System load model for the OFDMA network

In this letter we introduce our system load model for the orthogonal frequency division multiple access (OFDMA) network. We formulate the requirements to the system load model and present its definition. The system load model comprises the uplink load, the downlink load, the sector load, and the network load. We describe our approach to combine the time-frequency and power shared system resources in the OFDMA network.     

Sexual functioning after multimodality treatment for disseminated nonseminomatous testicular germ cell tumor

PURPOSE: We determined sexual functioning after chemotherapy for disseminated nonseminomatous testicular germ cell tumor, and evaluated the impact of resection of post-chemotherapy residual retroperitoneal tumor. MATERIALS AND METHODS: A total of 155 consecutive patients treated with chemotherapy for disseminated nonseminomatous testicular germ cell tumor (between 1980 and 1994) was questioned about their sexual functioning. The patients were divided in 2 subgroups: patients treated with or without resection of post-chemotherapy residual retroperitoneal tumor. Volume and location (divided into left para-aortal or right paracaval/interaortacaval) of the resected tumor were related to absence of ejaculation as well as decreased semen amount. In addition, libido, arousal, erection and orgasm were related to ejaculatory dysfunction. RESULTS: A total of 43 patients (27.7%) was treated with chemotherapy only and 112 (72.3%) had additional resection of post-chemotherapy residual retroperitoneal tumor mass. Overall, 22.4% reported loss of libido, 14.1% decreased arousal, 16% erectile dysfunction, 23.1% decreased orgasmic intensity, 17.4% decreased semen amount and 18.7% complete absence of antegrade ejaculation. With exception of absence of ejaculation, sexual dysfunctions were reported in similar frequencies in both treatment subgroups. In the resection of post-chemotherapy residual retroperitoneal tumor subgroup, 25.9% of the patients had complete absence of ejaculation. The other sexual dysfunctions were related neither to decreased semen amount nor to complete absence of ejaculation. The mean volume of resected tumor was higher (95 cm.3) in patients with absence of ejaculation than in those without (40 cm.3), and patients with right paracaval/interaortacaval tumor (20 of 58, 34.5%) reported more often absence of ejaculation than those with left para-aortal tumor (9 of 54, 16.7%). CONCLUSIONS: In patients treated for disseminated nonseminomatous testicular germ cell tumor, post-chemotherapy sexual morbidity cannot be neglected. Except for loss of antegrade ejaculation, sexual dysfunctions are not related to resection of post-chemotherapy residual retroperitoneal mass. A high volume of tumor and a right paracaval/interaortacaval location predispose to loss of antegrade ejaculation.     

Diagnosis and management of the autonomously functioning thyroid nodule: the Walter Reed Army Medical Center experience, 1975-1996

Skeletal muscle atrophy and weakness are thought to be stimulated by tumor necrosis factor alpha (TNF-alpha) in a variety of chronic diseases. However, little is known about the direct effects of TNF-alpha on differentiated skeletal muscle cells or the signaling mechanisms involved. We have tested the effects of TNF-alpha on the mouse-derived C2C12 muscle cell line and on primary cultures from rat skeletal muscle. TNF-alpha treatment of differentiated myotubes stimulated time- and concentration-dependent reductions in total protein content and loss of adult myosin heavy chain (MHCf) content; these changes were evident at low TNF-alpha concentrations (1-3 ng/ml) that did not alter muscle DNA content and were not associated with a decrease in MHCf synthesis. TNF-alpha activated binding of nuclear factor kappaB (NF-kappaB) to its targeted DNA sequence and stimulated degradation of I-kappaBalpha, an NF-kappaB inhibitory protein. TNF-alpha stimulated total ubiquitin conjugation whereas a 26S proteasome inhibitor (MG132 10-40 microM) blocked TNF-alpha activation of NF-kappaB. Catalase 1 kU/ml inhibited NF-kappaB activation by TNF-alpha; exogenous hydrogen peroxide 200 microM activated NF-kappaB and stimulated I-kappaBalpha degradation. These data demonstrate that TNF-alpha directly induces skeletal muscle protein loss, that NF-kappaB is rapidly activated by TNF-alpha in differentiated skeletal muscle cells, and that TNF-alpha/NF-kappaB signaling in skeletal muscle is regulated by endogenous reactive oxygen species.     

G/C-modified oligodeoxynucleotides with selective complementarity: synthesis and hybridization properties

Modified oligodeoxyribonucleotides (ODNs) that have unique hybridization properties were designed and synthesized for the first time. These ODNs, called selective binding complementary ODNs (SBC ODNs), are unable to form stable hybrids with each other, yet are able to form stable, sequence specific hybrids with complementary unmodified strands of nucleic acid. To make SBC ODNs, deoxyguanosine (dG) and deoxycytidine (dC) were substituted with deoxyinosine (dI) and 3-(2'-deoxy-beta-D-ribofuranosyl)pyrrolo-[2,3-d]-pyrimidine-2-(3H)-one (dP), respectively. The hybridization properties of several otherwise identical complementary ODNs containing one or both of these nucleoside analogs were studied by both UV monitored thermal denaturation and non-denaturing PAGE. The data showed that while dI and dP did form base pairs with dC and dG, respectively, dI did not form a stable base pair with dP. A self-complementary ODN uniformly substituted with dI and dP acquired single-stranded character and was able to strand invade the end of a duplex DNA better than an unsubstituted ODN. This observation implies that SBC ODNs should effectively hybridize to hairpins present in single-stranded DNA or RNA.     

High affinity recognition of serotonin transporter antagonists defined by species-scanning mutagenesis. An aromatic residue in transmembrane domain I dictates species-selective recognition of citalopram and mazindol

Human and Drosophila melanogaster serotonin (5-HT) transporters (SERTs) exhibit similar 5-HT transport kinetics and can be distinguished pharmacologically by many, but not all, biogenic amine transporter antagonists. By using human and Drosophila SERT chimeras, major determinants of potencies of two transporter antagonists, mazindol and citalopram, were tracked to the amino-terminal domains encompassing transmembrane domains I and II. Species-scanning mutagenesis, whereby amino acid substitutions are made switching residues from one species to another, was employed on the eight amino acids that differ between human and Drosophila SERTs in this region, and antagonist potencies were reassessed in 5-HT uptake assays. A single mutation in transmembrane domain I of human SERT, Y95F, shifted both citalopram and mazindol to Drosophila SERT-like potencies. Strikingly, these potency changes were in opposite directions suggesting Tyr95 contributes both positive and negative determinants of antagonist potency. To gain insight into how the Y95F mutant might influence mazindol potency, we determined how structural variants of mazindol responded to the mutation. Our studies demonstrate the importance of the hydroxyl group on the heterocyclic nucleus of mazindol for maintaining species-selective recognition of mazindol and suggest that transmembrane domain I participates in the formation of antagonist-binding sites for amine transporters.     

Are we maintaining the ratio of private practicing pediatric dentists to the number of children?

Using recent ADA and Bureau of the Census reports, national, region and state ratios of pediatric dentists per 100,000 children are provided for the mid-1990s. While national averages continue to improve, there are wide variations at more local levels.