Identification of two HIV inhibitors that also inhibit human RNaseH2.

A total of 140,000 compounds were screened in a targetfree cell-based high throughput assay against HIV-1 infection, and a subset of 81 promising compounds was identified. Secondary screening of these 81 compounds revealed two putative human RNaseH2 inhibitors, RHI001 and RHI002, with IC50 value of 6.8 µM and 16 µM, respectively. RHI002 showed selective activity against human RNaseH2 while RHI001 inhibited HIV-RNaseH, E. coli RNaseH, and human RNaseH1 with IC50 value of 28.5 µM, 7.9 µM, and 31.7 µM, respectively. Kinetic analysis revealed that both inhibitors had non-competitive inhibitor-like properties. Because RNaseH2 is involved in the etiology of Aicardi-Goutier syndrome and has been suggested as an anticancer drug target, small molecule inhibitors modulating its activity would be useful for investigating the cellular function of this molecule.

Inherited tertiary hypothyroidism in Sprague-Dawley rats.

Thyroid hormones (THs) are important in the development and maturation of the central nervous system (CNS). The significant actions of THs during CNS development occur at the time when TH levels are lower than those in the mother and the hypothalamic-thyroid (HPT) axis is not fully functional. In the developing rat nervous system, primarily the cerebellum, the first three postnatal weeks represent a period of significant sensitivity to thyroid hormones. This study presents a spontaneous, inherited recessive hypothyroidism in Sprague-Dawley rats with devastating functional consequences to the development of the CNS. The clinical signs develop around 14 day's postnatal (dpn) and are characterized by ataxia, spasticity, weight loss and hypercholesterolemia. The afflicted rats died at 30 days due to severe neurological deficits. The deterioration affects the entire CNS and is characterized by progressive neuronal morphological and biochemical changes, demyelination and astrogliosis. The cerebellum, brain stem, neocortex, hippocampus and adrenal gland medulla appear to be most affected. Thyroid Stimulating Hormone (TSH), T3 and T4 levels were significantly lower in hypothyroid rats than control. Immunohistochemistry and RT-PCR demonstrated a reduction of Thyrotropin Releasing Hormone (TRH) in the hypothalamus of hypothyroid rats. The weight of both thyroid and pituitary glands were significantly less in hypothyroid rats than the corresponding normal littermate controls. Transmission electron microscopy demonstrates consistent postsynaptic dendritic, synaptic and spine alterative changes in the brain of hypothyroid rats. These data suggest that we discovered a tertiary form of inherited hypothyroidism involving the hypothalamus.

Freeze lesion-induced focal cortical dysplasia predisposes to atypical hyperthermic seizures in the immature rat.

PURPOSE: To determine the effects of focal cortical dysplasia on the behavioral and electrographic features of hyperthermia-induced seizures (HSs) in rats. METHODS: A right sensorimotor cortex freeze lesion was induced in postnatal day 1 (P1) rat pups, and HSs were provoked at P10 under continuous monitoring of core temperature; EEGs were recorded from the right amygdala during and after hyperthermia. Controls included both sham-operated at P1 and naïve rats. RESULTS: HSs began with jaw myoclonus, followed by hindlimb clonus and generalized convulsions (GCs), and terminated by a period of posthyperthermia depression. The threshold temperature and latency of jaw myoclonus were similar across the groups. However, both the threshold temperature and latency of GCs were significantly lower in lesioned pups than in controls (40.5 +/- 0.5 degrees C, n = 24, vs. 42.0 +/- 0.2 degrees C, n = 21; p < 0.001; 6.7 +/- 0.6 min, n = 20, vs. 8.4 +/- 0.6 min, n = 22; p < 0.05). In lesioned pups, the threshold and latencies for jaw myoclonus and hindlimb clonus were similar, whereas in controls, the progression from one to the other was marked by significant differences in both parameters. Posthyperthermia depression was longer in lesioned (13.3 +/- 1.2 min, n = 21) than in control (8.0 +/- 0.8 min, n = 20; p < 0.0001) pups. Ictal EEG activity was recorded during both behavioral seizures and posthyperthermia depression. CONCLUSIONS: An HS in rats with a localized freeze lesion results in lower threshold GC and prolonged ictal manifestations, thus supporting a pathophysiologic link between focal cortical dysplasia and atypical febrile seizures, conditions that have a high prevalence in children with mesial temporal lobe epilepsy.