Conformation of DNA modified at a d(GG) or a d(AG) site by the antitumor drug cis-diamminedichloroplatinum(II)

The purpose of this work was the comparison of the conformational changes induced in the double helix by the adducts formed at d(GG) and d(AG) sites in the reaction between the antitumor drug cis-diamminedichloroplatinum(II) (cis-DDP) and DNA. Two duplexes (20-mer) containing either a single d(A*G*) or a single d(G*G) adduct were studied by means of gel electrophoresis and artificial nuclease and chemical probes. It is shown that the d(G*G*) and the d(A*G*) adducts bend DNA similarly, but at the nucleotide level they distort differently the double helix. We suggest that the weaker interactions between platinated A residues and the other nucleotides, as compared to the interactions between platinated G residues and the other nucleotides, are largely responsible for the differences in the distortions induced in DNA by the d(A*G) and d(G*G*) adducts. This suggestion is supported by the study of the distortions induced in duplexes by the d(G*G*) adducts, one of the platinated G residues being paired with a T residue.

Characterization of cDNA clones encoding two putative isoforms of the alpha 1 subunit of the dihydropyridine-sensitive voltage-dependent calcium channel isolated from rat brain and rat aorta

cDNA clones encoding rat brain and rat aorta isoforms of the alpha 1 subunit of the dihydropyridine-sensitive, voltage-dependent calcium channel were isolated and sequenced. These tissue-specific cDNA clones share significant amino acid similarity with the rabbit skeletal muscle calcium channel alpha 1 subunit (75% and 66% amino acid identity for rat brain and rat aorta isoforms, respectively). Northern analysis revealed transcript sizes of 6.5 and 8.6 kb in aorta and 8.6 kb in brain.

Evidence for the existence of a cardiac specific isoform of the alpha 1 subunit of the voltage dependent calcium channel

Biochemical, pharmacological and electrophysiological evidence implies the existence of tissue specific isoforms of the L-type VDCC. The alpha 1 and alpha 2 subunits of the skeletal muscle calcium channel have been previously cloned and their amino acid sequence deduced. Here we report the isolation and sequencing of a partial cDNA that encodes a heart specific isoform of the alpha 1 subunit. The amino acid sequence deduced from this part cDNA clone shows 64.7% similarity with the skeletal muscle alpha 1 subunit. Northern analysis reveals 2 hybridizing bands, 8.5 and 13 kb, in contrast to one 6.5 kb band in the skeletal muscle. Selective inhibition of mRNA expression in Xenopus oocytes by complementary oligodeoxy-nucleotides derived from the heart clone provides further evidence that the cDNA corresponds to an essential component of the VDCC. These data further support the existence of tissue-specific isoforms of the L-type VDCC.

Developmental regulation of expression of the alpha 1 and alpha 2 subunits mRNAs of the voltage-dependent calcium channel in a differentiating myogenic cell line

The voltage-dependent calcium channel (VDCC) in skeletal muscle probably plays a key role in transducing membrane charge movement to the calcium release channel. We report here that the expression of VDCC alpha 1 and alpha 2 mRNAs is developmentally regulated in differentiating C2C12 myogenic cells. The alpha 1 mRNA is not detectable in the myoblast form of C2C12 cells while its expression is induced 20-fold in differentiated myotubes. In contrast, the alpha 2 mRNA is weakly expressed in myoblasts but is also induced upon myogenic differentiation.

Changing patterns of neuroleptic dosage over a decade

A study of patterns of neuroleptic dosage for 206 schizophrenic inpatients showed significant differences over time and among three centers--a general hospital psychiatric unit, a community mental health center, and a state hospital. In 1982 patients' mean dose at discharge was higher than the peak mean daily dose in 1973, and high-potency neuroleptics were being used almost exclusively. The mean length of stay decreased from 49 days in 1973 to 34 days in 1982. The possible relationship, if any, between increasing dosage, decreased length of stay, and the switch from low-potency to high-potency neuroleptics remains undetermined.

New positive inotropic agent OPC-8212 modulates single Ca2+ channels in ventricular myocytes of guinea pig

The effects of a new positive inotropic drug, OPC-8212 (a quinolinone derivative, 3,4-dihydro-6-[4-(3,4-dimethoxybenzoyl)-1 -piperazinyl]-2(1H)-quinolinone), on whole-cell and single-channel calcium currents of guinea pig ventricular myocytes were studied by the patch-clamp method. OPC-8212 increased whole-cell calcium currents in a concentration-dependent manner. The concentration-response curve was fitted by a single binding site model that has an ED50 of 2.7 microM. At the single-channel level, OPC-8212 increased calcium currents mainly by increasing the probability of channel opening on depolarization; the open times were slightly increased, but single-channel conductance did not change. The actions of OPC-8212 on single calcium channel currents were compared with those of forskolin, isoproterenol, and caffeine, agents that cause positive inotropic effects associated with an increase in cytoplasmic cyclic AMP level, and with those of the dihydropyridine calcium channel agonist (-)Bay K 8644, an agent that has a positive inotropic effect but does not act through cyclic AMP. OPC-8212 increased calcium currents in a manner that resembled the actions of forskolin, isoproterenol, and caffeine rather than the actions of (-)Bay K 8644. We suggest that activation of calcium currents by OPC-8212 is mediated by an elevation of intracellular cyclic AMP. Since OPC-8212 produces bradycardia and antitachycardiac effects in animals and humans, unlike agents that increase cyclic AMP, additional effects on other currents are likely.

Rate-dependent electrophysiological effects of OPC-8212: comparison to sotalol

The rate-dependent effects of OPC-8212 (6 microM), a new positive inotropic drug which lengthens cardiac action potential duration were studied in dog cardiac Purkinje fibers and compared to the effects of sotalol (30 microM), a class III antiarrhythmic using conventional microelectrode technique. Both OPC-8212 and sotalol lengthened action potential duration in a frequency-dependent manner. Both had a greater effect at slower pacing frequencies than at fast. The maximum rising velocity of the action potential upstroke was not affected by either compound at any of the pacing cycle lengths applied (300-2000 ms). The effects of OPC-8212 and sotalol on action potential duration and maximum rising velocity were also compared following abrupt changes in pacing cycle length (i.e. coupling intervals ranging between approximately 250-3000 ms). The effects of both OPC-8212 and sotalol following abrupt changes in pacing cycle length were similar to one another. Neither OPC-8212 nor sotalol altered the time constants for restitution of action potential duration or the kinetics for recovery of the maximum rising velocity of the action potential upstroke. These results indicate that the rate-dependent electrophysiological effects of OPC-8212 closely mimic those of sotalol and suggest that OPC-8212 may be an effective class III antiarrhythmic in addition to being a positive inotropic compound.

The DNA bending by acetylaminofluorene residues and by apurinic sites

We have studied the distortions induced in double-stranded oligonucleotides by covalently bound acetylaminofluorene residues and by apurinic sites. Within the acetylaminofluorene-modified oligonucleotide three base-pairs are unpaired as detected by the chemical probes chloroacetaldehyde and osmium tetroxide. These two probes reveal that the bases adjacent to the apurinic site are paired. In both the modified double-stranded oligonucleotides, the backbone on the 5' side of the modification is more reactive with 1,10-phenanthroline copper than the backbone on the 3' side. On polyacrylamide gels, the ligated multimers of acetylaminofluorene or apurinic site-modified oligonucleotides migrate slower than the multimers of the unmodified oligonucleotides. It is suggested that the acetylaminofluorene-modified guanine residues and the apurinic sites behave more as hinge joints than as the centres of directed bends.

The scintigraphic characteristics of ventricular pre-excitation through Mahaim fibers with the use of phase analysis

The phase image pattern of blood pool scintigrams was blindly assessed in 11 patients exhibiting conduction through Mahaim pathways, including 6 nodoventricular and 5 fasciculoventricular. These patterns were compared with the phase image findings in normal subjects, patients with left and right bundle branch block in the absence of pre-excitation and patients with pre-excitation through atrioventricular (AV) connections. In all patients with a Mahaim pathway, the site of earliest phase angle was septal or paraseptal. Phase progression was asymmetric and the pre-excited ventricle demonstrated the earliest mean ventricular phase angle in 10 of 11 patients. This pattern, and the associated ventricular phase difference, appeared to vary from that in normal subjects and in those with a septal AV connection, in whom phase progression is generally symmetric. Scintigraphic phase analysis provided localizing information and presented patterns consistent with Mahaim pathways. Although not able to differentiate among Mahaim pathway subtypes, these phase patterns differed from those in normal subjects, those with right and left lateral free wall pathways and most patients with a septal AV pathway. However, the phase pattern of patients with a Mahaim pathway may not differ from that of patients with a septal AV connection displaying an asymmetric pattern of phase progression, or those with left and right bundle branch block in the absence of pre-excitation. Objective, yet imperfect phase measurements supported these differences. Such image findings may complement the often complex electrophysiologic evaluation of patients presenting with pre-excitation.

Management of an enlarging aortic aneurysm in the presence of radiation induced retroperitoneal fibrosis

Despite a thoracoabdominal retroperitoneal approach to an enlarging symptomatic infrarenal aortic aneurysm, proximal aortic dissection was hazardous due to radiation induced retroperitoneal fibrosis. Iliac artery ligation and thoracic aorta to iliac artery bypass has resulted in successful management during 14 months of follow-up.

The validity and reliability of photographic documentation of proliferative vitreoretinopathy

The Silicone Study is a multicentered, randomized surgical trial designed to compare the tamponade effectiveness of silicone oil versus long-acting gas in the treatment of proliferative vitreoretinopathy (PVR) by vitrectomy and associated techniques. Fundus photographs are taken to provide documentation of the anatomic status of eyes proposed for entry and are graded at an independent Reading Center. This article describes the protocol for photographic documentation of PVR as a continuum of increasing pathology, in which the pathology may only be present in the anterior retina, and the retina is usually highly elevated. In a validity and reliability study, agreement between photographic and clinical observation within one step was obtained for 88% of the eyes; intra- and inter-observer agreement within one step was 85 and 80%, respectively. Differences between the surgeon's grade and the Reading Center's were caused about equally by disagreement regarding extent of fixed folds and width of the funnel. Rarely did peripheral folds not visible in the photographs appear to be the sole explanation of the disagreement. Differences among readers were concerned mainly with differentiation of true full-thickness fixed folds from folds due to simple redundancy of the detached retina. These results demonstrate that complicated retinal detachment (RD) can be photographically documented and independently assessed.

[Eosinophilic histiocytic granuloma of the vulva and cervix]

In a patient aged 29 a recurrent histiocytic granuloma developed in vulva, vagina and cervix. The patient was treated by cervical resection followed by irradiation. Langerhans cells with Birbeck granules in plasma of the cells, besides multiple eosinophilic leucocytes were evidenced by electron microscope. The eosinophilic histiocytic granuloma is suggested to be a benign variety of histiocytosis X, whose basic cellular component is the Langerhans cell. Eosinophil leucocytes represent a local immune response in the benign variety of histiocytosis X.

Cytomegaloviral and cryptosporidial cholecystitis in two patients with AIDS

We report two cases of acalculous cholecystitis due to infection with cytomegalovirus (CMV) and cryptosporidium. Both involved homosexual men who presented with right upper quadrant pain and elevations of serum alkaline phosphatase and bilirubin. Cholecystectomy specimens showed a thickened gallbladder wall and ulcerated mucosa. There were no stones. CMV inclusion bodies were found in granulation tissue at the base of ulcers and intact mucosa surrounding ulcers. Cryptosporidia were aligned along the luminal surface of intact mucosal epithelial cells. Both organisms have a patchy distribution; hence the diagnosis requires a high degree of suspicion. The prognosis is poor. Following cholecystectomy, both patients pursued a downhill course with development of pancreatitis and cholangitis. Both patients are now dead.

Insulin-like growth factor II mRNA expression in human breast cancer

Insulin-like growth factor II is a growth factor important in fetal development. Several cancer tissues and cell lines have been reported to express IGF-II and rat IGF-II is mitogenic for breast cancer cell lines. Using Northern analysis and ribonuclease protection assays, IGF-II mRNA was detected in normal fibroblasts and in the established breast cancer cell line, T47D. In this cell line, steady state levels of IGF-II message were increased by treatment with estradiol. 10 nM IGF-II, purified from human serum, was mitogenic for breast cancer cell lines. In vitro, IGF-II may act as an autocrine growth factor for some cell lines. RNA derived from breast cancer, pathologically normal breast tissue, and benign breast disease also contained IGF-II mRNA. When paired samples of normal and cancer tissue were obtained from the breast of the same patient, the level of IGF-II mRNA expression in the normal tissue was at least that found in the cancer. This is consistent with previous observations that show IGF-II is expressed in mesenchyme. These findings suggest that in breast cancer IGF-II is produced by stromal tissue elements and potentially by the malignant epithelial cells. Therefore, IGF-II may function as an autocrine or a paracrine growth factor in different breast tumors.

Cyclic AMP-dependent and cyclic AMP-independent actions of a novel cardiotonic agent, OPC-8212

Possible cAMP-dependent and cAMP-independent mechanisms of action for the cardiac effects of OPC-8212, a novel piperazinyl-quinolinone derivative, were evaluated. OPC-8212 was tested for in vitro potency as an inhibitor of soluble bovine cardiac phosphodiesterases using a rapid isolation and assay method involving monoclonal antibodies that distinguish among isozymes. The drug was selective for a low-Km, cGMP-inhibited phosphodiesterase (CGI-PDE) with an IC50 (half-maximal inhibition concentration) of 7.4 mumol/l when measured at a substrate level of 0.35 mumol/l cAMP. Under the conditions used, sulfolane, the solvent for OPC-8212, did not affect CGI-PDE activity. In electrophysiological measurements, OPC-8212 prolonged the action potential duration in canine Purkinje strand preparations up to 148% (APD90) at 10 mumol/l. Concomitantly, OPC-8212 produced a 100% increase in developed force. Both prolongation of the action potential duration and the positive inotropic effect were readily reversed after exposure to tetrodotoxin, 3 mumol/l. Using Na-selective microelectrodes, intracellular Na+ ion activity increased 225% upon exposure to 10 mumol/l OPC-8212. OPC-8212 represents a novel type of positive inotropic agent, possessing both cAMP-dependent (selective PDE isozyme inhibition) and cAMP-independent (activation of intracellular Na+) mechanism of action.

Receptors for calcium antagonists

Calcium antagonists have been divided into 3 different subclasses represented by nifedipine, verapamil and diltiazem. These drugs have different pharmacologic effects and are not interchangeable. Previous studies suggested that all calcium antagonists bind to a 170 kd polypeptide (now called the alpha 2 subunit of the voltage-dependent calcium channel). The apparent molecular weight of this polypeptide characteristically decreased from 170 to 140 kd upon disulfide reduction as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Recent studies demonstrated that calcium antagonists bind to a previously unrecognized 165 kd polypeptide (alpha 1 subunit) that does not change its electrophoretic mobility on disulfide reduction. Because of their similar molecular weights, the 2 polypeptides may overlap each other on polyacrylamide gels. The primary structure of both polypeptides clearly shows, however, that they are different from each other and only the alpha 1 subunit has the features expected of an ion channel.

A clinical diagnostic model for the assessment of asbestosis: a new algorithmic approach

Asbestosis, one of the pneumoconioses that is defined by a set of clinical, radiographic, and pathologic findings, occurs as a result of exposure to asbestos fibers. Several approaches have attempted to describe the presence, progression, or extent of asbestosis. However, these approaches have attempted to describe the presence, progression, or extent of asbestosis. However, these approaches have limitations or lack correlations with other diagnostic modalities. We propose a comprehensive clinical diagnostic model that uses the sensitivities and specificities of the various clinical, radiographic, and pathologic findings to generate a set of "likelihood numbers." These likelihood numbers, contribute to the calculation of a value that can indicate the probability of asbestosis. The clinical diagnostic model is heuristic in that a specific feature supportive of the diagnosis of asbestosis may be tested as to its sensitivity and specificity, and new features may be added to the model. The model also indicates how probabilistic a given set of findings is in the diagnosis of asbestosis and suggests what additional data may make the diagnosis more or less statistically probable. Regarding the radiologic considerations of asbestosis, the strength of the clinical diagnostic model is that it is capable of supporting a diagnosis of asbestosis in the presence of a normal chest radiograph and, conversely, may reject the diagnosis of asbestosis despite the radiographic finding of pulmonary fibrosis.