Publications by authors named "Christopher Rizzo"

17 Publications

  • Page 1 of 1

Pseudohyperkalaemia in essential thrombocytosis: an important clinical reminder.

Endocrinol Diabetes Metab Case Rep 2021 Apr 1;2021. Epub 2021 Apr 1.

Mater Dei Hospital of Malta, Department of Medicine, Msida, Malta.

Summary: An 82-year-old female was admitted to a general hospital due to progressive bilateral lower limb weakness. A T8-T9 extramedullary meningioma was diagnosed by MRI, and the patient was referred for excision of the tumour. During the patient's admission, she was noted to have persistent hyperkalaemia which was refractory to treatment. Following a review by an endocrinology team, a diagnosis of pseudohyperkalaemia secondary to thrombocytosis was made. This case demonstrates the importance of promptly identifying patients who are susceptible to pseudohyperkalaemia, in order to prevent its potentially serious consequences.

Learning Points: Pseudohyperkalaemia should be considered in patients with unexplained or asymptomatic hyperkalaemia. It should also be considered in those patients who are resistant to the classical treatment of hyperkalaemia. A diagnosis of pseudohyperkalaemia is considered when there is a difference of >0.4 mmol/L of potassium between serum and plasma potassium in the absence of symptoms and ECG changes. In patients who are presenting with consistently elevated serum potassium levels, it may be beneficial to take venous blood gas and/ or plasma potassium levels to rule out pseudohyperkalaemia. Pseudohyperkalaemia may subject patients to iatrogenic hypokalaemia which can be potentially fatal. Pseudohyperkalaemia can occur secondary to thrombocytosis, red cell haemolysis due to improper blood letting techniques, leukaemia and lymphoma.
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http://dx.doi.org/10.1530/EDM-21-0013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8115417PMC
April 2021

Paradoxical deterioration in seizure control due to anticonvulsant-induced hypocalcaemia.

BMJ Case Rep 2019 Dec 5;12(12). Epub 2019 Dec 5.

Department of Diabetes and Endocrinology, Mater Dei Hospital, Msida, Malta.

Hepatic cytochrome P450 enzyme induction is associated with certain antiepileptic drugs (AEDs) and may result in hypocalcaemia secondary to vitamin D deficiency. We report a case of a 44-year-old man with a history of epilepsy, who presented with breakthrough seizures after having previously been seizure-free for 11 years. Investigations revealed severe hypocalcaemia with a corrected calcium of 1.7 mmol/L. His phenytoin dose was increased, and he was started on calcium supplementation. He was discharged with a corrected calcium level of 2.05 mmol/L but was readmitted 1 week later with further seizures and a corrected calcium of 1.89 mmol/L. 25-hydroxyvitamin D was low. AED-induced hypocalcaemia was suspected, which had been made paradoxically worse by the increase in phenytoin dose. Alfacalcidol was prescribed and he was switched from phenytoin to levetiracetam with resolution of hypocalcaemia and no further seizures. The authors recommend screening for calcium and vitamin D deficiency in patients on enzyme-inducing AEDs.
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http://dx.doi.org/10.1136/bcr-2019-232429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904164PMC
December 2019

SENTINEL1: Two-Season Study of Respiratory Syncytial Virus Hospitalizations among U.S. Infants Born at 29 to 35 Weeks' Gestational Age Not Receiving Immunoprophylaxis.

Am J Perinatol 2020 03 16;37(4):421-429. Epub 2019 Apr 16.

AstraZeneca, Gaithersburg, Maryland.

Objective: The SENTINEL1 observational study characterized confirmed respiratory syncytial virus hospitalizations (RSVH) among U.S. preterm infants born at 29 to 35 weeks' gestational age (wGA) not receiving respiratory syncytial virus (RSV) immunoprophylaxis (IP) during the 2014 to 2015 and 2015 to 2016 RSV seasons.

Study Design: All laboratory-confirmed RSVH at participating sites during the 2014 to 2015 and 2015 to 2016 RSV seasons (October 1-April 30) lasting ≥24 hours among preterm infants 29 to 35 wGA and aged <12 months who did not receive RSV IP within 35 days before onset of symptoms were identified and characterized.

Results: Results were similar across the two seasons. Among infants with community-acquired RSVH ( = 1,378), 45% were admitted to the intensive care unit (ICU) and 19% required invasive mechanical ventilation (IMV). There were two deaths. Infants aged <6 months accounted for 78% of RSVH observed, 84% of ICU admissions, and 91% requiring IMV. Among infants who were discharged from their birth hospitalization during the RSV season, 82% of RSVH occurred within 60 days of birth hospitalization discharge.

Conclusion: Among U.S. preterm infants 29 to 35 wGA not receiving RSV IP, RSVH are often severe with almost one-half requiring ICU admission and about one in five needing IMV.
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http://dx.doi.org/10.1055/s-0039-1681014DOI Listing
March 2020

Identification of an p.Gly292fs Frameshift Mutation Presenting as Diabetes During Pregnancy in a Maltese Family.

Clin Med Insights Case Rep 2019 20;12:1179547619831034. Epub 2019 Feb 20.

Department of Medicine, Mater Dei Hospital, Msida, Malta.

The diagnosis of maturity onset diabetes of the young (MODY) is a challenging process in view of the extensive clinical and genetic heterogeneity of the disease. Mutations in the gene encoding hepatocyte nuclear factor 1α () are responsible for most forms of monogenic diabetes in Northern European populations. Genetic analysis through a combination of whole exome sequencing and Sanger sequencing in three Maltese siblings and their father identified a rare duplication/frameshift mutation in exon 4 of that lies within a known mutational hotspot in this gene. In this report, we provide the first description of an -MODY3 phenotype in a Maltese family. The findings reported are relevant and new to a regional population, where the epidemiology of atypical diabetes has never been studied before. This report is of clinical interest as it highlights how monogenic diabetes can be misdiagnosed as either type 1, type 2, or gestational diabetes. It also reinforces the need for a better characterisation of monogenic diabetes in Mediterranean countries, particularly in island populations such as Malta with a high prevalence of diabetes.
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http://dx.doi.org/10.1177/1179547619831034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6383084PMC
February 2019

Primary Bilateral Non-Hodgkin's Lymphoma of the Adrenal Gland Presenting as Incidental Adrenal Masses.

Case Rep Med 2015 22;2015:620381. Epub 2015 Nov 22.

Diabetes and Endocrine Centre, Mater Dei Hospital, Msida MSD 2090, Malta ; Department of Medicine, University of Malta Medical School, Msida MSD 2080, Malta.

Although lymphoma may occasionally involve the adrenal glands as part of a generalized disease process, primary adrenal lymphoma (PAL) is a rare disease. We present a case of a 62-year-old woman with a history of mild/moderate hereditary spherocytosis with a well-compensated baseline haemoglobin, who presented with rapidly progressive symptomatic anaemia. During the diagnostic workup, imaging revealed bilateral large adrenal masses and she was later diagnosed with diffuse large B-cell non-Hodgkin's lymphoma (DLBCL), with the adrenal glands being the dominant site of the disease. The patient was started on systemic chemotherapy, but her disease progressed with neurological involvement which responded to second-line therapy. Her adrenal disease however was refractory to further therapy.
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http://dx.doi.org/10.1155/2015/620381DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4670633PMC
December 2015

Refractory hypocalcaemia complicating metastatic prostatic carcinoma.

BMJ Case Rep 2015 Jun 29;2015. Epub 2015 Jun 29.

Diabetes and Endocrine Centre, Mater Dei Hospital, Msida, Malta Department of Medicine, University of Malta Medical School, Msida, Malta.

A 72-year-old man with a background of ischaemic heart disease was referred to the accident and emergency department with a 1-week history of worsening dyspnoea and lethargy. A chest X-ray revealed a right-sided lobar pneumonia and a prolonged corrected QT interval was noted on his ECG at presentation. Laboratory investigations confirmed severe hypocalcaemia, significant vitamin D deficiency and relative hypoparathyroidism. A markedly elevated prostate-specific antigen was also identified. Bone scintigraphy demonstrated widespread osteoblastic bone metastases. Severe hypocalcaemia persisted despite treatment and he succumbed after 60 days of hospitalisation.
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http://dx.doi.org/10.1136/bcr-2015-210003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4488614PMC
June 2015

Athletic trainers have a place in interprofessional education and practice.

J Interprof Care 2015 May 29;29(3):256-7. Epub 2014 Jul 29.

Department of Exercise and Sport Performance, University of New England , Biddeford, ME , USA .

Athletic trainers (ATs) are healthcare providers who work in collaboration with physicians, nurses, physical therapists and others to provide care to physically active individuals. Founded in 1950, the National Athletic Trainers' Association (NATA) represents certified ATs and other individuals who support the athletic training profession. The Board of Certification (BOC) has the only accredited certification program for ATs in USA. It establishes and regularly reviews both the standards for the practice of athletic training and the continuing education requirements for certified ATs. In order to attain certification, candidates must demonstrate successful completion of either a bachelor's degree or master's degree program accredited by the Commission on Accreditation of Athletic Training Education (CAATE) and pass the BOC certification exam. Currently, there are ∼42 000 ATs practicing in USA, with 48 states who regulate their practice. The purpose of this article is to provide a background for the profession of athletic training as well as describe and discuss the importance of including ATs in interprofessional education and practice initiatives.
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http://dx.doi.org/10.3109/13561820.2014.942778DOI Listing
May 2015

Transcriptome profiling of the rice blast fungus during invasive plant infection and in vitro stresses.

BMC Genomics 2011 Jan 19;12:49. Epub 2011 Jan 19.

Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA.

Background: Rice blast is the most threatening disease to cultivated rice. Magnaporthe oryzae, its causal agent, is likely to encounter environmental challenges during invasive growth in its host plants that require shifts in gene expression to establish a compatible interaction. Here, we tested the hypothesis that gene expression patterns during in planta invasive growth are similar to in vitro stress conditions, such as nutrient limitation, temperature up shift and oxidative stress, and determined which condition most closely mimicked that of in planta invasive growth. Gene expression data were collected from these in vitro experiments and compared to fungal gene expression during the invasive growth phase at 72 hours post-inoculation in compatible interactions on two grass hosts, rice and barley.

Results: We identified 4,973 genes that were differentially expressed in at least one of the in planta and in vitro stress conditions when compared to fungal mycelia grown in complete medium, which was used as reference. From those genes, 1,909 showed similar expression patterns between at least one of the in vitro stresses and rice and/or barley. Hierarchical clustering of these 1,909 genes showed three major clusters in which in planta conditions closely grouped with the nutrient starvation conditions. Out of these 1,909 genes, 55 genes and 129 genes were induced and repressed in all treatments, respectively. Functional categorization of the 55 induced genes revealed that most were either related to carbon metabolism, membrane proteins, or were involved in oxidoreduction reactions. The 129 repressed genes showed putative roles in vesicle trafficking, signal transduction, nitrogen metabolism, or molecular transport.

Conclusions: These findings suggest that M. oryzae is likely primarily coping with nutrient-limited environments at the invasive growth stage 72 hours post-inoculation, and not with oxidative or temperature stresses.
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http://dx.doi.org/10.1186/1471-2164-12-49DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037901PMC
January 2011

Linking practices with community programs to improve immunization rates.

Pediatr Ann 2006 Jul;35(7):513-5

Case Western Reserve University School of Medicine, The MetroHealth System, Cleveland, OH 44109, USA.

Pediatricians should be knowledgeable about programs available in their community and support efforts to collaborate with other providers, public health departments and immunization coalitions in their community. Through immunization coalitions and widespread use of an immunization registry, together with participating private providers, case management and home visitation programs can improve immunization rates among the highest risk children.
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http://dx.doi.org/10.3928/0090-4481-20060701-08DOI Listing
July 2006

Improving immunization rates in practice settings.

Pediatr Ann 2006 Jul;35(7):493-7

Case Western Reserve University School of Medicine, The MetroHealth System, Cleveland, OH 44109, USA.

Many pediatricians do not know the immunization rate of patients in their practice. Evidence-based standards of practice have been established, leading to improved rates. Quality improvement efforts aimed at immunization are effective and may lead to improvement in other preventive health services. By providing more vaccines in the medical home, communities can decrease the need for higher cost case management and outreach services targeting patients with delayed immunizations.
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http://dx.doi.org/10.3928/0090-4481-20060701-05DOI Listing
July 2006

Maximizing office-based immunization.

Pediatr Ann 2006 Jul;35(7):480, 482-4

Vaccines are a great public health achievement only if we can deliver those vaccines to individual patients. It is impressive that gradually increasing immunization rates are so consistent in spite of a new birth cohort every year, complexity of the schedule, shortages, changes in reimbursement policies, and vaccine news stories. Pediatricians have always embraced their public health role, especially as immunization providers. By helping practices improve their immunization delivery system, rates can be raised throughout a community by first maximizing office-based immunization.
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http://dx.doi.org/10.3928/0090-4481-20060701-03DOI Listing
July 2006

Utility of lab-on-a-chip technology for high-throughput nucleic acid and protein analysis.

Electrophoresis 2005 Oct;26(19):3674-81

Department of Global Sciences and Information, AstraZeneca, Mereside, Alderley Park, Cheshire, UK.

On-chip electrophoresis can provide size separations of nucleic acids and proteins similar to more traditional slab gel electrophoresis. Lab-on-a-chip (LoaC) systems utilize on-chip electrophoresis in conjunction with sizing calibration, sensitive detection schemes, and sophisticated data analysis to achieve rapid analysis times (<120 s). This work describes the utility of LoaC systems to enable and augment systems biology investigations. RNA quality, as assessed by an RNA integrity number score, is compared to existing quality control (QC) measurements. High-throughput DNA analysis of multiplex PCR samples is used to stratify gene sets for disease discovery. Finally, the applicability of a high-throughput LoaC system for assessing protein purification is demonstrated. The improvements in workflow processes, speed of analysis, data accuracy and reproducibility, and automated data analysis are illustrated.
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http://dx.doi.org/10.1002/elps.200500166DOI Listing
October 2005

CYP3A4 induction by drugs: correlation between a pregnane X receptor reporter gene assay and CYP3A4 expression in human hepatocytes.

Drug Metab Dispos 2002 Jul;30(7):795-804

Drug Metabolism and Pharmacokinetics, Bristol-Myers Squibb Pharma Company, Newark, Delaware, USA.

Induction of cytochrome P450 3A4 (CYP3A4) is determined typically by employing primary culture of human hepatocytes and measuring CYP3A4 mRNA, protein and microsomal activity. Recently a pregnane X receptor (PXR) reporter gene assay was established to screen CYP3A4 inducers. To evaluate results from the PXR reporter gene assay with those from the aforementioned conventional assays, 14 drugs were evaluated for their ability to induce CYP3A4 and activate PXR. Sandwiched primary cultures of human hepatocytes from six donors were used and CYP3A4 activity was assessed by measuring microsomal testosterone 6beta-hydroxylase activity. Hepatic CYP3A4 mRNA and protein levels were also analyzed using branched DNA technology/Northern blotting and Western blotting, respectively. In general, PXR activation correlated with the induction potential observed in human hepatocyte cultures. Clotrimazole, phenobarbital, rifampin, and sulfinpyrazone highly activated PXR and increased CYP3A4 activity; carbamazepine, dexamethasone, dexamethasone-t-butylacetate, phenytoin, sulfadimidine, and taxol weakly activated PXR and induced CYP3A4 activity, and methotrexate and probenecid showed no marked activation in either system. Ritonavir and troleandomycin showed marked PXR activation but no increase (in the case of troleandomycin) or a significant decrease (in the case of ritonavir) in microsomal CYP3A4 activity. It is concluded that the PXR reporter gene assay is a reliable and complementary method to assess the CYP3A4 induction potential of drugs and other xenobiotics.
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http://dx.doi.org/10.1124/dmd.30.7.795DOI Listing
July 2002

Spanking. Counterpoint.

Clin Pediatr (Phila) 2002 Mar;41(2):88-90; discussion 90-1

Department of Ambulatory/Academic Pediatrics, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH 44109, USA.

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March 2002

Hepatitis C virus NS3 protease requires its NS4A cofactor peptide for optimal binding of a boronic acid inhibitor as shown by NMR.

Chem Biol 2002 Jan;9(1):79-92

DuPont Pharmaceuticals Company, Wilmington, DE 19880, USA.

NMR spectroscopy was used to characterize the hepatitis C virus (HCV) NS3 protease in a complex with the 24 residue peptide cofactor from NS4A and a boronic acid inhibitor, Ac-Asp-Glu-Val-Val-Pro-boroAlg-OH. Secondary-structure information, NOE constraints between protease and cofactor, and hydrogen-deuterium exchange rates revealed that the cofactor was an integral strand in the N-terminal beta-sheet of the complex as observed in X-ray crystal structures. Based upon chemical-shift perturbations, inhibitor-protein NOEs, and the protonation state of the catalytic histidine, the boronic acid inhibitor was bound in the substrate binding site as a transition state mimic. In the absence of cofactor, the inhibitor had a lower affinity for the protease. Although the inhibitor binds in the same location, differences were observed at the catalytic site of the protease.
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http://dx.doi.org/10.1016/s1074-5521(01)00096-5DOI Listing
January 2002
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