Covalent binding of 7,12-dimethylbenz[a]anthracene to lymphoid and nonlymphoid tissues following oral administration to B6C3F1 mice.

Previous studies have shown that 7,12-dimethylbenz[a]anthracene (DMBA) is cytotoxic to various murine lymphoid tissues, including the spleen, thymus, mesenteric lymph nodes (MLNs), and Peyer's patches (PPs). In the present studies, we measured the amount of covalent binding of [3H]DMBA to lymphoid and nonlymphoid tissues and correlated these findings with the overall levels of [3H]DMBA (and derived substances) present in various tissues following a single oral administration to mice. Results show that [3H]DMBA was taken up relatively rapidly from the GI tract and that it was nearly completely eliminated within 24 hr via the feces. Peak plasma levels were obtained approximately 6 hr after gavage, and most organs (including brain, heart, liver, lung, kidney, spleen, and thymus) achieved their peak level of DMBA at this time. Maximal concentrations of DMBA were detected in gut-associated lymphoid tissues (i.e., PPs and MLNs) at 4 hr, during which time covalent binding of [3H]DMBA was also maximal. The time course for covalent binding was different in the liver, lung, thymus, and spleen, peaking at 6-12 hr. The amount of covalent binding of [3H]DMBA and derived metabolites in the spleen was more than twice that seen in the other tissues examined. Since the spleen has previously been found to be less sensitive to DNA fragmentation induced by DMBA than the PPs, these results suggest that covalent binding may not be the primary determinant of lymphotoxicity in these organs.     

Clinical utility of dorsal sural nerve conduction studies in healthy and diabetic children.

OBJECTIVE: Monitoring of the dorsal sural sensory nerve action potential (SNAP) is a sensitive method for detection of peripheral neuropathies. We tried to determine the normal dorsal sural nerve conduction values of the childhood population and assessed the clinical utility of this method in diabetic children who have no clinical sign of peripheral neuropathy. METHODS: In the study, 36 healthy and 27 diabetic children were included. In all subjects peripheral motor and sensory nerve studies were performed on the upper and lower limbs including dorsal sural nerve conduction studies. RESULTS: The dorsal sural SNAP mean amplitude was 8.24+/-3.08 microV, mean latency was 2.47+/-0.48 ms, mean sensory conduction velocity was 41.63+/-5.43 m/s in healthy children. Dorsal sural SNAPs were absent bilaterally in one diabetic patient. In the other 26 diabetic patients, the mean dorsal sural nerve distal latency was longer (2.93+/-0.63 ms, P = 0.004), mean SCV was slower than in healthy subjects (36.68+/-7.66 m/s, P = 0.005). However, dorsal sural nerve amplitude was not different between the groups. A dorsal sural nerve latency of more than 2.9 ms had a sensitivity of 50% and a specificity of 75%. A dorsal sural nerve velocity of less than 36 m/s had a sensitivity of 54% and a specificity of 92%. CONCLUSIONS: We designated the reference values of the dorsal sural nerve in healthy children. In addition, our findings suggest that dorsal sural nerve conduction studies may have value to determine neuropathy in the early stages in children with diabetes. SIGNIFICANCE: The dorsal sural nerve conduction studies in diabetic children may have value to determine the neuropathy in its early stages.     

Neurophysiological aspects of chronic motor cortex stimulation

Chronic motor cortex stimulation is a treatment option for neuropathic drug-resistant pain and possibly associated movement disorders. Preliminary studies suggest the possibility to treat symptoms of Parkinson disease in selected patients. Recently, MCS has been suggested to enhance motor recovery in patients with poststroke hemiparesis. One or more electrodes are placed extradurally over the motor cortex through a burr hole or a small craniotomy, and then connected to a totally implantable neurostimulator. The accurate positioning of the stimulating electrodes over the motor cortex is the key point of the surgical procedure. Motor cortex identification results from the integration of anatomical, neuroradiological, functional, and neurophysiological data, taking into account the huge population variability. Intraoperative neurophysiological mapping of the motor cortex is of paramount importance, in spite of very sophisticated neuroradiological mathematical reconstructions of the motor area. We discuss and compare the different techniques that are utilized by different authors. Moreover, clinical neurophysiology is also helpful in evaluating the results of this neuromodulation procedure and in hypothesizing the mechanisms that are put in play by MCS.     

Effects of social stress and intrauterine position on sexual phenotype in wild-type house mice (Mus musculus)

Wild-type house mice were used to test the effect of intrauterine position on anogenital distance (AGD) and to verify whether crowding stress would masculinize female pups, developing at all intrauterine positions, as has been demonstrated in CF-1 mice stressed by restraint, heat, and light. Stress of crowding was documented by comparing aggressive behavior, litter birth weights, and plasma corticosterone levels among females in different densities. AGDs were recorded from pups born to females housed from day 12 to 19 of gestation either individually with their mate (nonstressed) or in one of two group-housed densities. Female pups from nonstressed dams positioned between two males in utero (2M females) had longer AGDs than females positioned between two females (0M females). AGDs of males from nonstressed dams did not differ on the basis of intrauterine position. Group-housed pregnant females in the higher of two densities had female pups with longer AGDs than female pups of other dams. However, variance in female pup AGD was no different among dams in different densities. These results extend to the wild house mouse previous findings in albino mice that intrauterine position influences sexual phenotype. In addition, social stress can induce masculinization of female pups in wild mice as physical stress has been shown to do in albinos. This suggests that intrauterine position effects and their modification by crowding stress can potentially influence the dynamics of wild house mouse populations.     

Prevalences, genotypes, and risk factors for HIV transmission in South America

HIV cross-sectional studies were conducted among high-risk populations in 9 countries of South America. Enzyme-linked immunosorbent assay screening and Western blot confirmatory testing were performed, and env heteroduplex mobility assay genotyping and DNA sequencing were performed on a subset of HIV-positive subjects. HIV prevalences were highest among men who have sex with men (MSM; 2.0%-27.8%) and were found to be associated with multiple partners, noninjection drug use (non-IDU), and sexually transmitted infections (STIs). By comparison, much lower prevalences were noted among female commercial sex workers (FCSWs; 0%-6.3%) and were associated mainly with a prior IDU and STI history. Env subtype B predominated among MSM throughout the region (more than 90% of strains), whereas env subtype F predominated among FCSWs in Argentina and male commercial sex workers in Uruguay (more than 50% of strains). A renewed effort in controlling STIs, especially among MSM groups, could significantly lessen the impact of the HIV epidemic in South America.     

Increased promoter diversity reveals a complex phylogeny of human immunodeficiency virus type 1 subtype C in India

OBJECTIVE: To evaluate human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) sequence diversity among distinct populations within India and to determine the prevalent subtype. STUDY DESIGN/METHODS: Analysis of the 3'LTR was conducted from 28 HIV-1-positive samples: 1992-1993 (Pune, New Delhi) and 1995-1996 (Pune, Mumbai and Vellore). Genomic DNA was extracted from cocultivated peripheral blood mononuclear cells (PBMCs) and used for polymerase chain reaction (PCR) amplification and sequencing using dye terminator chemistry. Sequences were edited, aligned, and analyzed phylogenetically utilizing gap-stripped and bootstrapping parameters. Mobility shift assays were used to confirm binding activity. RESULTS: All nucleotide sequences were HWV-1 subtype C based on phylogenetic analysis. The isolates from Pune/Delhi formed subclusters when analyzed separately, irrespective of time or sample source. However, no significant subclustering was observed with isolates from Mumbai or Vellore or with the entire sample set when analyzed collectively. Subtype-specific enhancer analysis revealed an expected third NF-kappaB site but also revealed six isolates with insertions and deletions not previously described, one of which resembles an AP-1 binding site. CONCLUSIONS: The results confirm the prevalence of HIV-1C and suggest increasingly complex phylogeny of HIV-1C within India, such that the previously observed subclustering may no longer adequately reflect the diversity of isolates currently circulating throughout India.     

Five human immunodeficiency virus type 1 phenotypic variants with different MT-2 cell tropisms correlate with prognostic markers of disease

OBJECTIVES: We correlated virologic and immunologic parameters of disease progression with cytopathogenicity of HIV isolates. STUDY DESIGN/METHODS: Human immunodeficiency virus type 1 (HIV-1) isolates from 207 patients with CD4+ cell counts < 500/mm3 were examined for biologic phenotype in MT-2 cells. We used a cross-sectional study design. RESULTS: Three subtypes of syncytium-inducing (SI) strains with different times of appearance of syncytia formation in cell culture and two subtypes of non-syncytium-inducing (NSI) isolates, with (NSI/MT2+) or without (NSI/MT2-) replicative capacity in MT-2 cells, were identified. Early SI strains were associated with the lowest CD4+ cell counts and the highest levels of viral load, and NSI/MT2- isolates correlated with the highest CD4+ cell counts and the lowest viral loads. Patients with late SI and NSI/MT2+ strains showed minimal differences in immunologic and virologic markers. CONCLUSIONS: Five HIV phenotypic variants that correlate significantly (P < 0.001) with markers of disease progression were identified.     

Regulation of adhesion of AML14.3D10 cells by surface clustering of beta2-integrin caused by ERK-independent activation of cPLA2

We examined the role of cell surface clustering of beta2-integrin caused by protein kinase C (PKC)-activated-cPLA2 in adhesion of eosinophilic AML14.3D10 (AML) cells. Phorbol 12-myristate 13-acetate (PMA) caused time- and concentration-dependent adhesion of AML cells to plated bovine serum albumin (BSA), which was blocked by anti-CD11b or anti-CD18 monoclonal antibodies (mAb) directed against beta2-integrin. Inhibition of PKC with Ro-31-8220 or rottlerin blocked PMA-induced cell adhesion in a concentration-dependent fashion. Inhibition of cytosolic phospholipase A2 (cPLA2) with trifluoromethyl ketone or methyl arachidonyl fluorophosphonate also blocked PMA-induced cell adhesion. PMA caused time-dependent p42/44 mitogen-activated protein kinase (MAPK) (ERK) phosphorylation in these cells. U0126, a MAPK/extracellular signal-regulated protein kinase kinase (MEK) inhibitor, at the concentrations that blocked PMA-induced ERK phosphorylation, had no effect on PMA stimulated AML cell adhesion. Neither p38 MAPK nor c-Jun N-terminal kinase (JNK) was phosphorylated by PMA. PMA also caused increased cPLA2 activity, which was inhibited by Ro-31-8220, but not U0126. Confocal immunofluorescence microscopy showed that PMA caused clustering of CD11b on the cell surface, which was blocked by either PKC or cPLA2 inhibition. PMA stimulation also caused up-regulation of CD11b on the AML cell surface. However, this up-regulation was not affected by cPLA2- or PKC-inhibition. Using the mAb, CBRM1/5, we also demonstrated that PMA does not induce the active conformation of CD11b/CD18. Our data indicate that PMA causes AML cell adhesion through beta2-integrin by PKC activation of cPLA2. This pathway is independent of MEK/ERK and does not require change of CD11b/CD18 to its active conformation. We find that avidity caused by integrin surface clustering - rather than conformational change or up-regulation of CD11b/CD18 - causes PMA stimulated adhesion of AML cells.