Screening chest wall ultrasound in the mastectomy patient

BACKGROUND

While there are clear guidelines regarding chest wall ultrasound in the symptomatic patient, there is conflicting evidence regarding the use of ultrasound in the screening of women post-mastectomy.

OBJECTIVE

To assess the utility of screening chest wall ultrasound after mastectomy and to assess features of detected malignancies.

METHODS

This IRB approved, retrospective study evaluates screening US examinations of the chest wall after mastectomy. Asymptomatic women presenting for screening chest wall ultrasound from January 2016 through May 2017 were included. Cases of known active malignancy were excluded. All patients had at least one year of clinical or imaging follow-up. 43 exams (8.5 %) were performed with a history of contralateral malignancy, 465 exams (91.3 %) were performed with a history of ipsilateral malignancy, and one exam (0.2 %) was performed in a patient with bilateral prophylactic mastectomy.

RESULTS

During the 17-month period, there were 509 screening US in 389 mastectomy patients. 504 (99.0 %) exams were negative/benign. Five exams (1.0 %) were considered suspicious, with recommendation for biopsy, which was performed. Out of 509 exams, 3 (0.6 %) yielded benign results, while 2 (0.39 %) revealed recurrent malignancy, with a 95 % confidence interval (exact binomial) of 0.05 % to 1.41 % for screening ultrasound. Both patients who recurred had previously recurred, and both had initial cancer of lobular histology.

CONCLUSION

Of 509 chest wall screening US exams performed in mastectomy, 2 malignancies were detected, and each patient had history of invasive lobular carcinoma and at least one prior recurrence prior to this study, suggesting benefit of screening ultrasound in these populations.

Immediate and delayed risk of breast cancer associated with classic lobular carcinoma in situ and its variants

OBJECTIVE

To determine the risk of breast cancer due to lobular carcinoma in situ (LCIS).

METHODS

This retrospective IRB-approved study identified cases of LCIS after percutaneous breast biopsy from 7/2005 to 7/2022. Excluded were cases with less than 2 years of imaging surveillance or a concurrent ipsilateral breast cancer diagnosis within 6 months of the LCIS diagnosis. Final outcomes of cancer versus no cancer were determined by pathology at surgical excision or the absence of cancer on imaging surveillance.

RESULTS

A total of 116 LCIS lesions were identified. The primary imaging findings targeted for percutaneous biopsy included calcifications (50.0%, 58/116), MR enhancing lesions (25.0%, 29/116), noncalcified mammographic architectural distortions (10.3%, 12/116), or masses (14.7%, 17/116). Surgical excision was performed in 49.1% (57/116) and imaging surveillance was performed in 50.9% (59/116) of LCIS cases. There were 22 cancers of which 11 cancers were discovered at immediate excision [19.3% (11/57) immediate upgrade] and 11 cancers developed later while on imaging surveillance [18.6% (11/59) delayed risk for cancer]. Among all 22 cancers, 63.6% (14/22) occurred at the site of LCIS (11 at immediate excision and 3 at surveillance) and 36.4% (8/22) occurred at a location away from the site of LCIS (6 in a different quadrant and 2 in the contralateral breast).

CONCLUSION

LCIS has both an immediate risk (19.3%) and a delayed risk (18.6%) for cancer with 90.9% occurring in the ipsilateral breast (63.6% at and 27.3% away from the site of LCIS) and 9.1% occurring in the contralateral breast.

Isolated Flat Epithelial Atypia: Upgrade Outcomes After Multidisciplinary Review-Based Management Using Excision or Imaging Surveillance

Objective

To compare flat epithelial atypia (FEA) upgrade rates after excision versus surveillance and to identify variables associated with upgrade.

Methods

This single-institution retrospective study identified isolated FEA cases determined by percutaneous biopsy from April 2005 through July 2022 with excision or ≥2 years surveillance. All cases were recommended for excision or surveillance based on multidisciplinary discussion of clinical, imaging, and pathologic variables with emphasis on sampling adequacy and significant atypia. Truth was determined by pathology at excision or the absence of cancer on surveillance. Upgrade was defined as cancer occurring ≤2 cm from the biopsy site. Demographic, imaging, and biopsy variables were compared between those that did and did not upgrade.

Results

Among 112 cases of isolated FEA, imaging findings included calcifications in 81.3% (91/112), MRI lesions in 11.6% (13/112), and distortions or masses in 7.1% (8/112). Excision was recommended in 12.5% (14/112) and surveillance in 87.5% (98/112) of cases. Among those recommended for excision, 28.6% (4/14) of cases were upgraded, all to ductal carcinoma in situ. In those recommended for surveillance, 1.0% (1/98) were upgraded to invasive cancer. Overall, FEA had a 4.5% (5/112) upgrade rate, and 2.7% (3/112) also developed cancer >2 cm from the FEA. There were no significant differences in demographic, imaging, and biopsy variables between those that did and did not upgrade to cancer.

Conclusion

Multidisciplinary management of isolated FEA distinguishes those at higher risk of upgrade to cancer (28.6%) in whom surgery is warranted from those at low risk of upgrade (1.0%) who can be managed non-operatively.

Diagnostic ultrasound of the chest wall in the symptomatic patient after mastectomy

BACKGROUND

Lack of standardized imaging recommendations among mastectomy patients has led to variability in how recurrences are detected.

OBJECTIVE

To describe the findings and assess the diagnostic efficacy of ultrasound in the evaluation of symptomatic post-mastectomy patients.

MATERIALS AND METHODS

This single institution, retrospective study included 749 consecutive diagnostic chest wall ultrasound examinations performed in mastectomy patients, from January 2016 to June 2017. Chest wall ultrasound evaluated the mastectomy bed with or without reconstruction. Electronic health records were queried for the primary breast cancer histology prior to mastectomy, clinical symptoms prompting the diagnostic ultrasound, ultrasound findings, subsequent cytology and pathology, and follow-up data. Excluded were patients with a known recurrence, asymptomatic patients, and those with <2 years of clinical or imaging follow-up. Descriptive and comparative statistical analyses were performed.

RESULTS

Among the 749 ultrasounds performed, 58 malignancies were identified for a 7.7% (58/749) malignancy rate, with a median tumor size of 20 mm. Patients diagnosed with a malignancy most often presented with a palpable abnormality (79.3%, 46/58) or skin changes (13.8%, 8/58) and rarely with pain (1.7%, 1/58). Patients who underwent a biopsy yielding a benign result most often presented with a palpable abnormality (41.5%, 287/691), pain (25.6%,177/691), or postoperative swelling/suspected fluid collection (17.8%, 123/691). Diagnostic ultrasound yielded a 91.4% sensitivity (95% CI 81.0, 97.1), 96.1% specificity (95% CI 94.4, 97.4), 66.3% PPV₃ (95% CI 57.4, 74.1), and 99.3% negative predictive value (95% CI 98.3, 99.7) for cancer detection. There were 5 false negative ultrasound cases after a skin punch biopsy was performed due to clinically suspicious skin changes.

CONCLUSIONS

Chest wall ultrasound has a high sensitivity and negative predictive value for detection of breast cancer recurrence in symptomatic patients after mastectomy. Skin changes remain an important clinical manifestation of a cancer recurrence.

Identifying and Reducing Barriers to Breast Imaging

Purpose of Review

The purpose of this review is to discuss disparities in breast health care access and outcomes related to race, gender, cultural diversity, sexual orientation, socioeconomic status, geographic location, and disability. The authors recognize the complexity of eliminating inequalities in health care but are optimistic that all patients will one day have equal access to care through dialogue, acknowledgment, recognition, and action.

Recent Findings

After lung cancer, breast cancer is the second leading cause of death among American women. Mammography as a preventative screening tool has resulted in significant reductions in breast cancer mortality. Despite existing breast cancer recommendations, it has been projected that 43,250 women will die from breast cancer in 2022.

Summary

Disparities in healthcare outcomes exist for many reasons including inequalities based on race, gender, cultural diversity, religion, sexual orientation, and socioeconomic status. Disparities, no matter how large or complex, are not insurmountable.

Nipple Discharge Imaging Evaluation with Mammography, Ultrasound, Galactography, and MRI

RATIONALE AND OBJECTIVE

To determine the diagnostic yield of various imaging tests used to evaluate nipple discharge.

MATERIALS AND METHODS

A single institution, IRB-approved, retrospective study was performed of 320 consecutive patients presenting with nipple discharge. Imaging and pathology were reviewed to determine the yield for malignancy, atypical high-risk lesions (HRLs), and intraductal papillomas (IDPs).

RESULTS

Of the 320 patients, pathology or follow up confirmed 40 breast malignancies (40/320, 12.5%),14 atypical HRLs (14/320, 4.4%), 71 IDPs (71/320, 22.2%), 48 other benign pathologies (48/320,15.0%), and 147 unknown but benign cases (147/320, 45.9%). Physiologic discharge characteristics were observed in a minority of malignant cases: nonspontaneous (4/40, 10.0%); neither bloody nor clear (4/40, 10.0%); bilateral (3/40, 7.5%). Malignancy was associated with older age (p < 0.001) and bloody discharge (odds ratio 6.5, p < 0.0001). The combination of digital mammography and ultrasound had a 93% sensitivity and a 98% NPV, while contrast enhanced MRI (CE-MRI) had a 100% sensitivity and a 100% NPV for malignancy. Only three galactography examinations were performed among the malignant cohort, with minimal contribution (1 of 3) to the diagnostic evaluation. In this case, galactography findings helped determine imaging-pathology discordance, prompting a recommendation for surgical excision and subsequently a malignant diagnosis.

CONCLUSION

The combination of mammography and ultrasonography detected 93% of breast malignancies associated with nipple discharge and had a 98% NPV for malignancy. The value of CE-MRI is its ability to detect the remaining malignancies, not detected on mammography or ultrasound, and its ability to obviate the need for surgical duct excision.

Imaging Updates to Breast Cancer Lymph Node Management

Metastatic lymph node involvement in breast cancer is a key determinant of the overall stage of disease and prognosis. Historically, lymph node status was determined by surgery first, with adjuvant treatments determined based on the results of the final surgical pathologic analysis. While this sequence is still applicable in many cases, neoadjuvant systemic treatment (NST) is increasingly being administered as the initial treatment. In cases that demonstrate good therapeutic response to drug therapies, NST may permit the option to perform less radical surgeries subsequently. Current breast cancer treatment has become multidisciplinary, with overlapping roles from the different disciplines. As surgery may be postponed, imaging and image-guided lymph node interventions have gained importance as the primary means of lymph node assessment. Imaging enables evaluation of all regional nodal basins, including locations where surgery is not usually performed. By differentiating limited versus extensive nodal involvement, imaging findings help determine whether initial treatment should be surgical or medical. If medical treatment with NST is indicated, imaging is performed to monitor the in vivo nodal response to drug therapy and ultimately to help determine the surgical technique to perform on the basis of the final imaging findings after NST. The authors discuss the imaging features of nodal metastases and the indications and techniques for the various image-guided procedures. The relative usefulness and shortcomings of the various imaging examinations are reviewed to discuss how they can be applied when biopsy results are not available. The role of imaging in the multidisciplinary team approach is emphasized based on past clinical trials of lymph node management and recent evolving knowledge of breast cancer staging. Online supplemental material is available for this article. ^©RSNA, 2021.

Breast cancer recurrences in myocutaneous flap reconstruction

Autologous flap reconstruction is widely used after skin sparing mastectomy to reconstruct the appearance of the breast. We present 2 cases of breast cancer recurrence in a deep inferior epigastric perforator reconstruction, including a 65-year-old female with history of papillary carcinoma and a 35-year-old female with history of a high grade invasive ductal carcinoma with extensive ductal carcinoma in situ. Differential imaging considerations of the post mastectomy patient are reviewed. Typical appearance of a deep inferior epigastric perforator flap reconstruction as well as location and timing of presentation may help differentiate a recurrence from the more commonly encountered postsurgical etiologies.

Telemammography: Technical Advances Improve Patient Access in Breast Care

Screening mammography's efficacy in reducing breast cancer deaths depends on patient compliance with screening recommendations and the radiologist's interpretative skills. Reasons for suboptimal screening compliance may be multifactorial, including possible limitations in access. Additionally, while studies show experienced breast radiologists are more accurate in their mammographic interpretation, only a minority of the nation's mammograms are interpreted by breast imaging specialists. To simultaneously optimize the benefit of early breast cancer detection while minimizing the harms associated with a false positive interpretation, delivery models that help improve access to breast expertise should be considered. Telemammography is one such delivery model that may be underutilized in current practice. While radiologists and other stakeholders of healthcare have accepted teleradiology interpretation of non-mammography studies as routine, telemammography use and acceptance is less well known. In this article, we review the operational components of a telemammography practice in today's information- and technology-dependent society. Current use of telemammography and remaining potential challenges are discussed. Telemammography can improve healthcare delivery and access by bringing together patients and breast expertise. If accepted, use of telemammography can help meet Centers for Disease Control's Healthy People 2020 goals related to breast cancer.

Pulmonary Langerhans cell histiocytosis: emerging concepts in pathobiology, radiology, and clinical evolution of disease

Pulmonary Langerhans cell histiocytosis (PLCH) is an uncommon disorder of adult smokers associated with a significant morbidity. Arising from the aberrant accumulation of Langerhans and other immune cells, PLCH tends to cause a relatively isolated pulmonary involvement as compared to other forms of Langerhans cell (LC) and histiocytic disorders. Increased knowledge of cytokine triggers, dendritic cell trafficking, and clonality of LC populations in PLCH have resulted in an improved understanding of the pathobiology of PLCH. High-resolution CT (HRCT) of the chest has led to better appreciation of nodular and cystic radiographic abnormalities characteristic of the disease. Correlation of HRCT abnormalities with lung pathologic changes has led to an improved comprehension of clinical evolution of PLCH. Current clinical predictors for PLCH outcomes remain poor, although long-term follow-up and radiologic monitoring may help to define disease progression. This review discusses advances in PLCH emphasizing the etiopathologic bases of the disease and currently available radiologic modalities for monitoring disease progression.

Breaking the language barrier: an emergentist coalition model for the origins of word learning

How do children learn their first words? The field of language development has been polarized by responses to this question. Explanations range from constraints/principles accounts that emphasize the importance of cognitive heuristics in language acquisition, to social-pragmatic accounts that highlight the role of parent-child interaction, to associationistic accounts that highlight the role of "dumb attentional mechanisms" in word learning. In this Monograph, an alternative to these accounts is presented: the emergentist coalition theory. A hybrid view of word learning, this theory characterizes lexical acquisition as the emergent product of multiple factors, including cognitive constraints, social-pragmatic factors, and global attentional mechanisms. The model makes three assumptions: (a) that children cull from multiple inputs available for word learning at any given time, (b) that these inputs are differentially weighted over development, and (c) that children develop emergent principles of word learning, which guide subsequent word acquisition. With few exceptions, competing accounts of the word learning process have examined children who are already veteran word learners. By focusing on the very beginnings of word learning at around 12 months of age, however, it is possible to see how social and cognitive factors are coordinated in the process of vocabulary development. After presenting a new method for investigating word learning, the development of reference is used as a test case of the theory. In 12 experiments, with children ranging in age from 12 to 25 months of age, data are described that support the emergentist coalition model. This fundamentally developmental theory posits that children construct principles of word learning. As children's word learning principles emerge and develop, the character of word learning changes over the course of the 2nd year of life.

Deposition of eosinophil-granule major basic protein and expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in the mucosa of the small intestine in infants with cow's milk-sensitive enteropathy

BACKGROUND

Cow's milk-sensitive enteropathy (CMSE) is an important cause of chronic diarrhea and failure to thrive in infancy. The immunopathology of the mucosal lesion associated with CMSE has not yet been described.

OBJECTIVES

This study investigated the eosinophil activation and the role of adhesion molecules in the pathogenesis of intestinal mucosal damage associated with CMSE.

METHODS

Twenty-one patients with chronic diarrhea and abnormal mucosa on duodenal biopsy specimens were included. The patients had negative responses to skin prick tests and RASTs with milk. Fourteen patients were diagnosed with CMSE by milk challenge test and were designated as the CMSE group. Seven patients with no milk intolerance were defined as the non-CMSE group. Four infants with frequent vomiting and no mucosal abnormalities were also studied as the control group. Immunohistochemical stains for eosinophil major basic protein (MBP), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 on endoscopic duodenal biopsy specimens were performed.

RESULTS

The degree of eosinophil degranulation, as evidenced by localization of extracellular MBP, was significantly greater in the CMSE group compared with the non-CMSE and control groups (P <.05). Expression of VCAM-1 on mononuclear cells was higher in the CMSE group compared with the non-CMSE and control groups (P <.05). The severity of villous atrophy was positively correlated with the deposition of MBP (r = 0.79, P <.001).

CONCLUSION

These results strongly suggest eosinophils and VCAM-1 are implicated in the pathogenesis of mucosal damage associated with CMSE.

Diagnosis of trichomoniasis by polymerase chain reaction

The clinical usefulness of polymerase chain reaction (PCR) for the diagnosis of trichomoniasis was evaluated in comparison with other conventional tests. PCR was used for specific detection of Trichomonas vaginalis by primers based on the repetitive sequence cloned from T. vaginalis (TV-E650). Between June 1996 and August 1997, 426 patients visited the department of obstetrics and gynecology, Hanyang University Kuri Hospital and were examined for trichomoniasis using wet mount examination, Papanicolaou (Pap) smear, culture and PCR. One hundred and seventy-seven patients (group A) visited with the symptoms of vaginal discharge and 249 patients (group B) visited for regular cervical Pap smear with no vaginal symptoms. From group A (n = 177), 3 infections (2.0%) were detected by wet mount, 6 infections (3.3%) by Pap smear and culture, and 17 infections (10.4%) by PCR. From group B (n = 249), 4 patients (1.6%) were found to have T. vaginalis by culture and 6 infections (2.4%) were detected by PCR. Therefore, in both groups, PCR for T. vaginalis showed a higher detection rate compared with conventional wet mount, Pap smear or culture. The detection by PCR was specific for T. vaginalis since no amplification was detected with DNAs from other protozoa and Candida albicans. The sensitivity and specificity of PCR were 100%. This method could detect T. vaginalis in vaginal discharge at a concentration as low as 1 cell per PCR mixture. These results indicate that PCR could be used as a specific and sensitive diagnostic tool for human trichomoniasis.

Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke

A new-technology cigarette has been developed. While the new cigarette burns some tobacco, it does not use tobacco as the fuel to sustain combustion and provide heat to the cigarette. Rather, the new cigarette primarily heats tobacco thereby reducing products of smoke formation mechanisms such as tobacco combustion, tobacco pyrolysis and pyrosynthesis. The mainstream smoke composition from a cigarette based on the new design (TOB-HT) has been characterized in comparative chemical testing with two reference cigarettes using the FTC puffing regimen. Thermal properties, UV absorption characteristics, elemental composition and materials balance studies all suggest a simplified smoke aerosol. Twenty-five smoke constituents ("target compounds") identified by the scientific community as compounds that may contribute to the diseases statistically associated with smoking have also been measured. Mainstream smoke concentrations of most target compounds are significantly lower with the TOB-HT cigarette when compared with reference cigarettes in the ultra-light "tar" and light "tar" categories. Taken together, chemical analysis results suggest simplified TOB-HT smoke chemistry with marked reductions in specific chemicals reported to be biologically active.

Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke

A new-technology cigarette has been developed. While the new cigarette burns some tobacco, it does not use tobacco as the fuel to sustain combustion and provide heat to the cigarette. Rather, the new cigarette primarily heats tobacco thereby reducing products of smoke formation mechanisms such as tobacco combustion, tobacco pyrolysis and pyrosynthesis. The mainstream smoke composition from a cigarette based on the new design (TOB-HT) has been characterized in comparative chemical testing with two reference cigarettes using the FTC puffing regimen. Thermal properties, UV absorption characteristics, elemental composition and materials balance studies all suggest a simplified smoke aerosol. Twenty-five smoke constituents ("target compounds") identified by the scientific community as compounds that may contribute to the diseases statistically associated with smoking have also been measured. Mainstream smoke concentrations of most target compounds are significantly lower with the TOB-HT cigarette when compared with reference cigarettes in the ultra-light "tar" and light "tar" categories. Taken together, chemical analysis results suggest simplified TOB-HT smoke chemistry with marked reductions in specific chemicals reported to be biologically active.

Surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae)

The surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae) was studied by scanning electron microscopy(SEM). The adult worms were recovered from experimentally infected cats and from a naturally infected patient. They were leaf-like, ventrally concave, and ovoid or pyriform in shape. Ciliated knob-like sensory papillae (type I) were observed in single or grouped forms on and around the oral sucker, whereas non-ciliated round swellings (type II papillae) were seen on the lip of the ventral sucker. The tegumental spines around the oral sucker were 5-9 pointed, whereas those between the two suckers were 12-17 pointed. Ventrolaterally, three groups of 5-6 type I papillae were located between the oral and ventral suckers, with single ones alternating between them. The genital sucker was protruded or depressed, depending on the contraction state of the flukes, and the gonotyl spine number ranged 50-60. The number of tip points of tegumental spines was decreased posteriorly; finally they became 1-3 pointed. On the dorsal surface, 4 groups of 4-5 type I papillae were symmetrically located on both lateral sides, and the shape and distribution of tegumental spines were similar to those of the ventral surface. Although the tegumental ultrastructure of H. nocens was generally similar to those of other heterophyids, the genital sucker morphology including the number of gonotyl spines and/or the distribution pattern of tegumental spines and sensory papillae were suggested to be the characteristic features of H. nocens.

Metacercariae of Pharyngostomum cordatum found from the European grass snake, Rhabdophis tigrina, and its experimental infection to cats

The metacercariae of Pharyngostomum cordatum were found naturally infected in the European grass snake, Rhabdophis tigrina, purchased from a local snake collector in Jinju, Kyongsangnam-do. They were experimentally fed to several kinds of animals such as mice, rats, hamsters, ducklings, a dog, and cats. The adult worms were recovered from the cats 5 weeks after the infection, but none from other animals. The measurements and other morphological characters of the metacercariae and adults were both compatible with those of P. cordatum described by previous authors. The present study confirmed that the snake, Rhabdophis tigrina, serves as a second intermediate (or paratenic) host of P. cordatum in Korea.

Analysis of flue-cured tobacco essential oil by hyphenated analytical techniques

The major components of an alkaloid-free, flue-cured, tobacco essential oil sample are isolated and identified. This is accomplished by utilizing modern hyphenated analytical methods. The instrumentation developed to accomplish this are an automated multidimensional gas chromatograph/mass spectrometer/flame ionization detector (MDGC/MS/FID) and a multidimensional gas chromatograph/matrix isolation/Fourier transform infrared spectrometer (MDGC/MI/FTIR). A total of 306 compounds is identified in the essential oil, of which 80 are found as tobacco constituents for the first time.

Analogues of chloramphenicol: circular dichroism spectra, inhibition of ribosomal peptidyltransferase, and possible mechanism of action

Circular dichroism spectra of series of chloramphenicol derivatives la-r were measured in water at pH 7. Compounds 1a-o exhibit two positive Cotton effects at 310--340 and 240--260 nm, respectively, and a weaker negative Cotton effect at 280--300 nm. In analogues 1c, 11, and 1m there is only a minimum between the two positive Cotton effects. Derivatives 1p--r possess a strong negative Cotton effect at ca. 280 nm. Compounds 1a--r were examined as inhibitors of the puromycin reaction with Escherichia coli 70S ribosome-poly(U)-N-AcPhe-tRNA complex. Analogues 11, 1n, lo, and lq are potent competitive inhibitors of puromycin comparable to or better than chloramphenicol (1b). Compounds 1k and 1m are less active, whereas 1d--g and 1j are only moderately effective. The rest of the analogues have marginal or no activity. The results are compared with previous biological data and discussed in terms of a retro-inverso relationship of chloramphenicol (1b) to the aminoacyl moiety of puromycin (aminoacyl-tRNA) and to a hypothetical transition state of peptide bond formation.

Ethchlorvynol: potential of metabolites for adverse effects in man

Identification of low levels of a metabolite of unaltered skeletal structure, 1-chloro-3-ethynylpent-1-en-3,4-diol (VII), detected in biological specimens of both nonfatal and fatal poisonings with DL-1-chloro-3-ethylpent-1-en-4-yn-3-ol (ethchlorvynol, la), has been achieved by high-resolution GC/MS. Corroborative evidence for the assigned structure (VII) was provided by synthesis, the design of which included as a central objective, concurrent access to 1-chloro-3-ethynyl-3,4-epoxy-1-pentene (VI), the putative direct precursor of VII. The diastereomeric epoxide mixture (VI) is mutagenic toward Escherichia coli WP2 try-hcr-, a UV-deficient repair strain. By contrast, neither Ia, VI, nor VII proved to be mutagenic toward Salmonella typhimurium (TA98, TA100, TA1535, and TA1539) with or without a liver postmitochondrial fraction. However, the epoxides (VI) proved cytotoxic to, for example, TA100, which apparently overlies its potency as a mutagen. The cytotoxicity of VI was also apparent in an in vitro culture system.

IV. Synthesis and assay of analogs of adenosine 3',5'-diphosphate as inhibitors of bovine adrenal estrogen sulfotranferase

Analogs of adenosine 3',5'-diphosphate are described which aid in the characterization of the inhibition of estrone sulfurylation by 3'-phosphoadenosine 5'-phosphosulfate as mediated by bovine adrenal estrogen sulfotransferase (3'-5'-phosphosulfate:estrone 3-sulphotransferase, EC 2.8.2.4). The facile conversion of ribonucleosides to 2',3'-cyclic phosphate 5'-phosphate in neat pyrophosphoryl chloride is utilized to provide a reliable route to the requisite intermediates for enzymatic regiospecific conversion to ribonucleoside 3',5'- and 2',5'-diphosphates. The importance of the 3'-phosphate ester to inhibition of estrone sulfurylation is confirmed by Ki measurements. Replacement of the 6-amino group by hydrogen or oxygen leads to considerable loss in affinity for the enzyme as does also dimethylation of the exocylic amino group. Alterations in the pyrimidine ring are not well tolerated by the sulfotransferase but modifications in the imidazole ring as in tubercidin (7 -deazaadenosine) and 8-bromoadenosine 3',5'-diphosphate lead to an enhanced affinity. The latter findings are discussed in terms of an hypothesis of stacking of the aromatic ring of the estrogen substrate and the purine moiety and its analogs.