Interplay of Immunosuppression and Immunotherapy Among Patients With Cancer and COVID-19

Importance

Cytokine storm due to COVID-19 can cause high morbidity and mortality and may be more common in patients with cancer treated with immunotherapy (IO) due to immune system activation.

Objective

To determine the association of baseline immunosuppression and/or IO-based therapies with COVID-19 severity and cytokine storm in patients with cancer.

Design, Setting, and Participants

This registry-based retrospective cohort study included 12 046 patients reported to the COVID-19 and Cancer Consortium (CCC19) registry from March 2020 to May 2022. The CCC19 registry is a centralized international multi-institutional registry of patients with COVID-19 with a current or past diagnosis of cancer. Records analyzed included patients with active or previous cancer who had a laboratory-confirmed infection with SARS-CoV-2 by polymerase chain reaction and/or serologic findings.

Exposures

Immunosuppression due to therapy; systemic anticancer therapy (IO or non-IO).

Main Outcomes and Measures

The primary outcome was a 5-level ordinal scale of COVID-19 severity: no complications; hospitalized without requiring oxygen; hospitalized and required oxygen; intensive care unit admission and/or mechanical ventilation; death. The secondary outcome was the occurrence of cytokine storm.

Results

The median age of the entire cohort was 65 years (interquartile range [IQR], 54-74) years and 6359 patients were female (52.8%) and 6598 (54.8%) were non-Hispanic White. A total of 599 (5.0%) patients received IO, whereas 4327 (35.9%) received non-IO systemic anticancer therapies, and 7120 (59.1%) did not receive any antineoplastic regimen within 3 months prior to COVID-19 diagnosis. Although no difference in COVID-19 severity and cytokine storm was found in the IO group compared with the untreated group in the total cohort (adjusted odds ratio [aOR], 0.80; 95% CI, 0.56-1.13, and aOR, 0.89; 95% CI, 0.41-1.93, respectively), patients with baseline immunosuppression treated with IO (vs untreated) had worse COVID-19 severity and cytokine storm (aOR, 3.33; 95% CI, 1.38-8.01, and aOR, 4.41; 95% CI, 1.71-11.38, respectively). Patients with immunosuppression receiving non-IO therapies (vs untreated) also had worse COVID-19 severity (aOR, 1.79; 95% CI, 1.36-2.35) and cytokine storm (aOR, 2.32; 95% CI, 1.42-3.79).

Conclusions and Relevance

This cohort study found that in patients with cancer and COVID-19, administration of systemic anticancer therapies, especially IO, in the context of baseline immunosuppression was associated with severe clinical outcomes and the development of cytokine storm.

Trial Registration

ClinicalTrials.gov Identifier: NCT04354701.

Detection of cancer signal for over 50 AJCC cancer types with a multi-cancer early-detection test

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Background: The Circulating Cell-free Genome Atlas study (CCGA; NCT02889978) previously demonstrated that a blood-based multi-cancer early detection (MCED) test utilizing cell-free DNA (cfDNA) sequencing in combination with machine learning could detect cancer signals across multiple cancer types and predict cancer signal origin. Cancer classes were defined within the CCGA study for sensitivity reporting. Separately, cancer types defined by the American Joint Committee on Cancer (AJCC) criteria, which outline unique staging requirements and reflect a distinct combination of anatomic site, histology and other biologic features, were assigned to each cancer participant using the same source data for primary site of origin and histologic type. Here, we report CCGA ‘cancer class’ designation and AJCC ‘cancer type’ assignment within the third and final CCGA3 validation substudy to better characterize the diversity of tumors across which a cancer signal could be detected with the MCED test that is nearing clinical availability. Methods: CCGA is a prospective, multicenter, case-control, observational study with longitudinal follow-up (overall population N = 15,254). Plasma cfDNA from evaluable samples was analyzed using a targeted methylation bisulfite sequencing assay and a machine learning approach, and test performance, including sensitivity, was assessed. For sensitivity reporting, CCGA cancer classes were assigned to cancer participants using a combination of the type of primary cancer reported by the site and tumor characteristics abstracted from the site pathology reports by GRAIL pathologists. Each cancer participant also was separately assigned an AJCC cancer type based on the same source data using AJCC staging manual (8th edition) classifications. Results: A total of 4077 participants comprised the independent validation set with confirmed status (cancer: n = 2823; non-cancer: n = 1254 with non-cancer status confirmed at year-one follow-up). Sensitivity was reported for 24 cancer classes (sample sizes ranged from 10 to 524 participants), as well as an “other” cancer class (59 participants). According to AJCC classification, the MCED test was found to detect cancer signals across 50+ AJCC cancer types, including some types not present in the training set; some cancer types had limited representation. Conclusions: This MCED test that is nearing clinical availability and was evaluated in the third CCGA substudy detected cancer signals across 50+ AJCC cancer types. Reporting CCGA cancer classes and AJCC cancer types demonstrates the ability of the MCED test to detect cancer signals across a set of diverse cancer types representing a wide range of biologic characteristics, including cancer types that the classifier has not been trained on, and supports its use on a population-wide scale. Clinical trial information: NCT02889978.

Patterns and predictors of treatment in muscle-invasive bladder cancer (MIBC): A real-world study

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Background: Among the approaches to curative-intent therapy for MIBC, neoadjuvant cisplatin-based chemotherapy (NAC) is recognized as the gold standard. The combined modality approach of concurrent chemo-radiation is also considered a standard of care. Despite guidelines recommending multidisciplinary care, studies have shown a low adoption rate of multidisciplinary approaches for MIBC. This study aimed to describe the treatment patterns for MIBC pts using real world data. Methods: Following the appropriate IRB approvals, investigators followed a common protocol under the auspices of the Rapid Case Ascertainment at the Yale Cancer Center. Manual chart review was performed on MIBC pts diagnosed in Connecticut from 2004 –2015 and treated at investigator-affiliated hospitals. Information on medical history, comorbidity, and treatment types were recorded. This data set was linked to the Surveillance, Epidemiology, and End Results (SEER) database for demographic information. The descriptive and logistic regression were used to analyze treatment patterns and predicators in each treatment lines: surgery alone, chemotherapy alone, radiation alone and standard care (NAC followed by surgery; surgery followed by adjuvant chemotherapy and concurrent chemo-radiation). Results: The number of adult MIBC pts in the cohort was 1,198. Among them, 290 (24.2%) received surgery as the only treatment; 117 (9.8%) received chemotherapy only; 100 (8.3%) received concurrent chemo-radiation; 96 (8.0%) received NAC followed by surgery. Besides age ( OR: 0.546, 95% CI: 0.289-0.986), when comparing female to male patients on the likelihood of receiving NAC to the alternative treatment types (radiation or surgery), female pts were less likely to receive NAC than males (OR: 0.421, 95% CI: 0.184-0.930). Conclusions: Regardless of demographics, the overall adoption rate of standard care was low, consisting of 236 pts (19.7%) of the population. From the logistic regression results, age was consistently shown as a predictor for receiving NAC over the alternative treatment types, and sex was identified as another strong predictor. Older and female patients were less likely to receive NAC than younger males.[Table: see text]

Performance of a targeted methylation-based multi-cancer early detection test by race/ethnicity

3071

Background: Disparities in cancer screening and outcomes based on factors such as gender, socioeconomic status, and race/ethnicity are well documented.1 The Circulating Cell-free Genome Atlas study (CCGA; NCT02889978) was designed to develop and validate a blood-based multi-cancer early detection (MCED) test analyzing plasma cell-free DNA (cfDNA) to detect cancer signals across multiple cancer types and simultaneously predict cancer signal origin. Findings stratified by race/ethnicity from the third and final CCGA validation sub-study are reported. Methods: CCGA is a prospective, multicenter, case-control, observational study with longitudinal follow-up (overall N = 15,254). In this pre-specified exploratory analysis from the third substudy, key objectives were to evaluate test performance for cancer signal detection (specificity, overall sensitivity, and sensitivity by clinical stage) among racial/ethnic groups. Plasma cfDNA from evaluable samples was analyzed using a targeted methylation bisulfite sequencing assay and a machine learning approach. Overall, 4077 participants comprised the independent validation set with confirmed status (cancer: n = 2823; non-cancer: n = 1254). The groups stratified by race/ethnicity were White Non-Hispanic, Black Non-Hispanic, Other Non-Hispanic (including but not limited to Asian, Native Hawaiian, Pacific Islander, American Indian, Alaska Native), Hispanic (all races), and Other/unknown. The study was not powered to detect statistical differences between groups. Results: Cancer and non-cancer groups were predominantly White (2316/2823, 82.0% and 996/1254, 79.4%, respectively). Across racial/ethnic groups, specificity for cancer signal detection was 99.6% (White Non-Hispanic: 992/996, 95% confidence interval [99.0-99.8%]), 100.0% (Black Non-Hispanic: 85/85 [95.7-100.0%]), 100.0% (Other Non-Hispanic: 33/33 [89.6-100.0%]), 98.1% (Hispanic: 101/103 [93.2-99.5%]), and 100% (Other/unknown: 37/37 [90.6-100.0%]). Despite slight differences in cancer type and staging across racial/ethnic groups, overall sensitivity for cancer signal detection among groups ranged from 43.9% to 63.0% (White Non-Hispanic: 50.5%, 1169/2316 [48.4-52.5%], Black Non-Hispanic: 53.9%, 104/193 [46.8-60.8%], Other Non-Hispanic: 43.9%, 25/57 [31.8-56.7%], Hispanic: 63.0%, 121/192 [56.0-69.5%], and Other/unknown: 52.3%, 34/65 [40.4-64.0%]). For all racial/ethnic groups, sensitivity generally increased with clinical stage (with limited exceptions at Stage IV in some groups with small sample sizes). Conclusions: The MCED test demonstrated consistent specificity and sensitivity across racial/ethnic groups, though results are limited by sample size for some groups. These findings indicate broad applicability and support clinical implementation of this MCED test on a population scale. 1. Zavela et al. Brit J Cancer 2021. Clinical trial information: NCT02889978.

Effect of Bacillus Calmette-Guerin (BCG) exposure on severity of COVID-19 infection: A COVID-19 and Cancer Consortium (CCC19) study

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Background: Oncology patients experience more severe disease outcomes from COVID-19 infection than the general population. BCG is a live bovine tuberculosis bacillus with immunotherapeutic effects in urothelial cancers; it is also used as vaccination against Mycobacterium tuberculosis in parts of the world. As BCG vaccination has been associated with broad protection against viral pathogens, BCG exposure through vaccination or intravesical therapy may modulate host immunity and reduce the severity of COVID-19 infection. We report the effect of BCG exposure on COVID-19 severity in oncology patients from the CCC19 registry. Methods: The CCC19 registry (NCT04354701) was used to identify patients with prior BCG exposure. Cohort A received intravesical treatment for bladder carcinoma, and cohort B received prior BCG vaccination. Each cohort was matched 3:1 to non-BCG-exposed controls by age, sex, race, primary cancer type, cancer status, ECOG performance status (PS) and calendar time of COVID-19 infection. The primary endpoint was COVID-19 severity reported on an ordinal scale (uncomplicated, hospitalized, admitted to ICU +/- ventilated, died within 30 days) of patients exposed to prior BCG compared to matched non-exposed controls. 2-sided Wilcoxon rank-sum tests were used. Results: As of 6-Feb-2021 we included 124 patients with BCG exposure, 68 patients with bladder carcinoma who had received intravesical BCG (Cohort A), and 64 cancer patients with prior BCG vaccination (Cohort B). Median age was 76 years, IQR 69-83 (Cohort A) and 67 years, IQR 62-74 (Cohort B). Bladder cancer pts were predominately male (78%) vs 55% for Cohort B. Patients with PS 2+ were uncommon, 18% in Cohort A and 16% in Cohort B. COVID-19 illness severity was no different in patients exposed to prior intravesicular BCG (p=0.87). COVID-19 illness severity was no different in patients exposed to prior intradermal BCG vaccination (p=0.60). Conclusions: Despite this being the largest such cohort reported to date, we failed to demonstrate an association of prior BCG exposure with modulation of severity of COVID-19 illness. Prospective trials evaluating the protective effect of BCG vaccination are ongoing and will add further insight into the effect of BCG on COVID-19 illness.[Table: see text]

Potential role of rituximab in metastatic castrate-resistant prostate cancer

Nearly all men with prostate cancer who are treated with androgen deprivation therapy develop disease progression. There is considerable evidence to suggest that CXCL 13 released by tumor cells leads to B-cell infiltration into the prostate cells. This B-cell infiltration has been postulated to play a role in development of disease progression following androgen-deprivation therapies. We present a case of a patient who achieved remission of metastatic castrate-resistant prostate cancer after receiving rituximab and bendamustine for the treatment of follicular lymphoma. The findings in this report suggest that further investigation is warranted for utilizing B-cell targeted therapy in delaying progression of castrate-resistant prostate cancer.

Subcutaneous metastasis from recurrent basaloid squamous cell carcinoma of the esophagus

Background

Esophageal cancer is the 11th most common cause of cancer mortality in the United States. It is aggressive in nature and has an ability to spread rapidly through direct extension, lymphatic spread, or hematogenously. With an estimated incidence of 1%, cutaneous metastases from esophageal cancer are extremely rare.

Case presentation

In this case study and review, we describe a case of recurrent esophageal basaloid squamous cell carcinoma presenting as multiple, rapidly progressing and tender subcutaneous nodules. A 69-year-old male with history of basaloid squamous cell carcinoma of the esophagus treated with concurrent chemoradiation, presented to his oncologist with complaints of a large, painful nodule at the nape of his neck approximately two years after completing treatment. On further examination, he was noted to have multiple, well circumscribed, solid, tender nodules on his abdominal wall along with a painful nodule on the pulp of his index finger. Histopathology from all sites revealed skin infiltration by high-grade invasive basaloid subtype of squamous cell carcinoma, similar to patient’s prior known and treated primary esophageal cancer. Further imaging work up showed extensive metastatic disease involving lung, liver, and brain.

Conclusion

Esophageal squamous cell carcinoma rarely metastasize to the skin. Subcutaneous nodules can be the first presentation of recurrent disease. The lesions are commonly confused with skin infections and treated inappropriately with antibiotics, leading to delay in diagnosis of recurrent disease. Early biopsy of suspicious lesions should be performed, especially in patients with history of cancer, such that prompt diagnosis and treatment can occur to maximize patient outcomes.

SATB1 and bladder cancer: Is there a functional link?

PURPOSE

SATB1, a global genome organizer, has been shown to play a role in the development and progression of some solid tumors, but its role in bladder cancer is undetermined. Moreover, there is conflicting data about the role of SATB1 in other tumors. This study was initiated to assess a potential role for SATB1 with the hypothesis that SATB1 acts as a tumor promoter in bladder cancer.

MATERIALS AND METHODS

We evaluated SATB1 expression in bladder cancer cell lines (HTB-5, HTB-9) and compared them to a benign urothelial cell line (UROtsa). Short-hairpin RNA was used to silence SATB1 in multiple cell lines, and cell death and cell proliferation were assessed using multiple assays.

RESULTS

SATB1 expression was increased significantly in all cancer cell lines compared to benign urothelial cells. SATB1 expression was knocked down by short-hairpin RNA and functional outcomes, including cell number, cell-cycle arrest, cell viability, and apoptosis after cisplatin treatment, were measured. Surprisingly, knockdown of SATB1 in 2 high-grade cancer cell lines showed opposing functional roles. Compared to the non-silencing control, HTB-5 cells, showed decreased cellular proliferation and increased sensitivity to cisplatin, whereas HTB-9 cells, showed increased cell numbers and increased resistance to cisplatin.

CONCLUSION

We conclude that our results in bladder cancer are consistent with the conflicting data reported in other cancers, and that SATB1 might have different roles in cancer dependent on genetic background and stage of the cancer.

Evolving Treatment of Oligometastatic Hormone-Sensitive Prostate Cancer

Oligometastatic disease was postulated by Hellman and Weichselbaum in 1995 to be a disease state that may reflect a time point in the malignant process that may be amenable to local therapies to allow for patients to achieve a durable response or possible cure despite having advanced disease. Aggressive metastasis-directed therapy has been used in malignancies such as renal cell carcinoma, non–small-cell lung cancer, and colorectal cancer with some evidence of long-term benefit in selected patients. Recently, it has been proposed that some men with oligometastatic hormone-sensitive prostate cancer may also benefit from metastasis-directed therapy. As with most malignancies, optimal therapy for prostate cancer relies on multimodal therapy, best highlighted by the survival benefit seen in high-volume metastatic prostate cancer with the addition of docetaxel to androgen-deprivation therapy. This is becoming increasingly evident for oligometastatic prostate cancer, with emerging data sets suggesting a possible benefit of local ablative therapies for metastatic lesions combined with androgen-deprivation therapy. However, the bulk of the data is retrospective and thus subject to bias. Ongoing clinical trials are evaluating combination therapy to help elucidate the role of each therapy separately and together to determine optimal interventions for this population. This clinical review discusses the retrospective data evaluating local therapies such as radiation and surgery in men with lymph node–positive disease, as well as limited bone metastases, and outlines ongoing, prospective clinical trials designed to further investigate the role of multimodality therapy in the outcomes of men with oligometastatic hormone-sensitive prostate cancer.

Impact of a pharmacist-led oral chemotherapy-monitoring program in patients with metastatic castrate-resistant prostate cancer

Background

With the introduction of oral chemotherapy, the paradigm for cancer treatment is shifting. Use of oral chemotherapy agents offers a non-invasive option for patients with metastatic castrate-resistant prostate cancer. However, these medications are not without challenges including strict adherence for optimal effects, novel toxicity profiles, frequent lab parameter monitoring, high cost, and proper handling and disposal methods. Pharmacists are positioned to play a key role in providing patients with the education required to assure an optimal treatment course is carried out.

Methods

Two cohorts of patients receiving abiraterone, bicalutamide, or enzalutamide for metastatic castrate-resistant prostate cancer seen in our outpatient cancer center 21 months before and 24 months after the implementation of a pharmacist-led oral chemotherapy-monitoring program in December of 2012 were retrospectively compared. Patients were evaluated for number of interventions, adherence to lab parameter monitoring, and overall time on each therapy.

Results

Of the 64 patients identified, 31 patients fulfilled inclusion criteria. A significant increase in the average number of interventions per patient (6.9 vs. 2.6; P = 0.004) and adherence to lab parameter monitoring (10 vs. 3; P = 0.04) in the post-program implementation cohort was found. However, no significant difference in overall time on therapy (10.3 vs. 8.1; P = 0.341) between the two groups was observed.

Conclusion

These results suggest a potential opportunity exists to maximize oral chemotherapy treatment outcomes with the addition of a formalized monitoring program directed by an oncology pharmacist.

Smoking-induced immune deviation contributes to progression of bladder and other cancers

We propose here that cigarette smoke (CS), in addition to its established genotoxic effects, elicits chronic albeit sub-clinical immune suppression, which is a major contributor to cancer progression. This hypothesis, presented here primarily in the context of bladder cancers (BCs), is applicable to other cancers, including those without a confirmed link to smoking.

Physician–pharmacist collaboration for oral chemotherapy monitoring: Insights from an academic genitourinary oncology practice

Background

Oral chemotherapy is being routinely used in metastatic castrate-resistant prostate and renal cell cancer. Although convenient, these drugs require monitoring for adherence, toxicity, and drug interactions to maximize outcomes. Oncology pharmacists have the training and expertise that place them in an optimal position to collaboratively provide medication therapy management.

Methods

A board-certified oncology pharmacist, working in collaboration with a medical oncologist, initiated an oral chemotherapy–monitoring program. The pharmacist provided education, completed medication therapy management; monitored for adherence and toxicity; and recommended treatment of toxicity and supportive care issues. Patient encounters included one of the following: collaboration with medical oncologist visit, pharmacist visit, or telephone or email follow-up between visits.

Results

From December 2012 to May 2014, the pharmacist had 123 encounters with 20 patients with either metastatic prostate ( n = 17) or renal cell cancer ( n = 3). All patients were males (median age 80 years). Most encounters were clinic visits, in collaboration with physician visit or alone (52%); 36% were telephone encounters, and 11.3% were email follow-ups. Medication-related problems were identified in 25% of the 315 assessments made. Problems included: adverse drug reactions, 40%; inappropriate therapy, 20%; and noncompliance, 18%. Recommendations included: modification of laboratory monitoring, 25%; cancer or non-cancer therapy modification, 12%; drug discontinuation, 6.9%. Non-cancer therapy-related drug information and coordination of care accounted for 30% of recommendations.

Conclusion

Our program led to identification of a number of potentially clinically significant issues for patients on oral chemotherapy and demonstrated the benefit of the pharmacist in the multidisciplinary team to assist in addressing them.

Atypical presentation of fever as hypersensitivity reaction to oxaliplatin

Oxaliplatin, a third-generation, platinum-based agent is widely used, most commonly in the FOLFOX (5-fluorouracil, leucovorin and oxaliplatin) regimen, which is the first-line therapy in metastatic colorectal adenocarcinoma and adjuvant chemotherapy in stage III colorectal cancer. Platinum-based products are well known for causing hypersensitivity reactions. Fever associated with oxaliplatin-hypersensitivity reactions typically follows a specific pattern. It usually starts during the oxaliplatin infusion or immediately after (within hours instead of days) and happens after several administrations (mean 2–25) with unpredictable clinical presentations. We report a case of oxaliplatin-induced hypersensitivity reaction manifesting as fever but with unusual presentation than the aforementioned features.

The high-dose aldesleukin (IL-2) "select" trial: a trial designed to prospectively validate predictive models of response to high-dose IL-2 treatment in patients with metastatic renal cell carcinoma

For patients with metastatic renal cell carcinoma (RCC), the prognosis is poor. Despite the recent approval of drugs such as sorafenib, sunitinib, and temsirolimus, durable remissions of metastatic disease are rare. This is largely due to the fact that these drugs, while effective, do not result in the eradication of disease. In 1992, the FDA approved the use of high-dose interleukin-2 (IL-2) for the treatment of patients with metastatic RCC because of a small number of patients that achieved durable responses. However, IL-2 has not become a mainstay of treatment because of the expense and toxicity associated with this therapy. This review article discusses a phase II trial that investigates predictive biomarkers that might help clinicians identify the patient population with metastatic RCC that would benefit from IL-2 therapy and therefore limit patients who receive this toxic therapy to those most likely to benefit.

CTP:phosphocholine cytidylyltransferase: insights into regulatory mechanisms and novel functions

A key regulatory enzyme in phosphatidylcholine biosynthesis, CTP:cholinephosphate cytidylyltransferase (CCT), catalyzes the formation of CDP-choline. This review discusses the essential features of CCT and addresses intriguing new insights into the catalytic and regulatory properties of this complex enzyme. Characterization of a lipid-binding segment in rat CCT is described and the role of lipids in CCT activation is discussed. An analysis of the phosphorylation domain is presented and possible physiological rationales for reversible phosphorylation of CCT are discussed. The nuclear localization of CCT is examined in the context of multiple CCT isoforms, as is recent evidence establishing a potential link between CCT activity and vesicular transport.

Weaning from mechanical ventilatory support

Weaning patients from mechanical ventilatory support continues to be a major challenge in critical care units. This article discusses recent research in the area of weaning and identifies specific parameters related to successful weaning in clinical practice.

Na+/Ca2+ exchange in plasma membrane vesicles from a glucose-responsive insulinoma

Plasma membrane vesicles from a glucose-responsive insulinoma exhibited properties consistent with the presence of a membrane Na+/Ca2+ exchange. The exchange was rapid, reversible, and was dependent on the external Ca2+ concentration (Km = 4.1 +/- 1.1 microM). External Na+ inhibited the uptake in a dose-dependent manner (IC50 = 15 mM). Dissipation of the Na+ gradient by 10 microM monensin decreased Na+/Ca2+ exchange from 0.74 +/- 0.17 nmoles/mg protein/s to 0.11 +/- 0.05 nmoles/mg protein/s. Exchange was not influenced by veratridine, tetrodotoxin and ouabain, or by modifiers of cAMP. No effect was seen using the calcium channel blockers, nitrendipine or nifedipine. Glucose had no direct effect on Na+/Ca2+ exchange, while glyceraldehyde, glyceraldehyde-3-phosphate and dihydroxyacetone inhibited the exchange. Na+ induced efflux of calcium was seen in Ca2+ loaded vesicles and was half maximal at [Na+] of 11.1 +/- 0.75 mM. Ca2+ efflux was dependent on [Na+], with a Hill coefficient of 2.7 +/- 0.07 indicating that activation of Ca2+ release involves a minimum of three sites. The electrogenicity of this exchange was demonstrated using the lipophilic cation tetraphenylphosphonium [( 3H]-TPP), a membrane potential sensitive probe. [3H]-TPP uptake increased transiently during Na+/Ca2+ exchange indicating that the exchange generated a membrane potential. These results show that Na+/Ca2+ exchange operates in the beta cell and may be an important regulator of intracellular free Ca2+ concentrations.

Direct repeats at nuclear matrix-associated DNA regions and their putative control function in the replicating eukaryotic genome

Short DNA regions, known to contain replication origins, were isolated from 2 M NaCl resistant nuclear structures of Physarum polycephalum after predigestion with DNase. Regions of 100 bp average length were cloned and sequenced. About 25% of the clones contained direct repeats of 12 to 16 bp and variable base sequences, that have been shown to possess the potential of playing a crucial role in the control of DNA replication. In one of the two alternative three-dimensional configurations such repeats expose single-stranded loops that can function as sites for the initiation of new DNA strands. As these regions are converted into full-length duplexes by their own replication, reinitiation at the same site is excluded. Restoration of the initiationable configuration is considered to be coupled to structural rearrangements involved in the transient condensation of chromosomes in mitosis. This mechanisms ensures that any part of the entire eukaryotic genome is reproduced just a single time during one cell cycle.

Chromosome studies in IgA-deficient patients

Chromosome analysis was performed in 17 children with IgA-deficiency. In two patients a constitutional structural chromosome abnormality was found. A ring chromosome 22 was seen in one, while in the other a mosaicism of ring chromosome 18/18p+ was observed. Both patients were mentally retarded and showed distinct congenital defects. From ten asymptomatic patients, spontaneous as well as X-ray-induced chromosome instability was investigated. There was no increased spontaneous instability, and also after irradiation the induced chromosome damage was within normal control levels. A relationship between IgA-deficiency and X-ray hypersensitivity, as might be suggested by the frequently occurring coincidence of radiosensitivity and IgA-deficiency in ataxia telangiectasia patients, is not established.

Palindromic units from E. coli as binding sites for a chromoid-associated protein

Several hundred copies of a highly conserved extragenic palindromic sequence, 20-40 nucleotides long, exist along the chromosome of E. coli and S. typhimurium. These have been defined as palindromic units (PU) or repetitive extragenic palindromes (REP). No general function for PUs has been identified. In the present work, we provide data showing that a protein associated with a chromoid extract of E. coli protects PU DNA against exonuclease III digestion. This provides the first experimental evidence that PU constitutes binding sites for a chromoid-associated protein. This result supports the hypothesis that PUs could play a role in the structure of the bacterial chromoid.

Further sequence analysis of the phage lambda receptor site. Possible implications for the organization of the lamB protein in Escherichia coli K12

We present the DNA sequence alterations due to seven lamB missense mutations yielding resistance to phages lambda and K10. They reveal five different amino acid positions in the LamB protein. Three positions (245, 247 and 249) define a new region required for phage adsorption. The two other positions (148 and 152) belong to a region where mutations to phage resistance has already been detected. These two regions are hydrophilic and could belong to turns of the protein located at the surface of the cell. All the missense mutational alterations to phage resistance sequenced in the LamB protein correspond to 10 sites located in four different segments of the polypeptide chain. We discuss their location in terms of the notion of phage receptor site and of a working model for the organization of this protein in the outer membrane of Escherichia coli.

Analysis of lambda receptor and beta-lactamase synthesis and export using cloned genes in a minicell system

We have cloned lamB, the gene for lambda receptor (an outer membrane protein), on a small plasmid which also carries the gene for beta-lactamase (a periplasmic protein). We have identified a promoter in the region of malK, the gene immediately preceding lamB, which is active in minicells but relatively inactive in vitro. Using a minicell system, we have found that both lambda receptor and beta-lactamase are made as full length precursors which are subsequently processed. We also show that the lambda receptor precursor can be exported to the outer membrane before it is processed. Mature beta-lactamase is found only in the periplasm, suggesting that processing may be a requirement for export to the periplasm.

DNA sequence encoding the NH2-terminal peptide involved in transport of lambda receptor, an Escherichia coli secretory protein

lamB encodes the lambda receptor of Escherichia coli, an outer membrane protein. We have identified the beginning of the lamB gene by correlating DNA nucleotide sequence with a partial sequence of the primary translation product of lamB. We show that lambda receptor is synthesized as a precursor containing an extra 25 amino acids at its NH2 terminus. These amino acids are predominately hydrophobic and probably comprise a structure required for initiation of transport of lambda receptor from the cytoplasm to the outer membrane.

Gas-liquid chromatographic determination of butylated hydroxyanisole and butylated hydroxytoluene in edible oils

A method is described for the quantitative determination of butylated hydroxyanisole and butylated hydroxytoluene in edible oils. Both antioxidants are extracted with acetonitrile, and quantitated by gas-liquid chromatography, using a hydrogen flame ionization detection system and di-tert-butyl-4-hydroxyanisole as an internal standard. The standard addition technique is used. Recoveries from oils containing 70-400 ppm by weight of both antioxidants ranged from 88 to 104%.