Hidden from the host: Spiroplasma bacteria infecting Drosophila do not cause an immune response,but are suppressed by ectopic immune activation

Insects and other arthropods have an effective innate immune system that can clear infections with bacteria and other microorganisms. Despite this ability, one group of bacteria, the spiroplasmas, survive unharmed within the haemolymph of a wide range of arthropod hosts. We investigated the interaction between one member of this clade, a relative of Spiroplasma poulsonii, and the immune system of its Drosophila host. Expression of antimicrobial genes in spiroplasma-infected flies did not differ from wild-type controls either in the naturally infected state, nor after septic shock. We therefore concluded that spiroplasma infection did not induce an immune response in its host, but that this absence of response was unlikely to be because the bacterium inhibited response. Further experiments revealed immune reactions induced ectopically did reduce parasite titre. We therefore conclude that this bacterium has a novel form of interaction with its host, being hidden from the host immune system, but potentially suppressible by it.     

Color Doppler ultrasonography: diagnosis of ectopic thyroid gland in patients with congenital hypothyroidism caused by thyroid dysgenesis

The etiology of congenital hypothyroidism (CH) may play an important role in determining disease severity, outcome, and, therefore, its treatment schedule. Radionuclide imaging (RI) is currently the most precise diagnostic technique to establish the etiology of CH. Conventional ultrasound can identify an athyrotic condition at the normal neck position and has gained acceptance for the initial evaluation of CH; however, its ability in delineating ectopic thyroid is limited. We used color Doppler ultrasonography (CDU) to assess blood flow and morphology in the detection of ectopic thyroid in 11 CH patients disclosed by neonatal screening; thyroid glands were undetectable at the normal location by gray-scale ultrasonography (GSU). The patients studied consisted of two infants for initial investigation and nine children for reevaluating the cause of CH. All of the patients underwent GSU, CDU, RI, and magnetic resonance imaging (MRI) investigation. We set RI as the defining diagnostic test for detecting ectopic thyroid and compared the imaging of CDU with those of GSU and MRI. The results of RI showed 10 ectopic thyroids and one athyreosis. In the patients with ectopic thyroid, the sensitivity of CDU, GSU, and MRI for detecting ectopic thyroid was 90, 70, and 70%, respectively. We conclude that CDU is superior to GSU and MRI for detecting ectopic thyroid and that CDU may be adopted as the diagnostic tool for the initial investigation of suspected CH.     

Characteristics of 11 neonates with atrial septal defects detected by heart murmurs

The aim of this prospective study was to investigate, using echocardiography, the relationship between heart murmurs found in the neonatal period and atrial septal defect (ASD). Heart murmurs were detected in 115 of 5124 term neonates within 1 month after birth. The babies were followed by echocardiographic examination with attention to the atrial septal area. Heart murmurs of 11 term neonates (9.6%) were associated with interatrial shunts consistent with ASD. The defect closed spontaneously in 7 out of the 11 neonates by 18 months of age. Two neonates showed evidence of right ventricular overload from early infancy. This study showed that nearly 1 neonate in 10 with a heart murmur up to 1 month after birth had an interatrial shunt associated with ASD. We concluded that the absence of a flap sign (valve-like openings of the defects) affects the development of the heart murmur of ASD found in the neonatal period.     

Interleukin-2 production by peripheral blood mononuclear cells from patients with myasthenia gravis

We examined interleukin-2 (IL-2) production by phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMs) from 75 untreated myasthenia gravis (MG) patients and 48 control patients. Patients with MG consisted of those with elevated PBM IL-2 production (>1,250 pg/ml; mean + 2SD of the controls) (n = 29, 39%) and those with normal PBM IL-2 production (<1,250 pg/ml) (n = 46, 61%). Significant characteristics of patients with elevated PBM IL-2 production included elevated serum levels of anti-acetylcholine receptor antibodies, severe generalized symptoms, thymic hyperplasia, and marked effects of thymectomy (p < 0.05). These findings suggest that elevated PBM IL-2 production can reflect functional abnormalities of T cells in some patients with MG, and that PBM IL-2 production should be considered as a candidate target of therapy.     

Ependymal cell reactions in spinal cord segments after compression injury in adult rat

Recently, it has been suggested that neural stem cells and neural progenitor cells exist in the ependyma that forms the central canal of the spinal cord. In this study, we produced various degrees of thoracic cord injury in adult rats using an NYU-weight-drop device, assessed the degree of recovery of lower limb motor function based on a locomotor rating scale, and analyzed the kinetics of ependymal cell proliferation and differentiation by proliferating cell nuclear antigen (PCNA), nestin, glial fibrillary acidic protein (GFAP), or GAP-43 immunostaining. The results showed that the time course of the ependymal cell proliferation and differentiation reactions differed according to the severity of injury, and that the responses occurred not only in the neighborhood of the injury but in the entire spinal cord. An increase in the locomotor rating score was related to an increase in the number of PCNA-positive cells, and the differentiation of ependymal cells into reactive astrocytes was involved in injury repair. No apoptotic cells in the ependyma were detectable by the TUNEL method. These results indicate that the ependymal cells of the spinal central canal are themselves multipotent, can divide and proliferate according to the severity of injury, and differentiate into reactive astrocytes within the ependyma without undergoing apoptosis or cell death.