Preclinical mouse models for cancer chemoprevention studies

To aid in identifying the ability of chemopreventive agents to inhibit tumor development, new preclinical in vivo rodent models have recently been developed. Some of the models contain targeted mutations capable of increasing the incidence and progression of neoplastic lesions, whereas in other models dietary nutrients induce preneoplastic lesions in normal mice. These new preclinical models are assisting the analysis of genetic and environmental factors leading to neoplasia, and clinical studies to evaluate the chemopreventive efficacy of specific nutrients and pharmacological agents.

The DNA mismatch repair genes Msh3 and Msh6 cooperate in intestinal tumor suppression

Repair of mismatches in DNA in mammalian cells is mediated by a complex of proteins that are members of two highly conserved families of genes referred to as MutS and MutL homologues. Germline mutations in several members of these families, MSH2, MSH6, MLH1, and PMS2, but not MSH3, are responsible for hereditary non-polyposis colorectal cancer. To examine the role of MSH3, we generated a mouse with a null mutation in this gene. Cells from Msh3-/- mice are defective in repair of insertion/ deletion mismatches but can repair base-base mismatches. Msh3-/- mice develop tumors at a late age. When the Msh3-/- and Msh6-/- mutations are combined, the tumor predisposition phenotype is indistinguishable from Msh2-/- or Mlh1-/- mice. These results suggest that MSH3 cooperates with MSH6 in tumor suppression.

Treatment of in-stent coronary restenosis with excimer laser angioplasty

OBJECTIVE

To evaluate the efficacy and safety of excimer laser coronary angioplasty (ELCA) with adjunctive balloon angioplasty in patient with in-stent restenosis.

METHODS

ELCA was performed in 20 patients of instent restenosis. All patients were symptomatic and had class III-IV angina. ELCA was performed with the Spectranetics CVX-300 System. The laser catheter of Vittesse C (concentric) and E (eccentric) with diameter of 1.4-2.0 mm was used.

RESULTS

Laser catheter crossed all stenotic stents without difficulty. The lesion length was 4.6-51.2 mm, mean 20.7 +/- 13.7 mm, including 14 lesions > 10 mm. Laser treatment alone increased minimal lumen diameter (MLD) from 0.3 +/- 0.3 mm to 1.4 +/- 0.3 mm (P < 0.0001) and improved the diameter stenosis from 88.8% +/- 10.0% to 46.0% +/- 8.0% (P < 0.0001). Adjunctive balloon angioplasty further increased minimal lumen diameter to 2.3 +/- 0.7 mm and reduced diameter stenosis to 14.2% +/- 8.2% (P < 0.0001). At follow-up (1-17 months, mean 8.9 +/- 5.7 months), 17 (85%) patients had remained asymptomatic, 3 (15%) patients had mild to moderate exertional angina, 1 (5%) patient received CABG.

CONCLUSION

ELCA with adjunctive percutaneous transluminal coronary angioplasty (PTCA) is an efficient and safe technique to debulk tissue in the patient with in-stent restenosis. The incidence of procedural related complication was low and ELCA may be used as a good method for in-stent restenosis treatment.

Dual chamber implantable cardioverter defibrillator benefits and limitations

Dual chamber ICD capable of providing dual chamber pacing (DDD) and ventricular arrhythmia therapy is now available. We report our experience of clinical performance of dual chamber ICDs amongst Chinese population.

METHODS

9 patients (6 men and 3 women) received dual chamber ICDs, mean age 50 +/- 18.8 years. The indications were ventricular fibrillation (VF) [5], hemodynamic intolerant ventricular tachycardia (VT) [3] and unexplained syncope plus positive induction of VF [1]. The underlying cardiac pathology were congenital LQT syndrome(1), hypertrophic cardiomyopathy [2], coronary artery disease [2], rheumatic valvular disease [1], Brugada syndrome [1], arrhythmogenic right ventricular dysplasia [1] and idiopathic VF [1]. Four patients have documented paroxysmal atrial fibrillation (AF). All patients have defibrillation thresholds (DFT) determined with a binary search protocol starting at 12 joules (J) at implantation.

RESULTS

A total of 34 episodes of VF were induced at implantation with mean DFT 13.8 +/- 7 J. The average shocking impedance was 40 +/- 3.6 Omega. The mean acute P wave measured 3.3 +/- 1.3 mV and R wave measured 13.2 +/- 3.2 mV. Atrial and ventricular thresholds, at pulse width 0.5 ms, averaged 0.8 +/- 0.4 V and 0.4 +/- 0.2 V. During follow-up period, 16 episodes of VF were documented and were successfully treated with the first programmed shock. In the patient with LQT syndrome, DDD was initiated to prevent pause-dependant VF. Three episodes of inappropriate therapy (15.8%) were delivered. One patient experienced 2 shocks after exercise. Stored electrograms showed sinus tachycardia with first degree heart block which was misdiagnosed as VT with retrograde 1:1 conduction. Another inappropriate therapy occurred with AF with fast ventricular response within the VF zone and VT therapy inhibitor was disabled.

CONCLUSION

Dual chamber ICD allows combined benefits of DDD and VT/VF therapy. Storage of both atrial and ventricular electrograms provide more information in elucidation of nature of dysarrhythmias. Inappropriate shocks, though reduced, are still possible and the rigid algorithms of SVT discrimination from VT will need further published.

Determination of benzodiazepines in clinical serum samples: comparative evaluation of REMEDi system, aca analyzer, and conventional HPLC performance

Emergency toxicology or drug screening in clinical settings requires rapid qualitative and quantitative analysis with acceptable levels of sensitivity and specificity. The aim of this study was to comparatively evaluate the performance of the multi-column HPLC-based REMEDi drug profiling system (Bio-Rad), the aca analyzer (Du Pont), and the bench standard conventional HPLC method in the identification of 12 clinically important benzodiazepines. In this study, the presence of benzodiazepines in 133 patients' serum samples were qualitatively and comparatively analyzed by these three procedures. Among these methods, 120 of 133 samples were identified as benzodiazepine-positive by conventional HPLC (90%); 127 by aca analyzer (95%); and 84 by REMEDi (63%). Detection sensitivity of REMEDi for most of the benzodiazepines was found satisfactory when concentrations were greater than 1.0 microg/mL. When benzodiazepine concentrations were in the ranges of 0.3-1.0 microg/mL, detection sensitivity became varied among the benzodiazepine family of drugs by REMEDi method. REMEDi procedure should not be considered as the method of choice for detection of benzodiazepines if expected concentration levels are below 0.3 microg/mL, with the exception of bromazepam. Conventional HPLC displayed the highest sensitivity and specificity for the detection of benzodiazepines. In our studies, 36 REMEDi-negative samples were positive by HPLC, although in 16 of the 36 REMEDi negative samples (13.3%), the presence of benzodiazepines was detected but only listed as candidates without positive identification of the individual compounds by REMEDi. In our series, however, there were no false positives by the REMEDi method whereas aca procedure showed 13 false positive results (9%) and 6 cases of false negative (4%). Our data indicate that the REMEDi procedure can be used on serum samples for rapid qualitative screening of clinically important high levels of benzodiazepines with high specificity. However, due to the relatively low sensitivity of REMEDi in samples with low benzodiazepine levels and relatively low specificity by aca, all samples should be further confirmed by conventional HPLC procedure.

Tumorigenesis in Mlh1 and Mlh1/Apc1638N mutant mice

An3 1 KAL I MutL homologue 1 (MLH1) is a member of the family of proteins required for DNA mismatch repair. Germ-line mutations in MLH1 lead to the cancer susceptibility syndrome hereditary nonpolyposis colorectal cancer (HNPCC). We generated mice carrying a null mutation in the Mlh1 gene. We showed that mice heterozygous and homozygous for the Mlh1 gene are predisposed to developing tumors of the gastrointestinal (GI) tract, lymphomas, and a number of other tumor types. We also examined the role of adenomatous polyposis coli gene (Apc) gene mutations in the GI tumors of Mlh1 mutant mice by different methods and showed that the GI tumors in Mlh1 mice express little or no adenomatous polyposis coli protein. When an Apc gene mutation was bred into the Mlh1 mutant mice, the GI tumor incidence increased 40-100-fold. The wild-type Apc allele in these tumors was found to contain mutations. Together, these results show that we have developed two mouse models for human HNPCC and that the mechanisms of tumor development in the GI tract of these mice involve loss of Apc gene function in a manner very similar to that seen in the GI tumors of HNPCC.

Inverse relationship between Leydig cell density and metastatic potential of prostatic adenocarcinoma

PURPOSE

Evaluate the relationship between metastatic potential of prostatic adenocarcinoma (PC) and testicular Leydig cell density.

MATERIALS AND METHODS

Tissue samples from 111 men, age 52-85, with PC and bilateral orchiectomy were evaluated for Leydig cell density. The patients were divided into two groups: Group A were patients with metastasis (n = 36) and Group B were patients without metastasis (n = 75). Leydig cell density was determined by direct manual microscopic cell count on the tissue sections. The means of cell counts by four pathologists, expressed as cell/0.78 mm2 were used for analysis. The normally distributed data were analyzed by two-tail Student's t-test. Thirty-eight age-compatible autopsy cases who died of unrelated causes served as normal controls.

RESULTS

The mean of Leydig cell count in group A patients was 14.43 (14.43+/-1.19 SE). Mean of Group B was 47.05 (47.05+/-4.05 SE) whereas normal controls displayed a mean of 48.66 (48.66+/-2.94 SE). Group A was significantly different from control (p < 0.00001). Group A and Group B were also significant different (p < 0.001) whereas control was not significantly different from Group B (p > 0.75).

CONCLUSIONS

Patients with metastatic adenocarcinoma of prostate, as a group, have a significantly lower Leydig cell density than patients without metastasis or patients without PC in compatible age groups. The hormonal relationship between this observation is however unknown. One possible explanation is that PC subpopulation with metastatic potential may require different level of endogenous androgen or are androgen-independent.

Dietary modulation of carcinoma development in a mouse model for human familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is caused by a dominant mutation in the adenomatous polyposis coli (APC) gene. Individuals with FAP progressively develop adenomas and carcinomas of the colon and rectum. We developed a mouse model for this disorder by genetically modifying the Apc gene. The resulting mice Apc1638 progressively develop neoplasms in the colon and remainder of the gastrointestinal tract. In this study when Apc1638 mice were fed a Western-style diet, they developed an increased incidence of the end point of carcinomas and number of invasive tumors. The findings therefore demonstrated dietary modulation of carcinoma incidence in mice with a targeted mutation providing a model for the study of gene-environment interactions in cancer.

Modulation of abnormal colonic epithelial cell proliferation and differentiation by low-fat dairy foods: a randomized controlled trial

CONTEXT

Before the development of human colonic neoplasms, colonic epithelial cells showed altered growth and differentiation. These alterations characterized mucosa at risk for cancer formation and were termed intermediate biomarkers of risk. Modifications of the mucosa toward more normal features by nutrients or drugs are putative approaches to chemoprevention of colon cancer.

OBJECTIVE

To determine whether increasing calcium intake via dairy products alters colonic biomarkers toward normal.

DESIGN

Randomized, single-blind, controlled study.

SETTING

Outpatient clinic.

PARTICIPANTS

Seventy subjects with a history of polypectomy for colonic adenomatous polyps.

INTERVENTION

Low-fat dairy products containing up to 1200 mg/d of calcium. Subjects were randomized to 4 strata by diet (control vs higher calcium) and age (<60 vs > or = 60 years).

MAIN OUTCOME MEASURES

Changes in total colonic epithelial cells and number and position of thymidine-labeled epithelial cells and changes in the ratio of sulfomucins (predominantly secreted by distal colorectal epithelial cells) to sialomucins and expression of cytokeratin AE1, 2 markers of colonic cell differentiation.

RESULTS

During 6 and 12 months of treatment, reduction of colonic epithelial cell proliferative activity (P<.05), reduction in size of the proliferative compartment (P<.05), and restoration of acidic mucin (P<.02), cytokeratin AE1 distribution (P<.05), and nuclear size (P<.05) toward that of normal cells occurred. Control subjects showed no differences from baseline proliferative values at 6 and 12 months (P>.05).

CONCLUSION

Increasing the daily intake of calcium by up to 1200 mg via low-fat dairy food in subjects at risk for colonic neoplasia reduces proliferative activity of colonic epithelial cells and restores markers of normal cellular differentiation.

Mutation in the mismatch repair gene Msh6 causes cancer susceptibility

Mice carrying a null mutation in the mismatch repair gene Msh6 were generated by gene targeting. Cells that were homozygous for the mutation did not produce any detectable MSH6 protein, and extracts prepared from these cells were defective for repair of single nucleotide mismatches. Repair of 1, 2, and 4 nucleotide insertion/deletion mismatches was unaffected. Mice that were homozygous for the mutation had a reduced life span. The mice developed a spectrum of tumors, the most predominant of which were gastrointestinal tumors and B- as well as T-cell lymphomas. The tumors did not show any microsatellite instability. We conclude that MSH6 mutations, like those in some other members of the family of mismatch repair genes, lead to cancer susceptibility, and germline mutations in this gene may be associated with a cancer predisposition syndrome that does not show microsatellite instability.

A mouse model of human familial adenomatous polyposis

In an effort to generate a good mouse model for human colorectal cancer, we generated mice which carry a mutation in the adenomatous polyposis coli (Apc) gene. Mice which are heterozygous for the mutation, designated Apc1638, develop colonic polyps and tumors of the small intestine. Neoplasms were found in 96% of animals studied, and they included adenomas, adenocarcinomas, and polypoid hyperplasias. The mice developed an average of 3.3 tumors, with the highest number in duodenum, followed by jejunum, stomach, ileum, and colon. Focal areas of dysplasias were observed in the colonic mucosa in 50% of mice which were 10 months old or older. These results suggest that mice carrying the Apc1638 mutation can serve as a good model to study the initiation, progression, and inhibition of gastrointestinal tumors.

Significance of p53 overexpression in urinary bladder transitional cell carcinoma in situ before and after bacillus Calmette-Guérin treatment

OBJECTIVES

Overexpression of p53, normally secondary to gene mutation, in invasive uroepithelial neoplasms (transitional cell carcinoma) and a high percentage of transitional cell carcinoma in situ (CIS) has been described; however, the role of p53 before and after bacillus Calmette-Guérin (BCG) treatment of CIS needs to be defined.

METHODS

Immunohistochemical reaction for p53 overexpression was performed on 12 patients with CIS before and after BCG treatment. Thirty cystectomy specimens with invasive TCC were also evaluated for the presence of CIS, hyperplasia, and dysplasia.

RESULTS

Twenty-three cases of CIS were identified. Approximately 90% of CIS cases (21 of 23) were positive for p53 overexpression, whereas transitional cell hyperplasia was uniformly negative. Less than 5% of the cells in morphologically dysplastic lesions were positively stained. Ten of 12 CIS patients displayed p53 overexpression before BCG treatment. After BCG treatment, 4 patients displayed residual CIS with p53 overexpression, and 8 patients showed no residual CIS or p53 overexpression. Three of the 4 patients with residual CIS and overexpression rapidly developed invasive transitional cell carcinoma requiring cystectomy. The 1 remaining patient was treated with a second course of BCG; further biopsies displayed the development of grade 1 papillary transitional cell carcinoma without invasion, and the patient is currently being followed

CONCLUSIONS

Our data suggest that follow-up biopsy procedures are essential in all patients with CIS treated with BCG. The biopsy specimens should be evaluated for p53 overexpression, because our data indicate that persistent p53 overexpression in uroepithelial lesions after BCG treatment is an ominous finding for probable tumor progression.

Use of low molecular weight heparin in postangioplasty management

The results of using low molecular weight heparin (LMWH) in postangioplasty management are examined. In comparison to intravenous unfractionated heparin, subcutaneous LMWH caused less groin complications and was simpler and cheaper to be administered by the medical personnel. The incidence of ischaemic complications after angioplasty including acute closure and myocardial infarction, however, remained similar and was not excessive. Subcutaneous administration of LMWH provides and alternative simple and cost-effective strategy for postangioplasty management.

Cytokeratin, lectin, and acidic mucin modulation in differentiating colonic epithelial cells of mice after feeding Western-style diets

Several studies have recently reported the development of colonic epithelial cell hyperproliferation in rodents following the ingestion of Western-style diets. In this study, additional measurements related to differentiation and maturation of the colonic epithelial cells were made after feeding this type of diet. Two Western-style diets high in fat and phosphate content and low in calcium and vitamin D were fed to C57BL/6J mice for 12, 24, and 52 weeks. Diet A contained American Blend fat as a source of lipids, diet B contained corn oil, and control diet C was a standard AIN-76A semisynthetic diet which is lower in fat content and higher in calcium and vitamin D. Colonic epithelial cells were studied for three biomarkers: cytokeratin catalogue no. 18 (clone LE64) expression, soybean agglutinin carbohydrate lectin binding, and acidic mucins including sialo- and sulfomucins. Feeding of diets A and B revealed that colonic epithelial cells had increased expression of cytokeratin catalogue 18 and SBA carbohydrate lectin binding compared to controls (P = 0.0001 for diet A versus C and diet B versus C). Significant differences were found between diets B and C (P = 0.0001) and diets A and C (P = 0.0001) in total acidic mucins and in the ratio of sialomucin:sulfomucin (P = 0.0001). These findings demonstrate that both functional and structural modifications occurred in colonic epithelial cells under these dietary conditions, and further defined this rodent model for preclinical evaluation of nutritional and chemopreventive interventions.

Increased phospholipid fatty acid remodeling in human and rat prostatic adenocarcinoma tissues

PURPOSE

To study the mechanism of diminished arachidonic acid levels in malignant prostatic tissues.

MATERIALS AND METHODS

Benign and malignant prostate tissues were obtained from human radical prostatectomy specimens and from rats using Pollard's Lobund/Wistar rat prostate cancer model. Fatty acid composition and a variety of enzyme activities involved in maintaining phospholipid fatty acid composition were compared in malignant and benign prostatic tissues.

RESULTS

Decreased arachidonic acid levels, previously reported in human prostate cancer, were present in malignant rat as well as in human tissues. There were 21% and 26% decreases of arachidonic acid levels in the rat and human malignant tissues compared with benign tissues. Fatty acid desaturase activity was undetectable. Fatty acyl-CoA hydrolase and synthetase activities were not altered in the malignant tissues. However, there was a 2-fold increase in phospholipase A2 activity and a 4- to 12-fold increase in fatty acyl-CoA lysophosphatidylcholine acyltransferase activity in malignant rat and human prostatic tissues.

CONCLUSIONS

These data indicate that, in malignant prostate tissues, the fatty acid remodeling mechanism is activated through the deacylation-reacylation cycle. This process may be a result of increased use of arachidonic acid for the formation of prostaglandins that may be crucial for the further development and growth of the malignant tissues.

[A novel RNA capture method for the extraction of HCV-RNA]

A novel method for the extraction of HCV-RNA by using DNA probe coated-latex microparticle (AmpliTex) was developed. This high density particle, with a large surface area, could be dispersed uniformly in a guanidium lysate of the serum. The DNA probe on the particles could hybridize with a few copies of HCV-RNA in the lysate. The RNA thus extracted on the particle can be subjected to the reverse-transcription and PCR reaction. Analytical sensitivity to detect HCV in serum was approximately 20 copies per ml. AmpliTex and the conventional organic extraction gave the same sensitivity and specificity (both 100%) to detect the HCV-RNA from fifty clinical specimens. It was also possible to extract the HCV-RNA from heparinated plasma.

Balloon mitral commissurotomy in a patient with situs inversus and dextrocardia

A patient with situs inversus and dextrocardia in whom a successful balloon mitral commissurotomy for symptomatic rheumatic mitral stenosis was performed after appropriate modifications in the technique of transseptal catheterization is described.

[A clinical and pathological analysis of 20 cases of lymphal follicular rectitis]

Lymphal follicular rectitis (LFR) recognized in recent years is a kind of benign lesion localizing in rectum. The lack of specific clinical and endoscopic manifestation causes the difficulty in its diagnosis. It was easily confused with ulcerative rectitis, even there were some cases which were misdiagnosed malignant rectal lymphoma. A retrograde analysis was made in our study in the 176 cases of pathologically diagnosed chronic rectitis between January 1993 and July 1994 in our hospital. Among the 176 cases, 20 were certain to be LFR (2 formerly diagnosed, 18 confirmed in the retrograde study). Endoscopic manifestations are as following: (1) granuliform proliferation, eminence and roughness can be seen in rectal mucosa with hyperemia, edema and vague vessels. The lesion is either diffused or localized. (2) single or multiple smooth polypoid apperances can be observed in rectal mucosa, which are 0.2-0.4 cm in diameter, and its pathological characteristics under microscope are: obvious lymphal follicular hyperplasia in the mucosa. A protecting zone and clear reactive germinal center in the hyperplastic follicules, coalescence of follicules occupying more than half of the lamina propria, a large amount of lymphocytes, some are in karyokinesis phase, some infiltrate the mucosa musculis and vessels proliferation in the hyperplastic lymphal tissue, scattered plasma cells, no neutrophil, no eosinophil and no abscess, which is quite different from ulcerative rectitis. Clinical manifestations of the group include: 7 intermittent hematochezia, 4 abdominal pain associated with alternative constipation and diarrhea, 2 mucous stool, 1 tenesmus, 1 pyohemofecia, 2 abdominal distension and 6 asymptomatic. From our study, the diagnosis of LFR mainly depends on its endoscopic polymorphic characteristics and specific histopathologic appearences. And it is important to differentiated LFR from other rectal diseases with lymphal tissue proliferation.

Prior enrichment of human immunodeficiency virus DNA with probe DNA particles for efficient PCR diagnosis

We report here a novel method by which one can recover human immunodeficiency virus (HIV) DNA in a small volume (approximately 50 microliters) of solution from 8 ml of crude cell lysate which contains as few as several HIV DNA copies. The method uses the specific binding of HIV DNA to HIV probe DNA particles. The HIV DNA thus concentrated on the particles can be subjected to the PCR assay. The method also enables the examination of 100 individual blood specimens in a combined form.

[Prior enrichment of HIV-DNA with probe-DNA particles for an efficient PCR diagnosis]

PCR mediated detection of HIV-DNA has been widely used. However, compared with traditional immunological diagnoses, the extraction of DNA is a laborious and time consuming step. We have developed a procedure for the efficient isolation and concentration of HIV-DNA from cell lysates. We report here a novel method by one can recover HIV-DNA in a small volume (approximately 50 microliters) of solution from a large volume of crude cell lysate which contains as few as several copies. The method uses the specific hybridization of HIV-DNA to HIV probe-DNA particles. This prior enrichment augmented the sensitivity in the detection of HIV-DNA by PCR, and allows us to make a diagnosis even if the specimen contained an extremely low copy number of HIV-DNA molecules in a large volume, which would have otherwise resulted in false-negative data with the conventional extraction method. The method also enables the examination of 100 individual blood specimens in a combined form. Thus, the application of the present enrichment procedure with HIV probe-DNA particles should reduce the labor and cost of HIV diagnosis, since the HIV positive samples represent a very minor group of people among specimens subjected to clinical laboratory tests, and particularly, among blood samples voluntarily donated to be used for transfusions.

Laboratory and clinical evaluation of Mycobacterium xenopi isolates

Mycobacterium xenopi and Mycobacterium avium complex (MAC) are biochemically similar. To define the laboratory characteristics of M. xenopi that distinguish it from MAC, 53 M. xenopi isolates from different areas in the United States and 47 isolates recovered at one hospital were evaluated by 13 biochemical tests, AccuProbe MAC (Gen-Probe, Inc., San Diego, CA, USA), colony morphology, formation of X-colonies, pigmentation in response to light, growth on MacConkey agar without crystal violet, and relative growth rates at 25 degrees C, 36 degrees C, and 45 degrees C on solid media. Relative growth rates of 10 M. xenopi and 11 MAC isolates were measured at 25 degrees C, 36 degrees C, and 42 degrees C in Middlebrook broth processed using the BACTEC TB System. Ten M. xenopi were tested for p-nitro-alpha-acetylamino-beta-hydroxypropiophenone inhibition at 36 degrees C and 42 degrees C. Reevaluation of 81 isolates previously identified as MAC by biochemical tests alone revealed that two were M. xenopi. The most reliable characteristics distinguishing M. xenopi from MAC were the presence of X-colonies (M. xenopi 97% vs MAC 1%), positive 3-day arylsulfatase (M. xenopi 88% vs MAC 1%), growth at 25 degrees C (M. xenopi 0% vs MAC 100%), and AccuProbe MAC test results (M. xenopi 0% hybridized). Retrospective chart review of 37 patients using American Thoracic Society criteria revealed that six (16%) patients had clinically important isolates. At one of our hospitals M. xenopi was the second most common mycobacterial species isolated for 1990-1992, accounting for 27% of all isolates, whereas at our other hospital it accounted for 1% of isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of heterozygosity and overexpression of p53 gene in human primary prostatic adenocarcinoma

We have examined the loss of heterozygosity (LOH) of codon 72 and evaluated the overexpression of the tumor suppressor gene p53 in 43 primary human prostatic adenocarcinomas (PC). DNA from tumors and normal tissues were extracted from radical prostatectomy specimens. LOH was determined by restriction fragment length polymorphism analysis (RFLP) of the codon-specific endonuclease-digested polymerase chain reaction (PCR) products. Results showed 17 heterozygous cases (39%) among this patient group. Seven of the heterozygous cases displayed LOH. Six of the seven LOH cases were high-grade PCs with Gleason's combined score of > or = 7 and showed capsular invasion. One of the LOH cases, however, displayed an intermediate morphological score of 6 but also with evidence of capsular invasion. The 43 primary PCs were also examined for overexpression of p53 by a monoclonal antibody-mediated immunofluorescence reaction. Overexpression of nuclear p53 as detected by antibody was demonstrable only in tumors with combined morphological Grade > or = 7. No significant overexpression of p53 was noted in lower-grade tumors. In addition, 10 cases of benign prostatic hyperplasia (BPH) were evaluated for p53 expression. All 10 cases showed no detectable p53 overexpression.

Application of the RLGS method to large-size genomes using a restriction trapper

We developed a method for producing restriction landmark genomic scanning (RLGS) profiles of large-size genomes, such as those of higher plants or amphibians using a restriction trapper. Use of the conventional RLGS method is limited to genomes smaller than 3 x 10(9) bp, because the larger genomic DNAs, especially those of more than 1 x 10(10) bp, produce high background due to incorporation of radioactivity at non-specifically damaged sites. Our new method reduces the background levels by reducing genome complexity to 1/200-1/300 using a purification step to enrich DNA fragments carrying specific restriction landmarks at their ends using a restriction trapper. This step makes it possible to obtain RLGS patterns of larger genomes. Our paper describes the practical application for the RLGS method using a restriction trapper with the pine tree genome (3 x 10(10) bp/haploid genome; Pinus koraiensis Sieb. et Zucc.) as an example.

Effects of sennosides and nonanthranoid laxatives on cytochemistry of epithelial cells in rat colon

The cytochemical effects of laxatives on rat colonic epithelial cells were studied. A total of 32 rats was divided into four groups. Three groups were treated with bisacodyl, picosulfate and sennosides for 12 weeks, and a fourth group served as control. The rectum, midcolon and cecum were studied for acidic mucins, lectin soybean agglutinin (SBA) and cytokeratin AE1. Most striking and consistent changes were found in the rectum including total acidic mucin content which significantly increased, with sulfomucin decreased and sialomucin increased in the three treatment groups. Cytokeratin AE1 expression increased on picosulfate and sennosides. SBA total binding increased on bisacodyl and picosulfate. The present findings were thought to be of functional origin and do not represent early precancerous lesions.

Application of rejection criteria for stool cultures for bacterial enteric pathogens

Over 20 months, we prospectively assessed the yield of cultures for Salmonella, Shigella, and Campylobacter spp. from adults and children. In the first 10 months, 53% (567 of 1,097) of specimens from adults were from patients who had been in the hospital for > 3 days. Overall, only 2.6% (29 of 1,097) of specimens contained pathogens, and all were from patients who had been in the hospital for < or = 3 days. Over the second 10 months, specimens from adults in the hospital for > 3 days were not cultured unless special reasons existed. Thirty percent (368 of 1,229) of specimens were rejected. Concurrently, 7.5% (51 of 677) of stool specimens from children were positive. Only one positive specimen came from a child who had been in the hospital for > 3 days. Neither stool consistency nor fecal leukocytes were useful predictors for the presence of an enteric pathogen. We recommend that specimens from both adults and children in the hospital for > 3 days not be cultured unless there are delineated plausible clinical or epidemiological reasons to do so.

Deregulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor in murine macrophage cell line J774A.1

J774A.1 immortalized macrophage tumor cells display several phenotypes and functional capacities similar to that of murine peritoneal exudate macrophages (PEM). Both populations display comparable number of M-CSF receptors. Yet the number of GM-CSF receptors on J774A.1 cells is only one-fourth that of PEM (1,500 vs. 6,000 per cell). Unlike J774A.1 cells, which constitutively express c-myc transcripts, normal PEM required rMuGM-CSF for the induction of c-myc expression. Nevertheless, the growth of J774A.1 cells can be further enhanced in the presence of exogenous rMuGM-CSF, rHuM-CSF, and rMuIL-3. Treatment with either rMuIL-3 (20 ng/ml) and rHuTGF-beta 1 (1.0 ng/ml) for 24 hr at 37 degrees C, markedly enhanced the expression of GM-CSF receptors on normal PEM but not leukemic J774A.1 cells. J774A.1 cells also did not respond by autologous upregulation of GM-CSF receptors as seen in PEM following treatment with rMuGM-CSF. Treatment with either pertussis toxin (20-100 ng/ml) or H-8 (50 microM) for 24 hr led to an enhanced expression of GM-CSF receptors on J774A.1 cells in a time- and dose-dependent manner but did not result in enhanced receptor expression on normal PEM. These findings suggest that the expression of GM-CSF receptors may be regulated by mechanisms involving Gi-proteins and their downstream elements, which in turn are linked to regulatory pathways of other cytokine receptors. In J774A.1 cells, such regulatory interaction may not exist.

Microprocedure for in situ nick translation of chromosomes

We have modified the procedure of in situ nick translation to shorten the autoradiographic exposure time from 1 month to 3 days and reduce the volume of nick translation solution by a factor of at least 10. The modified procedure can be carried out on individually chosen chromosome spreads. The procedure was used on chromosome spreads of three related lines of mouse mammary epithelium (+SA, -SA, CL-S1) with different degrees of tumorigenicity. We found that the autoradiographic silver grains that are observed following in situ nick translation were often placed at the apparent junction site of chromosome translocations or at the breakpoint of chromosomal pieces. We found also that silver grains were located above double minute chromosomes, which suggests that there are active genes in double minutes.

Up-regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors in murine peritoneal exudate macrophages by both GM-CSF and IL-3

Murine peritoneal exudate macrophages (PEM) display multiple CSF receptors. In this study, the expression of granulocyte-macrophage (GM)-CSF receptors in PEM was studied. PEM displayed over 5000 single type, high affinity GM-CSF receptors/cell with a Kd = 38 to 42 pM and an apparent molecular mass of 86,000 Da. Treatment of PEM with low, but not high, concentrations of recombinant murine (rMu) GM-CSF continuously for 24 h resulted in a marked up-regulation of GM-CSF receptors in PEM. A similar up-regulation of GM-CSF receptors also was detected in PEM cultures treated with rMuIL-3 (1-100 ng/ml) for 24 h or longer, regardless the doses of rMuIL-3 added in this case. Scatchard analysis of equilibrium binding showed that the enhanced binding activities in both cases were due to an increase in total number of GM-CSF receptors rather than changes in receptor affinity. Contrariwise, treatment with recombinant human macrophage-CSF (greater than 100-1000 ng/ml) partially inhibited the expression of GM-CSF receptors in PEM. Removal of rMuGM-CSF from culture medium 24 h after treatment led to a further up-regulation of GM-CSF receptors over a 4 to 24-h period, depending on the doses of initial treatment. On the other hand, removal of rMuIL-3 from culture medium after prolonged treatment did not result in further increase in GM-CSF receptors. The protein synthesis inhibitor cycloheximide abrogated GM-CSF receptor up-regulation induced by both rMuIL-3 and rMuGM-CSF, whereas actinomycin D inhibited only the second (8-24 h) phase of GM-CSF receptor up-regulation induced by exposure to high concentrations rMuGM-CSF (10 ng/ml). These findings suggest that rMuGM-CSF and rMuIL-3 up-regulate GM-CSF receptors in PEM in part through similar or identical metabolic pathways and provide further evidence of a close linkage between IL-3 and GM-CSF receptors.

Up-regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors in murine peritoneal exudate macrophages by both GM-CSF and IL-3

Murine peritoneal exudate macrophages (PEM) display multiple CSF receptors. In this study, the expression of granulocyte-macrophage (GM)-CSF receptors in PEM was studied. PEM displayed over 5000 single type, high affinity GM-CSF receptors/cell with a Kd = 38 to 42 pM and an apparent molecular mass of 86,000 Da. Treatment of PEM with low, but not high, concentrations of recombinant murine (rMu) GM-CSF continuously for 24 h resulted in a marked up-regulation of GM-CSF receptors in PEM. A similar up-regulation of GM-CSF receptors also was detected in PEM cultures treated with rMuIL-3 (1-100 ng/ml) for 24 h or longer, regardless the doses of rMuIL-3 added in this case. Scatchard analysis of equilibrium binding showed that the enhanced binding activities in both cases were due to an increase in total number of GM-CSF receptors rather than changes in receptor affinity. Contrariwise, treatment with recombinant human macrophage-CSF (greater than 100-1000 ng/ml) partially inhibited the expression of GM-CSF receptors in PEM. Removal of rMuGM-CSF from culture medium 24 h after treatment led to a further up-regulation of GM-CSF receptors over a 4 to 24-h period, depending on the doses of initial treatment. On the other hand, removal of rMuIL-3 from culture medium after prolonged treatment did not result in further increase in GM-CSF receptors. The protein synthesis inhibitor cycloheximide abrogated GM-CSF receptor up-regulation induced by both rMuIL-3 and rMuGM-CSF, whereas actinomycin D inhibited only the second (8-24 h) phase of GM-CSF receptor up-regulation induced by exposure to high concentrations rMuGM-CSF (10 ng/ml). These findings suggest that rMuGM-CSF and rMuIL-3 up-regulate GM-CSF receptors in PEM in part through similar or identical metabolic pathways and provide further evidence of a close linkage between IL-3 and GM-CSF receptors.

Transforming growth factor-beta 1 bifunctionally regulates murine macrophage proliferation

Transforming growth factor-beta (TGF-beta) is a family of polypeptide growth factors with multiple functional activities. Recent studies suggest that TGF-beta is a selective inhibitor of hematopoietic cells. In this report, we study the effect of TGF-beta 1 on the proliferation of murine peritoneal exudate macrophages (PEM) in response to purified murine recombinant granulocyte-macrophage colony-stimulating factor (rMuGM-CSF) and human recombinant M-CSF (rHuM-CSF). In mice, PEM and other types of tissue macrophages display multiple types of receptors for CSFs and respond to them, either alone or in combination, to undergo extensive proliferation in vitro. Recombinant human TGF-beta 1 (rHuTGF-beta 1) (0.1 to 1.0 ng/mL) markedly enhanced the growth of PEM in response to rMuGM-CSF but inhibited their responsiveness to rHuM-CSF. Similar effects of rHuTGF-beta 1 were also detected using murine pulmonary alveolar macrophages (PAM) and bone marrow-derived macrophages (BMDM). Receptor binding assays using iodinated rMuGM-CSF and rHuM-CSF showed that rHuTGF-beta 1 treatment greatly enhanced the expression of GM-CSF receptors in PEM, in a time- and dose-dependent manner, suggesting a possible mechanism for the synergistic effect of TGF-beta 1. On the other hand, the expression of M-CSF receptors was not affected by TGF-beta 1 treatment. Analysis by mRNA PCR showed that the synergistic effect of TGF-beta 1 is not due to autocrine CSFs produced by treated cells. Our results suggest that TGF-beta 1 is an important regulator of macrophage proliferation. Depending on the types of CSFs present, TGF-beta 1 may act either as a growth promoter or inhibitor.

Murine recombinant IL-4 is a bifunctional regulator of macrophage growth induced by colony-stimulating factors

Murine peritoneal exudate macrophage (PEM) coexpress receptors for both granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) and can be induced by both factors, either alone or in combination, to undergo extensive proliferation in vitro. In this study the effect of murine rIL-4 (MurIL-4) on the proliferation of PEM was examined. MurIL-4 alone did not support macrophage proliferation but prolonged their survival in vitro. When MurIL-4 was combined with human (Hu)rM-CSF, it enhanced the proliferative response of PEM to rHuM-CSF in a dose-dependent manner, reaching a maximum at approximately 10 ng/ml. Contrarily, MurIL-4 suppressed the proliferative response of PEM to MurGM-CSF. Receptor binding assays using radiolabeled ligands showed that MurIL-4 selectively enhanced the expression of M-CSF receptors; suggesting that at least part of the synergistic effect of MurIL-4 is mediated at the receptor level. Of relevance to this effect is the finding that MurIL-4 greatly promoted the responsiveness of PEM to low concentrations of HurM-CSF. Unlike M-CSF receptors, however, MurIL-4 treatment failed to modulate the levels of GM-CSF receptors in PEM. The proliferative responses of PEM to both MurGM-CSF and HurM-CSF could be inhibited by MurIFN-gamma with similar sensitivity. This inhibitory effect of MurIFN-gamma was partially neutralized by MurIL-4 in cultures containing HurM-CSF but not those containing MurGM-CSF. This study demonstrates that IL-4 is involved directly in the regulation of macrophage production by modulating their responsiveness to various cytokines.

Murine recombinant IL-4 is a bifunctional regulator of macrophage growth induced by colony-stimulating factors

Murine peritoneal exudate macrophage (PEM) coexpress receptors for both granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) and can be induced by both factors, either alone or in combination, to undergo extensive proliferation in vitro. In this study the effect of murine rIL-4 (MurIL-4) on the proliferation of PEM was examined. MurIL-4 alone did not support macrophage proliferation but prolonged their survival in vitro. When MurIL-4 was combined with human (Hu)rM-CSF, it enhanced the proliferative response of PEM to rHuM-CSF in a dose-dependent manner, reaching a maximum at approximately 10 ng/ml. Contrarily, MurIL-4 suppressed the proliferative response of PEM to MurGM-CSF. Receptor binding assays using radiolabeled ligands showed that MurIL-4 selectively enhanced the expression of M-CSF receptors; suggesting that at least part of the synergistic effect of MurIL-4 is mediated at the receptor level. Of relevance to this effect is the finding that MurIL-4 greatly promoted the responsiveness of PEM to low concentrations of HurM-CSF. Unlike M-CSF receptors, however, MurIL-4 treatment failed to modulate the levels of GM-CSF receptors in PEM. The proliferative responses of PEM to both MurGM-CSF and HurM-CSF could be inhibited by MurIFN-gamma with similar sensitivity. This inhibitory effect of MurIFN-gamma was partially neutralized by MurIL-4 in cultures containing HurM-CSF but not those containing MurGM-CSF. This study demonstrates that IL-4 is involved directly in the regulation of macrophage production by modulating their responsiveness to various cytokines.

Nonclonal lymphocytic proliferation in cutaneous lymphoid hyperplasia: a flow-cytometric and morphological analysis

Cutaneous lymphoid hyperplasia, follicular B cell pseudolymphoma or lymphadenosis benigna cutis and lymphocytic infiltration of Jessner-Kanof are a group of benign lymphoid hyperplastic disorders which usually involve the skin of the face or head and neck. These lesions may be difficult to differentiate from malignant lymphocytic lymphomas both morphologically and clinically. To evaluate whether quantitative flow-cytometric analysis and DNA ploidy determination of the lymphoid cells in the lesions would provide additional and more precise diagnostic parameters, we have correlatively analyzed a case by morphological, flow-cytometric and immunohistochemical methods. The two latter methods both revealed that the lesions harbored nonclonal heterogeneous subpopulations of lymphoid cells, but 62% of the cells analyzed were of B cell lineage progenies. No pre-B cells, immature B or T determinants were detected. Ploidy analysis of the isolated lymphocytes disclosed predominantly diploid (2 N) cells with about 1% 4 N and a few (less than 5%) hyperdiploid (2.2 N) cells. Cell cycle analysis showed that 97.2% of the cells were in G0-G1 phase. Phenotyping and DNA ploidy study of the lymphocytes of the lesion may provide quantitative diagnostic parameters to distinguish this benign lesion from true lymphocytic lymphoma involvement of skin. The eventual biological behavior of the minor hyperdiploid subpopulation of lymphoid cells found in this lesion is currently uncertain, however.

Heterogeneous subpopulations of human prostatic adenocarcinoma cells: potential usefulness of P21 protein as a predictor for bone metastasis

Expression of the p21 protein of the ras oncogene family was studied in a case of human prostatic adenocarcinoma tissue and the cell line was derived from the primary tumor. Flow cytometry analysis of the tumor cells obtained from the primary tumor indicated that approximately 25 per cent of the cells were positive for this oncogene product. However, by the immunoperoxidase method almost all of the tumor cells at the vertebral metastatic sites in the same patient were positive for the p21 protein. The cell line established from the primary tumor displayed 2 distinct subpopulation growth patterns in vitro: a monolayer, density-inhibited growth and a multicellular aggregate type growth morphology. These 2 subpopulations could be separated by density elutriation centrifugation. The isolated subpopulation cells were noted to express prostatic acid phosphatase and prostate specific antigen at high frequency. High levels of expression of these 2 prostatic markers also were found in the tumor cells at the vertebral metastatic sites. However, when the isolated subpopulations were analyzed for the expression of p21 protein, the multicellular grown cells were almost 90 per cent positive for the p21 antigen, whereas only approximately 5 per cent of the monolayer grown cells were positive for the same protein. Our findings suggest that primary prostatic carcinomas are composed of heterogeneous subpopulations of neoplastic cells while only specific subpopulations have metastatic potential. Quantification of prostatic acid phosphatase and prostate specific antigen in the primary tumor cells probably will not offer a predictive value for the eventual behavior of the tumors. However, evaluation of oncogene products, such as the p21 protein, may be useful as a clinical predictor for metastatic potential.

Amiodarone-associated pulmonary fibrosis. Evidence of an immunologically mediated mechanism

A case of pulmonary fibrosis attributed to amiodarone was studied immunologically and morphologically. A specific antibody of the IgG class was identified in the serum of this patient which reacted with the patient's own lung tissue. The immunoglobulin did not react with normal lung tissue nor was there evidence of reaction with lung tissue from patients with pulmonary fibrosis but without a history of amiodarone therapy. The patient probably developed a humoral antibody response to a lung-amiodarone complex with the amiodarone acting as a hapten which bound in vivo to the lung tissue. The subsequent antibody-antigen reaction stimulated a proliferation of pulmonary fibroblasts and probably enhanced the fibro-collagen deposition in the lung.

Co-culture study of rat neuron-glial interaction: evidence of neuronal influence on myelination

Organotypic cultures of newborn rat brains were exposed to the neurotoxin kainic acid or the DNA synthesis inhibitor arabinoside C. The cultures were subsequently co-cultured and the myelination-related enzymatic activities, such as 2',3'-cyclic nucleotide phosphohydrolase and uridine diphosphate-galactose-ceramide galactosyl transferase, were determined under various culture conditions. The newly formed myelin basic protein in the cultured brain tissue was determined by the radioimmunoprecipitation method. The myelination-related enzymatic activities and the synthesis and accumulation of myelin basic protein in the co-cultured brain tissue were found compatible to the control cultures which were not exposed to either drug. The cultures which had been treated with either drug, but not subsequently co-cultured, were found to have decreased enzymatic activities and myelin basic protein synthesis. The experimental data suggest that myelinogenesis requires an interaction between functional neurons and oligodendroglial cells and further supports the hypothesis that the neuron exerts a regulatory effect on the glial myelination mechanism.

Adenomatoid tumor of ejaculatory duct

Adenomatoid tumors are generally restricted to the epididymal region and occasionally the spermatic cord in the male. Herein we report on a case of adenomatoid tumor apparently originating from the ejaculatory duct which to our knowledge has not been reported previously.

Urethral verumontanal polyp: evidence of prostatic origin

A papillary adenomatous polyp of the verumontanum was studied morphologically and immunochemically. This rare polypoid neoplasm displayed rather typical prostatic acinar epithelium, and by immunoperoxidase method differentiation products of prostatic origin could be demonstrated easily. Findings support the concept that this type of lesion is prostatic in origin and probably arising from ectopic prostatic tissue in the prostatic urethra. The clinical symptoms of this lesion usually are hematospermia or hematuria, and this lesion can be effectively treated by transurethral excision.

Diffuse pulmonary interstitial fibrosis. Evidence of humoral antibody mediated pathogenesis

Immunochemical studies of post-mortem lung tissue from a patient suffering from diffuse pulmonary interstitial fibrosis were conducted. Identifiable deposition of IgG on the alveolar septa was noted by immunoperoxidase and immunofluorescein methods. The antemortem serum obtained from the patient showed high affinity immunologic binding to normal human lung tissue. An antibody-antigen reaction was also detectable by microcomplement fixation procedure with buffer extracts of normal lung tissue, while normal pooled serum showed no significant reaction. These findings, in addition to the gross, light microscopic, and electron microscopic observations, strongly suggest that a humoral antibody mediated reaction is one of the underlying pathogenetic mechanisms eliciting the morphologically and clinically observable manifestations of diffuse interstitial pulmonary fibrosis.

Preferential synthesis of differentiation related cytoplasmic proteins in low-serum adapted differentiated glioma cells

Rat glioma (C6) cells can be induced to morphological and biochemical differentiation by culturing in serum-deprived conditions. The induced differentiated cells were found to preferentially synthesize some distinct cytoplasmic proteins, and the rate of synthesis quantitatively correlated well with the degree of morphological differentiation, whereas the total mRNA synthesis was decreased in the differentiated cells. These findings suggest that reduced total mRNA syntheses and preferential translation of differentiation-related mRNAs are parts of the biochemical events during the differentiation process of neuroglia.

Predicting the probability of bone metastasis through histological grading of prostate carcinoma: a retrospective correlative analysis of 81 autopsy cases with antemortem transurethral resection specimen

In a retrospective correlative analysis of postmortem findings and antemortem transurethral resection specimens from 81 patients with prostatic carcinoma a simple and reliable prediction index was found. This index was derived from the transurethral resection specimen in regard to the probability of ultimate bone metastasis by tumor and was obtained by dividing the number of prostatic tissue chips involved with tumor by the total number of prostatic tissue chips examined microscopically. We found that when 75 per cent or more of the transurethral resection chips were involved with tumor, regardless of the degree of tumor differentiation, the probability of bone metastasis was more than 9.0 (greater than 90 per cent), whereas the probability was 0.58 for 50 to 75 per cent involvement, 0.38 for 30 to 50 per cent involvement, 0.27 for 20 to 30 per cent involvement, 0.10 for 10 to 20 per cent involvement and 0.06 for less than 10 per cent involvement. Other tumor grading systems, such as the Gleason system, also were compared. A good correlation was obtained by the Gleason grading system in the prediction of bone metastasis but the system is not as simple or as reproducible as the tumor involvement index described herein. Other parameters, such as prostatic acid phosphatase and prostatic specific antigen as determined by the immunoperoxidase method, had no specific or significant value in the prediction of bone metastasis. Our findings reaffirm the relatively old concept that the extensiveness of tumor involvement in the transurethral resection specimen is the single most important factor in the prediction of the clinical behavior of the prostatic carcinoma.

Hypercalcemia associated with renal cell carcinoma: probable role of neoplastic stromal cells

Sarcomatous proliferation of the fibroblast-like stromal cells in renal cell carcinoma was found in three patients who had apparently tumor-associated hypercalcemia but no evidence of bone metastases. The proliferation of stromal cells was not found in 20 patients who also had renal cell carcinoma without hypercalcemia. Immunoreactive parathormone-like substance was detected in two of the three patients with hypercalcemia, despite high levels of serum calcium. The parathormone assay was not conducted on the third hypercalcemic patient, however. Buffer extract from one of the tumors associated with hypercalcemia was able to elicit an increase of the serum calcium in rats, whereas buffer extract from a tumor not associated with hypercalcemia failed to induce hypercalcemia in rats. Findings suggest that the stromal cells of renal cell carcinoma may play a role in the tumor-associated hypercalcemia. The exact nature of the hypercalcemic agent is uncertain. However, in the case studied it appears that a parathormone-like substance was responsible.

S-100 protein synthesis in cultured glioma cell is G1-phase of cell cycle dependent

The kinetics of S-100 protein synthesis was studied in synchronized cultured glioma (C6) cells. The peak of the synthesis was detected at G1-phase of the cell cycle and apparently was not population density-dependent, since sparsely cultured G1-phase cells synthesized the same proportion of the protein per cell as that of confluent cultures, whereas the total cellular protein synthesis was found steadily increasing throughout the intermitotic phases.