A cis-acting element in the promoter region of the murine c-myc gene is necessary for transcriptional block

A block to elongation of transcription has been shown to occur within the first exon of the human and murine c-myc genes. The extent of this block was found to vary with the physiological state of cells, indicating that modulation of the transcriptional block can serve to control the expression of this gene. To determine which sequences are required in cis for the transcriptional block, we generated a series of constructs containing various portions of murine c-myc 5'-flanking and exon 1 sequences. We established populations of HeLa and CV-1 cells stably transfected with these constructs. The transcription start sites were determined by S1 nuclease mapping analysis, and the extent of transcriptional block was measured by nuclear run-on transcription assays. Our results demonstrate that at least two cis-acting elements are necessary for the transcriptional block. A 3' element was found to be located in the region where transcription stopped and showed features reminiscent of some termination sites found in procaryotes. A 5' element was positioned between the P1 and P2 (C. Asselin, A. Nepveu, and K. B. Marcu, Oncogene 4:549-558, 1989). Removal of the more 3' binding site abolished the transcriptional block.

Comparison of immunoblotting with other serological methods and virus isolation for the early detection of primary cytomegalovirus infection in allograft recipients

Sequential specimens from nine allograft recipients were examined by using a variety of methods to detect primary cytomegalovirus (CMV) infection as rapidly as possible posttransplantation. Sera were examined for immunoglobulin G (IgG) and IgM antibodies by immunoblotting, enzyme immunoassay, and immunofluorescence and also by complement fixation, latex agglutination, and an immunofluorescence test for antibody to CMV early antigen. Urine and occasionally blood, tissue, and other specimens were centrifuged onto cell cultures to enhance CMV infectivity. Eight of the nine patients showed laboratory evidence of primary CMV infection, and CMV was isolated from seven of the eight: in no case was virus isolated before seroconversion had become evident. However, serological tests differed in their abilities to detect antibody response to CMV infection in different patients; while immunoblotting, latex agglutination, and enzyme immunoassay for IgG antibodies generally detected seroconversion before complement fixation, this was not invariably the case. At present, optimal laboratory detection of CMV infections in these patients can be achieved only by a combination of serological methods and virus isolation.

Induction of rat liver microsomal and nuclear cytochrome P-450 by dietary 2-acetylaminofluorene and butylated hydroxytoluene

The influence of dietary 2-acetylaminofluorene (AAF) on the cytochrome P-450 content of rat liver microsomal and nuclear fractions was immunochemically probed with monoclonal and polyclonal antibodies to cytochromes P-450c and P-450d. Cytochrome P-450d but not P-450c was immunodetected in microsomes, nuclear envelopes, and nuclei from untreated rats. The levels of both cytochromes P-450c and P-450d were elevated after a diet of either 0.1% AAF for 1 week or 0.05% AAF for 3 weeks. However, the level of cytochrome P-450c relative to P-450d was lower after the more prolonged AAF feeding. Supplementation of AAF-containing diets with 0.3% butylated hydroxytoluene (BHT), which affords protection against AAF hepatocarcinogenesis in high-fat fed rats, protected and/or induced total (spectral) nuclear envelope cytochrome P-450 content. Immunochemical studies of liver fractions showed that BHT enhanced the AAF-dependent induction of cytochrome P-450c, but not of P-450d. This was a concerted effect of AAF + BHT since dietary BHT by itself did not affect the levels of cytochrome P-450c or P-450d as compared to control rats. Since 1- to 3-week dietary AAF had little effect on total (spectral analyses) microsomal cytochrome P-450 but markedly reduced total P-450 in nuclear envelopes, the coordinated induction of specific cytochrome P-450s in the different fractions suggests selective induction and depression of different forms of cytochrome P-450 and provides additional evidence for independent regulation of the drug-metabolizing system in nuclear envelope and microsomes. In addition, these results suggest that regulation of cytochrome P-450 may play a crucial role in the nutritional modulation of AAF hepatocarcinogenesis.

Subject-reported compliance in a chemoprevention trial for familial adenomatous polyposis

A high level of compliance with an assigned treatment regimen is fundamental to accurate assessment of treatment effectiveness in any clinical trial. If compliance is poor, an effective treatment may be confounded by inadequate delivery of the regimen. Although much research has focused on broad aspects of compliance dealing with clinical therapeutic situations, there was a need for further research dealing specifically with adherence issues in a long-term chemoprevention trial since subject motivation in the latter is likely to differ from that of the former. Examining subject-reported compliance over the first 2-year treatment periods of a long-term chemoprevention trial for familial adenomatous polyposis, it was found that (1) compliance decreased over time, (2) fiber compliance was lower than vitamin compliance, and (3) four explanatory variables which may be amenable to individualized study-team interventions emerged as useful prognosticators of fiber compliance.

Evidence for a PCN-P450 enzyme in chickens and comparison of its development with that of other phenobarbital-inducible forms

Of four monoclonal antibodies to purified rat liver cytochrome P450s, including those from 3-methylcholanthrene-, phenobarbital-, ethanol-, and pregnenolone-16-alpha-carbonitrile-treated rats, only the monoclonal antibody against pregnenolone-16-alpha-carbonitrile-inducible P450 immunodetected proteins in chicken liver microsomes after blotting from sodium dodecyl sulfate-polyacrylamide gels. This protein migrated identically with the pregnenolone-16-alpha-carbonitrile-inducible P450 detected in microsomes from dexamethasone-treated rats. It was most predominant in liver microsomes from chickens at 1 day posthatching, whereas much lower levels were observed in the embryo and at 36 days posthatch. Phenobarbital and dexamethasone were both effective inducers of this protein. The developmental profile and induction by phenobarbital and dexamethasone of several cytochrome P450-associated catalytic activities were compared with those of the immunodetected protein. Chicken liver microsomal erythromycin demethylase, a characteristic activity of rat pregnenolone-16-alpha-carbonitrile-inducible P450, was similar in developmental profile and induction to the immunodetected protein, with a high degree of augmentation at 1 day posthatch compared with that in the embryo and at 36 days posthatch; aldrin epoxidase, benzphetamine demethylase, ethylmorphine demethylase, and aminopyrine demethylase were more similar to each other in development and induction and were less well correlated with the immunodetected protein. This evidence suggests the presence in chicken liver of at least two types of P450, one a form related to the pregnenolone-16-alpha-carbonitrile-inducible P450 family. All of the catalytic activities were induced after pretreatment of chickens with phenobarbital but aldrin epoxidase was most effectively induced. Aldrin epoxidase was also detected in microsomes from untreated embryos as early as 7 days of incubation. Erythromycin demethylase was the only catalytic activity induced by dexamethasone. There was a trend of increased specific activity toward all the substances after hatching, indicating a more efficient P450 system, possibly due to a sharp increase in some isozymes, including the form from the pregnenolone-16-alpha-carbonitrile-inducible P450 family. This evidence for a pregnenolone-16-alpha-carbonitrile-inducible P450 in chickens agrees with sequence information that suggests the early evolution of this form and demonstrates the suitability of the chicken for studies of P450 evolution.

Human liver cytochrome P-450 related to a rat acetone-inducible, nitrosamine-metabolizing cytochrome P-450: identification and isolation

A monoclonal antibody (MAb) to a rat acetone-inducible and nitrosamine-metabolizing form of microsomal cytochrome P-450, P-450ac, detected a related P-450 in human liver microsomes by both immunoblot and competitive radioimmunoassay. This MAb was also used to immunopurify microsomal cytochromes P-450 from both human liver and acetone-treated rats; these were electrophoretically homogeneous with apparent molecular weights of 56,200 and 53,000 daltons, respectively. The structures of the cytochromes P-450 were compared by peptide mapping and amino-terminal sequence analyses. They differed in their peptide maps but displayed amino-terminal sequence similarity in their first 19 residues. This report thus demonstrates the utility of MAbs to rat cytochromes P-450 for detection, identification and structural characterization of human P-450s.

An acute dose-response pharmacodynamic evaluation of orally administered isradipine (PN-200-110) in hypertensive patients

This study was conducted to assess acute oral dose-responses of four dose levels (2.5, 5, 10, 20 mg) of isradipine, a new calcium channel blocking agent of the 1,4-dihydropyridine group. Sixteen patients with mild essential hypertension were investigated using a randomized, four-way cross-over, double-blind, placebo-controlled design. After a 2-week washout period, all patients were admitted to a research unit where they entered a 3-day placebo equilibration, followed by 9 days of double-blind single doses of isradipine. Drug administration was randomized, and baseline blood pressure values obtained preceding active medication doses were fairly constant. Dose-related reductions in supine and in standing blood pressures were obtained. The mean peak supine blood pressure decrements to doses of 2.5, 5, 10, and 20 mg were 17/16, 25/19, 35/22, and 37/25 mm Hg, respectively. Pulse rates increased slightly. Similar responses were obtained with patients in the erect position. Peak hypotensive responses occurred within 3 hours after dosing. The duration of effect persisted as long as 21 hours, particularly after the 10- and 20-mg doses (15/9 and 17/12 mm Hg mean supine blood pressure decrements, respectively).

The independent regulation of tRNA(iMet) and tRNA(Asn) synthesis during Friend cell erythroid differentiation

In this report, we have compared the changes in the production of tRNA(iMet) (initiator tRNA(Met] and tRNA(Asn), which occur during erythroid differentiation in the Friend erythroleukemia cell. The relative steady-state concentration of these two tRNAs (relative to the total tRNA population) was measured by aminoacylation. The results show that while the relative steady-state concentration of tRNA(iMet) changes very little in the cytoplasmic tRNA population, the relative concentration of tRNA(Asn) decreases during the first two days of differentiation and then undergoes an increase. This difference in the behavior of these two tRNAs is also seen when their relative concentrations in newly synthesized tRNA is examined. When tRNA is labeled with tritiated uridine for 24 h in vivo prior to isolation, the hybridization of this labeled tRNA to filter-bound tRNA genes shows that the relative concentration of tRNA(iMet) in newly synthesized tRNA changes very little, while the relative concentration of newly synthesized tRNA(Asn) again decreases through the first 2 days of differentiation, and then undergoes a smaller increase. Thus, the production of these two tRNAs appears to be independently regulated. Independent regulation of synthesis is also observed when examining the production of these two tRNAs in isolated nuclei. During erythroid differentiation, the relative synthesis of tRNA(iMet) (relative to total nuclear RNA synthesis) remains constant, while the relative synthesis of tRNA(Asn) undergoes periodic increases and decreases in value.

Liver disease associated with occupational exposure to the solvent dimethylformamide

STUDY OBJECTIVE

to characterize an outbreak of liver disease among workers in a fabric coating factory; and to determine the outbreak's cause and natural history and strategies for clinical recognition, treatment, and prevention.

DESIGN

clinical-epidemiological investigation.

SETTING

academic medical center, Occupational Medicine Clinic, and worksite.

PATIENTS

fifty-eight of sixty-six workers participated in the study. All had standard liver function tests at least once. Forty-six workers completed a questionnaire; 27 had more extensive clinical evaluation for recognized liver abnormalities.

RESULTS

a plant-wide outbreak of liver disease was recognized after a new employee presented with signs and symptoms of hepatitis. Evaluation of the worksite showed that dimethylformamide, a widely used industrial solvent and known hepatotoxin, was being used to coat fabric in poorly ventilated areas without appropriate skin protection. No other major hepatotoxic exposure was identified. Overall, 36 of 58 (62%) workers tested had elevations of either aspartate aminotransferase (AST) or alanine aminotransferase (ALT) levels. Enzyme abnormalities occurred almost exclusively in production workers (35 of 46 were abnormal), whereas only 1 of 12 nonproduction workers showed any elevations in enzyme levels (P less than 0.0001). Serologic tests excluded known infectious causes of hepatitis in all but 2 workers and changes characteristic of toxic liver injury were confirmed by histologic examinations of biopsy specimens from 4 workers. The ratio of AST to ALT levels was one or less in all but 1 worker. After modification of work practices and removal of workers most severely affected from exposure, improvement in liver enzyme abnormalities and symptoms in most patients were seen, although some patients showed persistent elevations of enzyme levels.

CONCLUSIONS

an outbreak of toxic liver disease has been associated with exposure to dimethylformamide in the workplace. The diagnosis of toxic liver disease was established by the clinical histories, negative viral serologies, an enzyme pattern of ALT levels being greater than AST levels, epidemiologic data on coworkers, and liver biopsy specimens. The high prevalence of unsuspected liver enzyme abnormalities in these workers suggests that occupational liver disease may occur more frequently than is generally recognized.

Comparison of high- and low-intensity exercise training early after acute myocardial infarction

The effects of the intensity of exercise training on cardiorespiratory variables were investigated in a consecutive series of men with recent (median 8 weeks) acute myocardial infarction. Forty-five patients were randomly assigned either to a high- (65 to 75% maximum oxygen consumption rate [VO2max]) or to a low-intensity (less than 45% VO2max) exercise group. Patients engaged in medically supervised aerobic training 3 sessions a week for 12 weeks. With training, mean VO2max significantly increased by 11% (2.09 to 2.31 liters/min) within the high group and by 14% (1.93 to 2.21 liters/min) within the low group. Differences between groups were not statistically significant. Both groups also had comparable changes in heart rate, blood pressure and double-product at submaximal and maximal workloads. Analysis of blood lipids revealed that both groups experienced a significant increase in high density lipoprotein cholesterol. There were no significant changes in total serum cholesterol or triglycerides. These findings suggest that within an unselected population of patients after acute myocardial infarction referred for cardiac rehabilitation, low- and high-intensity exercise training produces relatively similar changes in cardiorespiratory variables during the initial 3 months of exercise training.

Transcatheter electrical shock ablation of a concealed accessory pathway

Transcatheter electrical shock ablation of a concealed posteroseptal accessory pathway was performed on a 57-year-old man with drug-refractory paroxysmal supraventricular tachycardia. A single 300-joules shock delivered at the ostium of the coronary sinus abolished conduction in the accessory pathway and resulted in long-term cure of the arrhythmia. No complications were observed during the procedure.

Morphologic observations on experimental subretinal neovascularization in the monkey

Subretinal neovascularization is a poorly understood and potentially disastrous feature of many eye diseases. We used light and electron microscopy to study the sequence of events that lead to the formation of new vessels after laser photocoagulation of the retina and choroid of primates. In this animal model there is a rapid development of new blood vessels; one day after photocoagulation, endothelial cell degeneration and thrombus formation were observed in the capillaries, venules and arterioles of the choroid around the center of the lesion. Re-endothelialization began in some thrombosed choroidal vessels, with migration of the activated endothelial cells within the old basement membrane. Two days after photocoagulation, re-endothelialization was observed in almost all thrombosed choroidal vessels, and the initial stage of the endothelial cell budding was observed in the pre-existing choroidal vessels; this was especially prominent in venules with pericytes. Three days after photocoagulation, not only the endothelial cells in pre-existing vessels but also those in re-endothelialized vessels showed budding and lumen formation. The lumen of vessels was formed by the budding of adjacent endothelial cells that were coupled by transient intercellular junctions. Mitotic figures were frequently found in the endothelial cells distal to the growing tip. Five to eight days after photocoagulation, many new vessels extended into the subretinal space.

Characterization of a cDNA clone coding for a sea urchin histone H2A variant related to the H2A.F/Z histone protein in vertebrates

A cDNA clone coding for a sea urchin histone H2A variant has been isolated. The coding region of the clone has been sequenced and the sequence found to be closely related to the H2A.F sequence in chickens. The nucleotide sequence of the sea urchin H2A.F/Z is 74% conserved when compared to chicken H2A.F and 51% conserved compared to sea urchin H2A early and 60% compared to sea urchin H2A late. The nucleotide-derived amino acid comparisons show that H2A.F/Z is 97% homologous with H2A.F in chickens and 57% and 56% homologous when compared to sea urchin H2A early and late respectively. There are between 3-6 copies of the H2A.F/Z sequence in the S. purpuratus genome. The H2A.F/Z gene sequence codes for the previously identified H2A.Z protein. All embryonic stages and adult tissues tested contain mRNA for H2A.F/Z. The mRNA appears in the poly A+ RNA fraction after chromatography over oligo dT cellulose.

Vitreoretinal junction in infectious endophthalmitis in a primate eye

A primate eye affected by postoperative infectious endophthalmitis was studied early in the course of the disease. Retinal perivasculitis, vitreoretinal adhesions along the inflamed vessels, and traction of the partially separated posterior vitreous on the retina at the adhesion sites were observed. It is suggested that such vitreoretinal junction pathology may be responsible for the development of retinal detachment in infectious endophthalmitis.

Severe hypertension with absent secondary sex characteristics due to partial deficiency of steroid 17 alpha-hydroxylase activity

A genotypically female patient with 17 alpha-hydroxylase deficiency, and typical symptoms of hypertension, hypokalaemia and lack of secondary sex characteristics, is described. Plasma 17 alpha-hydroxycorticosteroid levels (cortisol, 11-deoxycortisol) and oestradiol were low. Those of 11-deoxycorticosterone, corticosterone, their 18-hydroxy- derivatives, ACTH and gonadotrophins were high and, with the exception of the gonadotrophins, suppressed to normal with dexamethasone which also corrected blood pressure (BP) and electrolyte abnormalities. Plasma aldosterone levels, initially suppressed, increased during treatment but, at 3 months, showed some signs of subnormal responsiveness. Possible reasons for this are discussed. The patient remains well after 9 years on dexamethasone and oestrogen therapy.

Idiopathic ventricular fibrillation: inducibility and beneficial effects of class I antiarrhythmic agents

Ventricular fibrillation in patients without recognizable heart disease is uncommon and electrophysiologic data on such patients is limited. Over a 7 year period, five patients (three men and two women, ranging in age from 24 to 52 years) without demonstrable heart disease underwent electrophysiologic studies with pharmacologic drug testing because of single (four patients) or multiple (one patient) documented episodes of ventricular fibrillation. The arrhythmic event was unrelated to myocardial ischemia or infarction, metabolic or electrolyte disturbances, drug toxicity, preexcitation, or prolonged QT syndromes. In all three patients receiving no antiarrhythmic drugs and in two pretreated with amiodarone, a rapid poorly tolerated ventricular tachyarrhythmia requiring cardioversion was induced by programmed ventricular stimulation with up to two extrastimuli. In all instances, addition of either oral quinidine or oral disopyramide prevented the induction of sustained ventricular arrhythmias. All five patients were placed on antiarrhythmic drug regimens found effective during electrophysiologic studies and remained asymptomatic during follow-up periods ranging from 12 to 93 (mean 52) months. We conclude that in the patients with idiopathic ventricular fibrillation in our study: programmed ventricular stimulation reliably replicated the spontaneous arrhythmia, class I antiarrhythmic agents effectively prevented induction of the arrhythmia in the laboratory, and in contrast to the severity of the presenting arrhythmia, a benign clinical course was observed during long-term therapy with class I antiarrhythmic agents.

Surgical revascularization following failed percutaneous transluminal coronary angioplasty

Percutaneous transluminal coronary angioplasty (PTCA) was performed on 200 patients and failed in 36, 12 of whom underwent myocardial revascularization within 3 hours after the angioplasty attempt. Elective operations were performed without complications in the other 24 cases. The 12 emergency operations were necessitated by major complications during or after PTCA, viz, coronary occlusion (6 patients) coronary dissection (2) and failed catheter passage or dilation with severe myocardial ischemia (4). Three of these 12 patients had signs of acute myocardial infarction preoperatively, and new infarction appeared postoperatively in two cases. All eight patients with ST-segment elevation preoperatively had raised levels of myocardial enzymes postoperatively, and two of them had new Q-waves. Three of the 12 patients required inotropic drugs following revascularization. There was one postoperative death. When complications arise in PTCA, emergency operation should be undertaken. When PTCA fails, but without complications, surgery can be electively performed.

Effect of the vitreous on retinal wound-healing

The healing process of experimental retinal wounds in nonvitrectomized and vitrectomized rabbit eyes was compared. Using light, transmission and scanning electron microscopy, a significant difference was observed at the late stages of the healing process. The retinal wounds in the nonvitrectomized eyes healed properly, forming regular and smooth scars, while the scars that developed in the vitrectomized eyes were irregular and hypertrophic. Our observations suggest that the vitreous plays a role in normal healing of retinal wounds.

The role of retinal pigment epithelium in the involution of subretinal neovascularization

The extravascular milieu around laser-induced experimental subretinal neovascularization (SRN) was studied during the evolution of the neovascular membrane from its early leaky stage to its late involuted stage. When the first signs of visible leakage appeared on angiography, newly formed vessels were spread in the subretinal space around the break in Bruch's membrane, fluid was accumulating in the subretinal space, and retinal pigment epithelial (RPE) cells were proliferating in a papillary pattern around the newly formed vessels; the RPE proliferation began with the undamaged cells at the edges of the laser injury. With further maturation, the RPE continued to envelope the subretinal vessels. This RPE proliferation was associated with the disappearance of fluid between the enveloped vessels and the sensory retina, and the gradual cessation of fluorescein leakage during angiography. At the end of the involution process, when the neovascular membrane no longer demonstrated any leakage, the subretinal vessels were found to be tightly enveloped by RPE cells, and no fluid separated them from the sensory retina. The authors' results suggest that involution of the neovascular membrane with maturation, as demonstrated by the cessation of visible fluorescein leakage, is the result of RPE proliferation that tightly envelopes the newly formed vessels and probably resorbs the previously accumulated subretinal fluid, as well as preventing its further accumulation in the subretinal space.

Monoclonal antibodies to liver microsomal cytochrome P-450E of the marine fish Stenotomus chrysops (scup): cross reactivity with 3-methylcholanthrene induced rat cytochrome P-450

Hybridomas were prepared from myeloma cells and spleen cells of BALB/c female mice immunized with hepatic cytochrome P-450E purified from the marine fish, Stenotomus chrysops (scup). Nine independent hybrid clones produced MAbs, either IgG1, IgG2b, or IgM, that bound to purified cytochrome P-450E in radioimmunoassay. Antibodies from one clone MAb (1-12-3), also strongly recognized rat cytochrome P-450MC-B (P-450BNF-B; P-450c). The nine antibodies inhibited reconstituted aryl hydrocarbon hydroxylase (AHH) and ethoxycoumarin O-deethylase of scup cytochrome P-450E to varying degrees, and inhibited AHH activity of beta-naphthoflavone-induced scup liver microsomes in a pattern similar to that in reconstitutions, indicating that cytochrome P-450E is identical to the AHH catalyst induced in this fish by beta-naphthoflavone. MAb 1-12-3 also inhibited the reconstituted AHH activity of the major BNF-induced rat isozyme. Conversely, MAb 1-7-1 to rat cytochrome P-450MC-B had little effect on AHH activity of scup cytochrome P-450E, and did not recognize cytochrome P-450E in radioimmunoassay nor in an immunoblot. Scup cytochrome P-450E and rat cytochrome P-450MC-B thus have at least one common epitope recognized by MAb 1-12-3, but the epitope recognized by Mab 1-7-1 is absent or recognized with low affinity in cytochrome P-450E. The various assays indicate that the nine MAbs against cytochrome P-450E are directed to different epitopes of the molecule. These MAbs should be useful in determining phylogenetic relationships of the BNF- or MC-inducible isozymes and their regulation by other environmental factors.

Preparation and characterization of monoclonal antibodies to pregnenolone 16-alpha-carbonitrile inducible rat liver cytochrome P-450

Hybridomas were prepared from mouse myeloma cells and spleen cells derived from BALB/c female mice immunized with purified rat hepatic pregnenolone 16-alpha-carbonitrile (PCN) induced cytochrome P-450 2a/PCN-E. The monoclonal antibodies (MAbs) thus obtained were screened for binding to the purified P-450 2a/PCN-E by radioimmunoassay. Eleven independent hybrid clones produced MAbs, each of which was of a single mouse immunoglobulin subclass of the IgG1, IgG2a or IgG2b type. Each of the MAbs produced by the eleven individual hybrid clones bound strongly to P-450 2a/PCN-E as assessed by radioimmunoassay and immunoprecipitation of P-450 2a/PCN-E in Ouchterlony double-immunodiffusion plates. Of the eleven MAbs, three also bound strongly to the phenobarbital-inducible rat liver cytochrome P-450 PB-4. Thus, two classes of MAbs were obtained, one class specific for P-450 2a/PCN-E and a second class that bound to both PCN- and phenobarbital-inducible P-450 forms. The reactivities of one MAb from each class toward eight highly purified rat hepatic cytochromes P-450 were examined using solid phase enzyme-linked immunosorbent analyses. The MAb designated C2 was found to be specific for P-450 2a/PCN-E and did not cross-react with seven other P-450 forms. This MAb was shown to be an effective probe for monitoring, by Western blotting, the induction of microsomal P-450 2a/PCN-E by PCN and phenobarbital. The MAb designated C1 reacted both with P-450 2a/PCN-E and with the two major phenobarbital-inducible P-450 forms, PB-4 and PB-5. None of the MAbs was inhibitory towards P-450 2a/PCN-E-dependent aryl hydrocarbon hydroxylase, benzphetamine N-demethylase, ethoxycoumarin O-deethylase or ethymorphine N-demethylase activity, indicating that the epitopes recognized by these MAbs are not directly associated with catalytic activity. The strong reactivities of three of the MAbs with both P-450 2a/PCN-E and P-450s PB-4 and PB-5 indicate that these two structurally quite different cytochrome P-450 families share at least one common epitope. These new MAbs are additions to our library of MAbs to different cytochromes P-450 and should help further our understanding of the relationship of cytochrome P-450 phenotype and multiplicity to inter-individual differences in drug and carcinogen metabolism and sensitivity.

Experimental epiretinal proliferation induced by intravitreal red blood cells

We describe a reproducible animal model of epiretinal proliferation, based on intravitreal injection of red blood cells, that closely simulates the more benign proliferative extraretinopathies. Using light microscopy and scanning and transmission electron microscopy, we monitored the development and behavior of the experimental epiretinal membranes. We found breaks in the integrity of the retinal surface through which glial cells migrated onto the retina, proliferated into thick epiretinal tissue, and contracted to cause retinal pucker. All these steps were associated with the chronic inflammatory response to the long-lasting presence of red blood cells in the vitreous. Thus, the development of epiretinal membranes requires continuous intraocular stimulation in addition to a break in retinal integrity.

Newly-formed subretinal vessels. Fine structure and fluorescein leakage

The ultrastructure of experimentally induced newly formed subretinal vessels was correlated with the amount of fluorescein leakage demonstrated by the neovascular membranes during angiography. The membranes that demonstrated leakage contained subretinal vessels with a fenestrated endothelial wall and intermediate interendothelial cell junctions. As these subretinal plexi matured, they stopped demonstrating leakage. This involution process was accompanied by the formation of focal interendothelial tight junctions; however, loss of fenestrations was not observed. The membranes that never demonstrated fluorescein leakage also contained fenestrated subretinal vessels at both early and late stages of development; and their interendothelial junctions showed similar maturation from open to focal tight junctions. Thus all subretinal vessels had "leaky" morphology strongly resembling that of the normal choriocapillaris, whether they demonstrated fluorescein leakage or not. The authors conclude that newly formed subretinal vessels retain the characteristics of the choriocapillaris from which they are believed to proliferate; they have the potential to leak fluorescein at all stages of their development. The absence of fluorescein leakage during angiography cannot always be correlated with the absence of "leaky" morphology.

Retinal wound healing. Cellular activity at the vitreoretinal interface

Cellular activity at the vitreoretinal interface after full-thickness retinal wounds was studied in rabbit eyes, using light and electron microscopy. Glial cell extensions grew initially on the retinal surface around the wound site. This brief period of glial proliferation was associated with the posttraumatic inflammatory response and, more specifically, with phagocytic monocyte accumulation at the vitreoretinal interface. Once the inflammation subsided, this abortive attempt to grow membranes on the retinal surface stopped and true epiretinal membranes did not develop. Our observations suggest that intraocular inflammation and macrophage response determine the extent of healing and scarring on an injured retinal surface, and thus may play a key role in the pathogenesis of epiretinal membranes.

Experimental vitreous syneresis

Perfluoropropane gas was injected into the vitreous body of a primate eye. Clinical and morphologic studies revealed that the gas bubble created a large cavity within the vitreous. The cavity that subsequently filled with viscous liquid was completely enveloped by vitreous gel, thus simulating the clinical condition known as vitreous syneresis. The shell of residual vitreous, which was much thicker inferiorly and behind the lens than superiorly, seemed to be an intact and continuous layer. In spite of the extensive syneresis, posterior vitreous detachment failed to develop. Our findings suggest that a vitreous cavity, voluminous as it may be, is not sufficient to cause posterior vitreous detachment in the primate eye.

Insulin or increased concentration of zinc in liver, kidney or muscle does not alter the phosphoglucomutase activity in vivo

Injection of insulin into mice and rabbit has been reported to convert the latent form of phosphoglucomutase (E X Zn) to an active form (E X Mg) without any net increase in the protein associated with this enzyme (Hashimoto et al., Biochem. Biophys. Res. Commun., 27 (1967) 369 and Peck et al., J. Biol. Chem. 242 (1971) 1160). Because the injection of Cd in rats causes a 2-fold increase in Zn concentration in the liver, it appeared that such treatment in mice would increase the concentration of the latent enzyme and thereby enhance the insulin induced activation of the enzyme. The results however show that insulin or Cd treatment, alone or in combination do not alter the concentrations of the 2 forms of enzyme in liver, kidney or muscle of normal or fasted mice. In all instances the conversion of the latent enzyme to its activated form required preincubation with a chelating agent. Fractionation of the tissue homogenates showed that upon Cd injection the concentration of Zn in the fractions of Mr less and 1000 increased 6-fold in liver and 3-fold in kidney, that in muscle remained unchanged.

Disseminated talc granulomatosis. An unusual finding in a patient with acquired immunodeficiency syndrome and fatal cytomegalovirus infection

The association of disseminated magnesium silicate talc granulomatosis and acquired immunodeficiency syndrome is reported in a male homosexual who used intravenous drugs and who died of overwhelming cytomegalovirus (CMV) infection. Autopsy findings included widespread deposition of talc crystals in the lungs, liver, lymph nodes, bone marrow, and spleen. Typical CMV inclusions were seen in the lungs, kidneys, adrenal glands, gastrointestinal tract, and right eye. There was no evidence of malignancy. Analysis of peripheral blood neutrophil function revealed impaired chemotaxis and chemokinesis, but opsonophagocytosis had remained normal. The CMV infection in the small bowel was extensive and resulted in severe destruction of the muscularis propria and neural plexi, leading to marked dilatation and persistent diarrhea. The terminal course was marked by intractable hypotension, pneumonitis, and malnutrition, which could be attributed respectively to CMV involvement of the adrenal glands, lungs, and small bowel. The etiology and possible role of systemic talc granulomatosis in the development of immunosuppressive illness is reported herein.

Extensive endocardial mapping during sinus rhythm and ventricular tachycardia in a patient with arrhythmogenic right ventricular dysplasia

A 38 year old man with arrhythmogenic right ventricular dysplasia underwent electrophysiologic study with extensive endocardial mapping of the right ventricle. During sinus rhythm, markedly reduced amplitude with or without prolonged duration was noted in multiple electrograms of the right ventricle. Delayed activation of the right ventricular outflow tract electrogram was present. Two clinical types of ventricular tachycardia with a left bundle branch block configuration and either an inferior or a superior axis were induced by ventricular stimulation. Endocardial activation sequence during the tachycardias suggested that the tachycardia with an inferior axis originated near the infundibulum, while that with a superior axis originated near the midinferior area of the right ventricle. Both areas have been previously shown to be frequently impaired in right ventricular dysplasia.

Intravitreal expanding gas bubble. A morphologic study in the rabbit eye

The morphologic changes induced by an expanding bubble of perfluoropropane (C3F8) gas in the vitreous body have been studied in the rabbit eye by dissecting microscopy and scanning and transmission electron microscopy. Initial expansion of the gas displaces water from the vitreous; the remaining vitreous forms a compressed layer on the retinal surface. Subsequent absorption and contraction of the gas bubble is associated with gradual detachment of the compressed vitreous from the retina. Eventually, vitreous detachment is complete, except for residual attachments posteriorly to the medullary rays and anteriorly to the ciliary processes. The plane of vitreous separation is predominantly at the anatomic vitreoretinal junction, although scattered islands of outer cortical vitreous are found on the surface of the retina.

Diabetic neovascularization: permeability and ultrastructure

The permeability of newly formed blood vessels in proliferative diabetic retinopathy at different stages of development was correlated with their ultrastructural features. The young proliferating vessels were much more permeable to fluorescein than were the older vessels. Transmission electron microscopy revealed that the blood vessels within the young intravitreal proliferating fronds had intermediate interendothelial junctions, whereas the blood vessels within the old neovascular preretinal membranes had tight interendothelial junctions of the macula occludens type. Fenestrations were observed only rarely in the endothelial wall of either the young or the older proliferating vessels. We conclude that the principal route of fluorescein leakage from the newly formed blood vessels in proliferative diabetic retinopathy is via the interendothelial clefts.

Monoclonal antibodies to phenobarbital-induced rat liver cytochrome P-450

Somatic cell hybrids were made between mouse myeloma cells and spleen cells derived from BALB/c female mice immunized with purified phenobarbital-induced rat liver cytochrome P-450 (PB-P-450). Hybridomas were selected in HAT medium, and the monoclonal antibodies (MAbs) produced were screened for binding to the PB-P-450 by radioimmunoassay, for immunoprecipitation of the PB-P-450, and for inhibition of PB-P-450-catalyzed enzyme activity. In two experiments, MAbs of the IgM and IgG1 were produced that bound and, in certain cases, precipitated PB-P-450. None of these MAbs, however, inhibited the PB-P-450-dependent aryl hydrocarbon hydroxylase (AHH) activity. In two other experiments, MAbs to PB-P-450 were produced that bound, precipitated and, in several cases, strongly or completely inhibited the AHH and 7-ethoxycoumarin deethylase (ECD) activities PB-P-450. These MAbs showed no activity toward the purified 3-methylcholanthrene-induced cytochrome P-450 (MC-P-450), beta-naphthoflavone-induced cytochrome P-450 (BNF-P-450) or pregnenolone 16-alpha-carbonitrile-induced cytochrome P-450 (PCN-P-450) in respect to RIA determined binding, immunoprecipitation, or inhibition of AHH activity. One of the monoclonal antibodies, MAb 2-66-3, inhibited the AHH activity of liver microsomes from PB-treated rats by 43% but did not inhibit the AHH activity of liver microsomes from control, BNF-, or MC-treated rats. The MAb 2-66-3 also inhibited ECD in microsomes from PB-treated rats by 22%. The MAb 2-66-3 showed high cross-reactivity for binding, immuno-precipitation and inhibition of enzyme activity of PB-induced cytochrome P-450 from rabbit liver (PB-P-450LM2). Two other MAbs, 4-7-1 and 4-29-5, completely inhibited the AHH of the purified PB-P-450. MAbs to different cytochromes P-450 will be of extraordinary usefulness for a variety of studies including phenotyping of individuals, species, and tissues and for the genetic analysis of P-450s as well as for the direct assay, purification, and structure determination of various cytochromes P-450.

Comparative in vitro activities of teichomycin and vancomycin alone and in combination with rifampin and aminoglycosides against staphylococci and enterococci

The activity of teichomycin A2 was compared with that of vancomycin in vitro against clinical isolates of staphylococci and enterococci. Teichomycin A2 was more active than vancomycin active against all isolates tested. Synergistic studies also demonstrated that teichomycin A2 combined with rifampin is more active than vancomycin combined with rifampin against Staphylococcus aureus and Staphylococcus epidermidis isolates. Teichomycin A2, either singly or in combination with an aminoglycoside, was more active against Streptococcus faecalis isolates.

Clinical and microbiologic aspects of serious infections caused by Staphylococcus epidermidis

10 patients with serious infections caused by Staphylococcus epidermidis (8 cases of endocarditis in non-prosthetic valves, 1 was complicated by osteomyelitis, 1 case of osteomyelitis, and 1 case of septicemia) are described. Clinical and microbiologic features were evaluated including antibiotic sensitivity and synergy studies, phage typing and biotyping. Endocarditis tended to affect the elderly population and the clinical manifestations were quite similar to those caused by Streptococcus viridans. Both patients with osteomyelitis had involvement of the cervical spine with excellent response to antibiotic therapy. The only patient with septicemia acquired via hyperalimentation had delayed clearance of the bacteremia but ultimately responded to intravenous antibiotics. Rifampicin was the most effective of all antibiotics tested. All isolates were sensitive to penicillinase-resistant penicillins and cephalosporins and over half were sensitive to penicillin. Full synergistic activity was demonstrated with cephalothin and nafcillin in combination with rifampicin, and rifampicin-vancomycin was partially synergistic against the majority of the strains. Five of 8 available isolates were non-phage typeable and no definite pattern was established for various types of infections. Four of the 8 isolates were classified as biotype SIIa, 2 biotype SIIc and 2 biotype SVh.

A simplified method for cryopreservation of Plasmodium falciparum from continuous in vitro cultures

Human erythrocytes parasitized with Plasmodium falciparum, obtained from in vitro continuous cultures and stored at -185 degrees C and at -70 degrees C for several months, were successfully recovered. Ten per cent glycerol or 10% dimethyl sulphoxide in growth medium RPMI 1640 were used and found equally effective as cryopreservatives. This simplified method does not require centrifugation or special media before storage or after recovery of the parasites. The viability of the parasites is monitored in vitro by initiating new continuous cultures.