Dominant thalassemia-like phenotypes associated with mutations in exon 3 of the beta-globin gene.

Mutations producing beta-thalassemia reach individual gene frequencies greater than .01 in malarial-endemic regions because beta-thalassemia trait individuals have increased genetic fitness over that of normal individuals. Exon 3 of the beta-globin gene has been relatively spared as a site of common beta-thalassemia mutations. Frameshifts caused by the loss of a single nucleotide and nonsense mutations produce beta-thalassemia trait when they occur in exons 1 and 2. In contrast, they usually produce chronic hemolytic anemia when present in exon 3. Certain missense mutations in exon 3 produce unstable globins and thalassemia intermedia with hemolysis in heterozygotes. Here we report two new mutations in exon 3 of the beta-globin gene. One is a single nucleotide deletion in codon 109 in a 78-year-old Lithuanian with chronic hemolytic anemia and features of thalassemia. It leads to an abnormal globin (beta Manhattan) that is elongated to 156 amino acids. The second is a CAG-CGG missense mutation at codon 127 that causes a Gln----Pro substitution (beta Houston) and a thalassemia intermedia with hemolysis in three generations of a British-American family. Although the clinical phenotypes of these two patients differed little, differences in globin-synthetic ratios were significant, presumably reflecting differences in the ability of each abnormal beta-globin to form alpha beta dimers. The paucity of high-frequency exon 3 mutations and their worldwide distribution is likely attributable to their phenotypic severity and loss of increased genetic fitness vis-a-vis malaria.     

Cellular Pharmacology and Potency of HIV-1 Nucleoside Analogs in Primary Human Macrophages

Understanding the cellular pharmacology of antiretroviral agents in macrophages and subsequent correlation with antiviral potency provides a sentinel foundation for definition of the dynamics between antiretroviral agents and viral reservoirs across multiple cell types, with the goal of eradication of HIV-1 from these cells. Various clinically relevant nucleoside antiviral agents, and the integrase inhibitor raltegravir, were selected for this study. The intracellular concentrations of the active metabolites of the nucleoside analogs were found to be 5- to 140-fold lower in macrophages than in lymphocytes, and their antiviral potency was significantly lower in macrophages constitutively activated with macrophage colony-stimulating factor (M-CSF) during acute infection than in resting macrophages (EC₅₀, 0.4 to 9.42 μM versus 0.03 to 0.4 μM, respectively). Although tenofovir-treated cells displayed significantly lower intracellular drug levels than cells treated with its prodrug, tenofovir disoproxil fumarate, the levels of tenofovir-diphosphate for tenofovir-treated cells were similar in lymphocytes and macrophages. Raltegravir also displayed significantly lower intracellular concentrations in macrophages than in lymphocytes, independent of the activation state, but had similar potencies in resting and activated macrophages. These data underscore the importance of delivering adequate levels of drug to macrophages to reduce and eradicate HIV-1 infection.     

Elongation of primed DNA templates by eukaryotic DNA polymerases.

The combined action of DNA polymerase alpha and DNA polymerase beta leads to the synthesis of full-length linear DNA strands with phi X174 DNA templates containing an RNA primer. The reaction can be carried out in two stages. In the first stage, DNA polymerase alpha catalyzes the synthesis of a chain that averaged 230 deoxynucleotides long and was covalently linked to the RNA primer. In the second stage, DNA polymerase beta elongates the DNA strand covalently attached to the RNA primer to full length. With DNA primers, DNA polymerase alpha catalyzes only limited deoxynucleotide addition whereas DNA polymerase beta alone elongates DNA primed templates to full length. DNA polymerase beta can also stimulate the synthesis of adenovirus DNA in vitro in the presence of a cytosol extract from adenovirus-infected cells. In all of these systems, dNMP incorporation catalyzed by DNA polymerase beta was sensitive to N-ethylmaleimide; however, this polymerase activity was resistant to N-ethylmaleimide with poly(rA) x (dT) as the primer template.     

Esophageal dysfunction and Raynaud's phenomenon in patients with scleroderma

The relationship of Raynaud's phenomenon (RP) to the degree of esophageal motility dysfunction was evaluated in 12 patients with scleroderma. Motility abnormalities of the smooth muscle esophagus were quantitated using a motility index (MI). MI of the scleroderma patients differed significantly from controls. No relationship was noted between the extent of motility abnormality and the duration or severity of the RP. A nearly uniform finding was the absence of coordinated esophageal peristalsis, occurring regardless of the duration or severity of the RP. The study demonstrates that it is not possible to predict the degree of esophageal motility dysfunction in scleroderma based on RP alone. The disease may have two different and independent pathogenetic components. One component is closely linked to RP and involves impairment of neuromuscular electrical transmission. The other component (independent of RP) involves progressive loss of muscle strength in the distal esophagus and in the lower esophageal sphincter.     

Processive DNA helicase activity of the minichromosome maintenance proteins 4, 6, and 7 complex requires forked DNA structures

The minichromosome maintenance (Mcm) proteins 2-7 are required for both the initiation and elongation steps of chromosomal DNA replication. Previous studies have shown that the Mcm complex consisting of the Mcm 4, 6, and 7 proteins contains 3' to 5' DNA helicase activity with limited processivity (displacing duplex DNA regions up to 30 nt). In this report, we show that the presence of both 5' and 3' single-stranded tails in DNA helicase substrates is essential for the processive helicase activity of the Mcm complex. The presence of both 5' and 3' tails facilitated the formation of double heterohexameric complexes of Mcm4/6/7 on substrate DNA, which appeared to be essential for the processive helicase activity. The double heterohexameric complex of Mcm4/6/7, in the presence of a single-strand DNA binding protein, is capable of unwinding duplex DNA region of about 600 bp in length. These results support the hypothesis that the Mcm4/6/7 complex can function as a replication helicase.     

Reduction of opioid use and improvement in chronic pain in opioid-experienced patients after topical analgesic treatment: an exploratory analysis

Objective: There is a need to identify safe and effective opioid-sparing multimodal alternative treatment strategies and approaches, including topical analgesics, for opioid-experienced chronic pain patients to mitigate the risk of addiction, misuse, and abuse of opioids.

Methods: This subset analysis from a prospective, observational study evaluated changes in opioid use, other concurrent medication use, and pain severity and interference in opioid-experienced patients (OEP) treated with topical analgesics for chronic pain with measures obtained at baseline and 3- and 6- month follow-up.

Results: The 3-month opioid-experienced patient (3-month OEP) group included 121 patients who completed baseline and 3-month follow-up assessments; 27 opioid-experienced patients completed baseline and 6-month follow-up assessments (6-month OEP). Demographic characteristics, and mean pain severity and interference scores were similar between groups at baseline. After treatment with topical analgesics, 49% of patients in the 3-month and 56% of patients in the 6-month group reported they had completely discontinued use of opioids. In addition, 31% of patients at the 3-month assessment and 30% at the 6-month assessment reported that they were no longer taking any pain medication. Other concurrent medications decreased by 65% after 3 months, and 74% after 6 months. There were statistically significant decreases from baseline in pain severity and interference scores within the 3- (CI:0.7–1.4, 1.4–2.2) and 6-month (CI:0.7–2.4 (severity); CI:1.2–3.5 (interference)) OEP groups.

Conclusions: Opioid use and other concurrent medications decreased among opioid-experienced chronic pain patients after 3- and 6- months of treatment with topical analgesics. Pain severity and interference scores also decreased. The topical analgesics were reported to be effective and safe for the treatment of chronic pain, with randomized controlled trials needed to confirm these findings.     

Spinal manipulation for low-back pain.

PURPOSE: To review the use, complications, and efficacy of spinal manipulation as a treatment for low-back pain. DATA IDENTIFICATION: Articles were identified through a MEDLINE search, review of articles' bibliographies, and advice from expert orthopedists and chiropractors. STUDY SELECTION: All studies reporting use and complications of spinal manipulation and all controlled trials of the efficacy of spinal manipulation were analyzed. Fifty-eight articles, including 25 controlled trials, were retrieved. DATA ANALYSIS: Data on the use and complications of spinal manipulation were summarized. Controlled trials of efficacy were critically appraised for study quality. Data from nine studies were combined using the confidence profile method of meta-analysis to estimate the effect of spinal manipulation on patients' pain and functional outcomes. RESULTS OF DATA SYNTHESIS: Chiropractors provide most of the manipulative therapy used in the United States for patients with low-back pain. Serious complications of lumbar manipulation, including paraplegia and death, have been reported. Although the occurrence rate of these complications is unknown, it is probably low. For patients with uncomplicated, acute low-back pain, the difference in probability of recovery at 3 weeks favoring treatment with spinal manipulation is 0.17 (for example, increase in recovery from 50% to 67%; 95% probability limits of estimate, 0.07 to 0.28). For patients with low-back pain and sciatic nerve irritation, the difference in probabilities of recovery at 4 weeks is 0.098 (probability limits, -0.016 to 0.209). CONCLUSIONS: Spinal manipulation is of short-term benefit in some patients, particularly those with uncomplicated, acute low-back pain. Data are insufficient concerning the efficacy of spinal manipulation for chronic low-back pain.