In vivo selection of anti-HIV-1 gene-modified human hematopoietic stem/progenitor cells to enhance engraftment and HIV-1 inhibition

Hematopoietic stem/progenitor cell (HSPC)-based anti-HIV-1 gene therapy holds great promise to eradicate HIV-1 or to provide long-term remission through a continuous supply of anti-HIV-1 gene-modified cells without ongoing antiretroviral therapy. However, achieving sufficient engraftment levels of anti-HIV gene-modified HSPC to provide therapeutic efficacy has been a major limitation. Here, we report an in vivo selection strategy for anti-HIV-1 gene-modified HSPC by introducing 6-thioguanine (6TG) chemoresistance through knocking down hypoxanthine-guanine phosphoribosyl transferase (HPRT) expression using RNA interference (RNAi). We developed a lentiviral vector capable of co-expressing short hairpin RNA (shRNA) against HPRT alongside two anti-HIV-1 genes: shRNA targeting HIV-1 co-receptor CCR5 and a membrane-anchored HIV-1 fusion inhibitor, C46, for efficient in vivo selection of anti-HIV-1 gene-modified human HSPC. 6TG-mediated preconditioning and in vivo selection significantly enhanced engraftment of HPRT-knockdown anti-HIV-1 gene-modified cells (>2-fold, p < 0.0001) in humanized bone marrow/liver/thymus (huBLT) mice. Viral load was significantly reduced (>1 log fold, p < 0.001) in 6TG-treated HIV-1-infected huBLT mice compared to 6TG-untreated mice. We demonstrated that 6TG-mediated preconditioning and in vivo selection considerably improved engraftment of HPRT-knockdown anti-HIV-1 gene-modified HSPC and repopulation of anti-HIV-1 gene-modified hematopoietic cells in huBLT mice, allowing for efficient HIV-1 inhibition.

Clinical outcomes among distinct groups of patients with severe tricuspid valve regurgitation

Introduction

Severe tricuspid valve regurgitation (TR) is associated with increased 1-year morbidity and mortality. Characterization by valve etiology (primary, secondary, and lead-associated), a classification borrowed from mitral valve disease, has not been universally shown to correlate with outcomes.

Purpose

Among a large, racially diverse cohort with newly identified severe TR, we aimed to 1) characterize outcomes of severe TR by etiology, and 2) assess whether unsupervised phenoclustering or supervised outcome-driven prediction trees were more effective in establishing subgroups of TR with differential clinical risk profiles.

Methods

We retrospectively analyzed outcomes of 5-year all-cause death and a composite of death or heart failure hospitalization (HFH) among adult patients with new severe TR identified by echocardiography between 2007 to 2018 at a large academic tertiary referral center in the United States. Patients were initially categorized by etiology of TR, including primary, secondary, and lead-associated. Second, we separately applied unsupervised hierarchical clustering to identify distinct clusters using demographics, clinical, and echo data at the time of diagnosis. Third, we applied a supervised recursive partitioning algorithm (survival trees) by each outcome to identify distinct TR subgroups. We estimated the cumulative incidence of death and composite death or HFH over 5 years by 1) etiology of TR, 2) distinct clusters, and 3) groups identified by supervised learning (prediction trees).

Results

Among 2,379 consecutive patients with newly identified severe TR, the median age was 70 years, 61% were female, and 40% were Black. Event rates (95% CI) were 30.9 (29.0 to 32.8) events/100 PY for death and 49.0 (45.9 to 52.2) events/100 PY for composite death or HFH over median follow-up of 1.6 years. Event rates were similarly high across TR etiology groups for both death and composite death or HFH (Figure 1). Multiple methods of unsupervised clustering did not yield distinct clusters by patient demographic and imaging characteristics. After applying supervised survival tree modeling, four phenoclusters with distinct clinical prognoses were separately identified for death and composite death or HFH (Figure 2). Variables identified to partition the cohort to discriminate both death and composite death or HFH were age, albumin, blood urea nitrogen, right ventricular contractility, and right ventricular systolic pressure (all p&lt;0.05).

Conclusions

Five-year cumulative incidence of adverse events among patients with newly diagnosed severe TR was 69% for death and 80% for composite death or HFH. TR etiology did not stratify prognosis, while supervised survival tree models identified phenoclusters with distinct clinical risk. The identified subgroups of severe TR with differential outcomes offer insights towards enrichment in clinical trials of TR and risk/benefit analysis in patients undergoing TR therapies.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Abbott

Inflammatory gene expression during acute high‐altitude exposure

Abstract

The molecular signalling pathways that regulate inflammation and the response to hypoxia share significant crosstalk and appear to play major roles in high‐altitude acclimatization and adaptation. Several studies demonstrate increases in circulating candidate inflammatory markers during acute high‐altitude exposure, but significant gaps remain in our understanding of how inflammation and immune function change at high altitude and whether these responses contribute to high‐altitude pathologies, such as acute mountain sickness. To address this, we took an unbiased transcriptomic approach, including RNA sequencing and direct digital mRNA detection with NanoString, to identify changes in the inflammatory profile of peripheral blood throughout 3 days of high‐altitude acclimatization in healthy sea‐level residents (n = 15; five women). Several inflammation‐related genes were upregulated on the first day of high‐altitude exposure, including a large increase in HMGB1 (high mobility group box 1), a damage‐associated molecular pattern (DAMP) molecule that amplifies immune responses during tissue injury. Differentially expressed genes on the first and third days of acclimatization were enriched for several inflammatory pathways, including nuclear factor‐κB and Toll‐like receptor (TLR) signalling. Indeed, both TLR4 and LY96, which encodes the lipopolysaccharide binding protein (MD‐2), were upregulated at high altitude. Finally, FASLG and SMAD7 were associated with acute mountain sickness scores and peripheral oxygen saturation levels on the first day at high altitude, suggesting a potential role of immune regulation in response to high‐altitude hypoxia. These results indicate that acute high‐altitude exposure upregulates inflammatory signalling pathways and might sensitize the TLR4 signalling pathway to subsequent inflammatory stimuli.

Key points

Inflammation plays a crucial role in the physiological response to hypoxia.

High‐altitude hypoxia exposure causes alterations in the inflammatory profile that might play an adaptive or maladaptive role in acclimatization.

In this study, we characterized changes in the inflammatory profile following acute high‐altitude exposure.

We report upregulation of novel inflammation‐related genes in the first 3 days of high‐altitude exposure, which might play a role in immune system sensitization.

These results provide insight into how hypoxia‐induced inflammation might contribute to high‐altitude pathologies and exacerbate inflammatory responses in critical illnesses associated with hypoxaemia.

Hypoxia and Inflammation: Insights From High-Altitude Physiology

The key regulators of the transcriptional response to hypoxia and inflammation (hypoxia inducible factor, HIF, and nuclear factor-kappa B, NF-κB, respectively) are evolutionarily conserved and share significant crosstalk. Tissues often experience hypoxia and inflammation concurrently at the site of infection or injury due to fluid retention and immune cell recruitment that ultimately reduces the rate of oxygen delivery to tissues. Inflammation can induce activity of HIF-pathway genes, and hypoxia may modulate inflammatory signaling. While it is clear that these molecular pathways function in concert, the physiological consequences of hypoxia-induced inflammation and how hypoxia modulates inflammatory signaling and immune function are not well established. In this review, we summarize known mechanisms of HIF and NF-κB crosstalk and highlight the physiological consequences that can arise from maladaptive hypoxia-induced inflammation. Finally, we discuss what can be learned about adaptive regulation of inflammation under chronic hypoxia by examining adaptive and maladaptive inflammatory phenotypes observed in human populations at high altitude. We aim to provide insight into the time domains of hypoxia-induced inflammation and highlight the importance of hypoxia-induced inflammatory sensitization in immune function, pathologies, and environmental adaptation.

Interventional radiology procedural volume changes during COVID-19 initial phase: A tertiary level Midwest health system experience

BACKGROUND

To evaluate Interventional Radiology (IR) procedural volume changes at a large Midwest health system between March 17, 2020 and April 30, 2020 following a state-mandated shutdown of nonessential procedures during the initial phase of COVID-19.

METHODS

IR procedural volumes were compiled, stratified by location and compared with Diagnostic Radiology (DR) volumes during the same timeframe. Procedure volume was categorized by type, including oncology, dialysis interventions, and drainage procedures with comparisons made using Z-score test for proportions. IR and system-wide surgical procedural volume was compared with baseline values.

RESULTS

System-wide IR procedural volume decreased by 35%, with a 41% decrease in outpatient and a 25% decrease in inpatient volume during the state-mandated order. DR volume decreased by 45%, with a 57% decrease in outpatient and a 22% decrease in inpatient volume. Total IR procedural volume during the mandate was 1077 versus 1518 during the preceding six weeks. The proportion of Interventional Oncology and dialysis interventions showed no significant change (p > 0.05) while that of drainage procedures increased (p < 0.05). Compared to baseline values, system-wide procedural volumes for IR, Vascular Surgery, Urology, General Surgery, Gastroenterology and Gynecology decreased by 3%, 11%, 25%, 20%, 38% and 31% in March 2020 and 25%, 47%, 68%, 63%, 79% and 73% in April 2020 respectively.

CONCLUSION

Outpatient IR volumes were less impacted compared to DR during the initial phase of COVID-19. Oncology, dialysis and drainage interventions may be considered essential procedures due to their stability. IR volumes were less affected compared to other procedural specialties.

Appendicular skeleton MRI in multiple myeloma: Utility and clinical implications

e19527

Background: Skeletal MRI plays an integral role in diagnosing Multiple Myeloma and, in many cases, dictates need for treatment. While axial skeleton MRI is performed with established clinical utility, appendicular MRI is performed sparingly with utility not fully ascertained. We aim to assess the utility of appendicular MRI while establishing clinical factors which may predict outcomes. Methods: 107 appendicular skeleton MRIs were included for retrospective analysis over 15 years. No statistically significant age or gender related variability was noted. Variables including patient age, diagnosis, disease stage/activity, indication, transplant status, MRI result, treatment course, and survival were analyzed via Likelihood Ratio Chi-Square test or logistic regression. Results: Patient age, disease stage, presence of active marrow disease, history of relapse, and presence of axial or appendicular osseous disease were found to have a statistically significant correlation with MRI result. Disease stage and presence of active hematologic disease correlated with post MRI management alterations. Additionally, presence of active hematologic disease at time of MRI demonstrated a correlation with post MRI management strategy. Furthermore, MRI result was a predictor of downstream development of additional skeletal lesions. Interestingly, MRI result was not a predictor of survival. Conclusions: Several parameters may be used to determine a clinical pre-test probability of appendicular disease at the time of MRI. In addition, these clinical parameters and MRI results correlate with trends in subsequent patient treatment strategies. [Table: see text]

Abstract P1-11-08: Assay for personalized prediction of chemotherapy-induced delayed nausea

Background: Chemotherapy-induced nausea and vomiting (CINV) is a distressing side effect according to patients. CINV can negatively affect nutritional habits, ability to work and motivation to follow treatment regimens. Assessment of CINV is an essential component of care for patients receiving chemotherapy. Multiple factors influence the incidence of CINV with the chemotherapy regimen, both type and dosage, being the primary risk factor. It is generally assumed that the strongest patient-related factors are younger age and female sex. However, reports in the literature have demonstrated that using these factors clinicians underestimate the prevalence of CINV, especially delayed nausea.

Thus, there is a need for risk assessment tools to accurately identify patients requiring anti-emetic regimens to improve quality of life of patients and their families.

Most chemotherapeutic agents cause bursts of reactive oxygen species (ROS) resulting in cellular damage and release of substances that can activate receptors in the chemoreceptor trigger zone. Glutathione (GSH), a key antioxidant, is responsible for maintaining redox homeostasis by neutralizing ROS elicited from chemotherapy. Therefore, we hypothesized that a patient's risk of CINV may reflect individual variations in the efficiency to scavenge free radicals after chemotherapy.

Methods: In our Institutional Review Board approved study, we have enrolled over 300 patients and completed assessment of 133 patients. These patients were treated with highly or moderately emetogenic chemotherapies for lung, colon, or breast cancer. Blood samples were drawn from chemotherapy naïve patients and used to determine the glutathione recycling capacity. The assay detects the conversion of a bioactive probe, hydroxyethyl disulfide, into mercaptoethanol, which once normalized to red blood cell count, indicates glutathione recycling capacity (ChemoTox). Nausea severity was reported using the Rotterdam Symptom Check-List at each treatment cycle. Self-reported symptoms were compared to notes in medical records and anti-emetic prescription history.

Results: We previously published the correlation between low ChemoTox and risk of delayed nausea for patients receiving platinum-based therapy for lung and colon cancer (N=64; correctly classified 88.5%; AUC 0.77). In this second evaluation, using SAS/STAT v.14.1 classification trees, we show the results from testing this prediction tool for breast cancer patients that typically are treated with anthracycline- or taxane-based chemotherapies. An early evaluation of anthracycline-based therapies (N=37) demonstrated a weak association between experienced nausea and ChemoTox (correctly classified 69.2%; AUC 0.64). In contrast, patients treated with taxane-based therapies (N=32) demonstrated a similar correlation between ChemoTox and severity of nausea as previously seen for platinum therapies. Also, a similar accuracy in identifying patients at risk of moderate-severe nausea was identified (correctly classified 77.3%; AUC 0.79).

Conclusion: The results from our prospective study suggests that a reduced ability to recycle GSH in the blood may offer an objective prediction of delayed nausea, possibly allowing for optimal anti-emetic regimen to improve the quality-of-life for breast cancer patients.

Citation Format: McCourt DD, Parikh K, Dadivas A, Brady AL, Kennedy J, Ali ZA, Zeger EL, Shevade A, Gilman PB, Wallon UM. Assay for personalized prediction of chemotherapy-induced delayed nausea [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-11-08.

Trends in overall survival and costs of multiple myeloma, 2000-2014

Little real-world evidence is available to describe the recent trends in treatment costs and outcomes for patients with multiple myeloma (MM). Using the Truven Health MarketScan Research Databases linked with social security administration death records, this study found that the percentage of MM patients using novel therapy continuously increased from 8.7% in 2000 to 61.3% in 2014. Compared with MM patients diagnosed in earlier years, those diagnosed after 2010 had higher rates of novel therapy use and better survival outcomes; patients diagnosed in 2012 were 1.25 times more likely to survive 2 years than those diagnosed in 2006. MM patients showed improved survival over the study period, with the 2-year survival gap between MM patients and matched controls decreasing at a rate of 3% per year. Total costs among MM patients have increased in all healthcare services over the years; however, the relative contribution of drug costs has remained fairly stable since 2009 despite new novel therapies coming to market. Findings from this study corroborate clinical data, suggesting a paradigm shift in MM treatment over the past decade that is associated with substantial survival gains. Future studies should focus on the impact on specific novel agents on patients' outcomes.

Severe diarrhoea due to Cystoisospora belli in renal transplant patient on immunosuppressive drugs

Cystoisospora belli, formerly known as Isospora belli, protozoal parasite endemic to many regions of the world including the Caribbean, Central and South America, Africa, and South-East Asia. It is frequently encountered in patients with acquired immunodeficiency syndrome (AIDS) and is considered to be an AIDS-defining illness. Chronic severe watery diarrhoea due to C. belli has also been reported in other immunodeficiency states. C. belli infection in immunosuppressed patients has rarely been described. We describe severe diarrhoea due to C. belli in a human immunodeficiency virus-negative renal transplant recipient on immunosuppressive drugs. Oocysts of C. belli were detected in direct smear preparation of the diarrheic stool sample of the patient. The patient responded to combination treatment with Bactrim-double-strength (trimethoprim-sulfamethoxazole) and Nitazoxanide.

Successful treatment of plastic bronchitis with low fat diet and subsequent thoracic duct ligation in child with fontan physiology

Plastic bronchitis is a rare condition characterized by the formation and expectoration of long, branching bronchial casts that develop in the tracheobronchial tree and cause airway obstruction. Plastic bronchitis has become increasingly recognized as a feared complication of the Fontan operation with a mortality of up to 50%. We report an 11 year old boy who developed severe plastic bronchitis following Fontan repair and the successful long-term control of cast formation utilizing a low-fat diet and subsequent thoracic duct ligation.

Iso-C/3-dimensional neuronavigation versus conventional fluoroscopy for minimally invasive pedicle screw placement in lumbar fusion

BACKGROUND

Minimally invasive spinal surgery (MISS) has evolved over the past years due to the combination of microsurgery, minimal access strategies and neuronavigation. Percutaneous or mini-open pedicle screw placement is a challenge, especially for surgeons not experienced in the use of biplanar fluoroscopy or stereotactic imaging techniques. The aim of the study was to compare the precision of pedicle screw fixation for lumbar fusion procedures using Iso-C/stereotactic 3D neuronavigation (3D NAV) vs. standard AP/lateral fluoroscopy (2D NAV).

METHODS

Our first 42 patients undergoing MISS for one- or 2-level lumbar or lumbosacral fusion procedures for degenerative lumbar pathology were included in this study. Either 3D NAV (n=29) or standard fluoroscopy (n=13) was used to aid screw placement. Demographics, operative time, blood loss, and screw placement accuracy were evaluated. Screw placement was evaluated postoperatively using lumbar CT scanning. Accuracy of 3D NAV was evaluated by comparing intraoperative planning screenshots to postoperative CT placement of screws.

RESULTS

There were no significant differences between groups for mean age, gender or intraoperative blood loss. 90.9% of 3D NAV screws and 73.7% of fluoroscopy screws had no pedicle perforation (p=0.04). Intraoperative navigation screenshots accurately predicted pedicle screw placement in 90.9% of cases. There was a positive correlation between 3D NAV accuracy and better screw grade (rs 0.45, p=0.036).

CONCLUSIONS

Utilization of 3D NAV for percutaneous or mini-open lumbar screw placement during the early learning curve for MISS was associated with higher screw accuracy. This study demonstrates that the use of 3D navigation can facilitate the learning curve for MISS.

Adenovirus-mediated human paraoxonase1 gene transfer to provide protection against the toxicity of the organophosphorus pesticide toxicant diazoxon

Human paraoxonase1 (hPON1) is a potential therapeutic against the toxicity of organophosphorus (OP) pesticides and chemical warfare nerve agents. We tested whether PON1 gene transfer using adenovirus provides protection against the toxicity of the OP diazoxon. Using an adenovirus construct containing hPON1 gene, we showed elevated levels of recombinant hPON1 in vitro in 293A cells and in vivo in mice. The recombinant enzyme was secreted by 293A cells into culture medium and into the systemic circulation of mice. Western blotting revealed that the virally expressed hPON1 had the expected molecular weight of 45 kDa. Recombinant hPON1 in mice was in complex with mouse high-density lipoprotein (HDL) and migrated more slowly than endogenous hPON1 in the human HDL complex. Mice injected with adenovirus expressed PON1 at 600-3480 U ml(-1) on day 5 post-treatment, which is 8-50-fold above endogenous. Six mice expressing hPON1 survived 2LD(50) doses of diazoxon. Four of the six mice survived a second dose of diazoxon (for a total of 4LD(50)) administered 24 h later. In contrast, none of the three mice in the control group survived one 2LD(50) dose. These results show that hPON1 in mice functions as a prophylactic and offers significant protection against lethal doses of diazoxon.

Periodic sedimentation in a Stokesian fluid

We study the sedimentation of two identical but nonspherical particles sedimenting in a Stokesian fluid. Experiments and numerical simulations reveal periodic orbits wherein the bodies mutually induce an in-phase rotational motion accompanied by periodic modulations of sedimentation speed and separation distance. We term these "tumbling orbits" and find that they appear over a broad range of body shapes.

Polyethylene glycosylation prolongs the circulatory stability of recombinant human butyrylcholinesterase

Previous studies in rodents and non-human primates have demonstrated that pretreatment of animals with cholinesterases could provide significant protection against organophosphate (OP) nerve agent toxicity. Gene delivery/therapy is emerging as an approach to achieve high-level expression of proteins in vivo that are very similar to their native counterparts. Recently, adenoviral (Ad) vectors have proven to be excellent vehicles for delivering genes to cells in vitro and in vivo. In this study, we explored the use of the newly designed AdenoVATOR system for the expression of recombinant human butyrylcholinesterase (rHu BChE) in human embryonic kidney 293A (HEK-293A) cells. In these cells, rHu BChE was expressed as mostly tetrameric form by the simultaneous expression of proline-rich attachment domain. By optimizing the culture conditions, 1.5-2.0 U/ml of rHu BChE could be expressed in HEK-293A cells. Recombinant Hu BChE was purified to homogeneity by ammonium sulfate fractionation followed by affinity column chromatography using procainamide Sepharose and cobalt Sepharose gels. The enzymatic and physico-chemical properties of purified rHu BChE were similar to those of native serum-derived Hu BChE. To determine the suitability of this preparation for use as an antidote against highly toxic nerve agents, its pharmacokinetics were evaluated in mice. Recombinant Hu BChE exhibited a mean residence time of 18.3 h which was 2.5-fold shorter than that observed for native Hu BChE in mice. However, rHu BChE chemically modified with polyethyleneglycol (PEG) displayed a mean residence time of 36.2 h suggesting that PEG-modification can prolong the circulatory stability of rHu BChE. The efficacy of Ad-Hu BChE to induce the production of therapeutic levels of bioscavenger in vivo is under evaluation.

Upregulation of galanin binding sites and GalR1 mRNA levels in the mouse locus coeruleus following chronic morphine treatments and precipitated morphine withdrawal

The neuropeptide galanin and its receptors are expressed in the locus coeruleus (LC), a brain area associated with drug dependence and withdrawal. Although galanin peptide mRNA levels do not change during withdrawal, it is not known whether galanin receptor levels are regulated following opiate withdrawal. This study demonstrates that galanin binding in the LC is upregulated by chronic-intermittent morphine administration or by precipitated withdrawal, but not by acute morphine treatment, suggesting that increased activity in the LC may be able to regulate galanin binding sites. Moreover, the increase in galanin binding sites seems to be caused by increased transcription or stabilization of the galanin receptor 1 (GalR1) gene, because there is a dramatic increase in mRNA levels following withdrawal in the LC. It is, therefore, possible that the increase in GalR1 could be an adaptive mechanism that leads to regulation of cAMP levels and possibly firing rate of LC neurons.

Centrally administered galanin blocks morphine place preference in the mouse

Galanin is a neuropeptide with appetitive, antinociceptive and neuroendocrine functions. Galanin and galanin binding sites are present in brain areas that mediate reinforcement, such as nucleus accumbens and ventral tegmental area, as well as locus coeruleus, an area known to be involved in development of drug dependence and withdrawal. This localization, coupled with the observation that there is a strong interaction between morphine and galanin in spinal cord, made it of interest to study whether galanin might have effects on morphine reinforcement. Using the place preference paradigm we found that galanin (1 microg i.c.v.) alone does not possess reinforcing or aversive properties but attenuates the preference conditioned by peripheral administration of morphine (5 mg/kg s.c.). Quantitative receptor autoradiography showed that morphine treatment that could condition a place preference decreased galanin binding in the nucleus accumbens and increased galanin binding in the locus coeruleus. In contrast, acute naltrexone administration increased galanin binding in the nucleus accumbens, suggesting that levels of galanin binding are tonically regulated by opioid receptors in that area. Contrary to what is seen in the spinal cord, these results indicate that galanin and morphine have an antagonistic interaction in the brain that results in attenuation of morphine reinforcement by activation of the galaninergic system.

Solid-phase sequence scanning for drug resistance detection in tuberculosis

DNA chip arrays hold considerable promise for diagnostic sequencing of polymerase chain reaction (PCR) products. To date, however, arrays have been relatively expensive, complex to use and difficult to interpret, preventing their adaptation to the clinical lab. A moderate density array method has been developed that enables efficient, easy-to-interpret and robust solid-phase PCR product sequencing. Here, the results of Mycobacterium tuberculosis rifampin resistance mutation detection by primer-extension-based sequence scanning of the rpo B gene of M. tuberculosis are presented. Rifampin resistant clinical isolates were identified in as little as 1 h post PCR amplification with visual results detection.

Nested genetic bit analysis (N-GBA) for mutation detection in the p53 tumor suppressor gene

There is a growing and significant demand for reliable, simple and sensitive methods for repeated scanning of a given gene or gene fragment for detection and characterization of mutations. Solid-phase sequencing by single base primer extension of nested GBATM primers on miniaturized DNA arrays can be used to effectively scan targeted sequences for missense, insertion and deletion mutations. This paper describes the use of N-GBA arrays designed to scan the sequence of a 33 base region of exon 8 of the p53 gene (codons 272-282) encompassing a hot spot for mutations associated with the development of cancer. Synthetic DNA templates containing various missense, insertion and deletion mutations, as well as DNA prepared from pancreatic and biliary tumor cells, were genotyped using the exon 8 arrays.

Comparison of virulence of Mycobacterium avium complex (MAC) strains isolated from AIDS and non-AIDS patients

Mycobacterium avium complex (MAC) strains from AIDS and non-AIDS patients and from the environment were studied for their colony morphology and virulence in beige mice. The majority of the MAC isolates from AIDS patients, in contrast to those from non-AIDS patients and the environment, showed increased virulence. Similarly, the majority of the MAC isolates from AIDS patients formed smooth transparent (ST) colonies, whereas most of the non-AIDS isolates formed smooth opaque (SO) or intermediate (IM) type of colonies. MAC isolates from the same AIDS patient obtained at different times were found to be heterogenic with respect to serotype, RFLP and glycolipid patterns, suggesting that these patients might be infected with more than one strain of MAC.