Multicenter evaluation of implantable cardioverter defibrillator testing after implant: the Post Implant Testing Study (PITS)

To reassess the function of the implantable cardioverter defibrillator (ICD) many electrophysiology centers perform a second test after the initial test at implant. A prospective multicenter study evaluated the necessity and yield of routine postimplant defibrillator testing. The results of 843 postimplant defibrillator tests were collected from 31 centers. The 764 routine tests in which ventricular fibrillation was successfully induced were analyzed. Variables examined included patient age, presenting arrhythmia, underlying heart disease, left ventricular ejection fraction, defibrillator age, make and model of ICD, electrode system, defibrillation threshold, polarity, and waveform. The overall failure rate was 3.1% (24/764). Units tested later than 365 days after implant tended to have a higher failure rate than those tested within the first month or the next eleven months (6.5%, 3.0%, 2.3%, respectively, P = 0.374). The failure rate was higher in patients with left ventricular ejection fraction < 40% than those with higher ejection fractions (3.8% vs 2.0%, P = 0.167). These trends did not reach statistical significance. No other baseline characteristic was associated with higher failure rates. Routine testing of ICDs reveals an overall failure rate of 3.1%. While the rate was low, defibrillator failure places the patient at high risk for sudden cardiac death. As any failure in this population is associated with a high risk of sudden cardiac death, routine defibrillator testing may be justified.

Signal transduction, cell cycle regulatory, and anti-apoptotic pathways regulated by IL-3 in hematopoietic cells: possible sites for intervention with anti-neoplastic drugs

Over the past decade, there has been an exponential increase in our knowledge of how cytokines regulate signal transduction, cell cycle progression, differentiation and apoptosis. Research has focused on different biochemical and genetic aspects of these processes. Initially, cytokines were identified by clonogenic assays and purified by biochemical techniques. This soon led to the molecular cloning of the genes encoding the cytokines and their cognate receptors. Determining the structure and regulation of these genes in normal and malignant hematopoietic cells has furthered our understanding of neoplastic transformation. Furthermore, this has allowed the design of modified cytokines which are able to stimulate multiple receptors and be more effective in stimulating the repopulation of hematopoietic cells after myelosuppressive chemotherapy. The mechanisms by which cytokines transduce their regulatory signals have been evaluated by identifying the involvement of specific protein kinase cascades and their downstream transcription factor targets. The effects of cytokines on cell cycle regulatory molecules, which either promote or arrest cell cycle progression, have been more recently examined. In addition, the mechanisms by which cytokines regulate apoptotic proteins, which mediate survival vs death, are being elucidated. Identification and characterization of these complex, interconnected pathways has expanded our knowledge of leukemogenesis substantially. This information has the potential to guide the development of therapeutic drugs designed to target key intermediates in these pathways and effectively treat patients with leukemias and lymphomas. This review focuses on the current understanding of how hematopoietic cytokines such as IL-3, as well as its cognate receptor, are expressed and the mechanisms by which they transmit their growth regulatory signals. The effects of aberrant regulation of these molecules on signal transduction, cell cycle regulatory and apoptotic pathways in transformed hematopoietic cells are discussed. Finally, anti-neoplastic drugs that target crucial constituents in these pathways are evaluated.

Movement of a cytokinesis factor cdc12p to the site of cell division

A key question in cytokinesis is how the plane of cell division is positioned within the cell. Although a number of cytokinesis factors involved in formation of the actomyosin contractile ring have been identified, little is known about how these factors are localized and assembled at the cell-division site. Cells of the fission yeast Schizosaccharomyces pombe divide using a medial actomyosin ring that assembles in early mitosis [1]. The S. pombe cdc12 gene encodes a formin, a member of a family of proteins that have functions in cytokinesis and cell polarity and that may bind Rho/Cdc42 GTPases, profilin and other actin-associated proteins [1] [2] [3] [4]. The cdc12 protein (cdc12p) is required specifically for medial-ring assembly during cytokinesis and is a component of this ring [2] [5]. In this study, cdc12p was found, during interphase, in a discrete, motile cytoplasmic spot that moved to the future site of cell division at the onset of mitosis. Three lines of evidence indicated that this cdc12p spot moved on both actin and microtubule networks: movement required either actin or microtubules; the spot was associated with actin and microtubule structures; and individual spots were seen to move along both microtubule and non-microtubule tracks. These findings demonstrate that a cytokinesis factor may travel on both microtubule and actin networks to the future site of cell division.

Technetium-99m labeled peptides--an investigation of multiple HPLC peaks

This laboratory, and others, have reported multiple radioactive peaks in the size exclusion high performance liquid chromatographic (HPLC) analysis of 99mTc-labeled peptides. In the case of one 99mTc-MAG3-labeled peptide studied in this laboratory, human neutrophil elastase inhibitor, all five radioactive peaks were shown to be due to active peptide rather than radiocontaminants. By a variety of experiments, the nature of these peaks have now been examined. A high molecular weight UV peak could be generated by heating the MAG3 coupled, but not the native, peptide. Furthermore, this UV peak did not appear upon heating the peptide if the sulfur within the MAG3 chelator was replaced with oxygen. This peak may therefore be due to polymers resulting from intermolecular disulfide bond formation between sulfurs in the MAG3 chelate and the peptide. Several peaks with apparent lower molecular weights were absent on analysis with a different size exclusion column with superior resolution in their molecular weight range. More importantly, they were also absent on analysis by SDS polyacrylamide gel electrophoresis. These "low" molecular weight radioactive peaks may therefore be due to interactions between the 99mTc-MAG3 chelate and the peptide which produce multiple molecular configurations of identical molecular weight but differing in shape, charge, isomerism or lipophilicity such that they are resolved under the conditions of certain analyses. In support of this possibility, lengthening the linker between MAG3 and the peptide reduced the number of radioactive peaks, while encouraging the interaction by replacing MAG3 with the shorter MAG2 seemed to increase the number of radioactive peaks. Finally, that the three "low" molecular weight radioactive peaks reappeared when a single peak fraction was reanalyzed suggests that the species responsible are in rapid equilibrium. One conclusion from this investigation is that the appearance of a single peak by any HPLC analysis offers no assurance that multiple peaks would not appear on alternative HPLC analyses. Evidence that each species is due to radiolabeled active peptide and not to radiocontaminants is therefore potentially more important than evidence of a single peak.

An interlaboratory study to determine the presence of human papillomavirus DNA in esophageal carcinoma from China

Esophageal-carcinoma samples originating from the high-incidence area of China were tested in 2 different laboratories, each using a different degenerate PCR approach. Results confirmed the notion that none of the PCR approaches available for HPV-DNA detection today, is optimal for detecting all known HPV types at equal sensitivity and specificity. In combining results obtained in both laboratories, HPV DNA was demonstrated in 20/117 (17.1%) esophageal-carcinoma samples analyzed. HPV DNA was detected in 3/70 (4.3%) diagnostic biopsies, 7/23 (30.4%) surgical specimen and 10/24 (41.6%) cytological scrapings originating from the entire surface of the esophagus. Mucosotropic HPV types were present in 7/117 (6%) samples, only 3 being of the high-risk types (HPV 16, 18, 33). Other mucosal types found were HPV 6, 11, 13, 53 and 54. Cutaneous HPV types were present in 14/117 (12.0%) samples. HPVs 20 and 38 were present in 3 (2.6%) of the total samples and, in each case, together with another HPV type within one lesion. Two putative new HPV types, DL347 and DL 369, were identified.

An interlaboratory study to determine the presence of human papillomavirus DNA in esophageal carcinoma from China

Esophageal-carcinoma samples originating from the high-incidence area of China were tested in 2 different laboratories, each using a different degenerate PCR approach. Results confirmed the notion that none of the PCR approaches available for HPV-DNA detection today, is optimal for detecting all known HPV types at equal sensitivity and specificity. In combining results obtained in both laboratories, HPV DNA was demonstrated in 20/117 (17.1%) esophageal-carcinoma samples analyzed. HPV DNA was detected in 3/70 (4.3%) diagnostic biopsies, 7/23 (30.4%) surgical specimen and 10/24 (41.6%) cytological scrapings originating from the entire surface of the esophagus. Mucosotropic HPV types were present in 7/117 (6%) samples, only 3 being of the high-risk types (HPV 16, 18, 33). Other mucosal types found were HPV 6, 11, 13, 53 and 54. Cutaneous HPV types were present in 14/117 (12.0%) samples. HPVs 20 and 38 were present in 3 (2.6%) of the total samples and, in each case, together with another HPV type within one lesion. Two putative new HPV types, DL347 and DL 369, were identified.

NHS-MAS3: a bifunctional chelator alternative to NHS-MAG3

This laboratory uses an N-hydroxysuccinimide derivative of S-acetylmercaptoacetyltriglycine (NHS-MAG3) to conjugate amines for subsequent labeling with 99mTc. However, the synthesis from triglycerine is general and not restricted to this tripeptide. We had earlier selected a small number of alternative tripeptides and synthesized the corresponding NHS derivatives. Each was then evaluated in a search for bifunctional chelators with properties superior to NHS-MAG3, such as lower serum protein binding or improved stability to cysteine challenge. Based on these preliminary results, NHS-S-acetylmercaptoacetyltriserine (NHS-MAS3) was selected for further investigation. We have now conjugated this bifunctional chelator to an biocytin and to an amine-derivatized peptide nucleic acid (PNA). Both carriers were also conjugated with NHS-MAG3 under identical conditions and all were labeled with 99mTc at neutral pH and at boiling temperature while the conjugated PNAs were radiolabelled at neutral pH and at room temperature. Regardless of the chelator, reverse phase HPLC radiochromatograms of the labeled biotins and PNAs after purification showed a single peak. However, by size exclusion HPLC, the radiochromatograms always showed several peaks even after purification, but the MAS3 radiochromatograms were less complicated. For biotin and PNA both, radiolabeling via MAS3 showed improved 99mTc stability in 37 degrees C serum and in cysteine solution. The four preparations were administered to mice implanted in one thigh with avidin beads (biotins) or complementary PNA beads (PNAs). At 5 h post-administration, no significant differences were observed in the targeting of PNA beads between the two chelators, however the target thigh/normal thigh ratio was significantly higher for MAS3-biotin compared to MAG3-biotin. We conclude that labeling biocytin and amine-derivatized PNA with NHS-MAS3 compared to NHS-MAG3 provides simpler radiochromatographic profiles, improved stability of the label in serum and cysteine solution and can improve in vivo targeting.

[Clinical observation on treatment of bile regurgitational gastritis with danwei capsule]

OBJECTIVE

To evaluate the therpeutic effect of Danwei capsule in treating bile regurgitational gastritis.

METHODS

One hundred and thirty-four patients with bile regurgitational gastritis were divided into two groups. Danwei capsule was used in therapeutic group and Motilium was used in control group.

RESULTS

The total effective rate in therapeutic group was 92.59%, and 71.70% in control group (P < 0.01). The improvement in symptoms, physical findings and bile regurgitation in therapeutic group was better than that of control.

CONCLUSION

Curative effect of Danwei capsule was better than that of Motilium, which should be used widely.

Profiling expression patterns and isolating differentially expressed genes by cDNA microarray system with colorimetry detection

A high-density cDNA microarray with colorimetry detection system to simultaneously monitor the expression of many genes on nylon membrane is described and characterized. To quantify the expression of genes and to isolate differentially expressed genes, the southern hybridization process on filter membranes was employed. The levels of gene expression were represented by color intensities generated by colorimetric reactions in place of hazardous radioisotopes or costly laser-induced fluorescence detection. The gene expression patterns on nylon membranes were digitized by devices such as an economical flatbed scanner or a digital camera. The quantitative information of gene expression was retrieved by image analysis software. Quantitative comparison of the northern dot-blotting method with the microarray system is described. Applications employing single-color detection as well as dual-color detection to isolate differentially expressed genes among thousands of genes are demonstrated.

Thoracoscopic anterior spinal procedures in children

METHODS

From February 1996 through July 1997, 20 patients were determined to be appropriate for a thoracoscopic approach for the anterior portion of their spinal surgery. Ages ranged from 8 to 17 years of age and weight from 20 to 70 kg. The diagnosis included severe idiopathic and neurogenic scoliosis or kyphosis (n = 20) and congenital hemivertebra (n = 4). The procedures performed included diskectomy and anterior release from two to nine vertebral levels, hemivertebrectomy, and epiphysiodesis. Four patients also had an open lumbar exposure and all had a posterior fusion.

RESULTS

All procedures were completed successfully endoscopically. Surgical times for the thoracoscopic portion of the procedure averaged 106 minutes and total procedure times were comparable with the standard open technique. Three patients were extubated at the end of the procedure with the majority extubated on postoperative day 1. Average intensive care unit stay was 1.8 days, and chest tubes were removed between postoperative day 1 and 5 (average, 2.2 days). In follow-up, surgical correction was deemed to be acceptable and equivalent to open techniques in all cases.

CONCLUSION

This technique has proven to be safe and effective in children and appears to be associated with less pain and morbidity as evidenced by earlier extubation and chest tube removal and shorter ICU stay.

Labeling peptides with technetium-99m using a bifunctional chelator of a N-hydroxysuccinimide ester of mercaptoacetyltriglycine

A modified mercaptoacetyltriglycine (MAG3) chelator, which has acetyl S-protection and which is derivitized with N-hydroxysuccinimide (NHS) ester for conjugation, has been used to radiolabel four small (approximately 6- to 7-kDa) peptides, bovine pancreatic trypsin inhibitor, epidermal growth factor, human neutrophil elastase inhibitor and plasmin inhibitor, with 99mTc.

METHODS

Each peptide was specifically labeled at the MAG3 chelation sites at ambient temperature and neutral pH. Specific activities of 100-150 mCi/mg were achieved at labeling efficiencies of about 50%, but specific activities of 3500 mCi/micromol could be attained.

RESULTS

By a variety of assays, protein activity was unimpaired by the conjugation and labeling for two of the four peptides. The activities for plasmin of the plasmin inhibitor and bovine pancreatic trypsin inhibitor were reduced by conjugation, presumably because of a sensitive lysine residue in the structure of each of these two peptides. Multiple peaks were present in the high-performance liquid chromatography radiochromatograms, especially of human neutrophil elastase inhibitor; however, most peaks could be shown to be labeled active peptide. Stability during cysteine challenge at modest cysteine-to-peptide molar ratios and during incubation in serum was observed in each case. Large differences among the labeled peptides were apparent in the 3-hr biodistributions of 99mTc in normal mice.

CONCLUSION

The use of NHS-S-acetyl-MAG3 may be a convenient method of radiolabeling peptides with 99mTc.

Early results in the irrational design of new bifunctional chelators

BACKGROUND

The development of a simple route for the synthesis of the N-hydroxysuccinimide (NHS) ester of S-acetyl-protected mercaptoacetyltriglycine (MAG3) has opened the possibility of preparing novel bifunctional N3S chelators for technetium-99m (99mTc) and other radionuclides. In particular, the synthesis may be applied to a vast number of tripeptides in place of triglycine, to provide a "library" of bifunctional N3S chelators, each with unique properties related to the particular amino acid residues within each tripeptide.

METHODS

The authors have synthesized by this simple route the NHS esters of four N3S chelators by reacting NHS-S-acetylthioglycolic acid with ala-gly-gly, phe-gly-gly, pro-gly-gly, and ser-ser-ser, in addition to gly-gly-gly. Each bifunctional chelator was conjugated to biocytin as a model primary amine and radiolabeled with 99mTc. The properties of the four chelators were compared with MAG3 with respect to the stability of the label in saline and serum, the extent of serum protein binding, and the instability to cysteine challenge.

RESULTS

A range of values was observed. Labeled mercaptoacetyltriserine showed stability towards transchelation to cysteine similar to that of MAG3 as well as lower serum protein binding; labeled mercaptoacetylalanyldiglycine showed slightly higher serum protein binding than labeled MAG3 but greater stability to cysteine challenge.

CONCLUSIONS

The authors concluded that this simple synthesis and evaluation scheme may be used to prepare and screen a large library of bifunctional chelators for those with useful properties.

Pretargeting using peptide nucleic acid

BACKGROUND

Pretargeting studies in animals and humans have usually involved (strept)avidin and biotin. Depending on the particular strategy, endogenous biotin can adversely influence localization when these molecules are used.

METHODS

As an alternative to (strept)avidin and biotin, we have explored the use of a single-stranded peptide nucleic acid (PNA) bound to a protein administered first and followed by the complementary single-stranded PNA radiolabeled with 99mTc. Target localization of the PNA-bound protein in a mouse infection and a mouse tumor model occurred by passive diffusion while the radiolabeled complementary PNA localized by in vivo hybridization. The PNA-streptavidin was prepared by adding biotin-conjugated PNA to streptavidin; the complementary PNA, derivatized with a primary amine, was conjugated with acetyl S-protected NHS-MAG3 bifunctional chelator and radiolabeled with 99mTc.

RESULTS

In both the infection and tumor mouse models, increased localization of radiolabel was achieved in animals receiving both injectates compared with control animals receiving only the radiolabeled PNA. In the infection model, the infected to normal thigh radioactivity ratio was 3.5 for the study animals compared with 1.7 for control animals (P = 0.0001). In the tumor model, these values were 1.7 versus 1.2 (P = 0.003).

CONCLUSIONS

We conclude that PNA may be considered an alternative to (strept)avidin and biotin for pretargeting studies.

Detection of medulloblastoma and astrocytoma-associated ganglioside GD3 in cerebrospinal fluid

Shedding of gangliosides by tumor cells may enhance tumor development. We recently showed that cells of the human brain tumor, medulloblastoma, shed gangliosides in vitro and have therefore examined ganglioside shedding by pediatric brain tumors into the cerebrospinal fluid (CSF). GD3, a major ganglioside in medulloblastoma and astrocytoma, was the target for detection in the CSF by immunostaining using the monoclonal antibody R24 and enhanced chemiluminescence detection. Mean CSF GD3 levels in patients with medulloblastomas (n = 9) and astrocytomas (n = 10) were significantly higher than those of controls (mean +/- SD 44.7 +/- 8.4 versus 18.2 +/- 1.9 pmol/ml, n = 20, P < 0.0002). Mass spectrometric analysis showed that tumor-derived ganglioside GD3 contained heterogeneous ceramide structures and, interestingly, the ceramide subspecies with shorter fatty acyl chains were selectively shed. The elevated CSF GD3 concentrations in patients with medulloblastoma and astrocytoma support the concept that ganglioside shedding, which may have significant biological consequences, is characteristic of human brain tumors.

Technetium-99m labeled epidermal growth factor-tumor imaging in mice

We have shown previously that the epidermal growth factor peptide (EGF) may be radiolabeled with 99mTc at room temperature and neutral pH by using the N-hydroxysuccinimide ester of S-acetyl mercaptoacetyltriglycine (MAG3) as a bifunctional chelator. By a competition binding assay, we found that MAG3-conjugated EGF retained biological activity. Furthermore, the labeled peptide exhibited saturation binding to EGF receptor-positive tumor cell lines which could be inhibited by presaturation of the cells with unlabeled, native EGF. Biodistribution in normal mice at 3 h postadministration showed rapid clearance with minimal retention of the label in sampled organs. We have now investigated the tumor localization properties in mice of this labeled peptide. Nude mice implanted with the EGF receptor-positive tumors A431 and LS-174T were administered labeled EGF and a labeled control peptide (BPTI, aprotinin). Tumor uptake at 12 h postadministration was 0.44% injected dose/g for EGF/g vs. 0.09 for the control. Pretreatment of tumored mice with unlabeled EGF blocked about half the tumor uptake. Animals were also administered an anti-EGF receptor antibody labeled with 99mTc via MAG3. Relative to the antibody, tumor-to-muscle ratios were improved from 6 to 15 and tumor-to-blood ratios from 0.4 to 7 with EGF. These favorable results along with documented evidence of overexpression of the EGF receptor in many human tumors suggest that 99mTc-EGF should be considered further for tumor detection.

Integration specificities of two lambdoid phages (21 and e14) that insert at the same attB site

It was shown previously that phage 21 and the defective element e14 integrate at the same site within the icd gene of Escherichia coli K-12 but that 21 integrase and excisionase excise e14 in vivo very infrequently compared to excision of 21. We show here that the reverse is also true: e14 excises itself much better than it excises an adjacent 21 prophage. In vitro integrase assays with various attP substrates delimit the minimal attP site as somewhere between 366 and 418 bp, where the outer limits would include the outermost repeated dodecamers suggested as arm recognition sites by S. J. Schneider (Ph.D. dissertation, Stanford University, Stanford, Calif., 1992). We speculate that the reason 21 attP is larger than lambda attP (240 bp) is because it must include a 209-bp sequence homologous to the 3' end of the icd transcript in order to allow icd expression in lysogens. Alteration of portions of 21 attP to their e14 counterparts shows that 21 requires both the arm site and core site sequences of 21 but that replacements by e14 sequences function in some positions. Consistent with Schneider's in vivo results, and like all other known integrases from lambdoid phages, 21 requires integration host factor for activity.

Shedding of gangliosides by human medulloblastoma cells

Shedding of immunosuppressive gangliosides is an important characteristic of both experimental and human tumors. Using a medulloblastoma cell line, Daoy, with a very high ganglioside expression (141 +/- 13 nmol/10(8) cells) and a well-characterized ganglioside complement, we have now studied ganglioside shedding by human brain tumor cells. Shedding of gangliosides, quantified by metabolic radiolabeling, was significant (169 pmol/10(8) cells/h) and was generalized with respect to the major ganglioside carbohydrate structures (G(M2), G(M3), and G(D1a)). For each ganglioside, however, shedding was selective for ceramide structures containing shorter fatty acyl chains. Rapid and ceramide-selective shedding was confirmed in two additional human medulloblastoma cell lines, D341 Med and D283 Med (112 and 59 pmol/10(8) cells/h). Significant ganglioside shedding is therefore a common characteristic of human medulloblastoma cells and may influence the biological behavior of this tumor, in view of immunosuppressive and other biological properties of shed gangliosides.

Preparation and use of NHS-MAG3 for technetium-99m labeling of DNA

The chelator mercaptoacetylglycylglycylglycine (MAG3) is on of several amidothiols that have been used successfully to radiolabeled proteins and other molecules with 99mTc. Prior to radiolabeling, the sulfur in these amidothiols is usually protected by a benzoyl group (i.e. S-benzoyl MAG3) which requires extreme alkaline pH or boiling water temperatures for rapid deprotection. As a result, the benzoyl-protected chelator is radiolabeled prior to conjugation (i.e. preconjugation labeling) in the case of carriers such as proteins or polypeptides which cannot withstand harsh conditions. We have employed a simple, two-step, synthesis of the N-hydroxysuccinimide ester of MAG3 in which the sulfur is protected with an acetyl group (i.e. S-acetyl NHS-MAG3). A single-stranded amine-derivitized DNA was coupled with NHS-S-acetyl MAG3. Radiolabeling was accomplished at room temperature and neutral pH by transchelation from 99mTc-tartrate. In comparison to labeled SHNH-DNA, the labeled MAG3-DNA was unstable to cysteine transchelation, however, in contrast to SHNH-DNA, no evidence for serum protein binding of the labeled MAG3-DNA was observed. We conclude that the S-acetyl NHS MAG3 bifunctional chelator may prove to be an attractive alternative method of radiolabeling DNA and other biologically important molecules with 99mTc.

Human medulloblastoma gangliosides

To establish a model system for the study of ganglioside metabolism of the human brain tumor, medulloblastoma, we have chemically characterized the gangliosides of the Daoy cell line. These cells contain a high concentration of gangliosides (143 +/- 13 nmol LBSA/10(8) cells). The major species have been structurally confirmed to be GM2 (65.9%), GM3 (13.0%), and GD1a (10.3%). Isolation of individual gangliosides homogeneous in both carbohydrate and ceramide moieties by reversed-phase HPLC and analysis by negative-ion fast atom bombardment collisionally activated dissociation tandem mass spectrometry have allowed us to unequivocally characterize ceramide structures. In the case of GM2, 10 major ceramide subspecies were identified: d18:1-hC16:0, d18:1-C16:0, d18:0-C16:0, d18:1-C18:0, d18:1-C20:0, d18:1-C22:0, d18:2-C24:1, d18:1-C23:1, d18:1-C24:1, and d18:1-C24:0. Taken together with previous studies, these findings in buman medulloblastoma cells support the view that high expression and marked heterogeneity of ceramide structure are general characteristics of tumor gangliosides, molecules which are shed by the tumor cells and which are biologically active in vivo.

In vivo hybridization of technetium-99m-labeled peptide nucleic acid (PNA)

Hybridization of a radiolabeled single-stranded DNA oligonucleotide with its single-stranded complement in vivo has not yet been convincingly demonstrated. A contributing factor may be unfavorable in vivo properties of the phosphodiester and phosphorothioate DNAs. Peptide nucleic acid (PNA) oligomers have been reported to possess in vivo properties more suitable for radiopharmaceutical applications.

METHODS

We have radiolabeled an amine-derivatized 15-base PNA oligomer with 99mTc through a modified MAG3 chelator.

RESULTS

The ability of the PNA to hybridize in vitro with its complement appeared to be unimpaired after conjugation and radiolabeling. Size-exclusion, high-performance liquid chromatography (HPLC) analysis of 37 degrees C serum after 24 hr of incubation showed the radiolabel to be present predominately as labeled PNA with indications of labeled serum proteins and a low molecular weight catabolite. Whole-body clearance in mice was rapid, with 50% of the label eliminated in about 2 hr. After 2.5 hr, the highest uptake (kidneys) was only 1.5% of the injected dose/g; less than 0.07%/g was present in all sampled tissues at 24 hr. To evaluate in vivo hybridization, beads were implanted subcutaneously in both thighs of normal mice. In the left thigh only, the beads were conjugated with complementary single-stranded PNA. At 23 hr following intraperitoneal administration of the labeled PNA, the left/right thigh radioactivity ratio was 6:1. Whole-body images at this time showed only bladder, kidneys and the left thigh.

CONCLUSION

Unlike the radiolabeled DNAs investigated in this laboratory, 99mTc-PNA displays stability and pharmacokinetic properties suitable for eventual use as radiopharmaceuticals.

The influence of temperature and alkaline pH on the labeling of free and conjugated MAG3 with technetium-99m

Benzoyl-protected mercaptoacetyltriglycine (S-benzoyl MAG3) is radiolabeled by tartrate transchelation at elevated temperatures or basic pH. The object of this investigation was to establish whether the same 99mTc labeled species are formed when S-acetyl (S-acetyl MAG3)-conjugated compounds are radiolabeled by tartrate transchelation at ambient temperature and neutral pH in contrast to labeling at 95 degrees C and pH 11. S-acetyl MAG3 was conjugated to biocytin and to the amine-derivitized oligomers DNA and PNA. Along with free S-acetyl MAG3, these were radiolabeled under the different conditions. Although labeling efficiencies were always lower when labeled at ambient temperature and neutral pH relative to labeling at 95 degrees C or pH 11 (free S-acetyl MAG3 could not be labeled at all), size exclusion and reverse phase HPLC showed no difference with labeling conditions in the radiochemical profiles for labeled DNA and biocytin. In the case of DNA, a cysteine challenge also failed to demonstrate a difference. However, in the case of PNA, some important differences were observed in the size exclusion HPLC radiochromatograms. In addition, PNA labeled at ambient temperature and neutral pH was less stable to transchelation to cysteine. In conclusion, S-acetyl MAG3 conjugated compounds may be radiolabeled at ambient temperature and neutral pH. In most cases, the radiochemical species produced appear to be identical to those formed when labeling is accomplished at 95 degrees C or pH 11.

cdc12p, a protein required for cytokinesis in fission yeast, is a component of the cell division ring and interacts with profilin

As in many other eukaryotic cells, cell division in fission yeast depends on the assembly of an actin ring that circumscribes the middle of the cell. Schizosaccharomyces pombe cdc12 is an essential gene necessary for actin ring assembly and septum formation. Here we show that cdc12p is a member of a family of proteins including Drosophila diaphanous, Saccharomyces cerevisiae BNI1, and S. pombe fus1, which are involved in cytokinesis or other actin-mediated processes. Using indirect immunofluorescence, we show that cdc12p is located in the cell division ring and not in other actin structures. When overexpressed, cdc12p is located at a medial spot in interphase that anticipates the future ring site. cdc12p localization is altered in actin ring mutants. cdc8 (tropomyosin homologue), cdc3 (profilin homologue), and cdc15 mutants exhibit no specific cdc12p staining during mitosis. cdc4 mutant cells exhibit a medial cortical cdc12p spot in place of a ring. mid1 mutant cells generally exhibit a cdc12p spot with a single cdc12p strand extending in a random direction. Based on these patterns, we present a model in which ring assembly originates from a single point on the cortex and in which a molecular pathway for the functions of cytokinesis proteins is suggested. Finally, we found that cdc12 and cdc3 mutants show a synthetic-lethal genetic interaction, and a proline-rich domain of cdc12p binds directly to profilin cdc3p in vitro, suggesting that one function of cdc12p in ring assembly is to bind profilin.

Tissue distribution and abundance of human FKBP51, and FK506-binding protein that can mediate calcineurin inhibition

We previously described the isolation of an FK506-binding protein, FKBP51, that is predominantly expressed in murine T cells and is capable of mediating drug-dependent calcineurin inhibition in vitro. In addition, the gene for FKBP51 is induced by glucocorticoids. Screening of a human thymus cDNA library resulted in the identification of the human homologue of FKBP51. Expression of the 3.7 kb mRNA corresponding to FKBP51 is induced by glucocorticoids in the human T cell line, C7TK.4. The 51.2 kDa protein encoded by this gene shares 87% identity to murine FKBP51 and demonstrates a similar IC50 value for the FK506-mediated inhibition of calcineurin phosphatase in vitro. The distribution and abundance of FKBP51 and FKBP12 in seventeen human tissues were compared by Western analysis. Unlike its murine counterpart, the human FKBP51 is abundantly expressed in numerous tissues and in many cases, is in molar excess over FKBP12.

Developmental change in the voltage-dependence of the pacemaker current, if, in rat ventricle cells

Myocytes were isolated from newborn and adult rat ventricle. Using the whole-cell patch clamp, the two cell populations were compared for the presence of the hyperpolarization-activated pacemaker current if. As in other mammalian species, the threshold voltage in acutely dissociated adult rat myocytes was extremely negative (-113 +/- 5 mV; n=12). In contrast, threshold in newborn cells was relatively positive, regardless of whether measured in acutely dissociated (-72 +/- 2 mV; n=6) or cultured cells (-70 +/- 2 mV; n=9). Current density was not reduced in the adult. These results suggest that with development the ventricle assumes its non-pacemaker function, at least in part, by a shift of the voltage dependence of if outside the physiological range.

p53 overexpression and human papillomavirus (HPV) infection in oesophageal squamous cell carcinomas derived from a high-incidence area in China

Oesophageal epithelium is frequently exposed to various carcinogens and mutagens, many of which may cause p53 gene mutations. The epithelium can also be infected with human papillomavirus (HPV), the E6 protein of which may complex with p53 protein and facilitate its degradation. To identify HPV infection and p53 overexpression in oesophageal cancer, we performed immunohistochemical analysis using CM-1 anti-p53 antibody and DNA in situ hybridization with biotinylated HPV DNA probes on paraffin-embedded sections in 36 patients with oesophageal squamous cell carcinomas derived from a high-incidence area in northern China. Samples from cancer tissue, adjacent epithelia, regional lymph nodes as well as resection margins were examined. p53 protein accumulation was detected in 55.6% (20/36) of cancer samples, in 20% (1/5) of hyperplastic epithelium, in 20% (2/10) of dysplastic lesions as well as in 67% (2/3) of carcinoma in situ lesions adjacent to invasive carcinomas. HPV DNA sequences were demonstrated in 3 patients (8.3% of the total). Two of these HPV-positive carcinomas were immunohistochemically negative for p53 and one was weakly positive. Our results suggest that p53 overexpression is frequently found in oesophageal carcinomas and that p53 alteration may be an early event in esophageal carcinogenesis. HPV and elevated p53 are not mutually exclusive events, instead they can coexist in some oesophageal squamous cell carcinomas.

[Treatment of the secondary hydrocephalus of tuberculous meningitis by lateral ventricular drainage and drug injection]

OBJECTIVE

To decrease intracranial pressure rapidly and cure the secondary hydrocephalus of tuberculous meningitis.

METHODS

Every case was drained at the frontal horn of lateral ventricle of non-predominant cerebral hemisphere, injected the mixture of 100 mg isoniazid and 2 mg dexamethasone into the lateral ventricle through ventricular drainage tube once every two days or once every day in some severe cases.

RESULTS

The high intracranial pressure of 23 cases suffered from tuberculous meningitis were immediately decreased to normal level. The symptoms of 8 cases complicated with brain hernia were quickly improved. The cerebrospinal fluid became normal within 2-4 weeks after lateral ventricular drug injection.

CONCLUSIONS

Lateral ventricular drainage and drug injection can obtain good result and provide a new approach to treatment of secondary hydrocephalus cases suffered from tuberculous meningitis.

Technetium-99m antibodies labeled with MAG3 and SHNH: an in vitro and animal in vivo comparison

The in vitro stability and animal pharmacokinetics of 99mTc bound to Sandoz and C110 IgG antibodies via a modified MAG3 has been compared with the hydrazino nicotinamide (SHNH) moiety as standard. For both antibodies, the stabilities of the label to challenge at up to 50:1 cysteine: IgG molar ratio were comparable, but at higher molar ratios, MAG3 showed greater instabilities. For the Sandoz antibody, size-exclusion HPLC analysis of 37 degrees C serum incubates and plasma samples from injected mice showed no clearly distinguishable differences. In the C110 case, some increased high molecular weight radioactivity was apparent with MAG3. Biodistributions in normal mice showed significant differences only in liver (Sandoz) and liver, spleen, intestines, stomach, and blood (C110), with SHNH usually providing higher levels. Thus, for two different antibodies and under the conditions of this study, the MAG3 chelator provided a 99mTc label with properties similar to that of SHNH moiety.

Cell division: why daughters cannot be like their mothers

A cell-fate determinant that segregates asymmetrically at cell division has been identified in budding yeast. Possible mechanisms for this asymmetric segregation are suggested by the identification of mutants in genes encoding cortically localized proteins.

HLA types in women with cervical human papillomavirus (HPV) lesions prospectively followed up for 10 years

Certain genotypes of HPV have been recently implicated in the etiology of carcinoma of the uterine cervix. In order to determine whether HLA antigen-controlled immunoregulatory functions have a role in the pathogenesis of HPV infections, class I and II HLA antigen typing was carried out on a series of 96 randomly selected women who were part of a cohort of 530 women prospectively followed up for cervical HPV infections in our clinic since 1981. The frequency of the DQ3 antigen, which has previously been reported to be increased among cervical cancer patients, was decreased in our HPV patients compared with the control group of Finnish women, but it was slightly increased in HPV16-infected women (P = 0.0812). However, we were able to demonstrate that HLA-DR5 antigen is significantly increased (i) in patients with high grade cervical intraepithelial neoplasia (CIN) (P < 0.02), and (ii) in women harbouring the high risk HPV type 16 (P = 0.0003), thus confirming earlier reports of an association of this HLA antigen and cervical cancer. Such a close association between the high risk HPV type 16 with an HLA antigen might have important implications in the possible immunogenetic basis of the increased risk for squamous cell carcinoma of the uterine cervix.

Selective behavioral alterations on addition of a 4'-phenyl group to cocaine

We synthesized a cocaine analog in which a phenyl group was added at the para-position of the benzene ring of cocaine. This substitution caused a modest reduction (four-fold compared with cocaine) in binding potency for the primate (Papio) dopamine transporter as judged by displacement of [3H]WIN 35,428 binding from caudate/putamen membranes. Behavioral effects of this structural modification in the mouse were complex and selective, comprising absence of stimulation of locomotor activity, enhanced inhibition of locomotion and reduced lethal potency. Convulsant potency was unaltered. Substituents at the 4'-position of cocaine are important in its actions. Simple changes in the chemical structure of this drug may produce complex and selective changes in its neurochemical and behavioral actions.

How fission yeast fission in the middle

In fission yeast, we propose that the division plane may be positioned by the position of the premitotic nucleus, perhaps by a signal emanating from the nucleus. Gene products involved in the assembly of the ring and its temporal and spatial controls are beginning to be characterized. Some of these, such as mid1p, may be involved in signals that position the division site. In animal cells, the division site may be determined by analogous signals emanating from the mitotic asters (Rappaport, 1986). We speculate that the signals defined in fission yeast will help identify signals that determine the division plane in all kinds of eukaryotes.

Isolation and characterization of fission yeast mutants defective in the assembly and placement of the contractile actin ring

Fission yeast cells divide by medial cleavage using an actin-based contractile ring. We have conducted a genetic screen for temperature-sensitive mutants defective in the assembly and placement of this actin ring. Six genes necessary for actin ring formation and one gene necessary for placement of the actin ring have now been identified. The genes can be further organized into different phenotypic groups, suggesting that the gene products may have different functions in actin ring formation. Mutants of cdc3 and cdc8, which encode profilin and tropomyosin respectively, display disorganized actin patches in all cells. cdc12 and cdc15 mutants display disorganized actin patches during mitosis, but normal interphase actin patterns. cdc4 and rng2 mutants display disorganized actin cables during mitosis, but normal interphase actin patterns. In mid1 mutants, the actin ring and septum are positioned at random locations and angles on the cell surface, although the nucleus is positioned normally, indicating that the mid1 gene product is required to couple the division site to the position of the nucleus. mid1 mutant cells may reveal a new cell cycle checkpoint in telophase that coordinates cell division and the proper distribution of nuclei. The actin ring forms medially in a beta-tubulin mutant, showing that actin ring formation and placement are not dependent on the mitotic spindle.

Absence of human papillomavirus DNA detected by polymerase chain reaction in French patients with esophageal carcinoma

BACKGROUND & AIMS

Recent studies have suggested that esophageal human papillomavirus infection could be a risk factor for esophageal squamous cell carcinoma. The aim of this study was to evaluate the prevalence of human papillomavirus DNA sequences in the esophagus of French patients with esophageal squamous cell carcinoma.

METHODS

Multiplex polymerase chain reactions with consensus primers directed to the L1 gene or specific primers for human papillomavirus types 6, 11, 16, 18, 31, and 33 directed to E6 gene (40 cycles followed by restriction mapping of the amplified products) were used to determine the presence of human papillomavirus DNA sequences in esophageal squamous cell carcinoma (n = 75), normal adjacent mucosa (n = 49), and metastatic lymphadenopathies (n = 5). As an internal control, a target located in the embryonic myosin heavy-chain gene was used in each reaction.

RESULTS

Human papillomavirus DNA sequences could not be detected in any of the tumoral samples, the normal adjacent mucosa, or the metastatic lymphadenopathies.

CONCLUSIONS

Human papillomavirus seems not to be implicated in esophageal carcinogenesis, at least in French patients, because the viral genomes are not associated with esophageal squamous cell carcinomas.

Generation of polyclonal catalytic antibodies against cocaine using transition state analogs of cocaine conjugated to diphtheria toxoid

Six novel transition state analogs (TSAs) of cocaine (10-14 and 17) and one non-cocaine, p-aminophenylphosphonyl ester of cyclohexanol (19), were synthesized and characterized by 1H- and 13C-NMR and FAB-MS. (1R)-ecgonine methyl ester or cyclohexanol were subjected to phenylphosphonylation in the presence of dicyclohexyl carbodiimde (DCC) and 4-N,N-dimethyl aminopyridine (4-DMAP). TSA-IV (10), however, was synthesized from norcocaine which was protected with dibromoethane to yield 4 before acid hydrolysis, esterification and phenylphosphonylation were carried out. TSA-III (11) TSA-I (12) and (19), using various length spacer arms, were coupled with the immunogenic protein, diphtheria toxoid (DT). The TSAs coupled with DT were used to immunize mice and after appropriate boosts their sera were tested for the presence and titer of anti-TSA polyclonal antibodies using ELISA. Preliminary results show that the mice immunized with these TSAs produced high titers of polyclonal catalytic antibodies, except for (19), with the ability to hydrolyze the substrate 125I-4'-iodococaine in an in vitro assay, even in the presence of noncatalytic anti-TSA antibodies.

Pacemaker current i(f) in adult canine cardiac ventricular myocytes

1. Single cells enzymatically isolated from canine ventricle and canine Purkinje fibres were studied with the whole-cell patch clamp technique, and the properties of the pacemaker current i(f) compared. 2. Steady-state i(f) activation occurred in canine ventricular myocytes at more negative potentials (-120 to -170 mV) than in canine Purkinje cells (-80 to -130 mV). 3. Reversal potentials were obtained in various extracellular Na+ (140, 79 or 37 mM) and K+ concentrations (25, 9 or 5.4 mM) to determine the ionic selectivity of i(f) in the ventricle. The results suggest that this current was carried by both sodium and potassium ions. 4. The plots of the time constants of i(f) activation against voltage were 'bell shaped' in both canine ventricular and Purkinje myocytes. The curve for the ventricular myocytes was shifted about 30 mV in the negative direction. In both ventricular and Purkinje myocytes, the fully activated I-V relationship exhibited outward rectification in 5.4 mM extracellular K+. 5. Calyculin A (0.5 microM) increased i(f) by shifting its activation to more positive potentials in ventricular myocytes. Protein kinase inhibition by H-7 (200 microM) or H-8 (100 microM) reversed the positive voltage shift of i(f) activation. This effect of calyculin A also occurred when the permeabilized patch was used for whole-cell recording. 6. These results indicate i(f) is present in ventricular myocytes. If shifted to more positive potentials i(f) could play a role in ischaemia-induced ventricular arrhythmias. The negative shift of i(f) in the ventricle might play a role in differentiating non-pacing regions of the heart from those regions that pace.

Implications of the p53 tumor-suppressor gene in clinical oncology

PURPOSE

The p53 gene encompasses 16 to 20 kb of DNA on the short arm of human chromosome 17. It encodes for a 393-amino acid nuclear phosphoprotein involved in cell-cycle control. Loss of normal p53 function is associated with cell transformation in vitro and development of neoplasms in vivo. During the past few years, the dramatic progress in the molecular biology of p53 has raised the exciting prospect for cancer management. The purpose of this review is to assess the potential role of p53 in clinical oncology.

DESIGN

Data on the alterations in the p53 gene in human cancers, with special emphasis on the clinical implications of changes in the p53 gene in the pathogenesis, diagnosis, prognosis, and therapy of human cancers, are summarized in this review.

RESULTS AND CONCLUSION

Current evidence suggests that abrogation of normal p53 pathway is a common feature in human cancers, and it appears to be a critical step in the pathogenesis and progression of tumors. Analysis of p53 function and mutations in human cancers may lead to identification of the precise nature of the carcinogenic damage in human tissues. These laboratory investigations and biologic findings have raised the possibility to screen patients at increased risk for cancer, aid the diagnosis made by traditional methods, assess the prognosis of individual cancer patient, design treatment protocols, and test the response to therapeutic agents.

Human papillomavirus infections in vulvar precancerous lesions and cancer

To elucidate some of the recently arisen issues related to the bimodal disease pattern of vulvar intraepithelial lesions (VIN) and vulvar cancer, a series of 27 consecutive women with vulvar symptoms was analyzed for human papillomavirus (HPV) involvement by colposcopy, light microscopy and in situ hybridization (ISH) for HPV types 6, 11, 16, 18, 31, 33 and 42. Altogether, HPV DNA was discovered in 13/27 (48.1%) of the lesions by ISH; the rest were HPV DNA negative for the seven HPV types tested. HPV DNA was present in both of two exophytic lesions (HPV 6 in condyloma and HPV 16 in verrucous cancer). Of the flat lesions, 7/13 (53.8%) were HPV DNA positive. HPV 6 was confined to low grade lesions (HPV/non-VIN and VIN 1), whereas HPV 11 was found in a case of VIN 3 as well. Of the invasive carcinomas, three of four were HPV DNA positive (2 HPV 16 and 1 HPV 31). Dystrophic changes were detected in three of four invasive carcinomas and in all three HPV 16-positive lesions. Dystrophic changes were absent in 9 of 14 (64.3%) of HPV DNA-negative lesions. Fifty percent (7/14) of vulvar warty lesions (without concomitant VIN) were found in women younger than 60. Three of four invasive carcinomas occurred in women older than 60. This small series provided additional evidence of HPV involvement in the pathogenesis of VIN lesions, and the findings support the hypothesis of a multifactorial etiology in vulvar carcinogenesis in which HPV, dystrophic changes and chronic inflammatory disease play a synergistic role.

[Pharmacological studies of Polygonum capitatum Buch-Ham. ex D. Don]

The pharmacological effect of aqueous extract of Polygonum capitatum has been studied. The experimental results show that Polygonum capitatum markedly decreases WBC and RBC in urine of pyelonephritis mode in rats, the death rate of Escherichia coli infected mice, and the temperature of feverish rabbits. It has also been found that after oral administration of Polygonum capitatum the animal urine markedly inhibits the growth of Escherichia coli, but diuretic action of the herb has not been observed.

Individual Variability of Carbonyl Reductase Activity for Acetohexaminde in Human Erythorcytes

Acetohexamide, an oral antidiabetic agent, is metabolized by carbonyl reductase to hydroxyhexamide, which has a higher hypoglycemic potency than the parent compound. In the present study, interindividual variability of carbonyl reductase activity in erythrocyte was examined. Enzyme activity in 31 healthy subjects (23.9 plus minus 3.4 years, mean plus minus SD) was monitored by measuring formation of hydroxyhexamide using HPLC methods. Using 0.5 mM acetohexamide as substrate, reductase activity of 6.06 plus minus 0.06 nmol min(minus sign1) gHb(minus sign1) (range: 5.9--6.2) with a coefficient of variation of 15% was observed in erythrocytes. Acetohexamide-reducing activity in erythrocytes showed a normal distribution and the interindividual variability of the reductase activity was found to be small, implying that the large variability reported for the acetohexamide plasma half-life is not caused by the amount of reductase enzyme in erythrocytes.

Vagal release of vasoactive intestinal peptide can promote vagotonic tachycardia in the isolated innervated rat heart

OBJECTIVE

The aim was to determine the extent to which endogenous release of vasoactive intestinal polypeptide (VIP) might be implicated in the modulation of sinoatrial rate in the presence and absence of muscarinic blockade or beta blockade.

METHODS

Langendorff perfused rat hearts were studied with the right vagus intact. The hearts were maintained in sinus rhythm and subjected to right vagal stimuli of 5, 10, 20, and 30 Hz.

RESULTS

Administration of exogenous VIP, 10(-8) M, increased sinus rate by 20% (p < 0.05). This increase in heart rate was reduced significantly to 8% by the VIP antagonist [D-p-Cl-Phe6, Leu17]VIP, 10(-7) M, which alone had no effect on sinus rate. Vagal stimulation reduced sinus rate from a control of 254(SEM 2) to 164(17) beats.min-1 (p < 0.05) at 20 Hz. VIP, 10(-8) M, increased these rates to 284(6) and 220(21) beats.min-1 (p < 0.05). In another eight vagally stimulated hearts, frequencies of 5-20 Hz reduced sinus rate. At 30 Hz heart rate increased in five, and the resultant rate was significantly faster in these [154(10) beats.min-1] than in the remainder [98(12) beats.min-1, p < 0.05]. Vagal stimulation also increased sinus rate (p < 0.05) in four of seven additional hearts perfused with atropine, 2 x 10(-6) M. This increase was completely abolished by [D-p-Cl-Phe6, Leu17]VIP. That the effect was not beta adrenergic was demonstrated in eight experiments using atropine plus propranolol, 1 x 10(-7) M. A vagally induced increment in rate still occurred (p < 0.05) and was abolished by [D-p-CL-Phe6, Leu17]VIP. The ability to ascribe a rate change to VIP release was maximal in the presence of propranolol and atropine, intermediate in the presence of atropine alone, and minimal in the absence of muscarinic or beta blockade.

CONCLUSIONS

Vagally released VIP is capable of limiting the decrement in sinus rate that occurs at high frequencies of vagal stimulation, and in some circumstances can actually increment sinus rate. Its role as an endogenous modulator of vagal effects on heart rate and as a possible cause of vagal and postvagal tachycardias should be further explored.

Transitional cell carcinoma of the bladder: failure to demonstrate human papillomavirus deoxyribonucleic acid by in situ hybridization and polymerase chain reaction

Human papillomaviruses have been implicated in the pathogenesis of a variety of malignancies, particularly those of the anogenital tract. Some recent reports on the presence of human papillomavirus in bladder cancer have raised the possibility that it might be involved in the development of this malignancy as well. To study this concept, a series of 108 transitional cell carcinomas of the bladder were screened for the presence of human papillomavirus deoxyribonucleic acid (DNA) by in situ hybridization with biotin-labeled human papillomavirus cocktail probe and polymerase chain reaction with human papillomavirus L1 consensus primers. Although the positive controls showed strong hybridization signals, no evidence for human papillomavirus DNA was found in any of the bladder carcinomas by in situ hybridization. Similarly, despite the amplification of a 450 bp product in cervical human papillomavirus lesions (used as positive controls), no signals were obtained in any of the bladder tumors studied. beta-globin gene sequences (110 bp), serving as internal controls, were consistently amplified from all tumor samples, suggesting that cellular DNAs from the carcinoma specimens were sufficient for the amplification reaction. These data indicate that human papillomavirus infection is rare in transitional cell carcinoma of the bladder. The significance of these findings is discussed in relation to previous reports on human papillomavirus involvement in bladder carcinomas.

Frequent mutations of p53 gene in oesophageal squamous cell carcinomas with and without human papillomavirus (HPV) involvement suggest the dominant role of environmental carcinogens in oesophageal carcinogenesis

Epidemiological evidence suggests that alcohol intake, use of tobacco, ingestion of mycotoxins and nitrosamines and nutritional deficiencies are high-risk factors for the development of oesophageal cancer. Similarly, viral infections have been postulated to play a role in some tumours. However, the molecular events underlying the development of oesophageal carcinoma are poorly understood as yet. Loss of p53 tumour-suppressor gene function has been found in different human malignancies, and it can occur in a variety of ways, including gene mutation and interaction with the E6 protein of oncogenic human papillomaviruses (HPVs). Because the oesophageal mucosa is potentially exposed to mutagens and HPVs, we studied DNA samples derived from nine HPV-positive squamous cell carcinomas and 12 HPV-negative tumours. Exons 5-9 of the p53 gene containing phylogenetically conserved domains were examined using the polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) technique. HPV detection was done using DNA in situ hybridisation with biotin-labelled HPV DNA probes. Mutations were detected in eight (38%) out of the 21 cases. Three mutations were found in exons 5/6, three in exon 7 and two in exon 8/9. Six (50%) of the 12 HPV-negative carcinomas showed p53 mutations. Two (22.2%) of the nine HPV-positive carcinomas were found to contain p53 mutations as well; one contained HPV 16 DNA sequences and showed p53 mutation in exon 8/9, and the other was HPV 6/11 positive with the mutation in exon 5/6. Although mutations were more common in HPV-negative tumours (50.0% vs 22.2%), the difference in p53 mutations in HPV-positive and -negative tumours did not reach statistical significance (P = 0.1946). These data indicate that inactivation of the p53 gene is a frequent event in oesophageal squamous cell carcinomas and such an inactivation might be an important molecular pathway for the development of oesophageal cancer. The findings of p53 mutations in HPV-positive oesophageal carcinomas suggest that HPV and p53 mutation were not mutually exclusive events. The presence of frequent mutations of p53 gene in both HPV-positive and -negative oesophageal carcinomas suggests a dominant role of environmental carcinogens in oesophageal carcinogenesis.

The state of the p53 gene in human papillomavirus (HPV)-positive and HPV-negative genital precancer lesions and carcinomas as determined by single-strand conformation polymorphism analysis and sequencing

Human papillomavirus (HPV) is frequently associated with cervical carcinoma. Inactivation of the p53 tumor suppressor gene product by binding to the HPV encoded E6 protein is considered as an important pathway for malignant progress in HPV-infected cells. In contrast, mutations of the p53 gene have been found in HPV-negative cervical carcinoma cells. To evaluate the involvement of p53 inactivation for the development of genital carcinoma, we determined the state of the p53 gene in 20 genital precancer lesions and carcinomas, which had been previously studied for the expression of p53 protein and the presence of HPV DNA. Exons 5 through 9 of the p53 gene were analyzed by single-strand conformation polymorphism analysis of polymerase chain reaction (PCR)-amplified DNA fragments, and the results obtained by the PCR-SSCP analysis were confirmed by DNA sequencing. No mutations were detected in any of the specimens, including the three HPV-negative cases. The present results suggest that the functional inactivation of p53 is not invariably required for the induction of malignant transformation in the genital tract, and thus other genetic events can also significantly participate in genital carcinogenesis.