and CD40 expression on cell surface was examined by flow cytometrical analysis. We also examined the expression of CD40 in human HCC tissues (45 cases) and nontumor liver tissues (30 cases) by immunohistochemistry. To examine the function of CD40 in HCC cells, we investigated the effect of CD40 signaling on anti-Fas antibody and TNF-alpha-induced apoptosis in HepG2 cells. In addition, intracellular levels of cysteine protease P32 (CPP32) protein in HepG2 cells were also determined by Western blotting. We have shown that 6 HCC cell lines constitutively expressed CD40 mRNA and membrane-bound CD40 antigen, which was slightly up-regulated by interferon gamma (IFN-gamma). In addition, 60% of human HCC tissues demonstrated positive staining for CD40, whereas nontumor tissues showed little detectable staining. In HepG2 cells, CD40 stimulation does not affect cell viability, but significantly inhibited Fas and TNFR-mediated apoptosis in a dose-dependent manner by blocking the activation of CPP32. From these results, we conclude that CD40 expression in HCCs plays an important role in tumor biology, especially the resistance against Fas and TNFR-mediated apoptosis.

[Paragonimiasis Miyazakii with variable X-ray shadows]

A 77-year-old woman was admitted to our hospital with hemoptysis and weight loss. She had eaten 15 raw freshwater crabs about 5 months before the onset of her clinical symptoms. Chest X-ray films obtained on the first admission showed left pleural effusion. After 1 week of chemotherapy with SBTPC, the pleural effusion disappeared. Two months later, the patient was re-admitted with recurrent hemoptysis. Chest X-ray films showed a solitary nodular lesion in the right lung. Eosinophilia and increased serum IgE levels were detected. The solitary nodular lesion moved from the middle to upper field of the right lung during the patient's 3-week stay in the hospital. Serologic tests yielded a conclusive diagnosis of Paragonimiasis miyazakii infection. Praziquantel administration relieved the patient's symptoms.

Computerized tomography nephroscopic images of renal pelvic carcinoma

PURPOSE

Computerized tomography (CT) endoscopy is an interactive 3-dimensional image acquired by helical CT. We assess the usefulness of CT nephroscopy in the diagnosis of renal pelvic cancers.

MATERIALS AND METHODS

Surface rendering CT nephroscopy was performed after intravenous administration of contrast agent and furosemide in 32 patients with suspected renal pelvic carcinoma. Retrospective review revealed that 23 patients later underwent nephroureterectomy. Two observers blinded to the pathology results independently reviewed the CT nephroscopic and axial CT images of the 23 patients to localize pelvic tumors and to determine the extent of the disease. The CT nephroscopic and axial CT images were correlated with the pathological findings.

RESULTS

Pathological examination revealed 4 polypoid, 6 pedunculated, 7 sessile, 1 sessile with ulceration and 6 infiltrating renal pelvic carcinomas in the 23 patients. CT nephroscopy revealed 22 carcinomas (92%) and CT demonstrated 20 (83%). CT nephroscopy was superior to axial CT in detecting 4 pedunculated and 3 infiltrating carcinomas but failed to detect 1 sessile carcinoma which completely replaced the upper portion of a double renal pelvis and 1 polypoid tumor associated with infiltrating carcinoma. The CT nephroscopic images correlated well with pathological findings.

CONCLUSIONS

CT nephroscopy is useful to visualize the complex morphology of renal pelvic carcinomas noninvasively and is superior to axial CT for the detection of infiltrating and pedunculated carcinomas.

Growth of Salmonella typhimurium and Salmonella enteritidis in egg yolks from highly immunized hens

This experiment was conducted to ascertain whether the growth of Salmonella Enteritidis (SE) or Salmonella Typhimurium (ST) would be suppressed in the presence of antibodies contained in egg yolks. Specific pathogen-free chickens (102 days of age) were subcutaneously immunized with oil-adjuvanted bacterin of SE or ST, twice within a four-week interval. During 160 to 170 days of age, eggs were collected, the yolks were removed and mixed with an equal volume of physiological buffered saline, inoculated with ten colony forming units (CFU) of SE or ST, and incubated at 37 degrees C or 20 degrees C for 23 hr. The growth of organisms in each yolk solution was examined. The egg yolk derived from non-immunized hens was examined in the same manner as the controls. There was no difference in the growth titer between the antibody-positive yolk and the negative yolk. The result suggests that the antibodies in the yolk do not influence the growth of each organism, even if the hens are highly immunized.

Enterococcus hirae vacuolar ATPase is expressed in response to pH as well as sodium

The Enterococcus hirae ntp operon encodes both a vacuolar ATPase, which transports Na+ as well as Li+, and the KtrII K+ transporter. A plasmid, in which the chloramphenicol acetyltransferase gene (CAT) was placed downstream of the ntp promoter, was introduced into a mutant totally defective in Na+ extrusion. The CAT activity of this transformant was increased preferentially by addition of NaCl, but not by LiCl, in the media or by elevating the medium pH, correlating well with the increase in amounts of the ATPase subunits observed by Western blotting. The physiological significance of these responses of the ntp promoter is discussed.