Functional analysis and chromosomal gene assignment of rat kidney prostaglandin EP3 receptor

We have reported two isoformes of rat prostaglandin EP3 receptor with their different carboxyl-terminal tails (rEP3A and rEP3B receptors), which are derived by alternative RNA splicing, and both receptors have been shown to be localized to renal distal tubules. In the present study, we characterized the signal transduction system of rat kidney EP3 receptors either in a renal cell line mimicking renal distal tubule cells, TKC2, or in COS-7 cells by functional expression of these receptors. We also examined the chromosomal localization of the EP3 receptor gene by fluorescence in situ hybridization (FISH). In TKC2 cells, vasopressin (AVP, 10(-7) M), prostaglandin (PG) E2 (10(-7) M), or forskolin (10(-8) M) markedly stimulated cyclic AMP formation. Overexpression of the rEP3A receptor significantly attenuated the AVP-, PGE2- or forskolin-induced cyclic AMP formation, whereas there was no change with rEP3B receptor expression. On the other hand, in COS-7 cells transfected with rEP3A receptor cDNA, PGE2 (10(-7) M) did not affect cytosolic free calcium concentration ([Ca2+]i), whereas transfection of rEP3B receptor cDNA evoked PGE2-induced increases in [Ca2+]i. Moreover, we have revealed that the rEP3 receptor gene is localized to rat chromosome 2q44-45. In conclusion, rEP3A or rEP3B receptor is suggested as a mediator of the natriuretic/diuretic action of PGE2 in renal distal tubules via a decrease in cyclic AMP formation or an increase in [Ca2+]i, respectively. Information of the gene assignment of rat EP3 receptor to rat chromosome 2q44-45 is useful for further analysis of the role of EP3 receptor in genetically hypertensive rat models.

Angiotensin II attenuates vascular contractility in the rabbit mesenteric artery

We observed the effects of angiotensin II (AII) on the contractile response and the Ca2+ transient induced by high K+ solution in the rabbit mesenteric artery. In the control condition, the repeated application of high K+ solution with 90 min interval induced a gradually increasing contraction, which was accompanied with a significant elevation of the intracellular calcium concentration ([Ca2+]i). Treatment of the tissue with AII for one to two hours abolished the incremental response of the contraction. The change in [Ca2+]i induced by high K+ solution, however, was not significantly different with and without treatment with AII. Pretreatment of the tissue with actinomycin D abolished the inhibitory action of AII on the incremental contraction, indicating the involvement of a transcriptional process. These results indicate that AII impairs vascular contractility through the modulation of Ca(2+)-sensitivity of the contractile machinery.

Competition between Mg2+ and spermine for a cloned IRK2 channel expressed in a human cell line

1. A cloned inwardly rectifying K+ channel, IRK2, was expressed in a human cell line, human embryonic kidney (HEK) 293T. Its electrophysiological properties were examined using the patch clamp technique in the whole-cell, cell-attached and inside-out patch configurations. 2. The cells transfected with IRK2 cDNA exhibited a K+ current which showed classical properties of inwardly rectifying K+ channels at both whole-cell and single-channel levels. 3. In the inside-out patch configuration, intracellular Mg2+ (Mg2+i blocked the outward currents in a voltage-dependent and virtually time-independent manner. Mg2+i (1-100 microM) caused a decrease in the unitary current amplitude of the IRK2 channel by inducing subconducting levels. 4. In the absence of Mg2+i, intracellular spermine blocked the outwardly flowing IRK2 currents in a voltage- and time-dependent manner. Spermine (1-100 nM) did not affect the unitary channel current amplitude but reduced the channel open probability. The spermine block showed a slower time and steeper voltage dependence than the Mg2+i++ block. 5. When both these blockers were present, Mg2+i apparently attenuated the inhibitory effect of spermine on the outwardly flowing IRK2 currents. This interaction was voltage and time dependent, and could be well explained by a model in which Mg2+i and spermine competitively bind to the channel with their individual first-order kinetics. This competition would induce time-dependent transits of the channel between the Mg2+i -and spermine-blocked states via a single open state, thereby preserving a certain size of persistent outward currents at depolarized potentials.

[Tactile extinction following the cerebral sinus thrombosis. A study using event-related potentials]

We reported a 46-year-old woman in whom cerebral sinus thrombosis manifested itself in headache and weakness while she was on an oral estrogen preparation. The neurological examinations revealed monoparesis of the right upper extremity, hyperactive right deep tendon reflex and disturbance of the joint sense, stereognostic sense, two-point discrimination and skin writing sense in the right upper extremity, in addition to tactile extinction. Brain CT showed empty triangle sign. MRI revealed infarction near the left postcentral gyrus and thrombosis of right sigmoid sinus. In the MRA study, there was low signal intensity in the posterior portion of the superior sagittal sinus and right transverse sinus. Short latency SEP in upper extremity showed that the central conduction time was normal, while the amplitude of wave components after N20 was reduced on the right side. Both palms were given bilateral or unilateral pressure stimuli. When event-related potentials (ERP) were evoked, using bilateral stimuli as a rare target, and left unilateral stimuli as a non-target, the P 300 latency was prolonged to 450 msec but was restored to normal with the improvement of tactile extinction. These results seem to suggest that the tactile extinction is ascribable to a disturbance of recognition at the higher brain function level and that ERP can be a useful objective yardstick in the evaluation of extinction phenomenon.

Orientation dependence in homologous recombination

Homologous recombination was investigated in Escherichia coli with two plasmids, each carrying the homologous region (two defective neo genes, one with an amino-end deletion and the other with a carboxyl-end deletion) in either direct or inverted orientation. Recombination efficiency was measured in recBC sbcBC and recBC sbcA strains in three ways. First, we measured the frequency of cells carrying neo+ recombinant plasmids in stationary phase. Recombination between direct repeats was much more frequent than between inverted repeats in the recBC sbcBC strain but was equally frequent in the two substrates in the recBC sbcA strain. Second, the fluctuation test was used to exclude bias by a rate difference between the recombinant and parental plasmids and led to the same conclusion. Third, direct selection for recombinants just after transformation with or without substrate double-strand breaks yielded essentially the same results. Double-strand breaks elevated recombination in both the strains and in both substrates. These results are consistent with our previous findings that the major route of recombination in recBC sbcBC strains generates only one recombinant DNA from two DNAs and in recBC sbcA strains generates two recombinant DNAs from two DNAs.

Genetic analysis of children of atomic bomb survivors

Studies are under way for the detection of potential genetic effects of atomic bomb radiation at the DNA level in the children of survivors. In a pilot study, we have examined six minisatellites and five microsatellites in DNA derived from 100 families including 124 children. We detected a total of 28 mutations in three minisatellite loci. The mean mutation rates per locus per gamete in the six minisatellite loci were 1.5% for 65 exposed gametes for which mean parental gonadal dose was 1.9 Sv and 2.0% for 183 unexposed gametes. We detected four mutations in two tetranucleotide repeat sequences but no mutations in three trinucleotide repeat sequences. The mean mutation rate per locus per gamete was o% for the exposed gametes and 0.5% for the unexposed gametes in the five microsatellite loci. No significant differences in the mutation rates between the exposed and the unexposed gametes were detected in these repetitive sequences. Additional loci are being analyzed to increase the power of our study to observe a significant difference in the mutation rates at the 0.05 level of significance.

Osteoclast function is activated by osteoblastic cells through a mechanism involving cell-to-cell contact

We have established a method for obtaining an enriched preparation of functionally active osteoclast-like multinucleated cells (enriched OCLs) from co-cultures of mouse primary osteoblasts and bone marrow cells. Using these enriched OCLs, the effect of osteoblastic cells on osteoclast function was examined in two assays: a pit formation assay and an assay for actin ring formation. The enriched OCLs cultured for 24 h on dentine slices formed only a few resorption pits. When various numbers of primary osteoblasts were added to the enriched OCLs, the areas of the resorption pits increased proportionally to the number of osteoblasts added. Like primary osteoblasts, the established cell lines of osteoblastic cells (MC3T3-E1 and KS-4) and bone marrow-derived stromal cells (MC3T3-G2/PA6 and ST2) potentiated the pit formation caused by enriched OCLs. In contrast, the fibroblastic cell lines NIH3T3 and C3H10T1/2) and the myoblastic cell line (C2C12) failed to activate OCL function. When cell-to-cell contact between MC3T3-E1 cells and enriched OCLs was prevented, only a few resorption pits were formed. Pit formation by enriched rat osteoclasts placed on dentine slices was also stimulated by adding MC3T3-E1 cells. Actin ring formation and pit forming activity were well correlated in either culture of enriched mouse OCLs or authentic rat osteoclasts on dentine slices. These results indicate that osteoclast function is activated by osteoblastic cells through a mechanism involving cell-to-cell and/or cell-to matrix contact.

Regionalized expression of the Dbx family homeobox genes in the embryonic CNS of the mouse

Here we report the identification of a novel homeobox gene family Dbx in mouse, which consists of Dbx and Dbx2. The two genes share similar structural organization and are encoded by different chromosomes. The predicted Dbx and Dbx2 proteins share 85% identity in their homeodomain amino acid sequences, but otherwise showed no significant similarity. Characterization of the expression of these two genes in the embryos suggested their role in the development of the CNS. In the forebrain, Dbx is expressed in various regions, while Dbx2 showed a more restricted pattern of expression. In the midbrain, the expression domains of Dbx and Dbx2 overlap along the dorso-lateral wall of the ventricle. In the hindbrain and spinal cord, both genes are expressed in the boundary separating the basal and alar plates, which seems to correspond to the sulcus limitans. Expression of the Dbx/Dbx2 genes is restricted to the ventricular region of the embryonic CNS except for that of Dbx in the septum of the telencephalon. Together these observations indicate possible participation of the members of the Dbx family in regionalization of the CNS. While the expression of Dbx was restricted to the CNS, Dbx2 was also expressed in some of the mesenchymal cells, such as limb buds and tooth germs.

[Simple partial seizure consisting of complex visual hallucinations due to left temporo-occipital lesion]

We report a case of simple partial seizure consisting of elementary visual hallucinations and complex visual hallucinations due to left temporo-occipital lesion. The patient was a 45-year-old right-handed female who has been suffering from paroxysmal visual hallucinations in her right visual field for 15 days before admission. The properties of the hallucinations included several round colorful figures, the upper torsos of people in red, and green trees. CT scan showed a small low density area which, limited to the basal part of the left temporal and occipital lobes, was complicated partially by a high density area that was thought to be calcified. On T2-weighted MRI images, the lesion was shown as a small oval-shaped high signal intensity area surrounded by a low signal intensity area, and from its characteristic findings, a cavernous angioma was suspected. On the EEG, epileptic discharge was observed in the area limited to the left occipital region when elementary visual hallucinations occurred, and high amplitude diffuse slow waves were revealed predominantly on the left when complex visual hallucinations developed. It was thought that elementary visual hallucinations occurred in this patient following epileptic discharge of the occipital lobe, and complex visual hallucinations developed secondarily to the discharge which expanded from the occipital lobe to the surrounding area. Considering the investigation of non-epileptic visual hallucinations that are observed in the hemianopic visual field, we believe that disturbances of function of the temporo-parietal lobes around the occipital visual cortex has an important role in causing the development of complex visual hallucinations.

Translocation (9;11;22)(p22;q23;q11). A new type of complex variant translocation of t(9;11)(p22;q23) with MLL rearrangement

We describe a patient with acute monocytic leukemia (M5a, FAB classification) associated with a new type of variant translocation (9;11). Southern blot analysis showed the rearrangement of the MLL (ALL-1/HRX) gene at 11q23. Fluorescence in situ hybridization (FISH) with painting probes of chromosomes 9, 11, and 22 revealed the translocation as t(9;11;22) (p22;q23;q11). This is more evidence that the production of chimeric mRNA following the translocation of the LTG9 (MLLT3/AF9) gene at 9p22 to 11q is a critical event in this leukemia subtype.

Does inhibition of coronary nitric oxide synthesis alter coronary vascular tone in normal dogs?

To examine whether endothelial nitric oxide formation contributes to the vascular tone of resistance coronary vessels in vivo, we administered NG-nitro-L-arginine methyl ester (L-NAME) (10 and 100 micrograms/kg/min), a nitric oxide synthase inhibitor, as well as D-enantiomer into the left circumflex artery in normal dogs. Intracoronary L-NAME, which was associated with dose-related reductions in acetylcholine-induced coronary vasodilation, significantly reduced the baseline left circumflex blood flow by 6% and increased coronary vascular resistance of the left circumflex artery by 6%. D-enantiomer was ineffective in altering baseline coronary blood flow and vascular resistance of the left circumflex artery. These results indicate that continuous nitric oxide formation in the vasculature is important in the regulation of the coronary vascular tone of resistance vessels in vivo, and serves to maintain the vessels in a dilated state.

Surgical treatments of chronic idiopathic thrombocytopenic purpura and prognostic factors for splenectomy

To determine the prognostic factors for splenectomy in patients with chronic idiopathic thrombocytopenic purpura (ITP), 26 consecutive patients who had undergone splenectomy as a treatment for ITP in the last 20 years were investigated retrospectively. Predictive values of age, sex, the interval between diagnosis and surgery, presence of antiplatelet antibodies or accessory spleen, bleeding time, response to corticosteroids, response to high-dose immunoglobulin, weight of spleen, serum platelet-associated immunoglobulin G, preoperative maximal platelet count, and preoperative minimal platelet count were examined with multivariate analysis by multiple regression. Age less than 50 years at surgery, platelet count of 100 x 10(9)/l or more in response to high-dose immunoglobulin, and a maximal platelet count of 100 x 10(9)/l or more before splenectomy were favorable prognostic factors (p < 0.05). The correlation coefficient, sensitivity, specificity, and positive-predictive value of the analyzed multiple regression based on prognostic factors were 0.885, 68.8%, 85.7% and 91.7%, respectively. In conclusion, splenectomy is an effective treatment for younger patients, large maximal preoperative platelet counts and preoperative immunoglobulin dependence. Multivariate function analysis was useful for predicting outcome.

[Neuroendocrine carcinomas of the head and neck]

Neuroendocrine carcinomas (NECs) of the head and neck are rare. Between 1980 and 1995, only 163 cases of laryngeal and 30 cases of sinonasal NEC had been reported worldwide. We report two cases of sinonasal NEC. Case 1: A 49-year-old man complaining of left nasal obstruction was admitted to our hospital. A tumor with a tendency to bleed was seen in the left nasal cavity. CT scanning revealed an enhanced mass in the left nasal cavity and both maxillary and ethmoid sinuses. An open biopsy was performed to determine the diagnosis. The diagnosis of NEC was based on light microscopic and immunohistochemical findings. Chemotherapy and radiation were performed, but bone, liver and brain metastasis occurred 15 months after diagnosis and the patient died. Case 2: A 59-year-old man, complaining of right forehead swelling visited our department. CT scanning and MRI revealed that the right ethmoid sinus was filled by a tumor which had invaded the base of the skull. An open biopsy was performed. From the results of light microscopic and immunohistochemical investigations, NEC was highly suspected. Chemotherapy and radiation were performed, but the patient died 6 months after diagnosis. This study shows that there are aggressive types of nasal NEC, although these sinonasal carcinomas were reported in the literature to be not very lethal. The diagnosis, histopathological classification, treatment, and prognosis of sinonasal and laryngeal NECs were reviewed.

Detailed oligosaccharide structures of human integrin alpha 5 beta 1 analyzed by a three-dimensional mapping technique

Structures of N-linked oligosaccharides obtained from human integrin alpha 5 beta 1 are described. Integrin alpha 5 beta 1 (4.5 mg) was purified from human placenta and digested using trypsin and chymotrypsin. N-linked oligosaccharides were released from the glycopeptides by digestion with glycoamidase A (from almond). The reducing ends of the oligosaccharides were derivatized with 2-aminopyridine. The pyridylamino-oligosaccharides were separated and these structures were identified by a three-dimensional HPLC mapping technique on three kinds of HPLC columns [Takahashi, N., Nakagawa, H., Fujikawa, K., Kawamura, Y. & Tomiya, N. (1995) Anal. Biochem. 226, 139-146]. Finally, 35 different oligosaccharide structures were identified, 10 of which were neutral, 6 mono-sialyl, 10 di-sialyl, 7 tri-sialyl and 2 tetra-sialyl. The molar ratio of neutral, mono-sialyl, di-sialyl, tri-sialyl and tetra-sialyl oligosaccharides was 20.8%, 24.8%, 27.7%, 18.1% and 8.6%, respectively. High-mannose-type oligosaccharides accounted for only 1.5% of the total. The remaining oligosaccharides were all complex type. The most predominant structure was the diantennary di-alpha-(2,3)-sialyl fucosyl. Major linking of sialic acid was alpha-(2,3)-linkage, and over 50% of all oligosaccharides were fucosylated at the N-acetylglucosamine residue of the reducing end.

Intra-arterial chemotherapy for muscle-invasive urinary bladder cancer

A total of 9 patients with muscle-invasive bladder cancer (T3 or T4N0M0) were treated with a modified intra-arterial M-VEC (IA-M-VEC) regimen beginning in October 1992 to evaluate its therapeutic efficacy, and in 3 evaluable patients who subsequently underwent radical cystectomy, the possibility of bladder preservation was assessed. The responses of the 8 evaluable patients were rated as complete response (CRs) in 3, partial response (PRs) in 3 and no change (NCs) in 2. The objective response rate (PR + CR) was 75%. An obvious down-staging (T3 --> pT1b) was confirmed in 2 of the 3 evaluable patients, suggesting the possibility of bladder preservation. Otherwise similar changes to hemorrhagic cystitis with minimal muscular fibrosis were conspicuous in the normal bladder wall. These pathological findings corresponded with those obtained by dynamic single photon emission computed tomography (D-SPECT) using 99mTC-macroaggregate albumin (99mTC-MAA). Besides a buttock-to-perianal erosion with neuralgia on the injection side, mild to moderate sensory disturbance of the sacral plexus was observed.

G protein-gated K+ channel (GIRK1) protein is expressed presynaptically in the paraventricular nucleus of the hypothalamus

We prepared a specific antibody against GIRK1, the major subunit of the G protein-gated K+ (KG) channel. Immunohistochemical study revealed that GIRK1 immunoreactivity was detected in the presynaptic, but not in the postsynaptic, region in the paraventricular nucleus of the rat hypothalamus (PVN). Therefore, activation of the KG channel may underlie presynaptic inhibition of neurotransmitter release by various agonists, such as dopamine, noradrenaline, opioids, and histamine, in PVN.

The substrate-binding site in Escherichia coli cyclophilin A preferably recognizes a cis-proline isomer or a highly distorted form of the trans isomer

The three-dimensional structure of Escherichia coli cytosolic cyclophilin A (CyPA) complexed with a tripeptide (succinyl-Ala-Pro-Ala-p-nitroanilide) was refined at 1.8 A resolution by the multiple isomorphous replacement method to a crystallographic R-factor of 17.6%. As in human CyPA, the peptide binding site in E. coli enzyme is in a cleft created on the surface of the upper sheet of two orthogonal beta-sheets. In this cleft, the walls of the hydrophobic pocket are formed by the side-chains of five non-polar residues, Phe48, Met49, Phe107, Leu108, and Try120, with Phe99 at the bottom. When the cis isomer of the tripeptide binds to the enzyme, a cis-proline ring is inserted into the hydrophobic pocket. Since the binding pocket of CyPAs are largely hydrophobic, the cis isomer of a peptide can be bound more firmly than the trans isomer. Distortion of the trans isomer could lead to better binding, but at an energetic cost of the distortion energy. At the periphery of the upper beta-sheet in E. coli CyPA, conformations of loops L1, L3, and L4 and the segment connecting alpha1 and beta3 with deletions or insertions against human CyPA differ significantly from those in human CyPA. The refined model also shows that steric hindrance to attachment of cyclosporin A (CsA) prevents E. coli CyPA forming a complex with CsA. Thus, the extra amino acid residue of E. coli CyPA, polar Gln89, lies along the pathway to the hydrophobic pocket of CyPA and seems to prevent the access hydrophobic part of CsA to the cleft of CyPA.

Effect of low dietary calcium intake on blood pressure and pressure natriuresis response in rats: a possible role of the renin-angiotensin system

Dietary Ca is an important modulator of blood pressure in humans and rats. Since the kidney plays a key role in the pathogenesis of hypertension, the effects of a low Ca diet (0.01% Ca) on blood pressure and pressure natriuresis response were studied in normotensive Sprague-Dawley rats. In addition, a possible role of the renin-angiotensin system in the development of hypertension and an altered pressure natriuresis response resulting from low dietary Ca intake was examined. In the low Ca diet group, systolic blood pressure measured by the tail-cuff method was significantly higher than in the normal Ca diet group (1,1% Ca) 1 week after the diet (1 13.0 +/- 7.1 vs. 105.0 +/- 9.5mmHg, p < 0.05). After 4 weeks, the hypertension was more pronounced. Low dietary Ca intake significantly inhibited the water and sodium excretory responses to acute elevation of renal perfusion pressure by tightening an infrarenal aortic constriction. Treatment with an inhibitor of angiotensin-converting enzyme, captopril (30 mg/kg/day), completely abolished the elevation of blood pressure and attenuated the reduced pressure natriuresis response observed in Ca-deficient rats. Although plasma renin activity was not different between the low and normal Ca diet groups after the 2-week dietary regimen, the pressor response to angiotensin II was enhanced by 30% in the low Ca diet group and there was a significant difference in the pressor response between the two groups. These results suggest a possible involvement of the renin-angiotensin system in the development of hypertension and an inhibitory effect on the pressure natriuresis response caused by low dietary Ca intake, via an enhanced sensitivity to angiotensin II.

Redistribution on I-123 IMP SPECT in children and adolescents with partial seizures

To evaluate the redistribution phenomenon on delayed I-123 IMP SPECT images of children and adolescents with partial seizures, 25 patients were selected and investigated in the interictal state. Early and delayed SPECT were performed 15-20 minutes and 5 hours, respectively, after I-123 IMP injection. Redistribution patterns were classified into three groups: 1) redistribution (RD) (-) group (n = 5), in which a low-uptake area on the early image persisted or was enlarged on the delayed image, 2) RD (+) group (n = 14), in which a low-uptake area on the early image changed to normal distribution on the delayed image, and 3) marked redistribution (MRD) (+) group (n = 6), In which a low-uptake area on the early image changed to a high uptake area on the delayed image. Among the patients who were followed for at least 12 months after the SPECT scans, the short-term clinical outcome tended to be good in the RD (+) group, intermediate in the MRD (+) group, and poor in the RD (-) group. These results of our preliminary comparative study indicate that the redistribution pattern of I-123 IMP may be related to the clinical aspects in patients with partial seizures and that it may play an important role in predicting their short-term clinical outcome.

Interleukin-1 alpha activates an NF-kappaB-like factor in osteoclast-like cells

We investigated the NF-kappaB transcription factor in osteoclast-like cells. Osteoclast-like cells were differentiated from mouse bone marrow cells in co-culture with mouse calvaria-derived primary osteoblasts in the presence of 1alpha,25-dihydroxyvitamin D3 and prostaglandin E2 in collagen gel-coated dishes. We enriched osteoclast-like cells from the co-cultures by Pronase treatment. When the enriched osteoclast-like cells were treated with phorbol 12-myristate 13-acetate, interleukin-1 (IL-1), calcitonin, or macrophage colony-stimulating factor, only IL-1 activated an NF-kappaB-like factor, which specifically bound to a kappaB motif DNA sequence, as detected by an electrophoretic mobility shift assay. IL-1 also activated NF-kappaB induction in osteoblasts. However, the NF-kappaB-like factor induced by IL-1-stimulated osteoclast-like cells is of smaller molecular size than the factor in osteoblasts, as shown by an electrophoretic mobility shift assay. The NF-kappaB activity of osteoclast-like cells was recognized completely by antibodies against the p50 subunit, and only partially by antibodies against the p65 subunit of NF-++kappaB. Antibodies against c-Rel, Rel B, and p52 did not recognize the NF-kappaB-like factor. These results suggest that IL-1 activates an NF-kappaB-like factor in osteoclast-like cells, which contains p50 and p65-related proteins.

Caffeine induces ventricular tachyarrhythmias possibly due to triggered activity in rabbits in vivo

Caffeine induces delayed afterdepolarizations (DADs) and triggered activity in isolated cardiac tissue. We investigated the ability of caffeine to induce triggered ventricular arrhythmias in rabbits in vivo. During continuous infusion of caffeine at doses of 0.3 or 1.0 mg/kg per min, ventricular pacing was performed with 50 stimuli with a cycle length of 220 msec (basic pacing train) every 5 min until ventricular tachycardia (VT) was induced. The effects of programmed stimulation and pharmacologic agents on the induction of ventricular ectopic beats (VEBs) were examined. Pacing protocols were carried out in the presence of vagal-induced slowing of sinus rhythm. VT was induced by a basic pacing train during the infusion of caffeine at 1.0 mg/kg per min, but not at 0.3 mg/kg per min. An increase in the pacing rate or the number of stimuli resulted in 1) a decrease in the first postpacing interval, and 2) an increase in the number of postpacing VEBs. Induction of VT was suppressed by intravenous bolus injections of verapamil, propranolol and adenosine. At the time of the initial induction of VT, the plasma concentration of caffeine was 87 +/- 2 micrograms/ml and the plasma level of norepinephrine increased from 666 +/- 166 pg/ml at baseline to 1121 +/- 245 pg/ml. These results suggest that catecholamine-associated triggered activity may be responsible for caffeine-induced VT.

A phase III randomized trial of cisplatin plus vindesine versus cisplatin plus vindesine plus mitomycin C versus cisplatin plus vindesine plus ifosfamide for advanced non-small-cell lung cancer

A randomized trial of chemotherapy in 105 patients with advanced and metastatic non-small-cell lung cancer (NCSLC) was conducted in order to compare the effect of the additional drug mitomycin C (PVM) or ifosfamide (PVI), to the combination of cisplatin plus vindesine (PV). An objective response rate was observed in 42.8% of the patients treated with PVM, 42.4% with PVI and 28.6% with PV and these response rates were not statistically significant (P > 0.20). No patient achieved the complete response with either of the three regimens. Comparison of the median response durations among the three regimens showed an advantage of PVI over PVM (P < 0.02) and PV (P < 0.05). The median survival times (MST) were similar for all three regimens (PVM, 33.5; PVI, 40.0 and PV, 36.5 weeks); moreover, the difference in survival time between the three regimens of responders was not statistically significant. The univariate analysis showed that significant predictors of survival were performance status (PS) zero (P = 0.0002), limited disease (P = 0.004), no previous weight loss (P = 0.01) and normal serum albumin (P = 0.016), and in multivariate analysis by a stepwise Cox proportional hazard model, these were PS zero (a hazard ratio of 2.3, P = 0.0001) and limited disease (a hazard ratio of 1.9, P = 0.048). Toxicity did not differ among the three treatment regimens.