Cortical Bone Porosity in Rabbit Models of Osteoporosis

Cortical bone porosity is intimately linked with remodeling, is of growing clinical interest, and is increasingly accessible by imaging. Thus, the potential of animal models of osteoporosis (OP) to provide a platform for studying how porosity develops and responds to interventions is tremendous. To date, rabbit models of OP have largely focused on trabecular microarchitecture or bone density; some such as ovariectomy (OVX) have uncertain efficacy and cortical porosity has not been extensively reported. Our primary objective was to characterize tibial cortical porosity in rabbit-based models of OP, including OVX, glucocorticoids (GC), and OVX + GC relative to controls (SHAM). We sought to: (i) test the hypothesis that intracortical remodeling is elevated in these models; (ii) contrast cortical remodeling and porosity in these models with that induced by parathyroid hormone (1–34; PTH); and (iii) contrast trabecular morphology in the proximal tibia across all groups. Evidence that an increase in cortical porosity occurred in all groups was observed, although this was the least robust for GC. Histomorphometric measures supported the hypothesis that remodeling rate was elevated in all groups and also revealed evidence of uncoupling of bone resorption and formation in the GC and OVX + GC groups. For trabecular bone, a pattern of loss was observed for OVX, GC, and OVX + GC groups, whereas the opposite was observed for PTH. Change in trabecular number best explained these patterns. Taken together, the findings indicated rabbit models provide a viable and varied platform for the study of OP and associated changes in cortical remodeling and porosity. Intriguingly, the evidence revealed differing effects on the cortical and trabecular envelopes for the PTH model. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR)..     

Cognitive impairment in rapid‐onset dystonia‐parkinsonism

Rapid‐onset dystonia‐parkinsonism (RDP) is caused by mutations in the ATP1A3 gene. This observational study sought to determine if cognitive performance is decreased in patients with RDP compared with mutation‐negative controls. We studied 22 familial RDP patients, 3 non‐motor‐manifesting mutation‐positive family members, 29 mutation‐negative family member controls in 9 families, and 4 unrelated RDP patients, totaling 58 individuals. We administered a movement disorder assessment, including the Burke‐Fahn‐Marsden Dystonia Rating Scale (BFMDRS) and the Unified Parkinson's Disease Rating Scale (UPDRS) and a cognitive battery of memory and learning, psychomotor speed, attention, and executive function. The cognitive battery was designed to evaluate a wide range of functions; recognition memory instruments were selected to be relatively pure measures of delayed memory, devoid of significant motor or vocal production limitations. Comparisons of standardized cognitive scores were assessed both with and without controlling for psychomotor speed and similarly for severity of depressive symptoms. A majority of RDP patients had onset of motor symptoms by age 25 and had initial symptom presentation in the upper body (face, mouth, or arm). Among patients, the BFMDRS (mean ± SD, 52.1 ± 29.5) and UPDRS motor subscore (29.8 ± 12.7) confirmed dystonia‐parkinsonism. The affected RDP patients performed more poorly, on average, than mutation‐negative controls for all memory and learning, psychomotor speed, attention, and executive function scores (all P ≤ 0.01). These differences persisted after controlling for psychomotor speed and severity of depressive symptoms. Impaired cognitive function may be a manifestation of ATP1A3 mutation and RDP. © 2014 International Parkinson and Movement Disorder Society     

The importance of influenza vaccination during the COVID-19 pandemic

The COVID-19 pandemic and the measures taken to mitigate its spread have had a dramatic effect on the circulation patterns of other respiratory viruses, most especially influenza viruses. Since April 2020, the global circulation of influenza has been markedly reduced; however, it is still present in a number of different countries and could pose a renewed threat in the upcoming Northern Hemisphere winter. Influenza vaccination remains the most effective preventive measure that we have at our disposal against influenza infections and should not be ignored for the 2021–2022 season.     

Differential metabolism of deoxyribonucleosides by leukaemic T cells of immature and mature phenotype

Experimental evidence has indicated that T lymphoblasts are more sensitive to deoxynucleoside toxicity than are B lymphoblasts. These data have led to the use of purine enzyme inhibitors as selective chemotherapeutic drugs in the treatment of T cell malignancies ranging from T cell acute lymphoblastic leukaemia to cutaneous T cell lymphomas. We have compared the toxicities of 2'-deoxyadenosine, 2'-deoxyguanosine, and thymidine for T cell lines derived from patients with T cell acute lymphoblastic leukaemia with those for mature T cell lines derived from patients with cutaneous T cell leukaemia/lymphoma. We have found that both deoxynucleosides are far less toxic to the mature T cell lies than to T lymphoblasts and that the mature cells accumulate much lower amounts of dATP and dGTP when exposed to deoxyadenosine and deoxyguanosine, respectively. Similar studies performed on peripheral blood cells from patients with T cell leukaemias of mature phenotype and on peripheral blood T cells demonstrate similar low amounts of deoxynucleotide accumulation. Measurements of the activities of several purine metabolizing enzymes that participate in deoxynucleoside phosphorylation or degradation do not reveal differences which would explain the toxicity of deoxynucleosides for immature, as compared to mature, T cells. We conclude that deoxynucleoside metabolism in leukaemic T cells varies with their degree of differentiation. These observations may be relevant to the design of chemotherapeutic regimes for T cell malignancies.     

Syndrome of anosmia with hypogonadotropic hypogonadism (kallmann syndrome): Clinical and laboratory studies in 23 cases

We have studied 23 patients (14 men, nine women) in 18 kindreds with anosmia and hypogonadotropic hypogonadism. Seven kindreds had more than one affected member, and included five eugonadal persons with anosmia and two eusomic women with hypogonadotropic hypogonadism. Other clinical abnormalities observed included: obesity (in nine), cryptorchidism (six), osteopenia (six), mild neurosensory hearing loss (five), gynecomastia (five), diabetes mellitus (four), cleft lip or palate or both (three), high-arched palate (two), short fourth metacarpal (two), and clinodactyly, camptodactyly, shortened frenulum of the tongue, multiple facial anomalies, right-sided aortic arch, malrotation of the gut, renal diverticulum, and mild red-green color blindness (one each).Normal secondary sex characteristics developed in all 20 patients treated on a long-term basis with chorionic gonadotropin or gonadal steroids. Responses to a single injection of gonadotropin-releasing hormone were heterogeneous. Five men had no luteinizing hormone response, five had a depressed response, and one an exaggerated response; two had no follicle-stimulating hormone response, five responses were depressed, three were normal, and one was ex-aggerated. None of seven women achieved a normal luteinizing hormone response to gonadotropin-releasing hormone; two had depressed follicle-stimulating hormone response, four responses were normal, and one was exaggerated. None of 11 patients tested responded to clomiphene. Two men fathered children. Each of two other men who underwent biopsy of the testes before and after long-term chorionic gonadotropin therapy showed mildly increased spermatogenesis. Little or no maturation beyond primordial follicles was observed in two ovarian biopsy specimens. Fifteen of 17 patients had normal basal prolactin levels and 14 of 16 had normal thyrotropin-releasing hormone-induced prolactin increase, but nine of 15 tested had a decreased or absent response of prolactin to chlorpromazine. Circulating concentrations of thyroid hormones were normal, but four of 17 patients tested had depressed TSH (thyroid-stimulating hormone) responses to thyrotropin-releasing hormone, and one man had an exaggerated response. Three of 12 patients had a depressed cortisol response to insulin-induced hypoglycemia, and two of seven patients had slightly depressed deoxycortisol responses to metyrapone. Growth hormone and vasopressin release in all 14 and all 12 patients, respectively, studied were essentially normal.Patients with anosmia and hypogonadotropic hypogonadism may have hypothalamic defect(s) responsible for the hypogonadotropism and perhaps for certain additional deficiencies of anterior pituitary function found in some. The cause of less frequent phenotypic abnormalities has not been established. In certain pedigrees, the evidence suggests that the major manifestations of the syndrome are inherited as an autosomal recessive trait.     

Oncogene cooperation in tumor maintenance and tumor recurrence in mouse mammary tumors induced by Myc and mutant Kras

Most, if not all, cancers are composed of cells in which more than one gene has a cancer-promoting mutation. Although recent evidence has shown the benefits of therapies targeting a single mutant protein, little attention has been given to situations in which experimental tumors are induced by multiple cooperating oncogenes. Using combinations of doxycycline-inducible and constitutive Myc and mutant Kras transgenes expressed in mouse mammary glands, we show that tumors induced by the cooperative actions of two oncogenes remain dependent on the activity of a single oncogene. Deinduction of either oncogene individually, or both oncogenes simultaneously, led to partial or complete tumor regression. Prolonged remission followed deinduction of Kras(G12D) in the context of continued Myc expression, deinduction of a MYC transgene with continued expression of mutant Kras produced modest effects on life extension, whereas simultaneous deinduction of both MYC and Kras(G12D) transgenes further improved survival. Disease relapse after deinduction of both oncogenes was associated with reactivation of both oncogenic transgenes in all recurrent tumors, often in conjunction with secondary somatic mutations in the tetracycline transactivator transgene, MMTV-rtTA, rendering gene expression doxycycline-independent. These results demonstrate that tumor viability is maintained by each gene in a combination of oncogenes and that targeted approaches will also benefit from combination therapies.