The Potential of Endoscopic Spring Ligament Repair in Flatfoot Reconstruction

BACKGROUND

Spring ligament fulfills 2 main important functions: one, supporting the head of the talus and stabilizing the talonavicular joint, and the other, maintaining the longitudinal arch by acting as a static support. In this preliminary report, we describe an endoscopic repair for spring ligament injuries with modified portals.

METHODS

We performed a retrospective case series study from February 2019 to January 2022. Posterior tibial tendon and/or associated bone deformities were assessed at the same surgical procedure. All patients were ≥18 years old and they had more than 6 months of follow-up. The procedure was performed in 11 patients. Mean age was 46 years (range 18-63). Ten had concomitant bony realignment surgery, and 8 had posterior tibial tendon surgery.

RESULTS

In all patients, endoscopic spring ligament repair could be technically done. The modified portals were used in all procedures as described in the surgical technique. Three patients had a superficial lesion, 1 had a rupture <5 mm, 7 had a rupture >5 mm but not a complete rupture through the entire spring ligament. Most of the patients had good clinical results from the surgery that included endoscopic spring ligament debridement and/or repair at 2 years follow up.

CONCLUSION

In this small series we found that endoscopy may be an effective technique to diagnose and treat incomplete spring ligament injuries.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Seguridad de los portales para la reparación endoscópica del ligamento calcaneonavicular: estudio cadavérico

Introducción: La lesión del ligamento calcaneonavicular ha sido descrita como una de las causas de la deformidad en el pie plano del adulto. El objetivo de este artículo es describir portales modificados para el diagnóstico y la reparación endoscópica de las lesiones del fascículo superomedial del ligamento calcaneonavicular y evaluar la seguridad de los portales utilizados. Materiales y Métodos: Se llevó a cabo un estudio cadavérico con seis preparados reproduciendo una lesión del fascículo superomedial del ligamento calcaneonavicular con una punta de corte de radiofrecuencia y la posterior reparación endoscópica. Se crearon dos portales modificados para el abordaje. Luego se procedió a la disección anatómica para evaluar la seguridad de los portales en relación con las estructuras anatómicas. El primer portal se realiza inmediatamente proximal a una línea trazada desde la punta del maléolo medial dirigida al centro del talón, el segundo portal se emplaza 0,5 cm proximal a la inserción del tendón tibial posterior en el escafoides por transiluminación. Si es necesario, se coloca un portal accesorio inmediatamente dorsal al tendón tibial posterior a mitad de camino entre los dos portales antes descritos. Resultados: En todos los casos, fue posible la reparación del ligamento con el procedimiento endoscópico. En la disección anatómica de los portales, se observó una distancia promedio a las estructuras vasculonerviosas de 11,83 mm del portal proximal y de 9,66 mm del portal distal. Conclusión: Los portales modificados son seguros y permiten la visualización directa del haz superomedial del ligamento calcaneonavicular y su reparación endoscópica.

The patient with Down syndrome and pulmonary arterial hypertension associated with congenital heart disease: from childhood to adulthood

 

Pulmonary arterial hypertension (PAH) is a common complication of congenital heart disease (CHD) that significantly affects its prognosis. Down syndrome is a common comorbidity among patients with PAH associated with CHD. Children born in recent years with CHD have benefited from advances in pediatric cardiac surgery that have modified their evolution compared to adults with the same pathologies. Our objective was to know and compare the characteristics of the adult and pediatric population with DS and PAH associated with CHD.

REHAP and REHIPED are Spanish, voluntary, multicenter registries that include patients with PAH associated with CHD. REHAP started in 2007 and includes patients over 18 years of age. Patients diagnosed with PAH after this time were prospectively included, until 2021. Patients who were followed in the participating centers and diagnosed after January 1998 were retrospectively included in the registry. REHIPED started in 2009 and collects patients between 2 months and 18 years of age. Patients diagnosed with PAH after this time were prospectively included, until 2021. Patients who were followed and diagnosed after January 1998 were retrospectively included. 131 adults and 47 children with DS and PAH associated with CHD were analyzed. Their baseline characteristics, hemodynamics, treatment, and 10-year survival were compared.

Adult patients with DS presented more frequently complete atrioventricular canal defect as underlying heart disease and were mostly in Eisenmenger's situation (84%). In pediatric patients the largest group was post-repair PAH (50%). Functional class was similar in both groups, although adults presented significantly greater hemodynamic severity. Regarding medical treatment, no differences were observed between both groups: there was a very low use of prostanoids both at baseline and at follow-up, and a majority use of oral monotherapy. There were no significant differences in survival.

Corrective surgery in patients with DS has become more frequent over the years: adults are mostly in Eisenmenger's situation, while post-repair PAH is the most numerous group in children. Although adults show greater hemodynamic severity, survival is similar in both groups. Medical treatment, which showed no differences between pediatric and adult age, is very conservative, with most patients on oral monotherapy and rare use of prostanoids.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Janssen MSD

Minimally invasive neurectomy for Morton's neuroma with interdigital approach. Long term results

BACKGROUND

"Morton's Neuroma" is a frequent cause of chronic forefoot pain. It can affect general population, including athletes, and can lead to progressive foot pain and discomfort for daily life activities and sports.

HYPOTHESIS/PURPOSE

Our objective is to evaluate the long-term results in a series of 85 feet, operatively treated with minimally invasive interdigital approach for neurectomy.

STUDY DESIGN

Case series.

METHOD

83 patients (85 feet) were treated between January 2003 and December 2019. The AOFAS score and VAS scale were used to evaluate the patients pre and postoperatively. Results were analyzed using the JASP software.

RESULTS

Mean age was 50.58 years (range 23-77). Eleven (11) were men, and seventy-four (74) women, with two bilateral cases. Mean follow up was 49 months. Our series was evaluated with AOFAS and VAS scores, both showing statistically significant improvement posterior to the operative procedure.

CONCLUSIONS

A series of 85 feet operatively treated for Morton's neuroma with minimally invasive interdigital approach for neurectomy is presented. Long term results were similar to other published series with different approaches, with the advantage of minimal incision, minimum soft tissue dissection and no need to release intermetatarsal ligament, immediate weightbearing and quick return to daily activities and sports. It is concluded that minimally invasive neurectomy with interdigital approach is a safe procedure for Morton's neuroma treatment with similar results that other operative procedures.

LEVEL EVIDENCE

Level IV.

Flatfoot Deformity Due to Isolated Spring Ligament Injury

Patients with acquired flatfoot deformity due to isolated injury of the spring ligament, with healthy posterior tibialis tendon, are rarely identified. Between December 2004 and September 2011 (6 years and 9 months), we treated 10 patients with acquired flatfoot deformity due to spring ligament injury without tibialis posterior tendon tear. One patient (10%) was lost to follow-up. The mean age of the patients was 44.33 ± 12.91 years; 4 (44.4%) were female, and 5 (55.56%) were male. Clinical presentation included mild to moderate hindfoot valgus and pain extending from the inferior part of the medial malleolus to the navicular, inferior to tibialis posterior. Forefoot abduction was not always present. Weightbearing radiographs and magnetic resonance imaging (MRI) scans were obtained in all cases. Six patients (66.66%) of the patients had a history of minor trauma. Spring ligament repair was performed in all cases, and 4 patients (44.44%) underwent adjunct procedures. After surgery, a cast was applied, and weightbearing was avoided for 6 weeks. The mean preoperative American Orthopaedic Foot and Ankle Society (AOFAS) score was 39.66 ± 18.55, and this improved to 84.88 ± 12.41 after surgery (p = .023). No statistically significant differences were found between males and females or between isolated repairs and adjunct procedures. The mean duration of follow-up was 45.33 ± 37.11 months (range 15 to 120), and no complications were identified. Isolated injuries of the spring ligament with normal posterior tibialis tendon are rarely described and may be more prevalent than generally appreciated.

Pulmonary arterial hypertension in Spanish pediatric registry age: clinical characterization, management and survival

Background

Pulmonary arterial hypertension (PAH) includes idiopathic PAH and congenital heart disease (CHD) related PAH. A wide variety of CHD can develop PAH, but their clinical characteristics define four large groups: Eisenmenger, PAH associated with non-restrictive shunt, severe PAH associated with restrictive shunt and postoperative PAH. Our aim was to study the clinical and prognostic differences between these groups and idiopathic PAH.

Methods

The REHIPED registry is a Spanish, multicenter, observational and prospective registry on pulmonary hypertension in the pediatric population (&lt;18 years of age) that began in 2008. 183 patients were analyzed: baseline characteristics, functional class, right catheterization data, treatment and survival were compared

Results

183 patients were analyzed, characteristics are detailed in the table. In patients with idiopathic PAH, treatment with prostanoids was more frequently used as first line therapy and during follow up. The average follow-up time was 9 years. There was not a statistically significant difference in survival among the 4 clinical groups of CHD related PAH. There was a borderline significant difference (logrank p 0.05) in survival between the group of CHD related PAH and idiopathic PAH.

Conclusion

Idiopathic PAH patients have worse outcome than CHD related PAH patients although they have less comorbidities, less severe hemodynamics and are treated more aggressively.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Janssen, Ferrer

The "bubble point" for validation of drug release or simulated absorption tests for ointments

The aim of the present study was to design a test to ascertain the behaviour and reliability of a membrane used in drug release and simulated absorption tests in order to arrive at useful indications for simulating topical as well as gastro-intestinal absorption. The membrane can be used in two different conditions: a) as a simple porous membrane placed between the ointment and an accepting liquid phase, generally water phase; b) as a membrane soaked in a lipophilic liquid phase to simulate the horny layer between the ointment and accepting water phase. In this study the "bubble point test" was used to test the integrity of the soaking film as well as the membrane, during and after drug release and simulated absorption tests with different types of ointment. In the case of a drug release test from an ointment, the bubble point test may determine the test conditions, that is the ointment applied to either a dry or hydrated membrane. Only the use of a previously hydrated membrane can guarantee constant conditions in the in vitro model. Use of a dry membrane may lead to infiltration of liquid components of the ointment base, thus altering the contact conditions between the two phases of the cutaneous compartment model (lipogel and W/O creams). The use of a hydrated membrane may also lead to interactions between the two phases of the compartment, with osmotic exchanges between the acceptor phase and ointment sample (hydrogel, PEG gel, O/W creams). The hydrated membrane is therefore reliable only for comparison between lipophilic base ointments. In a simulated absorption test, determination of the bubble point makes it possible to ascertain the physical integrity of the lipoid liquid film immobilized by capillary action in the inner microporous structure of the membrane during the test. This condition is essential to maintain a balance between the parameters regulating the diffusion process between the different compartments of the system. The use of a lipoid-soaked membrane makes it possible to avoid interactions between the ointment sample and an aqueous acceptor phase, such as hydrosoluble bases. Since the diffusion across a lipoid film immobilised within a porous membrane depends on the drug release rate from the ointment base, the test allows a contextual evaluation of the release kinetics as well as an indication of the drug absorption possibilities through an in vitro model of the cutaneous compartment.

Relationship between tumour growth rate and carbogen-based functional MRI for a chemically induced HCC in mice

We previously performed MRI studies of HCC (hepatocellular carcinomas) in mice showing the feasibility of measuring a carbogen effect. In the present study carbogen response of the whole tumour was compared with growth characteristics during longitudinal follow-up. HCC were chemically induced. The imaging protocol at 4.7 T comprised a fast spin-echo sequence for high-resolution screening and measurement of growth curves, and a fast gradient echo sequence allowing an entire T2*w image acquisition per respiratory cycle to perform fMRI under carbogen breathing. A new parameter, T+, the fraction of tumour voxels with increased intensity under carbogen was measured on manually defined ROIs. Twenty-two HCC were followed for 3-10 weeks. Tumours were divided into two groups, "regularly" and "irregularly" growing tumours. A linear correlation between T+ and tumour growth rate was observed only for "regularly" growing HCC. These results suggest a link between tumour growth rates and tumour fractions exhibiting signal increase upon carbogen breathing. They are compatible with observations by others that rapidly growing tumours are more hypoxic than slowly growing ones. Combined measurement of T+ and tumour growth may become a useful noninvasive follow-up approach for assessment and/or management of therapies involving vasculature-targeting and anti-proliferative drugs.

Induction of DNA synthesis in mouse liver following increases of DNA adduct levels elicited by very low cumulative doses of the genotoxic hepatocarcinogen 7H-dibenzo[c,g]carbazole

The purpose of this work was to investigate the administration of very low but repeated doses of a genotoxic carcinogen and an eventual correlation with cellular DNA synthesis. The compound 7H-dibenzo[c,g]carbazole is a genotoxic carcinogen in the mouse liver and was administered topically at the dose of 13.35 microg per animal every 2 days to give a total of 13 applications. Animals were sacrificed 48 hours after every 2 applications until the 10th treatment, then 48 hours after every treatment. Postulated genotoxic effects such as DNA adduct formation were detected by the 32P-post labeling assay. Liver sections were examined for microscopic changes and DNA synthesis. Results showed an increase of the total DNA adduct level in the liver throughout the study with a slowing down in the level after the sixth application of the compound. This change could correspond to the onset of DNA synthesis and to the moderate hepatocellular apoptosis which was observed. The DNA synthesis, which was considered to be secondary to the cytotoxicity induced by the high level of DNA adducts altering normal cellular activity, could also be the opportunity to fix the DNA adducts into heritable mutations. These results raise the question regarding the risk assessment in humans exposed regularly to very low doses of chemicals in the environment: for non-proliferating tissue, the regular accumulation of DNA adducts could remain silent until a "threshold level" is reached from which stimulation of the DNA synthesis may fix the DNA adducts into heritable mutations, eventually leading to tumors.

Ultrasonic assessment of variations in thickness of subcutaneous fat during the normal menstrual cycle

OBJECTIVE

To verify the occurrence of natural variations in thigh and abdominal subcutaneous fat thickness related to the phases of the menstrual cycle, to assess the value of ultrasonography as a reliable method for monitoring subcutaneous fat thickness changes and to evaluate their amplitudes.

METHODS

This study included 10 women (19-39 years) who menstruated regularly. None had used oral contraceptives or slimming products during the 3 months prior to the study. At cycle day 2 (CD2), CD6, CD14, CD22, CD27 and CD30 days (CD0: beginning of menstruation), the subjects were submitted to: (1) measurement of weight and thigh perimeters, (2) measurements of thigh and abdomen subcutaneous fatty tissue thickness on B-mode images acquired at 10 MHz. A protocol was designed to guarantee a reproducible repositioning during the whole time course of the study and ultrasound examinations (US) were always performed by the same trained person to avoid inter-examiner variability.

RESULTS

Subcutaneous fat thicknesses decreased during the first half of the cycle and reached their lowest values at day 22 (-2.0% for the thighs; -3.3% for the abdominal region). Both thigh and abdomen subcutaneous fat reached their maximum thicknesses during menstruation with respective increases of +2.2 and +4.0%. The observed cyclic amplitude variations in the subcutaneous adipose tissue thickness accounted for 7.3% for the abdominal region and 4.1% for the thighs.

CONCLUSION

Variations in adipose tissue thickness during the menstrual cycle could be quantified and monitored by US. The thickness of the thigh and abdominal hypodermis was more important during menstruation and decreased in mid-cycle with a minimum occurring 1 week after ovulation.

Comparison of benzo[a]pyrene DNA adduct formation in the skin of two strains of mice selected for resistance (DBA/2) or susceptibility (C3H/HeN) to contact dermatitis

Two strains of mice were selected for resistance (DBA/2) or susceptibility (C3H/HeN) to contact dermatitis. Benzo[a]pyrene-DNA adduct formations was compared in the two mouse strains by a postlabeling procedure to determine if there was a significant effect. Results showed that adduct profiles in DBA/2 and C3H/HeN dermis were qualitatively similar. The total binding levels were higher in DBA/2 mice on the d 2 and the d 10. DNA adduct formation has been shown to inversely correlate with skin allergy induction. Data suggest that the expression of the genes responsible for the differences in responsiveness to chemical induced contact dermatitis in mouse may play an important role in benzo[a]pyrene-DNA adduct formation.

Radioactive technetium-99m labelling of Salmonella abortusovis for the assessment of bacterial dissemination in sheep by in vivo imaging

We report the development and validation of a 99mTc-labelling technique of bacteria, applied to Salmonella abortusovis. The radioactive labelling is obtained using a pre-tinning step of the cells followed by direct incubation of S. abortusovis suspension with 99mTc-pertechnetate. Several procedures with different amounts of stannous tin (SnF2 or SnCl2) were evaluated. The selected method, respectful of bacterial viability, provided a 30% labelling yield. Viability of 99mTc-labelled bacteria was assessed by flow cytometry using rhodamine 123 and was demonstrated to be unchanged, turbidimetric measurements showing only a slight increase in the growth rate for radiolabelled cells. Incubation of 99mTc-labelled S. abortusovis with pronase, saponine and urea demonstrated labelling stability and suggested an intra-cellular localization for 99mTc. A preliminary study was also conducted in sheep to evaluate the value of the imaging of radiolabelled S. abortusovis. Spatial and temporal patterns of their in vivo dissemination in the lymphatic system after a sub-cutaneous injection were compared with control lymphoscintigraphic agents. These imaging data supported the assumption that the radioactivity detected in vivo was proportional to the number of 99mTc-labelled bacteria.

Macrophage targeting with 99mTc-labelled J001 for scintigraphic assessment of experimental osteoarthritis in the rabbit

The potential of scintigraphy with technetium 99m-labelled J001 (99mTc-J001) to detect synovitis was studied in 15 rabbits with osteoarthritis (OA) of the right knee (section of cruciate ligaments), in five sham-operated rabbits and in four non-operated rabbits. J001 is a non-pyrogenic, acylated poly (1,3) galactoside isolated from the membrane of a non-pathogenic strain of Klebsiella pneumoniae which is able to bind selectively to macrophages via the binding to CD11b and CD14 molecules. The results of 99mTc-J001 scintigraphy were compared with those of scintigraphy with 99mTc-labelled methylene diphosphonate (99mTc-MDP) and GC-APG (a derivative of J001 unable to bind macrophages in vitro). The mean scintigraphic ratios (diseased healthy knee) of 99mTc-J001 were significantly higher in OA rabbits than in sham- and non-operated rabbits, from as early as day 18 until day 90. 99mTc-J001 scintigraphy demonstrated earlier increased uptake than 99mTc-MDP scintigraphy. The mean scintigraphic ratios of 99mTc-J001 were significantly higher than those of 99mTc-GC-APG (which remained normal) in OA rabbits. The normal scintigraphic ratios of 99mTc-J001 in sham-operated and non-operated rabbits, as well as of 99mTc-GC-APG in OA rabbits, suggested that the increased uptake demonstrated with 99mTc-J001 in OA rabbits, as early as day 18 corresponded to imaging of synovitis via elective macrophage targeting. These results showed that 99mTc-J001 scintigraphy should be a specific method of detecting synovitis in OA.

Macrophage targeting with 99mTc-labelled J001 for scintigraphy of joint inflammation in ovalbumin-induced arthritis in rabbits

BACKGROUND AND OBJECTIVE

J001 scintigraphy is a new approach, based on macrophage targeting, developed for tumor and inflammation imaging. J001, a non-pyrogenic acylated poly(1,3)galactoside purified from the membrane of a non-encapsulated strain of Klebsiella pneumoniae associates selectively with macrophages via binding to CD11b and CD14 molecules. Since macrophages play a primary role in inflammatory arthritis processes, J001 labeled with 99mTc appeared to be of interest for the scintigraphic imaging of inflammatory lesions. The purpose of this study was to assess the potential of J001 scintigraphy for imaging inflammatory arthritis in the model of ovalbumin-induced arthritis in rabbits.

MATERIAL AND METHODS

Ovalbumin-induced arthritis was developed in 17 rabbits. 99mTc-J001 scintigraphy was performed 4 weeks after arthritis induction in 17 rabbits and was repeated at 6 and 8 weeks in 8 rabbits. 99mTc-J001 and 99mTc-MDP scintigraphy were performed before and 2.5 months after radionuclide synovectomy with the intra-articular injection of a high energy beta-emitting radionuclide (186Re) in 3 rabbits and 186Re (first subjected to a complete decrease of radioactivity) in 3 rabbits.

RESULTS

99mTc-J001 scintigraphy was able to image inflammatory arthritis 4 weeks after induction. J001 scintigraphy demonstrated an increased uptake earlier than MDP, which was maintained at week 8. After radionuclide synovectomy, a clear decrease in the J001 scintigraphy ratio occurred, whereas the MDP scintigraphy ratio was stable. After the intra-articular injection of inactive 186Re, no changes in MDP and J001 scintigraphy ratio appeared.

CONCLUSION

99mTc-J001 scintigraphy is able to image joint inflammation and to assess the response to anti-inflammatory treatment in an experimental model of arthritis.

Influence of technetium-99m-labeling conditions on physico-chemical and related biological properties of an acylated poly-galactosidic macrophage targeting agent for inflammation imaging

The potential of 99m-Tc-J001 for the investigation of inflammatory lesions via the targeting of recruited macrophages (M phi) has already been documented in several experimental models and in human diseases. To achieve a functional imaging of inflammation via M phi targeting, minimal labeled colloid content and high in vivo stability of 99mTc-J001 are essential. The actual specificity of such scintigraphy is closely dependent upon the radiolabeling of only the J001 molecules available for M phi targeting. To develop an appropriate radiopharmaceutical kit, optimization of the labeling conditions was achieved from a series of pilot formulations that were evaluated for radiolabeling efficiency and both in vitro and in vivo 99mTc-J001 stability. Colloids were characterized using autocorrelation spectroscopy and multiangle laser-light scattering, radioactive colloid content of the formulations being deduced from biodistribution studies. This work has made possible the definition of a formulation exhibiting a radiolabeling yield > 97.0%, associated with in vivo stability and minimal colloid formation, thus greatly enhancing the specificity of such macrophage scintigraphy.

Functional contributions of alpha5 subunit to neuronal acetylcholine receptor channels

Ligand-gated ion channels are multi-subunit complexes where each subunit-type is encoded by several related genes. Heterologous expression of any one of the neuronal nicotinic acetylcholine receptors (nAChR) alpha-type subunits, either alone or with any beta-type subunit, typically yields functional nAChR channels. A striking exception is the nAChR alpha5 subunit: although apparently complexed with beta2 and beta4 nAChR subunits in neurons, and expressed in a subset of neurons within the central and peripheral nervous systems, heterologous expression of alpha5, either alone or with any beta-type subunit has failed to yield functional channels. We demonstrate here that alpha5 does participate in nAChRs expressed in hetrologous systems and in primary neurons, and further that alpha5 contributes to the lining of functionally unique nAChR channels, but only if coexpressed with both another alpha- and beta-type subunit. Furthermore, channels containing the alpha5 subunit are potently activated and desensitized by nanomolar concentrations of nicotine.

Macrophage targeting with technetium-99m labelled J001 acylated poly-galactoside for scintigraphy of inflammation: optimization and assessment of imaging specificity in experimental arthritis

J001, an acylated poly-(1,3)-galactoside purified from the membrane of Klebsiella pneumoniae, associates selectively with macrophages via the binding to CD11b and CD14 molecules. Inflammatory foci known to recruit macrophages could thus be imaged with technetium-99m labelled J001. This study aims to define the optimal scintigraphic protocol for 99mTc-J001 imaging and to evaluate the specificity of J001 scans. A dose range study was conducted in rabbits with immunological arthritis using six different specific activities ranging from 370 to 11840 MBq&middot;mg-1 while the intravenously injected activity was constant (37 MBq) Radiochemical purity for each preparation was documented together with the in vivo stability of the 99mTc-J001 complex using exclusion-diffusion radioHPLC of serum collected 1 h after radiopharmaceutical administration. Scintigraphic images were recorded at 2, 3 and 4h and analysed using indexes calculated from regions of interest. Specificity of the macrophage imaging was assessed by comparison with scans obtained after administration of 99mTcO4(- )or 99mTc-albumin nanocolloids. A protocol of plasma transfusion was also used to inject 99mTc-J001 after complete removal of radioactive colloids likely to be generated during the labelling. For the higher specific activities (5920 and 11840 MBq.mg-1), radiochemical purity degradation and in vitro 99mTc transchelation were noted. To prevent transchelation and 99mTc bond hydrolysis likely to impair imaging specificity, 1480 MBq.mg-1 corresponding to 25microg injected J001 was found to be the optimal usable specific activity. Results obtained with the various tracers support the hypothesis that macrophage targeting is the main factor involved in the J001 imaging of arthritis.

201T1 and 99Tcm-J001X macrophage scintigraphy: two radionuclide imaging techniques for the surveillance of acute localized radiation over-exposures

The therapeutic or surgical management of acute localized irradiation is very complicated due to the delayed occurrence of ionizing radiation effects. There is a great need for non-invasive imaging techniques to delineate healthy from exposed tissues. Such a technique should be of value considering that spread of damage can occur from apparently silent fibrotic foci. Of the scintigraphic procedures, 99Tcm first-pass scintigraphy has already been recommended by the International Atomic Energy Agency (IAEA) for the evaluation of irradiated tissues. In order to improve the scintigraphic surveillance of accidental over-exposures, the potentials of 201T1 and 99Tcm-J001X were evaluated on an experimental porcine model reproducing the late fibrotic effect encountered after localized irradiation. J001X, an acylated poly-(1,3)-galactoside of bacterial origin, was used for the functional imaging of the inflammatory reaction which took place after irradiation. This scintigraphy, based on targeting of activated macrophages recruited by lesions, was performed together with 201T1 scans for the assessment of blood perfusion and cellular metabolism. Our results demonstrate that these two radiopharmaceuticals provide reliable information for the management of accidental localized over-exposure, J001X allowing the assessment of the inflammatory reaction and 201T1-chloride being mainly useful for imaging the delayed onset of fibrosis.

Evaluation of possible interference of anti-inflammatory drugs upon scintigraphic imaging with macrophage targeting 99mTc-J001X: effects of methylprednisolone, dexamethasone, indomethacin and methotrexate

J001X, an acylated poly-(1,3)-galactoside isolated from Klebsiella pneumoniae proteoglycan, has been developed to target cells from the monocyte-macrophage lineage. Recent experimental work and initial clinical trials have proved the potential of this molecule labeled with 99mTc for the scintigraphy of inflammatory foci. In a model of radiation-induced inflammation in pigs, the scintigraphic contrast was observed to be very sensitive to a single injection of methylprednisolone given 12 h before scintigraphy. The present study was undertaken to confirm this effect and to estimate the possible interference of various anti-inflammatory agents on the in vivo targeting of macrophages by J001X. Methylprednisolone, dexamethasone, indomethacin and methotrexate used at an immunosuppressive dose were tested to assess the possible risk of false-negative examinations in patients thus treated. Analysis of the results indicated that among the four drugs tested, only methylprednisolone at 0.5-1 mg/kg could interfere with J001X scintigraphy.

Comparison of 7,12-dimethylbenz(a)anthracene-DNA adduction in the epidermis of two lines of mice selected for resistance (CAR-R) or susceptibility (CAR-S) to skin carcinogenesis

Two lines of mice were produced by bidirectional selective breeding: one resistant (CAR-R) and one susceptible (CAR-S) to two-stage skin carcinogenesis by dimethylbenz(a)anthracene and 12-O-tetradecanoyl-phorbol-13-acetate. The dimethylbenz(a)anthracene-DNA adduct formation was compared in the two lines by a postlabeling procedure so as to determine whether the striking interline difference observed as to tumor incidence could (in part) be due to differences in the formation of DNA-reactive metabolites. Results show that qualitatively, adduct profiles in CAR-R and CAR-S epidermis are similar. Quantitatively, the total binding level is slightly higher in CAR-S versus CAR-R mice during the 30-day follow-up. However, these minor differences do not increase in function of the response to selection observed through three consecutive generations. A 2- or 4-week promotion with 12-O-tetradecanoylphorbol-13-acetate enhances the decrease of adduct level in the two lines. This effect is somewhat more pronounced in CAR-S mice. Results strongly suggest that the expression of the genes responsible for CAR-R/CAR-S phenotypic difference affects mainly the postinitiation stages.

Scintigraphic potentials of J001X acylated poly-galactoside for imaging inflammatory lesions in pigs

Although several approaches already exist for the imaging of inflammatory foci, new specific strategies providing functional data on the lesions are required to determine the extent of the disease and also to assess anti-inflammatory treatment. In our study, we investigated the scintigraphic potential of 99mTc-J001X, an agent developed for the targeting of macrophages. Due to its well documented and progressive evolution of lesions, a model of radiation-induced inflammation in pigs was chosen. Our results demonstrated the ability of J001X to provide images of inflammatory foci with a high contrast. The contribution of some specific and non-specific parameters possibly involved in the scintigraphic behavior of J001X is discussed.

Photobiological activities of 1,6-dioxapyrene in pro- and eukaryotic cells

The photobiological effect of a new pyrene derivative, 1,6-dioxapyrene (1,6-DP), was studied in Salmonella typhimurium (strain TA100) and in the diploid strain D7 of the yeast Saccharomyces cerevisiae. In Salmonella, 1,6-DP shows little mutagenicity in the dark in comparison to benzo[a]pyrene (B[a]P). This mutagenic activity decreases in the presence of liver S9 homogenates from Aroclor induced XVIInc/Z mice. However, in combination with 365 nm (UVA) radiation and in the absence of S9 mix, 1,6-DP behaves as an effective photodynamic compound inducing lethal and mutagenic effects in both organisms. In yeast, its activity, like that of B[a]P, is highly dependent on the presence of oxygen. For the same incident dose of UVA, 1,6-DP is, however, at least 6 times more effective than B[a]P in inducing cytotoxic and mutagenic effects. At equitoxic doses, 1,6-DP is as photomutagenic as B[a]P, suggesting that in both cases mutagenicity is due to similar mechanisms. Spectrophotometric measurements indicate physical interaction of 1,6-DP with DNA in the dark. Laser flash photolysis experiments show that 1,6-DP generates singlet oxygen with a quantum yield of 0.17. In vitro 1,6-DP produces oxidative damage to guanine bases specific for singlet oxygen mediated reactions. Alkaline step elution analysis of 1,6-DP plus UVA treated yeast cells indicates a decrease in average molecular weights in DNA and an induction of single strand breaks (ssb) originating from alkali labile sites. This effect is enhanced by D2O and is thus likely to be due to the production of singlet oxygen. The strand breaks appear to differ from those induced by gamma-rays because little, if any, repair of these ssb occurs during 30 min of post-treatment incubation in complete growth medium. These results suggest that the photobiological effects of 1,6-DP are due to oxidative damage in DNA mostly induced by singlet oxygen.

Defining the structural requirements of a biologically active domain of human IL-1 beta

The immunostimulatory activity in vivo of the pleiotropic cytokine IL-1 beta can be retained by its nonapeptide VQGEESNDK, in position 163-171. A series of shorter and longer peptides around this position has been assayed for IL-1-like biological activity, in order to identify the structural requirements for full expression of adjuvant capacity. Elongated peptides, comprising the loop region 165-169 and up to six amino acids in the preceding beta strand or up to seven amino acids in the following beta strand, showed activity comparable or lower than that of the nonapeptide 163-171. This would indicate that the beta strand sequences are not required for optimizing the active conformation of the immunostimulatory IL-1 beta moiety. Accordingly, stabilization of the 163-171 peptide conformation by cyclization did not increase its biological activity. In contrast, the pentapeptide GEESN, corresponding the exposed loop 165-169 between two beta strands, had biological activity higher than that of the 163-171 nonapeptide and fully comparable to that of the entire IL-1 beta protein. Thus, the highly exposed fragment 165-169 within the IL-1 beta molecule may be the structure selectively responsible for the IL-1 beta immunostimulatory capacity in vivo.

Effect of partial hepatectomy on the formation and elimination of 3-methyldibenzo(c,g)carbazole and 5,9-dimethyldibenzo(c,g)carbazole-DNA adducts in mouse liver

Tritium-labeled 3-methyldibenzo(c,g)carbazole and 5,9-dimethyldibenzo(c,g)-carbazole, 2 organ-specific hepatocarcinogens in mice, were given intraperitoneally to partially hepatectomized animals at various times during the first cell division cycle following surgery. The former compound, more potent and cytotoxic, gave more striking results showing that the maximum number of adducts per unit weight of DNA in liver were formed when the carcinogen was given at the beginning of the S phase, which is evidence for the role of DNA replication in the initiation step of carcinogenesis. Elimination of these adducts led after several days to a residual number of lesions which was of the same order whatever the time of carcinogen administration. In the case of 5,9-dimethyldibenzo-carbazole there were fewer adducts formed after hepatectomy and their removal was much slower.

Radiolabeling of the biologically active peptide 163-171 of human interleukin-1 beta

N-succinimidyl[2,3-3H]propionate was used for the radiolabeling of the biologically active peptide fragment 163-171 of human interleukin-1 beta (VQGEESNDK). Suitable reaction conditions were studied to obtain useful labeling of the molecule. A mixture of mono- (70%) and bi- (30%) propionyl derivatives was obtained with a total 3H specific activity of 87 Ci/mmol of peptide. The conditions for an efficient chromatographic separation of labeled peptide from unreacted reagents and by-products were established. The labeled peptide maintained the same biological activity as that of the corresponding unlabeled molecule, indicating that the labeling procedure did not alter the biological characteristics of the peptide. This thus allows the use of the radiolabeled peptide for receptor binding studies.

Influence of the peptide insolubilization method on detection of anti-peptide antibodies in ELISA. Evaluation of nonspecific interactions

Different methods of peptide insolubilization in solid phase were compared in ELISA, to verify the influence of the peptide antigen presentation in the interaction with related antibodies. Our studies were performed using as model the peptide fragment 163-171 of human Interleukin 1 beta, and polyclonal or monoclonal anti-peptide antibodies. It was found that the peptide, N-terminally linked to a protein carrier before the adsorption on microtiter wells, interacted with specific polyclonal and monoclonal antibodies with high sensitivity and specificity. In contrast the recognition of similar random conjugates, prepared using a bivalent cross-linking reagent or the peptide covalently linked to poly-L-Lysine-pretreated wells, was hampered generally by very high levels of nonspecific binding. On the other hand, the free peptide adsorbed directly to the solid phase interacted with antibodies with very low sensitivity and specificity. Nonspecific interactions were found in particular between peptides and hyperimmune sera or nonrelated monoclonal antibodies. On the contrary pre-immune sera and normal mouse immunoglobulins never showed significant interactions with any of peptides. This nonspecificity was also overcome when N-terminally linked peptide-protein conjugates were used for the assay.

Comparison of the in vitro metabolisms and mutagenicities of dibenzo[a,c]anthracene, dibenzo[a,h]anthracene and dibenzo[a,j]anthracene: influence of norharman

The comparison of the behaviour of three dibenzoanthracene (DBA) isomers, dibenzo[a,c]anthracene (DB[a,c]A), dibenzo[a,h]anthracene (DB[a,h]A) and dibenzo[a,j]anthracene (DB[a,j]A), polycyclic aromatic hydrocarbons (PAHs), whose carcinogenicity varies from very potent to apparently inactive, has been carried out. Influence of norharman (NH; 9H-pyrido[3,4-b]indol) was investigated for mutagenicity (reversion of histidine prototrophy) on Salmonella typhimurium TA 100, using 3-methylcholanthrene (3-MC)-induced rat liver microsomes or S9 (post-mitochondrial fractions). A correlation with its influence, on the in vitro metabolism of radiolabelled molecules by the same enzymatic systems, was carried out. NH enhances the mutagenicities of DB[a,c]A and DB[a,h]A which are very well known mutagenic and carcinogenic PAHs. Contrary to its two isomers, the mutagenic potency of DB[a,j]A, which is considered as a weak mutagen and not a carcinogen, is strongly inhibited by NH. The balance sheets of the in vitro metabolism by microsomal enzymes, where the conjugation is excluded, were reported with or without NH. In the presence of the latter, the amounts of remaining DBAs slightly decreased while the metabolites covalently bound to microsomal proteins strongly decreased and the amount of hydrophobic metabolites highly increased. At the same time, the HPLC elution profiles of the metabolism pathways of the three DBAs are found to be modified in a similar way by NH: some of the metabolites are highly enhanced, and for all three DBAs, a tetraol, not detectable in the absence of NH, emerges. The results are discussed with regard to possible effects of NH.

Studies of the antigenic structure of two cross-reacting proteins, pertussis and cholera toxins, using synthetic peptides

Peptide fragments of pertussis toxin subunit 1 (PT-S1) have been synthesized in order to investigate their antigenic and immunogenic activity, and to evaluate their possible use as components of a new vaccine. Two peptides (sequence 73-82, EAERAGRGTG and sequence 107-116, YVDTYGDNAG) were selected for their predictable exposure on the surface of the molecule, and a third (8-18, YRYDSRPPEDV) for its homology with the sequence 6-16 of cholera toxin subunit A (CT-A 6-16) (YRADSRPPDEI). Antipeptide polyclonal antibodies produced in rabbits, were tested in different immunoassays for their ability to interact with toxin proteins. All of them proved interactive with recombinant PT-S1 (rPT-S1); CT-A interact not only, as expected, with anti 8-18 antibodies, due to the high homology between the two toxins in this region, but also, unexpectedly, with anti 107-116 antibodies, in spite of the lack of homology of this peptide with the entire CT. We also found a direct cross-reactivity between the two toxins: anti PT and anti rPT-S1 antibodies interacted with CT-A, whereas anti CT antibodies did not recognize PT. Antipertussis antibodies also recognized the peptide 8-18, which therefore represents at least a part of an antigenic determinant of the toxin, while no interaction could be evidenced between anti-cholera antibodies and any of the peptides, thus demonstrating important differences in the antigenic structures of the two toxins. None of the antipeptide antibodies examined showed protective activity against the toxins in a Chinese hamster ovary (CHO) cell test.

Interleukin 1 and its synthetic peptides as adjuvants for poorly immunogenic vaccines

The adjuvant activity of the peptide corresponding to the fragment 163-171 of human interleukin 1 beta (VQGEESNDK) has been evaluated on the immune response to both T-dependent and T-independent antigens. The hydrochloride derivative of the peptide showed an effect quantitatively comparable in molar terms to that of the entire protein. At variance with the entire IL 1 protein the peptide appeared devoid of inflammatory effects and therefore it may find clinical applications as adjuvant for poorly immunogenic vaccines or as immunorestorative agent. The activity of other fragments in proximity of the sequence 163-171 was also evaluated. The shorter fragment 165-171 appeared as active as the 163-171 peptide.

In vivo stimulation and restoration of the immune response by the noninflammatory fragment 163-171 of human interleukin 1 beta

The synthetic nonapeptide VQGEESNDK, corresponding to the fragment 163-171 of human IL-1 beta, showed in vivo immunomodulatory capacities qualitatively and quantitatively comparable to those of the mature human IL-1 beta protein. In fact, both IL-1 beta and the 163-171 fragment stimulated the immune response of normal mice and restored immune reactivities of immunocompromised animals. In addition, the synthetic IL-1 peptide was as efficient as the entire protein in inducing tumor rejection and radioprotection. On the other hand, the 163-171 fragment did not cause any of several inflammation-associated metabolic changes inducible by the whole IL-1 beta molecule in vivo: hypoferremia, hypoglycemia, hyperinsulinemia, increase in circulating corticosterone, SAA and fibrinogen, decrease in hepatic drug-metabolizing enzymes. Furthermore, at variance with IL-1 beta, the 163-171 peptide did not show the toxic effects causing shock and death in adrenalectomized mice. Thus, these results confirm our previous in vitro observations that functional domains are identifiable within the multipotent cytokine IL-1 beta, and demonstrate the biological relevance of this finding in a variety of in vivo systems. The identification of a selectively active fragment of a cytokine may thus represent a significant step towards a better directed and more rational immunotherapeutic approach.

Distribution of isoaccepting tRNAs and codons for proline and glycine in collagenous and noncollagenous chicken tissues

The relation between codon usage and tRNA content for proline and glycine, the major constituents of collagen, was studied in two tissues: the magnum of laying hen oviduct and the leg tendons of chick embryo where collagen is produced. Although the relative contents of tRNA(GCCGly) and tRNA(IGGPro) in tendons, as compared to magnum indicate a specialization of the tRNA population for collagen synthesis, the distribution of the preponderant codons in collagen mRNA is correlated but at a lesser extent to that of their cognate tRNAs.

In vivo immunostimulating activity of the 163-171 peptide of human IL-1 beta

The stimulating effect of a synthetic nonapeptide (fragment 163-171) of human interleukin 1 beta (IL-1 beta) on antibody responses to both T helper-dependent and T helper-independent antigens was investigated. It was shown that the nonapeptide enhanced the antibody response, as evaluated in the hemolytic plaque assay, of spleen cells from mice immunized with sheep red blood cells (SRBC). The activity of the 163-171 peptide on the primary response to SRBC was dose-dependent, being maximal when the peptide was inoculated at 100 mg/kg together with the antigen. Moreover, the 163-171 peptide was also effective in enhancing the secondary response to SRBC. The effect of the 163-171 peptide was to augment the frequency of cells specific for the antigen, inasmuch as no increase was ever observed in spleen cell numbers after treatment. In all these studies, human recombinant IL-1 beta gave effects qualitatively comparable to those of the 163-171 peptide, with a maximal activity at 20 ng/kg. Both the 163-171 peptide and human recombinant IL-1 beta were also able to enhance the in vivo immune response to a T helper-independent antigen such as SIII, a poorly immunogenic polysaccharidic antigen from Streptococcus pneumoniae type III. It can therefore be proposed that this synthetic nonapeptide of human IL-1 beta may represent a good candidate for use as adjuvant in vaccines.

In vivo immunostimulating activity of the 163-171 peptide of human IL-1 beta

The stimulating effect of a synthetic nonapeptide (fragment 163-171) of human interleukin 1 beta (IL-1 beta) on antibody responses to both T helper-dependent and T helper-independent antigens was investigated. It was shown that the nonapeptide enhanced the antibody response, as evaluated in the hemolytic plaque assay, of spleen cells from mice immunized with sheep red blood cells (SRBC). The activity of the 163-171 peptide on the primary response to SRBC was dose-dependent, being maximal when the peptide was inoculated at 100 mg/kg together with the antigen. Moreover, the 163-171 peptide was also effective in enhancing the secondary response to SRBC. The effect of the 163-171 peptide was to augment the frequency of cells specific for the antigen, inasmuch as no increase was ever observed in spleen cell numbers after treatment. In all these studies, human recombinant IL-1 beta gave effects qualitatively comparable to those of the 163-171 peptide, with a maximal activity at 20 ng/kg. Both the 163-171 peptide and human recombinant IL-1 beta were also able to enhance the in vivo immune response to a T helper-independent antigen such as SIII, a poorly immunogenic polysaccharidic antigen from Streptococcus pneumoniae type III. It can therefore be proposed that this synthetic nonapeptide of human IL-1 beta may represent a good candidate for use as adjuvant in vaccines.

Single-step high-yield purification of a synthetic peptide fragment of human interleukin 1 by preparative high-performance liquid chromatography

It was recently shown that fragment 163-171 of human interleukin 1 beta (hIL1 beta) possesses interesting biological properties, as it presents immunostimulatory activity both in vitro and in vivo, whilst being apparently devoid of the strong inflammatory properties that prevent the possible therapeutic use of the entire interleukin 1 molecule. Therefore, this peptide may represent the fragment of the protein responsible for its immunostimulatory activity, distinct from the part involved in the inflammatory activity of the entire molecule. Large amounts of highly purified peptide are needed for an adequate pharmacological characterization, in view of its possible therapeutic applications. A suitable method for the preparation of this peptide, was therefore studied paying particular attention to the purification step, which is essentially based on an efficient use of preparative high-performance liquid chromatography.

A short synthetic peptide fragment of human interleukin 1 with immunostimulatory but not inflammatory activity

Short peptide fragments of human and murine interleukin 1 (IL 1) were synthesized on the basis of their predicted exposure on the surface of the molecule in an attempt to identify the minimal structure responsible for the immunostimulatory activity of IL 1. One of these peptides, a fragment of nine residues of human IL 1 beta (VQGEESNDK, fragment 163-171), showed high T cell activation capacity, as judged by its ability to stimulate murine thymocyte proliferation and to potently induce interleukin 2 production in spleen cells. On the other hand, the 163-171 peptide was devoid of prostaglandin-inducing capacity in vitro and pyrogenic activity in vivo, two inflammatory features peculiar to the entire hu IL 1 beta molecule. Thus we propose that this peptide may represent one of the portions of hu IL 1 beta responsible for its immunostimulatory capacity.

A short synthetic peptide fragment of human interleukin 1 with immunostimulatory but not inflammatory activity

Short peptide fragments of human and murine interleukin 1 (IL 1) were synthesized on the basis of their predicted exposure on the surface of the molecule in an attempt to identify the minimal structure responsible for the immunostimulatory activity of IL 1. One of these peptides, a fragment of nine residues of human IL 1 beta (VQGEESNDK, fragment 163-171), showed high T cell activation capacity, as judged by its ability to stimulate murine thymocyte proliferation and to potently induce interleukin 2 production in spleen cells. On the other hand, the 163-171 peptide was devoid of prostaglandin-inducing capacity in vitro and pyrogenic activity in vivo, two inflammatory features peculiar to the entire hu IL 1 beta molecule. Thus we propose that this peptide may represent one of the portions of hu IL 1 beta responsible for its immunostimulatory capacity.

Sexual differences in the expression of gamma-glutamyl transpeptidase during 5,9-dimethyldibenzo[c,g]carbazole-induced hepatocarcinogenesis in mice

5,9-Dimethyl-7H-dibenzo[c,g]carbazole (5,9-diMeDBC) is an organ-specific carcinogen for mouse liver. It induces malignant hepatomas in 100% of XVIInc/Z and C57BL mice with a cumulative dose of only 12 mumol administered subcutaneously. Large sex-related differences in sensitivity towards this carcinogen were observed: entire males were much less sensitive than females. Castration of males nearly completely restored the sensitivity observed for females. The kinetics of appearance of gamma-glutamyl transpeptidase (gamma GT)-positive foci was enhanced in females and castrated males and was correlated with the tumour outbreak. On the contrary the expression of gamma GT in males was very reduced. The sex-dependent sensitivity seems to be regulated by a complex interplay of endogenous factors.

In vitro metabolism of N-methyl-dibenzo [c,g]carbazole a potent sarcomatogen devoid of hepatotoxic and hepatocarcinogenic properties

The metabolism of N-methyl substituted 7H-dibenzo[c,g]carbazole (N-Me DBC) was investigated in vitro using liver microsomes from 3-methylcholanthrene (MC)-, benzo[c]carbazole (BC) and Arochlor-pretreated mice and rats. N-Me DBC is a potent sarcomatogen devoid of hepatotoxicity and liver carcinogenic activity. The ethyl acetate-extractable metabolites were separated by high performance liquid chromatography (HPLC) and most of them were identified by proton magnetic resonance (PMR), mass spectrometry (MS) and comparison with synthetically prepared specimens. Mouse and rat microsomes gave rise to the same metabolites. The major metabolites were 5-OH-N-Me DBC (50%), N-hydroxymethyl (HMe) DBC (25-30%) and 3-OH-N-Me DBC (10%). Addition of 1,1,1-trichloropropene-2,3-oxide (TCPO) to the standard incubation medium permitted the identification of two dihydrodiols among the minor metabolites. No metabolite of DBC was observed after incubation of N-Me DBC, or its major metabolite N-HMe DBC, with either mouse or rat microsomes, but the possibility of a slight demethylation cannot be totally excluded. The lack of biotransformation at the nitrogen atom site may explain the lack of hepatotoxicity and liver carcinogenic activity of N-Me DBC. The modulation of metabolism by epoxide hydrolase, cytosol and glutathione was also investigated. The results are discussed in the light of data previously obtained with hepatotoxic and hepatocarcinogenic DBC.

Heterocyclic polycyclic aromatic hydrocarbon carcinogenesis: 7H-dibenzo[c,g]carbazole metabolism by microsomal enzymes from mouse and rat liver

The metabolism of dibenzo[c,g]carbazole (DBC), was studied in vitro using microsomal fractions of mouse and rat liver from animals, which were treated with 3-methylcholanthrene (MC). The separation of extractable metabolites by high pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) as well as identification of most of them by nuclear magnetic resonance, mass spectrometry and comparison with synthetically obtained products are described. The microsomes of both species produced the same twelve compounds of which the following have been identified: five monohydroxylated derivatives (phenols), the product of further oxidation of one of them, and a dihydrodiol. The 5-OH-DBC (60% including its spontaneously-formed dimer) and the 3-OH-DBC (14%) are the main metabolites. Three minor metabolites cochromatographed with synthetically prepared 2-OH-DBC, 4-OH-DBC and 6-OH-DBC. The dihydrodiol detectable in small quantity (4-6%) was tentatively identified as 3,4-dihydroxy-3,4-dihydro-DBC by the sensitivity of its formation to very low concentrations of the inhibitor of microsomal epoxide hydrolase, 1,1,1-trichloropropene oxide, by its molecular ion and major fragment in mass spectrometry and by its dehydration product 3-OH-DBC. No other dihydrodiols were detected. The qualitative and quantitative effects of various modulators of metabolism (enzyme inhibitors, apparently homogeneous epoxide hydrolase, glutathione, supernatant fraction) were investigated. The results are discussed with respect to possible ultimate carcinogens.

Enhancement of 5-iododeoxyuridine-induced endogenous C-type virus activation by polycyclic hydrocarbons: apparent lack of parallelism between enhancement and carcinogenicity

When mouse MLg cells were treated with 3-methylcholanthrene or 7,12-dimethylbenz[alpha]anthracene in the presence of microsomal enzymes and NADPH after 5-iododeoxyuridine (IUDR) treatment, the induction rate of the endogenous C-type virus was increased fivefold to sixfold in comparison with the culture treated with IUDR only. In this reaction, both the microsomal enzymes and NADPH were indispensable. 7,8-Benzoflavone, an inhibitor of the metabolism of hydrocarbons in hamster embryo cultures, inhibited the reaction. For detecting the enhancing activity, the concentration of IUDR for the pretreatment, the concentration of the test products, and the duration of the treatment with the products were important factors. In screening 30 polycyclic hydrocarbons, we were unable to detect a correlation between the in vivo carcinogenicity in the skin and the enhancing activity in the conditions tested.

Oxidation of Dibenzo[a,e]fluoranthene by Osmium Tetroxide

Dibenzo[a,e]fluoranthene is treated by osmium tetroxide, the nature, structure, and configuration of the compound obtained (a trans dihydro diol) are defined taking into account the chemical, theoretical, and physicochemical arguments.