Short-term antigen presentation and single clonal burst limit the magnitude of the CD8(+) T cell responses to malaria liver stages

Malaria sporozoites induce swift activation of antigen-specific CD8(+) T cells that inhibit the intracellular development of liver-stage parasites. The length of time of functional in vivo antigen presentation, estimated by monitoring the activation of antigen-specific CD8(+) T cells, is of short duration, with maximum T cell activation occurring within the first 8 h after immunization and lasting approximately 48 h. Although the magnitude of the CD8(+) T cell response closely correlates with the number of parasites used for immunization, increasing the time of antigen presentation by daily immunizations does not enhance the magnitude of this response. Thus, once a primary clonal burst is established, the CD8(+) T cell response becomes refractory or unresponsive to further antigenic stimulation. These findings strongly suggest that the most efficient strategy for the induction of primary CD8(+) T cell responses is the delivery of a maximal amount of antigen in a single dose, thereby ensuring a clonal burst that involves the largest number of precursors to become memory cells.     

Subependymal giant cell astrocytoma in children with tuberous sclerosis

METHODS: Out of 105 patients with tuberous sclerosis (TS) admitted to the Hospital Nacional de Pediatría "Juan P. Garrahan" (Buenos Aires, Argentina), we surgically treated 17 children between January 1988 and December 2000. Two patients were operated on because of epilepsy and 15 patients because of an intraventricular tumor (subependymal giant cell astrocytoma [SGCA]). In this report we focus on tumors. Twelve of the 15 patients presented with hydrocephalus but none of them had a preoperative shunt. All tumors were surgically resected using frontal transventricular or transcallosal routes. Total removal was achieved in 12 out of 15 and subtotal removal in 3 out of 15 patients (resection of 70-95%). RESULTS: Exeresis of the tumor was not accompanied by significant morbidity and there was no perioperative mortality. Seizures and mental retardation did not improve after tumor resection. It was necessary to insert a postoperative shunt a long time after surgery in only one patient. There were no recurrences of SGCA that were totally removed after a mean follow-up of 51.7 months. CONCLUSIONS: We encourage surgery as soon as a lesion is diagnosed as a tumor. The "transformation" of subependymal nodules (SEN) into tumors (SGCA) may be considered controversial.     

APOA1 (-75 G>A and 83 C>T) and APOB (2488 C>T) polymorphisms and their association with myocardial infarction,lipids and apolipoproteins in patients with type 2 diabetes mellitus

IntroductionThe increased risk of myocardial infarction (MI) in type 2 diabetes mellitus (T2DM) is well documented. Polymorphisms in APOA1 and APOB genes allow us to identify new genetic markers in the Mexican population with T2DM and MI.Material and methodsWe studied 135 patients with DMT2 and MI (DI); another 85 non-infarcted diabetic individuals with DMT2 but without previous ischemic events (NID) and 242 healthy subjects (HS). All three groups were selected with the aim to investigate the association between the polymorphisms and infarction when T2DM is present or absent.Results-75 G>A polymorphism: Differences were found in genotype distribution between DI and NID individuals (OR = 2.01, 95% CI: 1.117–3.623, p = 0.019) with an increased risk for A in the dominant model (OR = 1.77, 95% CI: 1.020–3.084, p = 0.042); also concentrations of ApoA-I for A/A were lower in comparison with G/A (p = 0.038) and LDL-C and HDL-C levels were lower in G/A compared to G/G carriers. 83 C>T polymorphism of APOA1: For DI individuals, HDL-C was lower in T/T compared to C/C and triglyceride levels were lower in C/T compared to C/C carriers.ConclusionsThe -75 G>A APOA1 polymorphism could be considered as a susceptibility factor for myocardial infarction in individuals with T2DM and 2488 C>T APOB polymorphism is associated with changes in HDL-C and LDL-C and triglycerides in the same group.     

Glandular Inclusions in Inguinal Hernia Sacs: A Clinicopathological Study of Six Cases

Glandular inclusions in inguinal hernia sacs are not frequent. We present six cases of inguinal hernia with this finding, which represents an incidence of 2.6% in males and shows a predominance in the prepubertal stage. Five patients showed cryptorchidism and two cases were related to congenital malformations of the single umbilical artery type and 47,XY chromosome disorder with chromosomal marker. The most important differential diagnosis must be made with normal histological structures such as the vas deferens or epididymis. The mean diameter of the inclusions was 0.1988 mm and there was a significant difference in size between the inclusions and the vas deferens, but not the epididymis. Differentiation from the latter is based on the absence of a well-developed muscular coat in the wall of the inclusions. It is important to recognize that these inclusions can occur in hernia sacs because of the clinical and medicolegal implications that arise if they are confused with true epididymis or vas deferens. They may arise from paratesticular embryonal remnants.     

Kinetics of hypodermically injected technetium-99m and correlation with cutaneous structures: an experimental study in dogs

We investigated the involvement of cutaneous structures in specific linear migration pathways of technetium-99m pertechnetate hypodermically injected at points of low electrical resistance in the metacarpus of male beagles. Skin-deep incisions were made in the front or back legs on either the same side as the ^99mTc injection or on the opposite side. Incisions in the back legs did not affect the migration pattern. Incisions in the front legs before the injection of ^99mTc prevented tracer migration. After the injection of ^99mTc, incisions in the front contralateral leg caused sudden cessation of the migration, while incisions in the ipsilateral leg caused immediate disappearance of the pathway previously observed. Radioactivity was not detected in flaps obtained from the skin overlying the migration pathway or from the corresponding area of the contralateral leg. In conclusion, the specific linear migration pathways of ^99mTc hypodermically injected at points of low electrical resistance cannot be explained by any known biological function. Although the migration of ^99mTc does not seem to be strongly linked to any cutaneous structure, the skin overlying the radioactive pathway and the corresponding area of the contralateral leg must be intact if tracer migration is to take place.     

Oral and vaginal epithelial cell anti-Candida activity is acid labile and does not require live epithelial cells

BACKGROUND: Candida albicans is the causative agent of oral and vaginal candidiasis. Innate host defenses against C. albicans are important against each infection. Among these are oral and vaginal epithelial cells that have anti-Candida activity. The mechanism of action includes a requirement for cell contact with no role for soluble factors, and a putative role for carbohydrates based on the sensitivity of the activity to periodic acid. METHODS: Periodic acid treatment of epithelial cells as well as the property of partial resistance of antifungal activity to fixation was used to further dissect the mechanism of action. RESULTS: The results herein effectively now challenge a role for carbohydrates alone. Firstly, the putative carbohydrate(s) released into supernatants of periodic acid-treated epithelial cells could not compete with fresh epithelial cells for activity, and equivalent abrogation of activity was observed by periodic acid-treated cells irrespective of the amount of carbohydrate released. Instead, the similar abrogation of activity following treatment with other acids or when cocultured under acidic conditions suggests that the activity is acid-labile. Finally, while activity requires intact epithelial cells, it does not require live cells; activity was minimally affected by fixing epithelial cells prior to coculture where the majority of cells remained impermeable to Trypan blue but were defined as non-viable by positive nuclear staining with propidium iodide. CONCLUSION: These results suggest that antifungal activity is dependent on contact by intact, but not necessarily live, epithelial cells through an acid-labile mechanism.