Hereditary 1,25-dihydroxyvitamin D resistant rickets due to a mutation causing multiple defects in vitamin D receptor function

Hereditary vitamin D-resistant rickets (HVDRR) is an autosomal recessive disease caused by mutations in the vitamin D receptor (VDR). We studied a young Saudi Arabian girl who exhibited the typical clinical features of HVDRR, but without alopecia. Analysis of her VDR gene revealed a homozygous T to C mutation in exon 7 that changed isoleucine to threonine at amino acid 268 (I268T). From crystallographic studies of the VDR ligand-binding domain, I268 directly interacts with 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] and is involved in the hydrophobic stabilization of helix H12. We recreated the I268T mutation and analyzed its effects on VDR function. In ligand binding assays, the I268T mutant VDR exhibited an approximately 5- to 10-fold lower affinity for [(3)H]1,25(OH)(2)D(3) compared with the wild-type (WT) VDR. The I268T mutant required approximately a 65-fold higher concentration of 1,25(OH)(2)D(3) to be equipotent in gene transactivation. Both retinoid X receptor heterodimerization and coactivator binding were reduced in the I268T mutant. Analogs of 1,25(OH)(2)D(3) have been proposed as potential therapeutics for patients with HVDRR. Interestingly, in protease sensitivity assays, treatment with the potent vitamin D analog, 20-epi-1,25(OH)(2)D(3), stabilized I268T mutant proteolytic fragments better than 1,25(OH)(2)D(3). Moreover, 20-epi-1,25(OH)(2)D(3) restored transactivation of the I268T mutant to levels exhibited by WT VDR treated with 1,25(OH)(2)D(3). In conclusion, we describe a novel mutation, I268T, in the VDR ligand-binding domain that alters ligand binding, retinoid X receptor heterodimerization, and coactivator binding. These combined defects in VDR function cause resistance to 1,25(OH)(2)D(3) action and result in the syndrome of HVDRR.     

An ultra-high-affinity small organic ligand of fibroblast activation protein for tumor-targeting applications

We describe the development of OncoFAP, an ultra-high-affinity ligand of fibroblast activation protein (FAP) for targeting applications with pan-tumoral potential. OncoFAP binds to human FAP with affinity in the subnanomolar concentration range and cross-reacts with the murine isoform of the protein. We generated various fluorescent and radiolabeled derivatives of OncoFAP in order to study biodistribution properties and tumor-targeting performance in preclinical models. Fluorescent derivatives selectively localized in FAP-positive tumors implanted in nude mice with a rapid and homogeneous penetration within the neoplastic tissue. Quantitative in vivo biodistribution studies with a lutetium-177–labeled derivative of OncoFAP revealed a preferential localization in tumors at doses of up to 1,000 nmol/kg. More than 30% of the injected dose had already accumulated in 1 g of tumor 10 min after intravenous injection and persisted for at least 3 h with excellent tumor-to-organ ratios. OncoFAP also served as a modular component for the generation of nonradioactive therapeutic products. A fluorescein conjugate mediated a potent and FAP-dependent tumor cell killing activity in combination with chimeric antigen receptor (CAR) T cells specific to fluorescein. Similarly, a conjugate of OncoFAP with the monomethyl auristatin E-based Vedotin payload was well tolerated and cured tumor-bearing mice in combination with a clinical-stage antibody-interleukin-2 fusion. Collectively, these data support the development of OncoFAP-based products for tumor-targeting applications in patients with cancer.

Small organic ligands which selectively bind with high affinity to tumor-associated antigens are increasingly applied as targeting delivery vehicles of small payloads such as radionuclides (1, 2), drugs (3–5), and fluorophores (6, 7) to tumor sites. In principle, the use of small ligands for targeting applications offers several advantages compared to intact immunoglobulins, including superior penetration of solid neoplastic lesions (8), lower immunogenicity (9), and a reduced cost of goods (10). Low molecular weight compounds may reach their target in vivo in a matter of seconds, thanks to rapid extravasation after intravenous administration (8). A strikingly selective accumulation of small ligands in neoplastic masses has been demonstrated for a small number of targets including somatostatin receptor type 2 (SSTR-2) (11), prostate-specific membrane antigen (PSMA) (12), and carbonic anhydrase IX (CAIX) (13), for which high-affinity small organic ligands are available. Those ligands are typically specific for defined tumor entities, such as neuroendocrine tumors (11), prostate cancer (3), and clear cell renal cell carcinoma (2).¹⁷⁷Lu-DOTATATE (Lutathera), a small-molecule product targeting SSTR-2, has been approved based on phase III data in which a clinically meaningful 82% reduction in the risk of disease progression or death was demonstrated in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs) (14). Similar data are expected from the currently ongoing phase III VISION trial for ¹⁷⁷Lu-PSMA-617 (clinical trial no. {"type":"clinical-trial","attrs":{"text":"NCT03511664","term_id":"NCT03511664"}}NCT03511664), a radiolabeled small molecule that binds with high affinity to PSMA and that enables targeted beta particle therapy in metastatic castration-resistant prostate cancer patients (15). PHC-102, a ^99mTc-labeled small-molecule derivative targeting CAIX, exhibited favorable uptake in primary and metastatic lesions in patients with renal cell carcinoma (RCC) (2). In light of the promising performance of small organic ligands, it would be desirable to discover and develop small molecules with a broader tumor-targeting potential, therefore covering multiple cancer types.Fibroblast activation protein (FAP) is a type II integral membrane serine protease which is abundantly expressed in the stroma of more than 90% of the epithelial cancers, including malignant breast, colorectal, skin, prostate, and pancreatic cancers (16, 17), while exhibiting a restricted expression in normal adult tissues (18, 19). Haberkorn and coworkers (1, 20, 21) have recently described a series of FAP ligands capable of selective accumulation in FAP-positive tumors in mice and in patients. One of these products (named FAPI-04) showed impressive tumor to background ratios at early time points (i.e., few hours after administration) in a broad range of different cancer types in patients. More than 28 tumor types including breast, lung, pancreatic, head and neck, esophagus, and colorectal cancer presented a remarkably high uptake of a FAP-targeted small molecule labeled with gallium-68 (1, 20, 21). For this reason, FAP has recently been dubbed as “the next billion-dollar target for theranostic products” (22).Here, we describe how the chemical modification of a quinoline moiety in position 8 led to the discovery of OncoFAP, a small organic FAP ligand with a dissociation constant in the subnanomolar concentration range. OncoFAP exhibited a strikingly selective and efficient tumor-targeting performance when equipped with various types of payloads, including radionuclides, fluorophores, and cytotoxic drugs. The targeting delivery of radionuclides to solid tumors is rapidly gaining in popularity, as it may open theranostic opportunities, associated with the use of gallium-68 for positron emission tomography (PET) imaging and of lutetium-177 for therapeutic applications (23). The delivery of fluorescein to tumors enables the conditional activation of chimeric antigen receptor (CAR) T cells, which display a potent biocidal activity only in the presence of fluorescein-labeled adaptor molecules specific to a tumor antigen (24, 25). Finally, small-molecule–drug conjugates (SMDCs) promise to represent a valid alternative to antibody–drug conjugates for cancer therapy, with better tumor penetration and a lower cost of goods (8, 26, 27).     

The association of differing measures of overweight and obesity with prevalent atherosclerosis: the Dallas Heart Study.

OBJECTIVES: This study sought to evaluate the associations between different measures of obesity and prevalent atherosclerosis in a large population-based cohort. BACKGROUND: Although obesity is associated with cardiovascular mortality, it is unclear whether this relationship is mediated by increased atherosclerotic burden. METHODS: Using data from the Dallas Heart Study, we assessed the association between gender-specific obesity measures (i.e., body mass index [BMI]; waist circumference [WC]; waist-to-hip ratio [WHR]) and prevalent atherosclerosis defined as coronary artery calcium (CAC) score >10 Agatston units measured by electron-beam computed tomography and detectable aortic plaque measured by magnetic resonance imaging. RESULTS: In univariable analyses (n = 2,744), CAC prevalence was significantly greater only in the fifth versus first quintile of BMI, whereas it increased stepwise across quintiles of WC and WHR (p trend <0.001 for each). After multivariable adjustment for standard risk factors, prevalent CAC was more frequent in the fifth versus first quintile of WHR (odds ratio 1.91, 95% confidence interval 1.30 to 2.80), whereas no independent positive association was observed for BMI or WC. Similar results were observed for aortic plaque in both univariable and multivariable-adjusted analyses. The c-statistic for discrimination of prevalent CAC was greater for WHR compared with BMI and WC in women and men (p < 0.001 vs. BMI; p < 0.01 vs. WC). CONCLUSIONS: We discovered that WHR was independently associated with prevalent atherosclerosis and provided better discrimination than either BMI or WC. The associations between obesity measurements and atherosclerosis mirror those observed between obesity and cardiovascular mortality, suggesting that obesity contributes to cardiovascular mortality via increased atherosclerotic burden.     

Impact of Vitamin D Status on Cardiometabolic Complications among Children and Adolescents with Type 1 Diabetes Mellitus

Objective:

There is an ongoing interest in the relationship between vitamin D status and diabetes control and complications. However, data from Saudi Arabia are limited. To determine the impact of vitamin D status on glycemic control and cardiometabolic complications of children and adolescents with type 1 diabetes mellitus (T1DM) attending a tertiary care diabetes clinic in Saudi Arabia.

Methods:

Demographic, clinical, and laboratory data of 301 children and adolescent subjects with T1DM (53.5% females) of a mean age of 13.9 years attending King Abdulaziz Medical City-Jeddah during 2010-2013 were retrospectively collected. Relationships between vitamin D status and frequency of hypoglycemia, hemoglobin A1c (HbA1c) level, body mass index (BMI), blood pressure, and lipid profile were evaluated.

Results:

The mean duration of diabetes was 7.7±3.7 years. Mean BMI value was 21.1±4.5 kg/m2 and HbA1c was 9.6±1.9% in both genders. Only 26.2% of the patients had a satisfactory HbA1c level. The mean level of 25-hydroxyvitamin D [25(OH)D] was 35.15 and that of cholesterol was 4.75. Vitamin D deficiency [25(OH)D≤37.5 nmol/L] was detected in 63.6% of the male and 67.7% of the female subjects. In males, it was inversely associated with frequency of hypoglycemia (p<0.01), BMI (p<0.05), diastolic blood pressure (p<0.05), and triglyceride levels (p<0.01), while in females, it was inversely associated with current age (p<0.05), age at diagnosis (p<0.01), and triglyceride levels (p<0.01). No significant correlation between HbA1c and vitamin D deficiency was observed.

Conclusion:

Vitamin D deficiency was highly prevalent in our study sample and was found to be associated with frequency of hypoglycemic episodes and with adverse cardiometabolic control.     

CT findings in a child with reflux oesophagitis.

We report the case of a 7-month-old boy who presented with a history of vomiting since birth. A computed tomography study showed circumferential thickening of the lower oesophageal wall with enhancement of the mucosa. After a period of antireflux medication, the patient underwent simultaneous oesophageal dilatation and Nissen fundoplication. He is doing well at 2-year follow up.     

Influence of gender and age of onset on the outcome in children with systemic lupus erythematosus

The objective of our study was to determine the influence of gender and age of onset on the outcome in Saudi children with systemic lupus erythematosus (SLE). Medical records of children with SLE treated at King Faisal Specialist Hospital and Research Center were reviewed. Outcome measures included Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index score (SLICC/ACR), renal disease requiring dialysis, or transplant and death related to SLE. Patients were classified based on age at disease onset into early onset (<5 years) and late onset (>5 years). Data were analyzed, and comparison was made according to the gender and age groups. Eighty-nine patients (76 female and 13 male) were included. The median disease duration was 5 years. Twelve patients had early-onset disease. There was no difference in the mean age, age at diagnosis, disease duration, and follow-up between the different groups. Logistic regression analysis showed significant association of high SLICC/ACR score with early-onset disease and male gender, while renal disease requiring dialysis and renal transplant was associated significantly with male gender independently of age of disease onset. In contrast, death related to SLE was influenced by early-onset disease. Male children and early onset disease of this cohort had poorer outcome. This finding indicates that gender and early-onset disease influence the long-term outcome of SLE in children.     

Systemic delivery of β-blockers via transdermal route for hypertension

Hypertension is the most common cardiovascular disease worldwide. Moreover, management of hypertension requires long-term treatment that may result in poor patient compliance with conventional dosage forms due to greater frequency of drug administration. Although there is availability of a plethora of therapeutically effective antihypertensive molecules, inadequate patient welfare is observed; this arguably presents an opportunity to deliver antihypertensive agents through a different route. Ever since the transdermal drug delivery came into existence, it has offered great advantages including non-invasiveness, prolonged therapeutic effect, reduced side effects, improved bioavailability, better patient compliance and easy termination of drug therapy. Attempts were made to develop the transdermal therapeutic system for various antihypertensive agents, including β-blockers, an important antihypertensive class. β-blockers are potent, highly effective in the management of hypertension and other heart ailments by blocking the effects of normal amounts of adrenaline in the heart and blood vessels. The shortcomings associated with β-blockers such as more frequent dose administration, extensive first pass metabolism and variable bioavailability, make them an ideal candidate for transdermal therapeutic systems. The present article gives a brief view of different β-blockers formulated as transdermal therapeutic system in detail to enhance the bioavailability as well as to improve patient compliance. Constant improvement in this field holds promise for the long-term success in technologically advanced transdermal dosage forms being commercialized sooner rather than later.     

Does moxifloxacin alter oxidant status in the cornea? An experimental study

Objective: In this experimental study, we investigated the possible effects of intracameral moxifloxacin on oxidative stress parameters and endothelial cell morphology in corneal tissue.

Methods: In total, 30 rats were randomly assigned to three groups of 10 rats: the sham group (Group 1, n?=?10); the control group (Group 2), where balanced salt solution (BSS) was administered at a dose of 0.01?cc (n?=?10); and the treatment group (Group 3), where moxifloxacin was administered at a dose of 0.05?mg/0.01?cc (n?=?10). Total antioxidant status (TAS) and total oxidant status (TOS) in corneal tissue and blood samples were measured and the oxidative stress index (OSI) was calculated. Also, corneal tissue histopathology was evaluated with caspase-3 and caspase-8 staining. Apoptotic activity was also evaluated.

Results: In blood samples, TAS, TOS, and OSI levels were not statistically significantly different (all p?>?0.05). Compared with the sham and control groups, TOS and OSI levels in cornea tissue were significantly different in the moxifloxacin group (all p?p?>?0.05). Compared with the sham and control groups, apoptotic activity was higher in the moxifloxacin group, in both immunohistochemical staining for caspase-3 and caspase-8.

Conclusions: Intracameral moxifloxacin injection seems to be safe systemically, but it may have toxic effects on corneal tissues, as suggested by oxidative stress parameters and a histopathological evaluation.     

Pneumococcal infection in hospitalized patients: a four-year study in Malaysia

A total of 90 cases of pneumococcal infections were identified at a major referral hospital in Kuala Lumpur, Malaysia during a study period of four years. Pneumonia was the most common clinical presentation (41 cases) followed by meningitis (19 cases). Of 48 patients who were followed-up during the microbiology consultation round, 11 died, 9 were children below two years old. Capsular typing was carried out on 57 strains of Streptococcus pneumoniae isolated from blood and body fluids of 43 children and 14 adults. 38 strains isolated from pharyngeal specimens were also typed. Types 6A (11 strains), 6B (7 strains), 14 (8 strains) and 19A (8 strains) predominated in children. The strains from older patients comprised 3 isolates from cerebrospinal fluid (types 18B, 6B and 14), five from blood (4 strains, type 1 and 1 strain, type 4) and six from pus (1 strain, type 14, 3 strains type 23F and 2 strains type 34). The isolates from pharyngeal specimens belonged to capsular type similar to those implicated in infections. 90% of the types reported in this study are included in the 23 valent pneumococcal vaccines. Minimum inhibitory concentrations of penicillin, cefuroxime, chloramphenicol and rifampicin were determined for selected strains. 4.1% of isolates were resistant to penicillin (3/74), 4.5% to cefuroxime (2/44), 6.5% to chloramphenicol (3/46) and 14.6% to rifampicin (6/41).     

Improving pediatric emergency department physicians’ adherence to clinical practice guidelines on the diagnosis and management of group A beta-hemolytic streptococcal pharyngitis—a cross-sectional study

Introduction

Pharyngitis is one of the major and commonly seen presentations in pediatric emergency departments. While it could be caused by both bacterial and viral pathogens, antibiotics are improperly prescribed regardless of the pathogen. Inappropriate usage of antibiotics has risen the concern of microbial resistance and the need for stricter guidelines. Many guidelines have been validated for this reason, and the Centor score (Modified/McIsaac) is most commonly implemented. This study aims to assess the adherence and enumerate the reasons behind the suboptimal adherence to guidelines (Centor/McIsaac score) of pediatric emergency department physicians in the diagnosis and management of GABHS pharyngitis to lay the groundwork for future actions and to employ educational programs and implement local guidelines for the prevention of the development of multi-drug resistant microorganisms.

Methodology

We surveyed pediatric emergency department physicians of ten teaching hospitals of Riyadh, Saudi Arabia. We used convenient sampling and estimated a sample size of 170 physicians, and interns and medical centers without pediatric emergency department were excluded from the study. Elements of the Centor score (Modified/McIsaac) were used as a part of the assessment of physicians’ knowledge of the guidelines. Adherence was assessed by requiring the participants to answer questions regarding their usage of diagnostic means when they suspect a bacterial cause of pharyngitis, as recommended by the guidelines.

Results

A total of 243 physicians answered the questionnaire, 43 consultants (17.6%) and 200 non-consultants (82.4%). On the knowledge score, 9.1% scored 0, and the majority of both groups, 46.5%, earned a score of 1. The remainder 44.4%, earned a score of 2. Adherence to guidelines was defined as when diagnostic tests (throat culture or rapid antigen detection test) were always requested prior to prescribing antibiotics when acute bacterial pharyngitis was suspected. Only 27.3% (n?=?67) of our sample are adherent to guidelines, whereas the majority, 72.7% (n?=?175), are non-adherent. Several factors were assessed as reasons for lack of adherence.

Conclusion

Lack of knowledge and adherence to guidelines is prevalent in our setting, with awareness, knowledge, and behavior of physicians playing as major factors behind this low adherence. Studies should aim towards the assessment of adherence towards locally developed guidelines.