Prospective, multi-centre, head-to-head comparison between allergists vs non-allergists in low-risk penicillin allergy delabelling: effectiveness, safety and quality of life (HK-DADI2)

BACKGROUND

Penicillin "allergy" labels are prevalent but frequently misdiagnosed. Mislabelled allergies are associated with adverse outcomes and increased antimicrobial resistance. With an urgent need to delabel the overwhelming number of mislabelled allergies, non-allergist evaluations have been advocated for low-risk individuals. Despite growing interest in non-allergist-led initiatives; evidence on their effectiveness, safety, and impact by direct comparisons are lacking.

OBJECTIVE

We assessed the comparative outcomes of penicillin allergy evaluations conducted by allergists vs. non-allergists.

METHODS

A prospective, multi-centre, pragmatic study was conducted at four tertiary hospitals (one allergist- vs. three non-allergist-led) for low-risk penicillin allergy patients in Hong Kong - the Hong Kong Drug Allergy Delabelling Initiative 2 (HK-DADI2).

RESULTS

Among 228 low-risk patients who underwent testing (32.9% by allergists, 67.1% by non-allergists), only 14 (6.1%) had positive penicillin allergy testing. Delabelling rates (94.1% vs. 93.3%, p=0.777), positive skin tests (2.6% vs. 2.7%, p=1.000) and drug provocation tests (3.3% vs. 2.7%, p=1.000) were similar between allergists and non-allergists. There were no systemic reactions in either cohort. All patients had significant improvements in health-related quality-of-life (DrHy-Q scores -5.00 vs. -8.33, p=0.072). Non-allergist evaluations had shorter waiting times (0.57 vs. 15.7 months, p<0.001), while allergists required fewer consultations with higher rate of completing evaluations within a single-visit (OR=0.04, p<0.001).

CONCLUSION

With training and support, non-allergists can independently evaluate low-risk penicillin allergies. Compared to allergists, evaluation of low-risk penicillin allergy by non-allergists can be comparably effective, safe, and impactful on quality-of-life. More multi-disciplinary partnerships to empower non-allergists to conduct allergy evaluations, should be encouraged.

Expert consensus on improving iron deficiency anemia management in obstetrics and gynecology in Asia

Iron deficiency anemia (IDA) is a major health burden among women in Asia. Key issues in IDA management in Asia are under-diagnosis and under-treatment. The lack of Asia-specific guidelines, and suboptimal utilization of treatment compounds the management of IDA. To address these gaps, a panel of 12 experts in obstetrics, gynecology, and hematology from six regions in Asia convened to review current practices and clinical evidence and provide practical guidance on IDA diagnosis and management in Asian women. The Delphi approach was used to obtain objective opinions and attain consensus on statements pertaining to awareness, diagnosis, and management of IDA. In total, 79 statements attained consensus and are summarized to provide guidance on raising awareness of IDA and approaches for improved diagnosis and treatment of IDA among women in various settings: pregnancy, postpartum, heavy menstrual bleeding, gynecologic cancers, and perioperative care. This clinician-led consensus integrates appropriate recommendations based on clinical evidence and best practices and is intended to guide decision making in the management of iron deficiency/IDA in women. The expert panel raises a call for timely diagnosis and utilization of appropriate treatment, including use of high-dose intravenous iron, stringent blood management, and interdisciplinary collaboration, for optimization of IDA management among women in Asia.

Posterior Oropharyngeal Saliva for the Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has put tremendous pressure on the healthcare system worldwide. Diagnostic testing remained one of the limiting factors for early identification and isolation of infected patients. This study aimed to evaluate posterior oropharyngeal saliva (POPS) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection among patients with confirmed or suspected COVID-19.

METHODS

The laboratory information system was searched retrospectively for all respiratory specimens and POPS requested for SARS-CoV-2 RNA detection between 1 February 2020 and 15 April 2020. The agreement and diagnostic performance of POPS against NPsp were evaluated.

RESULTS

A total of 13772 specimens were identified during the study period, including 2130 POPS and 8438 nasopharyngeal specimens (NPsp). Two hundred and twenty-nine same-day POPS-NPsp paired were identified with POPS and NPsp positivity of 61.5% (95% confidence interval [CI] 55.1-67.6%) and 53.3% (95% CI 46.8-59.6%). The overall, negative and positive percent agreement were 76.0% (95% CI 70.2-80.9%), 65.4% (95% CI 55.5-74.2%), 85.2% (95% CI 77.4-90.8%). Better positive percent agreement was observed in POPS-NPsp obtained within 7 days (96.6%, 95% CI 87.3-99.4%) compared with after 7 days of symptom onset (75.0%, 95% CI 61.4-85.2%). Among the 104 positive pairs, the mean difference in Cp value was 0.26 (range: 12.63 to -14.74), with an overall higher Cp value in NPsp (Pearson coefficient 0.579). No significant temporal variation was noted between the 2 specimen types.

CONCLUSIONS

POPS is an acceptable alternative specimen to nasopharyngeal specimen for the detection of SARS-CoV-2.

Risk of nosocomial transmission of coronavirus disease 2019: an experience in a general ward setting in Hong Kong

BACKGROUND

Coronavirus disease 2019 (COVID-19) was first reported in Wuhan in December 2019 and has rapidly spread across different cities within and outside China. Hong Kong started to prepare for COVID-19 on 31st December 2019 and infection control measures in public hospitals were tightened to limit nosocomial transmission within healthcare facilities. However, the recommendations on the transmission-based precautions required for COVID-19 in hospital settings vary from droplet and contact precautions, to contact and airborne precautions with placement of patients in airborne infection isolation rooms.

AIM

To describe an outbreak investigation of a patient with COVID-19 who was nursed in an open cubicle of a general ward before the diagnosis was made.

METHOD

Contacts were identified and risk categorized as 'close' or 'casual' for decisions on quarantine and/or medical surveillance. Respiratory specimens were collected from contacts who developed fever, and/or respiratory symptoms during the surveillance period and were tested for SARS-CoV-2.

FINDINGS

A total of 71 staff and 49 patients were identified from contact tracing, seven staff and 10 patients fulfilled the criteria of 'close contact'. At the end of 28-day surveillance, 76 tests were performed on 52 contacts and all were negative, including all patient close contacts and six of the seven staff close contacts. The remaining contacts were asymptomatic throughout the surveillance period.

CONCLUSION

Our findings suggest that SARS-CoV-2 is not spread by an airborne route, and nosocomial transmissions can be prevented through vigilant basic infection control measures, including wearing of surgical masks, hand and environmental hygiene.

Metabolic active peritoneal sites affect tumor debulking in ovarian and peritoneal cancers

Rationale and objectives

To evaluate the impact of metabolic parameters in the peritoneal cavity on the likelihood of achieving complete tumor debulking in patients with ovarian and peritoneal cancers.

Materials and methods

Forty-nine patients with ovarian and peritoneal cancers were included, who underwent pre-operative ¹⁸F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (¹⁸F-FDG PET/CT). The immediate surgical outcome was dichotomized into complete and incomplete tumor debulking. ¹⁸F-FDG PET/CT was qualitatively and quantitatively assessed by scrutinizing 15 anatomical sites for the presence of peritoneal carcinomatosis (PC). Patient-based and site-based diagnostic characteristics were described. Metabolic parameters (SUVmax, metabolic tumor volume and total lesion glycolysis) and the number of ¹⁸F-FDG avid peritoneal sites were evaluated between the two groups. Receiver operating curve (ROC) analysis was performed to determine the optimal cut-off value in predicting incomplete tumor debulking.

Results

Twenty-seven out of the 49 patients had PC and 11 had incomplete debulking. Patient-based and site-based accuracies for detection of PC were 87.8 and 97.6%, respectively. The number of ¹⁸F-FDG avid peritoneal sites was significantly different between complete and incomplete debulking groups (0.6 ± 0.8 versus 2.3 ± 1.7 sites respectively, p = 0.001), and the only independent significant risk factor among other metabolic parameters tested (odd ratio = 2.983, 95% CI 1.104–8.062) for incomplete tumor debulking with an optimal cut-off value of ≥4 (AUC = 0.816).

Conclusion

The number of ¹⁸F-FDG avid peritoneal sites increased the risk of incomplete tumor debulking after surgery and potentially useful in assisting treatment stratification in patients with ovarian and peritoneal cancers.

The treatment of nursing home-acquired pneumonia using a medically intensive Hospital in the Home service

OBJECTIVES

To compare the outcomes for patients with nursing home-acquired pneumonia (NHAP) treated completely in a Hospital in the Home (HITH) setting with those of patients treated in a traditional hospital ward.

DESIGN

Case-control study.

SETTING AND PARTICIPANTS

All patients admitted by the Royal Melbourne Hospital for treatment of NHAP from 1 July 2013 to 31 January 2014.

INTERVENTION

Admission to the Royal Melbourne Hospital HITH Unit within 48 hours of presentation.

MAIN OUTCOME MEASURES

Length of stay, in-hospital and 30-day mortality, hospital readmissions (30-day), complications and unplanned returns to hospital.

RESULTS

Sixty HITH patients and 54 hospital (control) patients were identified. Thirty-two patients (53%) were admitted directly to HITH without any hospital or emergency stay, 25 (42%) were referred directly from the emergency department. HITH patients were more likely to be male, older and dehydrated, and less likely to have an advanced care directive or to have had non-invasive ventilation. There were no significant differences in CURB-65 or CORB scores between the two patient groups; similar proportions were given intravenous fluids or supplemental oxygen. There were no adjusted differences in median length of stay between HITH and control patients (-1.00 days; 95% CI, -2.72 to 0.72; P = 0.252) or in overall mortality at 30 days (HITH v control patients: adjusted odds ratio [aOR], 1.97; 95% CI, 0.67-5.73). Inpatient mortality was lower for HITH patients (aOR, 0.19; 95% CI, 0.05-0.75) but unadjusted postdischarge 30-day mortality was higher (OR, 13.25; 95% CI 1.67-105.75). There were no differences between the two groups with regard to complications (falls and pressure wounds) and 30-day readmission rates (aOR, 1.59; 95% CI, 0.30-8.53).

CONCLUSIONS

This study suggests that HITH may be an effective and safe alternative to hospital treatment for residents of aged care facilities presenting with NHAP.

Denaturing HPLC for high-throughput screening of rifampicin-resistant Mycobacterium tuberculosis isolates

OBJECTIVE

To evaluate the use of denaturation high-performance liquid chromatography (dHPLC) as a rapid method to detect rifampicin (RMP) resistance based on mutations in the rpoB gene in a high-volume laboratory setting.

METHODS

A total of 132 RMP-resistant Mycobacterium tuberculosis strains with different rpoB mutation were used to optimise the running condition of dHPLC as a pilot study. A blind correlation study was subsequently done between dHPLC and in vitro RMP susceptibility tests on 3167 M. tuberculosis strains in a high-throughput clinical setting.

RESULTS

In the pilot study, rpoB mutation could be detected on 116/132 (87.9%) RMP-resistant strains by dHPLC. In the second phase of the study, 84/3107 (2.7%) clinical M. tuberculosis isolates were RMP-resistant. The sensitivity and specificity of dHPLC in the prediction of RMP resistance were 70/84 (83.3%) and 70/77 (91.0%), respectively. The specificity became 100% when 511 Leu to Pro mutation was excluded from the RMP resistance-related genetic changes.

CONCLUSION

In the detection of RMP resistance in a high-throughput laboratory setting, dHPLC has been demonstrated to be rapid, simple, workable, automatable and inexpensive in terms of running costs and the labour involved.

Use of developmental language scales in Chinese children

The Reynell Developmental Language Scale (RDLS) and Symbolic Play Test (SPT) have been useful language tests for assessing the language age of children. Both tests have been validated in English-speaking children. However, there have been no studies conducted for Chinese children, whether Mandarin (Northerners) or Cantonese (Southerners) is used as the main dialect. As the Chinese population is the largest ethnic group in the world, and Chinese emigration occurred to nearly all parts of the world, it is essential to test whether these language tools can be applied for this ethnic group. The objective of this research was to study whether RDLS and SPT are useful in assessing the language age of Chinese children. Both RDLS (Chinese version) and SPT are conducted for 116 Chinese (Cantonese-speaking) children, aged 13-59 months, in Hong Kong. There is a significant positive correlation of the language age using RDLS and SPT with the chronological age of Chinese children. Both RDLS and SPT can be adopted in determining the language/mental age of Chinese (Cantonese-speaking) children.

Inactivation of SSI-1, a JAK/STAT inhibitor, in human hepatocellular carcinomas, as revealed by two-dimensional electrophoresis

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) is one of the most common human cancers, and many efforts have been paid to discover aberrant expression control in HCC, however the specific molecular mechanisms involved in hepatocarcinogenesis remain to be determined.

METHODS

To investigate genomic changes that occur in human primary hepatocellular carcinomas (HCC), we carried out restriction landmark genomic scanning. This two-dimensional electrophoretic system displays 2000-3000 NotI-landmark sites in a single gel.

RESULTS

We detected one landmark spot that showed diminished signal intensities in a majority of the HCCs we examined. Cloning revealed that this spot represented a NotI-cluster sequence that was enriched with CpG dinucleotides in the promoter region of a gene encoding Janus kinase (JAK)-binding protein, SSI-1 (also known as JAB1 or SOCS-1). Expression of the SSI-1 gene was markedly reduced in half of eight HCCs analyzed.

CONCLUSIONS

This protein regulates the Janus kinase signal transducers and activators of transcription signal transduction pathway, which transmits signals from cytokines to the intracellular apparatus. These data suggest that dysregulation of the pathway relate with progression of HCC.

Apoptosis in human hepatoma cell line SMMC-7721 induced by water-soluble macromolecular components of Artemisia capillaris Thunberg

The aim of this study was to investigate the effect of water-soluble macromolecular components of Artemisia capillaris Thunberg (ACT) on human hepatoma cell line SMMC-7721 (SMMC-7721). The morphological changes of SMMC-7721 were observed under a light microscope and an electron microscope. Inhibition of proliferation was measured with a colorimetric MTT assay. It was discovered that ACT extract-treated cells exhibit morphological changes typical of apoptosis, including condensed chromatin and a reduction in volume. ACT extract at 25-200 microg/ml dose-dependently inhibited the proliferation of SMMC-7721. The 50% effective dose, evaluated on day 3 of exposure to the extract, was 64.52+/-3.53 microg/ml. Upon gel electrophoresis, the fragmented DNA showed a characteristic ladder pattern. Cell cycle analyses revealed that ACT induced cell cycle arrest at the G0/G1 phase.

Predictive sensitivity of human cancer cells in vivo using semipermeable polysulfone fibers

An in vivo experimental model was developed to predict efficiently and accurately chemosensitivity of human tumors. Human cancer cells either from cultured cell lines or from patients' tumors were injected directly into semipermeable polysulfone fibers subsequently implanted into immunocompetent rats. Results suggest utility of this novel model system for predicting tumor sensitivity to a wide range of anticancer agents and for potentially guiding the treatment of cancer patients in the clinical setting.

Phase I clinical and pharmacological studies of benzylacyclouridine, a uridine phosphorylase inhibitor

Benzylacyclouridine (BAU, IND 039655) is a potent and specific inhibitor of uridine phosphorylase (UrdPase; EC 2.4.2.3). This enzyme plays a major role in regulating uridine homeostasis and also catalyzes the conversion of fluoropyrimidine nucleosides to their respective bases. Inhibition of UrdPase enzyme activity 18-24 h after 5-fluorouracil (5-FU) administration increased plasma levels of uridine and enhanced the therapeutic index of 5-FU by rescuing normal tissues. Moreover, in vitro preclinical studies have also shown that inhibiting UrdPase enzyme activity by BAU prior to administration of 5-FU increased cytotoxicity in a number of human cancer cell lines. A series of preclinical studies was performed in dogs and pigs to evaluate the pharmacological and pharmacodynamic properties of BAU. These data showed a sustained elevation in plasma uridine concentration in both animal models. The rapid degradation of a tracer dose of uridine into uracil was virtually arrested by BAU administered both p.o. or i.v. The t1/2 of BAU was 1.8-3.6 h in dogs, with bioavailability levels of 85% (30 mg/kg) and 42.5% (120 mg/kg). In pigs, the half-life varied from 1.6 to 2.3 h, with a bioavailability of 40% at 120 mg/kg. The drug was distributed into most tissues with a tissue: plasma ratio of approximately 0.7. On the basis of these preclinical studies, we performed a Phase I clinical trial of BAU in patients with advanced cancer. Patients received 200, 400, 800, and 1600 mg/m2 BAU as a single oral dose. Toxicities included grade 2 anemia, grade 1 fever, grade 1 fatigue, grade 1 constipation, and grade 1 elevation in alkaline phosphatase; none of these toxicities were observed to be dose dependent. The maximum tolerated dose and dose-limiting toxicity were not reached at the doses given. BAU plasma concentrations and area under the curve correlated linearly with the oral dose level. The pharmacokinetics of BAU were consistent with a first-order clearance, with average peak concentrations ranging from 19 microM (200 mg/m2) to 99 microM (1600 mg/m2) and tbeta1/2 ranging from 3.0 to 3.9 h at the four dose levels. Compared with baseline plasma uridine, treatment of patients with 200, 400, 800, and 1600 mg/m2 BAU increased peak uridine concentrations by 120, 150, 250, and 175%, respectively. On the basis of this clinical study, the suggested Phase II starting dose of BAU in combination with 5-FU is 800 mg/m2. Studies combining BAU with 5-FU and incorporating appropriate molecular and biochemical end points to assess the effects of this drug combination on tumor and/or surrogate tumor tissue are under way.

Benzylacyclouridine enhances 5-fluorouracil cytotoxicity against human prostate cancer cell lines

At a nontoxic growth inhibitory concentration benzyloxyacyclouridine (BAU), a potent and specific inhibitor of uridine phosphorylase (UrdPase), enhanced 5-fluorouracil (5-FU) cytotoxic activity against human prostate cancer PC-3 and DU-145 cell lines. The BAU/5-FU combination exhibited greater antitumor activity in vivo using PC-3 human xenografts compared to 5-FU alone, with no associated increase in animal host toxicity. The mechanism(s) responsible for the enhanced in vitro and in vivo activity of this combination may involve enhanced formation of the 5-FU nucleotide metabolites FdUMP, FdUTP, and FUTP resulting in enhanced inhibition of thymidylate synthase (TS) and increased incorporation of fluoropyrimidine metabolites into tumoral RNA and DNA.

Inhibition of growth factor mitogenicity and growth of tumor cell xenografts by a sulfonated distamycin A derivative

Interference with growth factor-receptor interactions may have particular relevance in efforts to intervene clinically in both autocrine and paracrine aspects of malignancy. Suramin is a synthetic anticancer agent that works, in part, by blocking the binding of growth factors to their receptors. While initial clinical trials have been encouraging, its use in clinical applications is associated with significant toxicities. Suradista is a novel sulfonated distamycin derivative that is also effective at complexing and inactivating growth factors and cytokines while remaining relatively nontoxic. The goal of this study was to compare the antineoplastic properties of suramin and Suradista. To achieve this, the effects of these compounds on growth factor induced mitogenesis in normal mouse fibroblasts and human umbilical vein endothelial cells were examined, as well as their ability to inhibit the growth of NIH/3T3 cells that had been transformed by the introduction of a fibroblast growth factor (FGF) 1 coding region (residues 1-154) fused to the signal peptide of the hst/KS3 gene (sp-hst/KS3:FGF1-154). In each case, Suradista was more effective than suramin in inhibiting mitogenesis in normal cells, as well as the growth of the transformed cells. Furthermore, Suradista was also shown to be as effective as suramin at inhibiting the growth of sp-hst/KS3:FGF1-154-transformed NIH/3T3 xenografts grown in athymic nude mice when given at only 50% the dosage used for suramin (50 mg/kg for Suradista versus 100 mg/kg for suramin). In summary, these results indicate that novel compounds acting like suramin may be developed as effective antineoplastic agents and may also prove to be of clinical benefit.

Expression of mRNA for brain-derived neurotrophic factor in the dorsal root ganglion following peripheral inflammation

It is well known that the nerve growth factor (NGF) may serve as a link between inflammation and hyperalgesia. Recent experiments showed that systemic injection of NGF dramatically stimulated the expression of brain-derived neurotrophic factor (BDNF) mRNA in the dorsal root ganglion (DRG). In the present study, we evaluated the change of BDNF mRNA in the DRG following peripheral inflammation and also observed colocalization of BDNF and trkA mRNAs by means of in situ hybridization histochemistry in rats. Peripheral tissue inflammation produced by an intraplantar injection of Freund's adjuvant into the paws significantly increased BDNF mRNA levels in the DRG and many neurons expressing trkA mRNA showed increased expession of BDNF mRNA. Intraplantar injection of antibody to NGF together with Freund's adjuvant prevented the increase in BDNF mRNA. These findings suggest that peripheral inflammation induces an increased expression of BDNF mRNA which is mediated by NGF in DRG.

Enhancement of 5-fluoro-2'-deoxyuridine antineoplastic activity by 5-benzyloxybenzyloxybenzylacyclouridine in a human colon carcinoma cell line

The pyrimidine acyclonucleoside benzyloxybenzyloxybenzylacyclouridine (BBBAU) showed growth inhibitory activity against the human colon cancer HCT-8 cell line with a 50% inhibitory concentration of 55 microM. Unlike its parent compounds, BBBAU was an extremely weak inhibitor of uridine phosphorylase. This acyclonucleoside analogue is an inhibitor of thymidylate synthase (TS) as determined by inhibition of [6-3H]-2'-deoxyuridine incorporation into DNA, inhibition of 3H release from [5-3H]-2'-deoxyuridine, and decrease in both the free and total TS 5'-fluoro-2'-deoxyuridine 5'-monophosphate binding sites. Kinetic analysis revealed that BBBAUMP, the monophosphate analogue of BBBAU, is a competitive inhibitor of purified human recombinant TS with a Ki of 8.0 microM. Nucleoside transport and uptake studies revealed that BBBAU (30 microM) inhibited the initial rate of transport and the total uptake of thymidine (25 microM). In contrast, while BBBAU (30 microM) inhibited the initial rate of transport of 5-fluoro-2'-deoxyuridine (FdUrd, 25 microM), its intracellular accumulation was increased. BBBAU (10 and 50 microM, respectively) potentiated FdUrd growth inhibition of HCT-8 cells and significantly enhanced the cytotoxic effects of FdUrd (0.3 and 1 microM, respectively) against HCT-8 cells using a clonogenic assay system. This combination resulted in additive inhibitory effects on TS activity resulting in greater depletion of dTTP pools. Moreover, the incorporation of radiolabeled FdUrd into the DNA fraction of HCT-8 cells was enhanced. The potential importance of this novel combination for human colon cancer chemotherapy is discussed.

Cell culture of the mucinous variant of human colorectal carcinoma

Two cell lines, RW-2982 and RW-7213, have been established for the first time from the mucinous variant of human colorectal carcinoma, which is a distinctive and important subtype that has a worse prognosis than the more common nonmucogenic large bowel carcinoma. Methods of establishment and observations made during 7 and 3 years, respectively, of continuous culture are described. These cell lines required 4-9 months of adaptation to tissue culture conditions before noticeable growth occurred. Both cell lines have the following unique properties: (a) growth in vitro as delicate branching three-dimensional tumor particles within a wide gel of insoluble, often translucent mucus (proteoglycan); (b) production of large quantities of carcinoembryonic antigen; (c) ability to survive or adapt to growth in media free of serum, hormones, growth factors, and all protein; and (d) tumorigenicity in multiple sites in nude mice, including liver, with especially rapid growth in the peritoneal cavity as gelatinous material that is nonadherent and noninvasive and thus resembles pseudomyxoma peritonei. Unlike other reported colorectal cell lines, these mucus-coated particulate cell lines will not readily grow as monolayers and grow much more slowly with a doubling time of 2 weeks or more. A serially transplantable tumor from the RW-7213 surgical specimen has also been maintained in nude mice since August 8, 1984. This tumor retains properties of the original specimen. Observations made on the tumor biology of mucogenic colorectal carcinoma using these cell lines are discussed.

Inhibitors of purine nucleoside phosphorylase: effects of 9-deazapurine ribonucleosides and synthesis of 5'-deoxy-5'-iodo-9-deazainosine

9-Deazapurine ribonucleosides constitute a new class of noncleavable purine nucleoside phosphorylase inhibitors that have at least 30-fold greater affinity for the enzyme than the corresponding C-nucleosides of the formycin B series. 9-Deazaguanosine, 9-deazainosine, and 5'-deoxy-5'-iodo-9-deazainosine competitively inhibited human erythrocytic purine nucleoside phosphorylase with Ki values of 29, 20, and 1.8 X 10(-7) M. The last compound is the most potent nucleoside inhibitor of the enzyme presently available and its synthesis is described. In contrast, 7,9-dideaza-7-thiainosine is a very weak inhibitor of the enzyme. When tested as an inhibitor of 2'-deoxyguanosine phosphorolysis in intact human erythrocytes and MOLT-3 human T-cell lymphoblastic leukemia cells, 5'-deoxy-5'-iodo-9-deazainosine was equipotent with 8-aminoguanosine (which is a precursor for 8-aminoguanine, Ki = 2 X 10(-7) M). Similarly, 5'-deoxy-5'-iodo-9-deazainosine and 8-aminoguanosine both potentiated the growth inhibition of human T-lymphocytic MOLT-3 cells by 2'-deoxyguanosine, reducing the 50% inhibitory concentration from approximately 2 X 10(-5) to approximately 2 X 10(-6) M.

Differential characteristics of two newly established human breast carcinoma cell lines

Two human breast carcinoma cell lines, EP and MW, were established in culture from malignant pleural effusions. In addition to producing tumors in antithymocyte serum-immunosuppressed mice, both cell lines showed epithelial characteristics and anchorage-independent growth in soft agar. EP and MW differed in morphology (spindle-shaped versus round), chromosomal mode (hyperdiploid versus near triploid), estrogen receptor content (43.8 versus 5.1 fmol/mg protein), cloning efficiency (0.24 versus 15%), and activities (milliunits/10(6) cells) of creatine phosphokinase (25.7 versus 62.6) and lactate dehydrogenase (346.7 versus 778.5). Electron microscopy revealed that MW cells had more perinuclear filamentous material and more frequent intracytoplasmic vacuole formation than did EP cells. While having no effect on MW cells at the concentrations studied (10(-5) to 10(-11) M), beta-estradiol (10(-7) M) stimulated the growth of EP cells by 106% over the hormone-depleted control. In a variety of systems, EP was consistently the more drug sensitive of the two lines. In vitro, EP was significantly (p less than 0.001) more sensitive to methotrexate, vincristine, and 5-fluorouracil, respectively. In antithymocyte serum-mouse xenografts, EP displayed a greater response to three different dosages of a combination of cyclophosphamide, methotrexate, and 5-fluorouracil. One such dosage (cyclophosphamide, 32.0 mg/kg/day; methotrexate, 13.0 mg/kg/day; 5-fluorouracil, 190.0 mg/kg/day; for 1 day) reduced EP and MW tumor weights to 5.9 and 41% of controls, respectively. These results correlated well with the clinical responses.

5'-Deoxy-5'-methylthioadenosine phosphorylase--III. Role of the enzyme in the metabolism and action of 5'-halogenated adenosine analogs

5'-Deoxy-5'-halogenated adenosines are alternative substrates for 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAPase), an enzyme responsible for the metabolism of 5'-deoxy-5'-methylthioadenosine (MTA), a by-product of polyamine biosynthesis. The relative reactivity of these nucleosides with MTAPase from HL-60 human promyelocytic leukemia cells is MTA greater than 5'-deoxy-5'-fluoroadenosine (5'-FlAdo) greater than 5'-chloro-5'-deoxyadenosine (5'-ClAdo) greter than 5'-bromo-5'-deoxyadenosine (5'-BrAdo) greater than 5'-deoxy-5'-iodoadenosine (5'-IAdo). In MTAPase-containing cells, the adenine released from the 5'-halogenated adenosine was incorporated into adenine nucleotide pools; cleavage by (MTAPase appeared to be the rate-limiting step in this process. 5'-BrAdo and 5'-IAdo were growth inhibitors (EC50 values less than 10 microM) of MTAPase-containing cell lines (HL-60 human promyelocytic leukemia and the L5178Y murine lymphoblastic leukemia) but were much less active (EC50 values greater than 65 microM) against MTAPase-deficient cell lines (the CCRF-CEM human T cell leukemia and the L1210 murine leukemia). The full cytotoxicity of these compounds, therefore, appeared to be related to their phosphorolysis by MTAPase. Indirect evidence suggests that 5-halogenated ribose-1-phosphate derivatives of 5'-BrAdo or 5'-IAdo produced by the MTAPase reaction were the active metabolites of these 5'-halogenated adenosines.

Potentiation of 5-fluoro-2'-deoxyuridine antineoplastic activity by the uridine phosphorylase inhibitors benzylacyclouridine and benzyloxybenzylacyclouridine

At a nontoxic dose (50 microM), the two potent uridine phosphorylase inhibitors, benzylacyclouridine and benzyloxybenzylacyclouridine (BBAU), potentiated 5-fluoro-2'-deoxyuridine (FdUrd) growth inhibition of human pancreatic carcinoma (DAN) and, to a lesser extent, human lung carcinoma (LX-1) cells in culture. BBAU was more effective than benzylacyclouridine. BBAU (50 microM) enhanced the cytocidal effect of FdUrd (1 microM, 3 hr) on DAN grown on soft agar from 75 to 88%. In antithymocyte serum-immunosuppressed mice bearing DAN, the mean tumor weight in animals treated with FdUrd (50 mg/kg/day for 2 days) was 11% less than that of untreated controls. When BBAU (10 mg/kg/day for 2 days) was coadministered, the mean tumor weight at Day 10 was 78% less than untreated controls, with no apparent host toxicity, clearly demonstrating the potentiation of the antitumor effects of FdUrd by BBAU. The fact that DAN responded better than LX-1 to benzylacyclouridine and BBAU could be due, in part, to the lower relative activity of thymidine phosphorylase to uridine phosphorylase in DAN compared to LX-1. The activities of other enzymes involved in FdUrd metabolism, thymidine kinase, uridine kinase, orotate phosphoribosyltransferase, 5'-nucleotidase, and dihydrouracil dehydrogenase, did not differ between the two cell lines.

9-Deazaadenosine--a new potent antitumor agent

-Deazaadenosine (9-DAA), a novel purine analog, was found to be a potent inhibitor of the growth of nine different human solid tumor cell lines in vitro and of pancreatic carcinoma (DAN) in antithymocyte serum (ATS)-immunosuppressed mice. In culture, IC50 values ranged from 1.1 to 8.5 X 10(-8)M. Ovarian carcinoma (MR) was the only cell line in which the activity of 9-DAA was potentiated (about 10-fold) by pretreatment with the adenosine deaminase inhibitor 2'-deoxycoformycin (dCF). After incubation of cultured pancreatic DAN cells with 9-DAA (10(-5)M) for 2 hr, a peak appeared in the triphosphate region of HPLC nucleotide profiles that was identified tentatively as 9-deazaATP. Under the same incubation conditions, the incorporation of [3H]uridine into RNA and of [3H]thymidine into DNA was inhibited by 34 and 80% respectively. In vivo studies using ATS-immunosuppressed mice showed that 9-DAA at 0.4 mg/kg/day for 3 consecutive days reduced pancreatic carcinoma (DAN) tumor weights to approximately 50% of untreated controls. The nucleoside transport inhibitor p-nitrobenzyl-6-thioinosine (NBMPR) was shown to selectively protect host tissues from 9-DAA toxicity and, thereby, potentiated the antitumor activity of 9-DAA in vivo at optimal dosages.

Differential responses to x-irradiation of subpopulations of two heterogeneous human carcinomas in vitro

The responses of two heterogeneous human cancer cell lines and their derivative clones to graded single doses of X-rays were examined in vitro. One system consisted of the human colon carcinoma line DLD-1 and two subpopulations (clones A and D). The second system consisted of the human lung carcinoma line (LX1) and four subpopulations (LX1-1, LX1-2, LX1-3, and LX1-9). These subpopulations have previously been shown to be markedly heterogeneous in terms of such characteristics as karyotype, morphology, drug sensitivity, tumorigenicity, and expression of membrane glycoproteins (such as carcinoembryonic antigen and tumor colonic mucoprotein antigen). Exponentially growing cultures were irradiated with graded single doses of 100-kVp X-rays. Survival was assessed using colony formation as the end point, and responses from multiple experiments were fitted to the single-hit, multitarget equation of cell survival. Values for the mean lethal dose (D0, grays), quasithreshold dose (Dq, grays), and extrapolation number (n) were obtained. For the human colon adenocarcinoma system, these values for the three tumor lines were: DLD-1, 0.95, 2.34, and 11.7; clone A, 1.06, 2.23 and 8.20; and clone D, 1.08, 1.89, and 5.80. For the human lung carcinoma system, these values for the five sublines were: LX1, 1.14, 0.19, and 1.20; LX1-1, 0.96, 2.06, and 8.54; LX1-2, 0.98, 0.88, and 2.48; LX1-3, 0.68, 2.05, and 20.3; and LX1-9, 1.12, 0.00, and 1.00. These two human tumor systems therefore exhibit variability in their intrinsic sensitivity to X-irradiation. The data indicate that failure of some human carcinomas to respond to physical treatment modalities can be due to preexisting resistant subpopulations.

Evaluation of 2,2'-anhydro-1-(3'-Ok-acetyl-beta-D-arabinofuranosyl)-5-iodocytosine hydrochloride and related compounds as antineoplastic and antiviral agents

2,2'-Anhydro-1-(3'-O-acetyl-beta-D-arabinofuranosyl)-5-iodocytosine (anhydro-araIC 3'-acetate), previously synthesized and isolated as a crude product by Moffatt and his coworkers, was purified and characterized. The availability of pure anhydro-araIC 3'-acetate made possible a comparative study of the antineoplastic, antiviral and biochemical potencies of anhydro-araIC 3'-acetate with the structurally related agents 2,2'-anhydro-1-(3'-O-acetyl-beta-D-arabinofuranosyl)cytosine (anhydro-araC 3'-acetate) and 2,2'-anhydro-1-(beta-D-arabinofuranosyl)-5-iodocytosine (anhydro-araIC). The presence of the 5-iodo substituent and/or the 3'-O-acetyl group on 2,2'-anhydro1-(beta-D-arabinofuranosyl)cytosine (anhydro-araC) did not alter the capacity of these agents to exert cytotoxic and antineoplastic activity against L1210, P388, L5178Y and human leukemia cells and against human colon and rectal carcinomas, as well as antiviral activity against herpes simplex virus Type 1. All of the compounds caused inhibition of [3H]thymidine incorporation into the DNA of L1210 cells in culture, with anhydro-araIC 3'-acetate being significantly less inhibitory than the other derivatives. Little or no interference with RNA and protein synthesis was produced by these pyrimidine nucleosides. Both anhydro-araIC 3'-acetate and anhydro-araIC were potent inhibitors of the activity of DNA polymerase alpha from the L1210 leukemia at the nucleoside level, while anhydro-araC 3'-acetate and anhydroaraC were non-inhibitory; none of the agents caused inactivation of DNA polymerase beta. The findings suggest that the antineoplastic and antiviral activities of the 2,2'-anhydro-arabinosylcytosine nucleosides may be the result of biochemical actions different from those of araC.

Cytotoxic liponucleotide analogs. II. Antitumor activity of CDP-diacylglycerol analogs containing the cytosine arabinoside moiety

Among events limiting the effectiveness of cancer chemotherapy are the general lack of preferential uptake of anticancer drugs by tumor cells and the occurrence of drug resistance. An approach has been undertaken to explore whether or not such events can be favorably altered or circumvented therapeutically by development of a new class of anticancer molecules, cytotoxic liponucleotide analogs. The design of cytotoxic liponucleotide analogs encompasses both biochemical and biophysical aspects of liponucleotide and glycerophospholipid structure and metabolism. Several cytotoxic liponucleotide analogs of cytidine diphosphate diacylglycerol (CDPdiacylglycerol/dCDPdiacylglycerol), containing the 1-beta-D-arabinofuranosyl moiety, were tested for antitumor activity. Multispecies ara-CDPdiacylglycerol (1-beta-D-arabinofuranosylcytosine 5'-diphosphate diacylglycerol), which contains egg lecithin-derived mixed fatty acyl chains, was more active than 1-beta-D-arabinofuranosylcytosine (ara-C), a clinically used anticancer drug, against leukemia L5178Y and P388 ascites cells in mice. At identical single doses (50 mg/kg per day times 4) administered intraperitoneally, ara-CDPdiacylglycerol prolonged the life spans of L5178Y tumor-bearing mice 93%, while ara-C prolonged life by 18%. Ara-CDPdiacylglycerol increased life spans of P388 tumor-bearing mice by 357% at doses of 50 mg/kg per day times 4; the maximum increase with ara-C was 159% (85 mg/kg per day times 4). Against a P388 ara-C-resistant cell line (P/Ara-C, kinase deficient) in mice, ara-CDPdiacylglycerol prolonged survival times by 34% at a dose of 50 mg/kg per day times 4 and by 55% at 75 mg/kg per day times 4; the drug was not active against two other ara-C-resistant murine leukemia mutants (CA 55, CA5b). With cell line-derived human colon carcinoma HCT-15 grown in mice immunosuppressed with anti-thymocyte serum, ara-CDPdiacylglycerol at a single daily dose of 50 mg/kg per day times 4 significantly reduced tumor weights to 21% of the controls; the same dose schedule of ara-C caused no observable reduction of tumor weights. Results of these preliminary antitumor evaluations indicate that cytotoxic liponucleotide analogs should be investigated further to determine their potential as antineoplastic molecules.

Chemotherapy of cell-line-derived human colon carcinomas in mice immunosuppressed with antithymocyte serum

An in vivo model is described for assessing the antitumor activity of chemotherapeutic agents. Tumors derived from human colon carcinoma cell lines injected into antithymocyte serum (ATS) immunosuppressed mice were used. In this system, both antitumor effects and host toxicity can be quantitated, permitting calculation of a Therapeutic Index. Compared with other xenograft models, the present system is simple, experiments are completed in less than 2 weeks, and the use of cultured cell lines allows in vitro studies to be performed. The in vitro sensitivities of one colon cell line to 22 chemotherapeutic agents and of four cell lines to three agents is reported. Four drugs used in treating colon cancer (Mitomycin C, 5-FU, BCNU, and methyl-CCNU) show antitumor activity in vivo in this system. Each has a low therapeutic index. Further work with this model is indicated, with the goal of finding new drugs with high Therapeutic Indices.

A phospholipid derivative of cytosine arabinoside and its conversion to phosphatidylinositol by animal tissue

We have synthesized an analog (ara-CDP-DL-dipalmitin) of cytidine diphosphate diglyceride (CDP-diglyceride) in which the antitumor drug, cytosine arabinoside, is substituted for the cytidine moiety. Enzymes in rat and human liver convert this analog to phosphatidylinositol, thereby releasing cytosine arabinoside-5'-monophosphate, an obligatory intermediate in the activation of cytosine arabinoside. Unlike cytidine diphosphate diglyceride, however, ara-CDP-DL-diapalmitin is not an efficient substrate for phosphatidylglycerophosphate synthesis in liver or phosphatidylserine in Escherichia coli. The antitumor activity of ara-CDP-DL-dipalmitin in mice bearing L5178Y leukemia is described.

Synthesis and cytotoxicity of 6-selenopurine arabinoside and related compounds

6-Chloro-9-(beta-D-arabinofuranosyl)purine served as an intermediate for the chemical synthesis of a series of 6-substituted selenopurine arabinosides. In an in vitro test using murine leukemic cells (L-5178Y) these 6-substituted selenopurine arabinosides showed some cytotoxicity. Lengthening the side chain had no effect on their cytotoxicity. Selenourea was a useful reagent for synthesizing selenopurines, selenopurine nucleosides, and selenopurine arabinoside under mild conditions.

Synthesis and biological activity of some 8-substituted selenoguanosine cyclic 3',5'-phosphates and related compounds

8-Bromoguanosine cyclic 3',5'-monophosphate, 8-bromoguanosine 5'-monophosphate, and 8-bromoguanosine served as intermediates for the chemical synthesis of a series of 8-substituted seleno cyclic nucleotides, nucleotides, and their nucleosides. Selenourea was found to be a useful reagent in synthesizing these seleno-substituted nucleoside, nucleotide, and cyclic nucleotide. A nucleic acid analyzer was used to study the hydrolysis of these cyclic nucleotides by phosphodiesterase. It was found that all of the 8-substituted selenoguanosine cyclic 3',5'-phosphates synthesized, except 8-MeSe-cGMP, were resistant to hydrolyze by phosphodiesterase. These 8-substituted seleno cyclic GMP derivatives showed some antitumor activities against murine leukemic cells (L5178Y) in vitro and in vivo.