Prediction of transition to chronic atrial fibrillation in patients with paroxysmal atrial fibrillation by signal-averaged electrocardiography: a prospective study

BACKGROUND

It is well known that paroxysmal atrial fibrillation (PAF) often precedes the establishment of chronic atrial fibrillation (CAF). However, there have been no definite methods to predict the transition from PAF to CAF. The purpose of this report was to determine prospectively whether P-wave-triggered signal-averaged ECG (P-SAE) is useful for the prediction of the transition to CAF in patients with PAF.

METHODS AND RESULTS

One hundred twenty-two consecutive patients with PAF were prospectively followed after P-SAE, echocardiography, and 24-hour Holter monitoring at study entry. The duration (Ad) and root-mean-square voltage for the last 30 ms (LP30) of the filtered P wave were measured in P-SAE. The abnormality of P-SAE for the prediction of transition to CAF was defined as Ad > or = 145 ms and LP30 < 3.0 microV. Twenty-three (19%; group 1) of the patients had the abnormality of P-SAE, whereas the others (group 2) did not. During the follow-up period (mean, 26+/-12 months), 10 patients (43%) in group 1 acquired CAF, whereas the transition to CAF was observed in only 4 patients (4%) in group 2. Kaplan-Meier analysis revealed that the transition to CAF was significantly observed more often in group 1 than in group 2 (log-rank test, P<.0001). The Cox proportional hazards regression model identified that the variables most significantly associated with the transition to CAF were Ad (chi2=8.6, P=.003) and LP30 (chi2=5.1, P=.02), although significant differences in the left atrial dimension (40.8+/-5.3 versus 37.3+/-5.5 mm, P<.01) and the number of atrial premature contractions (3641+/-4524 versus 1489+/-2895 beats/d, P<.05) were observed between groups 1 and 2.

CONCLUSIONS

These results indicate that P-SAE could be useful to identify patients at risk for the transition from PAF to CAF.

[Future prediction of tuberculosis incidence rates by prefecture]

We tried to predict the tuberculosis incidence rates by the year 2000 and 2005, based on the trends of incidence rates from the year 1981 to 1995 reported by the Ministry of Health and Welfare (MOHW). According to the studies conducted, the tuberculosis incidence rate in 2000 was predicted as 29.8 (95% CI: 28.7-30.8) per 100,000 population and that in 2005 was predicted as 25.2 (95% CI: 24.2-26.3 per 100,000 population in Japan. The incidence rates by prefecture in 2000 and 2005 were also predicted. The MOHW introduced some new tuberculosis control plans and has set on interim goal by the year 2000 to achieve a tuberculosis incidence at below 20 per 100,000 population. Whereas the possibility of achieving the stated incidence rate goal even by the year 2005 is very low in Japan, among prefectures, several prefectures were predicted to reach this level by the year 2000. Over several years the incidence rate in Japan has been high in the west and low in the east. However this is expected to greatly change in the future. The speed of decline in tuberculosis incidence rates has been stagnated since around 1980 with average annual declination rate from the year 1981 to 1995 was 3.3%. Among 17 prefectures, Tokyo Metropolitan had the lowest declination rate with an average annual declination rate of 1.1%. The prefecture surrounding Tokyo also showed low declination speed. This may indicate that in the future, the problems of tuberculosis will be concentrated in and around the big cities.

Thyroid transcription factor-1 activates the promoter activity of rat thyroid Na+/I- symporter gene

We have cloned 15 kbp of rat thyroid Na+/I- symporter gene from liver genomic library, which contains 6 kbp upstream sequence from the translation initiation site. Southern blot analysis of the genomic DNA from the liver has revealed that thyroid Na+/I- symporter gene is the single gene in the rat. To study the tissue-selective expression mechanism of the gene, we at first determined the transcriptional start site of the gene. Results of a rapid amplification of cDNA end procedure as well as that of primer extension analysis indicated that the transcriptional start sites clustered between -96, -95, and -93 bp of the gene (A in ATG is designated as +1). Chimeras containing 1.9 kbp (-1967 to -46 bp) of the 5'-flanking sequence of the Na+/I- symporter gene and luciferase gene expressed significant enzyme activity when transfected into a rat thyroid cell line, FRTL-5, but little activity was observed in BRL-3A rat liver cells. Deletion analysis of the constructs indicated that a minimal region, exhibiting promoter activity and cell specificity, is located between -291 and -134 bp of the gene. Deoxyribonuclease I footprinting shows that nuclear extracts from FRTL-5, but not BRL-3A, cells protect a region between -245 and -230 bp. Electrophoretic mobility shift assays have demonstrated that nuclear extracts from FRTL-5 cells formed a specific DNA-protein complex with an oligonucleotide probe corresponding to -250 to -211 bp of the gene, but that from BRL-3A cells did not, suggesting that thyrocyte-selective nuclear factors bind to the region. When the nuclear extracts from FRTL-5 cells were preincubated with antibody against thyroid transcription factor-1 (TTF-1), homeodomain containing nuclear protein, formation of the complex was abolished and the band was supershifted. We also found that the probe formed a DNA-protein complex with the recombinant TTF-1 homeodomain, and mutations of the binding site eliminated factor binding. When pRc/CMV-TTF-1 was cotransfected with the minimal promoter fragment of thyroid Na+/I- symporter gene into FRT cells, which express no TTF-1, it caused a significant increase in the transcriptional activity of the reporter construct, but not of the construct having mutated TTF-1-binding element. These results suggest that TTF-1 confers the cell-selective expression of Na+/I- symporter gene in thyrocytes.

Cocaine-induced liver injury in mice is mediated by nitric oxide and reactive oxygen species

The modulating effects of nitric oxide (NO) and reactive oxygen species on cocaine-induced hepatotoxicity were examined by measuring plasma alanine aminotransferase activity and by carrying out histological studies. Liver injury was induced by a single injection of cocaine in adult male ICR mice. Pretreatment with aminoguanidine (an inhibitor of NO synthase), N-methyl-D-glucamine dithiocarbamate complex with iron ion (II) (Fe2+(MGD)2, a trapping reagent of NO) or deferoxamine complex with iron ion (III) (Fe3+-deferoxamine, a scavenger of NO) produced a marked inhibition of the hepatotoxicity induced by cocaine. In addition, pretreatment with allopurinol (an inhibitor of xanthine oxidase) and 1,3-dimethylthiourea (a scavenger of hydroxyl radical) also produced a potent inhibition. These findings suggest that a hydroxyl radical produced by the reaction of NO and superoxide anion (O2-) via peroxynitrite may be involved in the pathogenesis of cocaine hepatotoxicity.

Alpha-fetoprotein (AFP) levels in normal children

Alpha-fetoprotein (AFP) is an important tumor marker for yolk sac tumor and hepatoblastoma in childhood. We have been using the graph of the normal range of serum AFP made by Tsuchida et al, when we evaluate the serum AFP levels in early infancy. We measured the serum AFP levels by an immunoradiometric assay in 163 normal infants under 2 years of age, in order to make a more precise graph. Our normal range was a little wider than that of Tsuchida et al. According to our graph, false-positive cases would be fewer. Referring to the half-lives of serum AFP levels in normal infancy is also useful, when it is difficult to evaluate the AFP level.

The influence of restraint stress on the expression of mRNAs for IL-6 and the IL-6 receptor in the hypothalamus and midbrain of the rat

Using the reverse transcriptase-polymerase chain reaction (RT-PCR), we investigated the influence of restraint stress on the expression of the mRNA for interleukin-6 (IL-6) and the mRNA for the IL-6 receptor (IL-6R) in the rat brain. After rats had been restrained for 4 hours, the hypothalamus and midbrain were removed at fixed intervals up to 24 hours, and levels of IL-6 mRNA and of IL-6R mRNA in these regions were determined by RT-PCR. Restraint stress significantly enhanced the expression of IL-6 mRNA and reduced that of IL-6R mRNA in the midbrain, whereas the stress caused the reduced expression of IL-6R mRNA without any change in the level of IL-6 mRNA in the hypothalamus. After the stress, the expression of mRNAs for IL-6 and IL-6R continued to diminish in both regions. These findings indicate that the levels of mRNAs for both of IL-6 and IL-6R in the rat brain can be influenced by restraint stress.

Suppression of serum-induced c-jun expression by activated Ki-ras in human colon cancer cells

Through gene-targeting, we have established human colon cancer cell lines, HK2-6 and HKe-3, with and without activated Ki-ras, respectively, derived from a human colon cancer cell line HCT116, and we have reported that activated Ki-ras is involved in the deregulation of c-myc expression. To further examine the relation between Ki-ras-mediated signals and other immediate early genes, c-jun was analyzed on these cells stimulated by serum. Rapid and strong induction of c-jun was observed in HKe-3, but not in HCT116 or HK2-6. To elucidate the regulatory mechanisms of c-jun expression by Ki-ras, protein kinase C (PKC) and c-Raf were examined at serum-starved and serum-stimulated conditions. Phosphorylations of c-Raf were same among these cells, however, the cytosolic PKC activity in HKe-3 was two times higher than that in HCT116 on serum-starved and serum-stimulated conditions. These results suggested that serum responsiveness of c-jun may be suppressed by activated Ki-ras through PKC rather than c-Raf pathway in colon cancer cells.

Calphostin C synergistically induces apoptosis with VP-16 in lymphoma cells which express abundant phosphorylated Bcl-2 protein

A newly established human lymphoma cell line (OZ) has the t(14;18)(q32;q21) translocation and expresses large amounts of Bcl-2 compared to CCRF-CEM cells. VP-16 (40 micrograms/mL), a promising agent against lymphoma, caused DNA fragmentation (26.9% of total DNA) typical for apoptosis at 6 h in CCRF-CEM cells, but no significant changes in OZ cells until 24 h after the addition of VP-16. However, coincubation with calphostin C (0.2 microgram/mL), a protein kinase C (PKC) inhibitor, induced DNA fragmentation in VP-16-treated OZ cells (13.5% of total DNA) at 6 h after the treatment. Simultaneous immunoblot analysis revealed that this induction of apoptosis coincided with the downregulation of serine-phosphorylated Bcl-2 (13% of control cells). By contrast, apoptosis induced by VP-16 in CCRF-CEM cells was attenuated by the addition of 0.5 microM phorbol 12-myristate 13-acetate, a potent PKC stimulator. These observations suggest that Bcl-2 function is partly regulated by phosphorylation/ dephosphorylation mechanisms of the PKC system, and that phosphorylated Bcl-2 in lymphoma cells may play a role in the prevention of apoptosis.

DNA typing of HLA class I (HLA-A) and class II genes (HLA-DR, -DQ and -DP) in Japanese patients with gastric cancer

Gastric cancer is multifactorial disease and several reports have described genetic factors involved in pathogenesis of gastric cancer. Recently, it was reported that HLA class II gene DQB1*0301 was strongly associated with gastric cancer in Caucasian population (20). We performed DNA typing of HLA class I (HLA-A) and HLA class II genes (HLA-DR, DQ and DP) to elucidate the HLA alleles or HLA haplotypes associated with gastric cancer in Japanese population using polymerase chain reaction-sequence-specific oligonucleotide probe analysis in 88 unrelated patients with gastric cancer and 525 unrelated healthy controls. We observed slight difference in frequencies of some HLA alleles and haplotypes between gastric cancer patients and controls; however, after Bonferroni correction, statistical significance was not confirmed. It is possible that environmental factors such as diet cover the contribution of genetic factors to the disease in Japanese population, which has a higher frequency of gastric cancer than do Caucasian populations, most likely due to more exposure to environmental risk factors.

Regulation of major histocompatibility complex class I gene expression in thyroid cells. Role of the cAMP response element-like sequence

The major histocompatibility complex (MHC) class I gene cAMP response element (CRE)-like site, -107 to -100 base pairs, is a critical component of a previously unrecognized silencer, -127 to -90 bp, important for thyrotropin (TSH)/cAMP-mediated repression in thyrocytes. TSH/cAMP induced-silencer activity is associated with the formation of novel complexes with the 38-base pair silencer, whose appearance requires the CRE and involves ubiquitous and thyroid-specific proteins as follows: the CRE-binding protein, a Y-box protein termed thyrotropin receptor (TSHR) suppressor element protein-1 (TSEP-1); thyroid transcription factor-1 (TTF-1); and Pax-8. TTF-1 is an enhancer of class I promoter activity; Pax-8 and TSEP-1 are suppressors. TSH/cAMP decreases TTF-1 complex formation with the silencer, thereby decreasing maximal class I expression; TSH/cAMP enhance TSEP-1 and Pax-8 complex formation in association with their repressive actions. Oligonucleotides that bind TSEP-1, not Pax-8, prevent formation of the TSH/cAMP-induced complexes associated with TSH-induced class I suppression, i.e. TSEP-1 appears to be the dominant repressor factor associated with TSH/cAMP-decreased class I activity and formation of the novel complexes. TSEP-1, TTF-1, and/or Pax-8 are involved in TSH/cAMP-induced negative regulation of the TSH receptor gene in thyrocytes, suppression of MHC class II, and up-regulation of thyroglobulin. TSH/cAMP coordinate regulation of common transcription factors may, therefore, be the basis for self-tolerance and the absence of autoimmunity in the face of TSHR-mediated increases in gene products that are important for thyroid growth and function but are able to act as autoantigens.

Alterations of p53 and Rb genes in a novel human GM-CSF-dependent myeloid cell line (OHN-GM) established from therapy-related leukaemia

A novel GM-CSF-dependent myeloid cell line, OHN-GM, was established from a patient who developed acute myelogenous leukaemia (AML) as a consequence of myelodysplastic syndrome (MDS). As the patient had previously received cytotoxic chemotherapy for Hodgkin's disease, the MDS and AML were probably related to such therapy. Sequential karyotypic analysis established a del(5q) as the initial cytogenetic abnormality. Additional alterations, including t(10;13)(q24;q14), had developed subsequently during disease progression. Southern blot analysis of OHN-GM cells suggested deletion of one allele of the IRF-1 gene, although no aberrant transcripts were detected. Fluorescence in situ hybridization analysis revealed the deletion of the Rb gene due to the t(10;13)(q24;q14) translocation, and Western blot analysis demonstrated the absence of Rb protein in OHN-GM cells. Finally, the OHN-GM cells exhibited two missense point mutations in highly conserved regions of the p53 gene. These observations suggest that a multistep process, involving alterations of Rb and p53 genes, may have contributed to the patient's disease development and progression. To our knowledge, OHN-GM is the first cell line derived from a therapy-related AML. These cells may aid the investigation of leukaemogenesis as well as the biology of secondary leukaemia.

Establishment of a novel human B-cell line (OZ) with t(14;18)(q32;q21) and aberrant p53 expression was associated with the homozygous deletions of p15INK4B and p16INK4A genes

The novel human pre-B cell line OZ was established from a patient with an aggressive form of non-Hodgkin's lymphoma. Karyotypic analysis of both the primary tumour and OZ cells revealed several marker chromosomes, including the t(14;18)(q32;q21) translocation, which involves the Bcl-2 gene, and alterations on chromosome 17p. Southern blot analysis found identical rearrangements in the 5' region of Bcl-2 gene in the primary tumour and OZ cells. Homozygous deletions of the p15INK4B and p16INK4A genes, however, were present only in OZ cells. Western blot analysis detected aberrant small molecular-weight p53 proteins in both cell types. In addition, OZ cells no longer expressed the CD20 antigen. These findings suggest that Bcl-2 gene rearrangement and aberrant p53 expression resulted in the original B-cell tumour. A subsequent transforming event involving the p15INK4B and p16INK4A genes may have generated more immature cells with a growth advantage during in vitro culture. The genetic alterations involving p53, p15INK4B, and p16INK4A may be implicated in the aggressive form of t(14;18)(q32;q21)-bearing tumours and their poor prognosis.

The Spirulina platensis adenylate cyclase gene, cyaC, encodes a novel signal transduction protein

A cyaC gene encoding an adenylate cyclase of the filamentous cyanobacterium Spirulina platensis was sequenced. The predicted amino acid sequence of the C-terminal region of cyaC is similar to the catalytic domains of adenylate cyclases in other cyanobacteria and eukaryotes. The sequences of other regions are similar to those of proteins consisting of the bacterial two-component signal transduction system: the sensory kinase and the response regulator. The predicted gene product of cyaC contains, from the N-terminal end, a receiver domain of the response regulator protein (R1), a domain similar to the ETR1 of Arabidopsis thaliana, a transmitter domain of the sensory kinase protein, a receiver domain of the response regulator protein (R2), and a catalytic domain of adenylate cyclase. The cyaC gene was expressed as an affinity-tagged protein in Escherichia coli, and the recombinant protein was purified. The purified protein had adenylate cyclase activity which was activated by Mu2+. The results of Western blotting using an anti-CyaC antiserum and the S.platensis cell extract confirmed that cyaC gene is expressed in S. platensis.

Isolation and characterization of multiple adenylate cyclase genes from the cyanobacterium Anabaena sp. strain PCC 7120

Adenylate cyclase genes, designated cyaA, cyaB1, cyaB2, cyaC, and cyaD, were isolated from the filamentous cyanobacterium Anabaena sp. strain PCC 7120 by complementation of a strain of Escherichia coli defective for the presence of cya. These genes encoded polypeptides consisting of 735, 859, 860, 1,155, and 546 amino acid residues, respectively. Deduced amino acid sequences of the regions near the C-terminal ends of these cya genes were similar to those of catalytic domains of eukaryotic adenylate cyclases. The remaining part of each cya gene towards its N-terminal end showed a characteristic structure. CyaA had two putative membrane-spanning regions. Both CyaB1 and CyaB2 had regions that were very similar to the cyclic GMP (cGMP)-binding domain of cGMP-stimulated cGMP phosphodiesterase. CyaC consisted of four distinct domains forming sequentially from the N terminus: a response regulator-like domain, a histidine kinase-like domain, a response regulator-like domain, and the catalytic domain of adenylate cyclase. CyaD contained the forkhead-associated domain in its N-terminal region. Expression of these genes was examined by reverse transcription-PCR. The transcript of cyaC was shown to be predominant in this cyanobacterium. The cellular cyclic AMP level in the disruptant of the cyaC mutant was much lower than that in the wild type.

Surgical treatment and outcome for node-negative gastric cancer

BACKGROUND

The clinicopathologic characteristics and prognosis for patients with node-negative gastric cancer have heretofore remained to be determined.

METHODS

We analyzed data on 730 of our patients with node-negative gastric cancer who underwent curative gastric resection in the Department of Surgery II, Kyushu University Hospital, between 1965 and 1990, with reference to prognostic factors. The presence of lymph node metastasis was determined by means of routine hematoxylin-eosin staining of excised tissues.

RESULTS

The 5-year survival rate was 91.7% and the 10-year rate was 88.5%; thus the prognosis was good for patients with node-negative gastric cancer. When the prognosis was analyzed by stratification of each clinicopathologic factor, the survival time was shorter for older patients when the size of the tumor was larger, when the tumor involved the entire stomach, and when-tissues revealed infiltrative growth, serosal invasion, and lymphatic invasion. Extensive lymph node dissection was performed for 86.6% of the patients, and for these patients the prognosis was better, with a statistical difference. In a multivariate analysis, tumor size, serosal invasion, and extensive lymph node dissection proved to be independent prognostic factors for patients with node-negative gastric cancer.

CONCLUSIONS

Prophylactic lymph node dissection for patients with gastric cancer will prolong the survival time.

[Long-term follow-up of the Le Duc-Camey antireflux technique]

BACKGROUND

An effective ureteroileal reimplantation without reflux and obstruction is indispensable for lower urinary reconstruction or diversion using an ileal segment. Based on our earlier experience of afferent nipple valve malfunction of the Kock pouch, we performed Le Duc-Camey antireflux ureteroileal implantation. In the present study, we evaluated the long-term outcome of the Le Duc-Camey technique on the upper urinary tract in patients with a postoperative observation period of 2 years or more.

PATIENTS AND METHODS

From 1989 to 1994, 39 patients (73 ureters) underwent Le Duc-Camey technique for prevention of reflux of a Kock pouch. In 28 patients the ileal reservoir was connected to the skin for cutaneous urinary diversion, and in 11 it was connected to the urethra for lower urinary reconstruction. The ureters were implanted into the reservoir through the anterior wall window of the reservoir. In most patients, excretory urography (DIP) was performed once a year after the first year. Retrograde cystography or voiding cystourethrography was performed within 12 months postoperatively. After the first year, retrograde study was performed once during the follow-up period in the majority of the patients. The mean follow-up period was 44.8 months (range 24-71 months).

RESULTS

There was no urinary tract dilatation in 68 renal units (93.1%), while slight dilatation was noted in 3 (4.1%), moderate dilatation in 1 (1.4%), and marked dilatation due to stenosis of ureteroileal anastomosis in 1 (1.4%). Retrograde studies revealed absence of reflux in all patients. Another complication that related to this procedure was not observed in any patients.

CONCLUSION

We conclude that Le Duc-Camey technique is effective in reflux prevention and protection of the upper urinary tract, and recommend it for use with detubularized ileal reservoir.

An approach to the detection of autonomic neuropathy by use of signal-averaged electrocardiography

The beat-to-beat variation of PR interval, which is thought to be a reflection of autonomic nervous system, is difficult to measure with accuracy because the variation is too subtle. However, R wave amplitude in the P wave triggered SAECG is easily attenuated in comparison to that in the R wave triggered SAECG, which might be due to PR interval fluctuation. To determine whether autonomic neuropathy could be detected by use of SAECG, two types of SAECGs triggered by P and R waves were recorded in 23 diabetics with autonomic neuropathy and 41 age matched controls. The peak voltage of filtered QRS complex was measured in the R wave and P wave triggered SAECGs. Percent attenuation of the filtered QRS voltage was calculated by dividing the difference between the voltages in the R wave and P wave triggered SAECGs by the voltage in R wave triggered SAECG. The percent attenuation of filtered QRS voltage was significantly smaller in diabetics with autonomic neuropathy than controls (4.6% +/- 4.9% vs 16.3% +/- 15.0%; P < 0.001). These results suggest that the degree of attenuation of filtered QRS voltage in the P wave triggered SAECG would be useful for the detection of autonomic neuropathy.

Comparison of the antagonistic activity of tamsulosin and doxazosin at vascular alpha 1-adrenoceptors in humans

alpha 1-Adrenoceptor blockers such as prazosin and doxazosin are used to treat hypertension as well as benign prostatic hyperplasia (BPH), whereas the new alpha 1-adrenoceptor blocker tamsulosin is used only for BPH and does not reduce blood pressure at the doses used to relax prostatic smooth muscle. In contrast to prazosin, tamsulosin has a higher affinity for prostatic than vascular alpha 1-adrenoceptors in vitro. The functional correlate of this observation in humans is the subject of this study. The alpha 1-adrenoceptor blockade by oral tamsulosin (0.2 mg), doxazosin (1 mg) or placebo on finger tip vascular and dorsal hand venous alpha 1-adrenoceptors stimulated by cold treatment (immersion in ice water) and the alpha 1-adrenoceptor agonist phenylephrine, was thus studied in a 3-way crossover study in eight, healthy, male adults. Finger tip vasoconstriction after cold stimulation was assessed by laser Doppler flowmetry. A linear variable differential transformer was used to assess the drug effect on phenylephrine-induced venoconstriction. All study parameters were assessed at around 2 and 3.5 h after oral intake of doxazosin and tamsulosin respectively. The drug plasma levels were not significantly different. No significant differences were found for blood pressure or heart rate in the three treatments in supine and erect position. The reduction in finger tip blood flow after cold stimulation was significantly smaller after doxazosin treatment (P < 0.01) than after tamsulosin or placebo, whereas there was no significant difference between tamsulosin and placebo treatments. The infusion rate of phenylephrine producing a half-maximum venoconstriction was significantly larger after doxazosin than after tamsulosin (P < 0.05) or placebo (P < 0.01), whereas there was again no significant difference between tamsulosin and placebo treatments. The data suggest that, at doses producing equal plasma levels after single oral doses in human subjects, the blocking activity at vascular alpha 1-adrenoceptors is lower for tamsulosin than for doxazosin.

Cloning of the single strand DNA-binding protein important for maximal expression and thyrotropin (TSH)-induced negative regulation of the TSH receptor

Contiguous with the 5'-end of the thyroid transcription factor-1 (TTF-1) element upstream of the minimal TSH receptor (TSHR) promoter and within it, there is an element on the noncoding strand with single strand- binding activity. Mutation analyses indicate that it is functionally distinct from the TTF-1 element and is important for the constitutive expression and TSH/cAMP-induced negative autoregulation of the TSHR in thyroid cells but only constitutive expression in nonthyroid cells. In this report we identify a cDNA encoding a single strand-binding protein (SSBP) that forms a specific complex with the noncoding strand of the TSHR, contiguous with the 5'-end of both TTF-1 elements; we term it SSBP-1. SSBP-1 increases promoter activity when contransfected with heterologous SV40 promoter-chloramphenicol acetyltransferase (CAT) chimeras containing the upstream SSBP-binding element from the TSHR promoter or with TSHR promoter-CAT chimeras containing both or only the downstream SSBP element. Mutational analyses reveal that a GXXXXG motif is important for the binding and enhancer function of SSBP-1. TSH/cAMP decreases SSBP-1 RNA levels, as well as SSBP-1/TSHR DNA complex formation, in functioning rat FRTL-5 thyroid cells but not nonfunctioning FRT thyroid or Buffalo rat liver cells that have no TTF-1. SSBP-1 RNA is present ubiquitously; however, its levels are higher in FRTL-5 cells and are increased by overexpression of TTF-1 in cells treated with TSH. This reverses TSH-induced negative regulation of the TSHR. SSBP-1 is, therefore, a positive regulator of TSHR gene expression that contributes to TSHR maximal expression by binding to the SSBP elements. It is a ubiquitous, single-strand transcription factor whose expression in FRTL-5 thyroid cells is, however, regulated by a thyroid-specific gene, TTF-1. TSH/cAMP induces negative autoregulation of the TSHR, in part, by decreasing maximal expression resultant from SSBP-1 binding to the SSBP elements. Like Y-box proteins, which are involved in negative regulation of the TSHR, SSBP-1 also interacts with the major histocompatibility class II promoter S-box; the interaction is single strand-specific. This supports the hypothesis that common transcription factors regulate TSHR and major histocompatibility gene expression. Of additional interest and again like Y-box proteins, SSBP-1 is a member of a family of SSBPs that interact with RNA and are important in RNA processing, can interact with the promoter of retroviruses, and can interact with a gene linked to growth and DNA replication, c-myc.

Presence of poorly stained myocytes in acute myocarditis predicts improvement in cardiac function

Histological findings in the acute phase of myocarditis were evaluated as a prediction of hemodynamic state in the chronic phase in 20 patients with clinical and pathological diagnoses of myocarditis who were followed up with echocardiography for at least 1 year. Endomyocardial biopsy samples were obtained from the left ventricle within 1 year of the onset of symptoms. Azan-Mallory staining was performed on the myocytes, which were categorized as either well stained or poorly stained. The point counting method was used to determine the fraction of each type. The improvement in ejection fraction within 1 year correlated significantly with the fraction of poorly stained myocytes (r = 0.46, p < 0.05). The ejection fraction at biopsy was negatively correlated with the volume fraction of well stained myocytes (r = -0.64, p < 0.01). The staining condition of myocytes may be useful in predicting the hemodynamic recovery of patients with myocarditis.

Effect of ranitidine on renal clearance of lomefloxacin

OBJECTIVE

To examine the effect of ranitidine on the renal clearance of lomefloxacin.

SETTING

Department of Clinical Pharmacology, Jichi Medical School.

METHODS

Lomefloxacin 200 mg and ranitidine 300 mg or its placebo were given orally in a randomised, double-blind, crossover design. Blood and urine samples were obtained during a 24-h period after dosing.

RESULTS

The area under the plasma concentration-time curve and the elimination half-life of lomefloxacin were significantly increased following coadministration with ranitidine. These effects were caused by significant decreases in total (7.8%) and renal (22%) clearance of lomefloxacin. In contrast, creatinine clearance and urinary excretion of electrolytes were not influenced by ranitidine.

CONCLUSION

As lomefloxacin and ranitidine are excreted in urine by renal tubular secretion, the present results suggest that the renal tubular secretion of lomefloxacin is diminished by ranitidine. As the reduction in lomefloxacin clearance is only marginal, it is probable that the drug interaction observed in this study is not of clinical significance.

Influence of age on venodilator effect of isoproterenol and amrinone

OBJECTIVE

To investigate the influence of age on the venodilator effect of isoproterenol, a beta-adrenoceptor agonist, and amrinone, a selective phosphodiesterase (PDE) III inhibitor, in human subjects.

METHODS

In eight young and eight elderly male subjects, the drugs were infused into a dorsal hand vein preconstricted with phenylephrine and its diameter was measured using a linear variable differential transformer.

RESULTS

The maximum venodilation (Emax) induced by isoproterenol was significantly smaller and the infusion rate of isoproterenol required to induce 50% of maximum venodilation (ED50) was significantly larger in the elderly than in the young subjects [Emax: 29.8 vs 95.1%, ED50: 97.3 vs 51.6 ng.min-1]. A significant age-related change in Emax or ED50 was not observed for amrinone (Emax: 95.8 vs 100.8%, ED50: 40.1 vs 31.6 micrograms.min-1).

CONCLUSION

The data show that the venodilator effect of amrinone is not influenced by age. As amrinone increases cyclic AMP by inhibition of PDE III, it is suggested that the action of cyclic AMP is not altered by age. The decreased effect of isoproterenol might be caused by reduced production of cyclic AMP in elderly subjects.