Asymmetric deactivation of HIV-1 gp41 following fusion inhibitor binding.

Both equilibrium and nonequilibrium factors influence the efficacy of pharmaceutical agents that target intermediate states of biochemical reactions. We explored the intermediate state inhibition of gp41, part of the HIV-1 envelope glycoprotein complex (Env) that promotes viral entry through membrane fusion. This process involves a series of gp41 conformational changes coordinated by Env interactions with cellular CD4 and a chemokine receptor. In a kinetic window between CD4 binding and membrane fusion, the N- and C-terminal regions of the gp41 ectodomain become transiently susceptible to inhibitors that disrupt Env structural transitions. In this study, we sought to identify kinetic parameters that influence the antiviral potency of two such gp41 inhibitors, C37 and 5-Helix. Employing a series of C37 and 5-Helix variants, we investigated the physical properties of gp41 inhibition, including the ability of inhibitor-bound gp41 to recover its fusion activity once inhibitor was removed from solution. Our results indicated that antiviral activity critically depended upon irreversible deactivation of inhibitor-bound gp41. For C37, which targets the N-terminal region of the gp41 ectodomain, deactivation was a slow process that depended on chemokine receptor binding to Env. For 5-Helix, which targets the C-terminal region of the gp41 ectodomain, deactivation occurred rapidly following inhibitor binding and was independent of chemokine receptor levels. Due to this kinetic disparity, C37 inhibition was largely reversible, while 5-Helix inhibition was functionally irreversible. The fundamental difference in deactivation mechanism points to an unappreciated asymmetry in gp41 following inhibitor binding and impacts the development of improved fusion inhibitors and HIV-1 vaccines. The results also demonstrate how the activities of intermediate state inhibitors critically depend upon the final disposition of inhibitor-bound states.

Kinetic dependence to HIV-1 entry inhibition.

Infection by human immunodeficiency virus type 1 (HIV-1) involves the fusion of viral and cellular membranes mediated by formation of the gp41 trimer-of-hairpins. A designed protein, 5-Helix, targets the C-terminal region of the gp41 ectodomain, disrupting trimer-of-hairpins formation and blocking viral entry. Here we show that the nanomolar inhibitory potency of 5-Helix (IC50 approximately 6 nm) is 4 orders of magnitude larger than its subpicomolar binding affinity (K(D) approximately 0.6 pm). This discrepancy results from the transient exposure of the 5-Helix binding site on gp41. As a consequence, inhibitory potency is determined by the association rate, not by binding affinity. For a series of 5-Helix variants with mutations in their gp41 binding sites, the IC50 and K(D) values poorly correlate. By contrast, an inverse relationship between IC50 values and association rate constants (k(on)) extends for over 2 orders of magnitude. The kinetic dependence to inhibition places temporal restrictions on an intermediate state of HIV-1 membrane fusion and suggests that access to the C-terminal region of the gp41 ectodomain is largely free from steric hindrance. Our results support the importance of association kinetics in the development of improved HIV-1 fusion inhibitors.

HIV-1 gp41 as a target for viral entry inhibition.

The recent success of the fusion inhibitor T-20 (enfuvirtide) in clinical studies has ushered in a new chapter in the development of anti-HIV-1 therapeutics. T-20 is the first FDA-approved drug that targets the viral transmembrane protein gp41. This protein, along with gp120, promotes viral entry through a coordinated cascade of conformational transitions that lead to the fusion of the HIV-1 and target cell membranes. The interaction of gp120 with CD4 and a chemokine receptor stimulates gp41 to extend and bridge the space between the virus and cell. Subsequently, gp41 collapses into a trimer-of-hairpins structure that brings the viral and cellular membranes into close proximity necessary for fusion. Enfuvirtide targets the gp41 amino-terminal region exposed in the transient extended state, blocking the ultimate collapse into the trimer-of hairpins and inhibiting membrane fusion. The vulnerability of this transient extended state has stimulated the development of new agents, ranging from small molecules to large proteins, that bind to gp41 and inhibit its structural transformations. The discovery and characterization of these inhibitors have not only led to new antiviral strategies, but have also shed light on the accessibility of gp41 epitopes that might play a role in HIV-1 vaccine development.

Prenatal diagnosis of hemoglobin Bart's hydrops fetalis by HPLC analysis of hemoglobin in fetal blood samples.

Since HbF and HbA are not found in fetuses with Hb Bart's hydrops fetalis the feasibility of prenatal diagnosis of homozygous alpha-thalassemia 1 by fetal hemoglobin typing was examined. Blood samples were obtained from fetuses at 18 to 22 weeks of gestation by cordocentesis in 32 pregnant women at risk of having a child with homozygous alpha-thalassemia 1 (alpha-thal-1). The samples were analyzed by a PCR-based method for the diagnosis of alpha-thal-1 (SEA type) and the proportion of hemoglobin fractions were determined by automated HPLC. DNA analysis showed that 8 of the 32 fetuses were homozygotes for alpha-thal-1, 17 were heterozygous for alpha-thal-1 (alpha-thal-1 trait), and a normal complement of four a-globin genes was found in 7 cases. The Hb typing in fetuses with homozygous alpha-thal-1 showed a peak of unbound Hb (Hb Bart's and Hb Portland) and no HbF, HbA and HbA The alpha-thal-1 trait chromatograms showed unbound Hb, pre HbF, HbF and HbA peaks. The chromatogram of normal fetuses showed HbF and HbA peaks without HbA2. In these cases the HbA proportion is between 3% and 10% with no apparent differences between the 18h and 22nd week of gestation. As the analysis of fetal Hb types by HPLC is facile and speedy and the results correspond with those obtained by DNA analysis, fetal Hb typing by automated HPLC is a convenient prenatal diagnostic method for homozygous alpha-thal-1. The method is recommended for prenatal diagnosis in populations with a high frequency of alpha-thal-1.

Prenatal diagnosis of beta-thalassemia major by high-performance liquid chromatography analysis of hemoglobins in fetal blood samples.

In Thailand and adjacent countries, most of the beta-thalassemia genes are beta(0)-thalassemia mutations that prevent the production of Hb A. We propose the quantitation of the Hb A fraction in fetal blood in the mid-trimester of pregnancy by automated high performance liquid chromatography as a reasonable prenatal diagnostic method to be applied in areas with limited laboratory facilities. Forty pregnant women at risk of delivering a child with beta-thalassemia major were identified using an erythrocyte osmotic fragility test and quantitation of Hb A2. Cordocentesis was performed at the gestational age of 18-22 weeks and fetal blood was analyzed for hemoglobin fractions by automated high performance liquid chromatography. The beta-globin gene mutations were characterized by beta-globin gene sequencing. The 4 bp deletion at codons 41/42 (-TTCT) was the most frequent of the 40 beta-thalassemia mutations observed (20/40 = 50%), followed by the splice site mutation IVS-I-1 (G-->T) (7/40 = 17.5%), the nonsense mutation at codon 17 (A-->T) (7/40 = 17.5%), the nonsense mutation at codon 35 (C-->A) (3/40 = 7.5%), and the beta(+)-thalassemia promoter mutation at -28 (A-->G) (3/40 = 7.5%). High performance liquid chromatography revealed nine fetuses which had only Hb F and no Hb A. All were homozygotes or compound heterozygotes for beta(0)-thalassemia mutations. In the remaining 31 fetuses, a Hb A peak was present in the chromatograms. One fetus with 0.5% Hb A was a compound heterozygote for the -28 (A-->G) and codons 41/42 (-TTCT) mutations. In the remaining 30 fetuses, the Hb A values ranged between 0.8 and 7.4%. Twenty of these, with a Hb A concentration of 1.82 +/- 0.49% (range 0.8-2.8%), were beta-thalassemia heterozygotes. The remaining 10 fetuses had Hb A values of 4.89 +/- 1.47% (range 2.9-7.4%) and normal beta-globin genes. The absence of Hb A in homozygotes or compound heterozygotes for beta(0)-thalassemia mutations and the presence of measurable amounts of Hb A in heterozygotes and normal homozygotes, permits the diagnosis of fetuses expected to develop postnatal beta-thalassemia major.

Prenatal eradication of Hb Bart's hydrops fetalis.

OBJECTIVE: To evaluate the effectiveness of prenatal prevention of Hb Bart's hydrops fetalis. STUDY DESIGN: The study was a prospective descriptive analysis of pregnant women attending an antenatal clinic between June 1990 and June 1998. The study consisted of two periods, the first half with no prenatal diagnosis (PND) (1990-1994) and the second half with PND. During the study period, all cases of Hb Bart's hydrops fetalis were prospectively collected and postnatally confirmed. In the second period, prenatal strategy to control severe thalassemia was introduced. The strategy included (1) carrier identification by retrospective (history review for known risk) and prospective screening (simple erythrocyte osmotic fragility test) in women without known risks, (2) the couples at risk were offered genetic counseling and cordocentesis, (3) analysis of fetal blood for diagnosis, and (4) counseling for termination of pregnancy. RESULTS: During the first half of the study, the prevalence of Hb Bart's hydrops fetalis was 0.305 (89 in 29,399 deliveries). There were no fetuses with Hb Bart's hydrops fetalis among 16,360 screened pregnancies in the second half. However, of 6,856 pregnancies in the second half not screened due to a late first visit, 10 (0.15%) fetuses had Hb Bart's hydrops fetalis. Among the screened group, cordocentesis was performed in 361 pregnancies at risk, 170 and 191 from retrospective and prospective screening, respectively; and 75 (20.8%) were proven to have Hb Bart's disease, which was diagnosed before hydropic changes occurred. CONCLUSION: The strategy proved effective in preventing Hb Bart's hydrops fetalis, and extensive experience with it suggests that it be considered an effective way to control severe thalassemia.

The distribution of D1S80 and VWA alleles in a Karen population from Northern Thailand.

The DIS80 and VWA loci were studied in a Karen population from Northern Thailand by the polymerase chain reaction and polyacrylamide gel electrophoresis. Twelve DIS80 and six VWA alleles were found. No deviations from the Hardy-Weinberg and linkage equilibrium were observed. The power of exclusion (PE) from the analysis of the DIS80 and VWA locus is 0.67 and 0.45, respectively, the power of discrimination (PD) is 0.95 and 0.85, respectively, with a combined PD of 0.99 and PE of 0.82.

[Bilateral idiopathic femur head epiphyseolysis ("slipped epiphysis") in cats: literature review and case description]. / Bilaterale idiopathische Femurkopfepiphyseolyse ("slipped epiphysis") bei der Katze: Literaturübersicht und Fallbeschreibung.

One case of a bilateral idiopathic slipped capital femoral epiphysis--"slipped epiphysis"--in a cat is described. The similarities and the differences between the cases in human and small animal medicine concerning the incidence, the hypotheses of the pathogenesis and the treatment options are discussed.

Screening for alpha-thalassemia-1 heterozygotes in expecting couples by the combination of a simple erythrocyte osmotic fragility test and a PCR-based method.

OBJECTIVE: To develop a simple method for the prospective identification of couples at risk of homozygous alpha-thalassemia-1 (Hb Bart's hydrops fetalis) in pregnancy. METHODS: Antenatal care (ANC) women and their husbands were analyzed using a simple erythrocyte osmotic fragility (EOF) test and a PCR-based method for the detection of the mutation leading to alpha-thalassemia-1 of the Southeast Asian type (SEA). RESULTS: Heterozygosity for the alpha-thalassemia-1 (SEA) deletion was found to correlate with an EOF value <60%. For a prospective screening, ANC women and their husbands are analyzed with the EOF test and only those having a value <60% were further checked by PCR. Of 2,769 cases analyzed during a 6-month period, 24 couples in which both partners are heterozygotes could be identified for genetic counseling and prenatal diagnosis. The application of the EOF test decreased the workload for PCR by approximately 80%. CONCLUSION: Prospective screening for alpha-thalassemia-1 (SEA) heterozygotes in northern Thailand is becoming easier to realize by the combination of EOF test and PCR.

An investigation of the TH01 locus in a population from northern Thailand.

The STR locus HUMTH01 was studied in 110 unrelated Thais from the area of Chiang Mai in North Thailand. By using PCR and vertical PAGE, six alleles were identified and the frequencies ranged from 0.005 to 0.400. The allele frequency distribution in this population showed significant differences from a Japanese population and other ethnic populations but was similar to Asians in the USA and Australia. The genotype distribution meets Hardy-Weinberg expectations. The average power of exclusion (in no-parent and one-parent cases) and the discriminating power (DP) were calculated to be 0.3020, 0.4761 and 0.8722 respectively.

Frequency distribution of D1S80 alleles in the northern Thai population analyzed by amplified fragment length polymorphism technique.

A population study on the D1S80 locus in 100 northern Thais was performed using polymerase chain reaction (PCR) and high resolution polyacrylamide gel electrophoresis. Sixteen alleles and 39 genotypes were observed with a heterozygosity of 82%. In contrast to other studies, the allele with 31 repeat units was found to be the most common, followed by alleles 24 and 18. Alleles with more than 41 repeat units were also observed in this study. When applying statistical tests for Hardy-Weinberg equilibrium, no significant deviations were found in this Thai population. The average power of exclusion (in no-parent and one-parent cases) and the discriminating power (DP) was calculated to be 0.52, 0.69 and 0.94, respectively.

Frequency of alpha-thalassemia-1 of the Southeast Asian-type among pregnant women in northern Thailand determined by PCR technique.

Five hundred pregnant women were analyzed for the presence of alpha-thalassemia-1 of the Southeast Asian (SEA)-type by polymerase chain reaction (PCR) technique at the Maharaj Nakhon Chiang Mai University Hospital in Chiang Mai during the period from April to June 1995. Forty-four of them (8.8%) were recognized as carriers, corresponding to a frequency of 0.044. Homozygous alpha-thalassemia-1 of the SEA-type, the fatal condition of hemoglobin Bart's hydrops fetalis, has an expected frequency of 0.00194, or about 2 hydrops fetalis cases per 1,000 births in this population.

Comparison of morphine and morphine with ketamine for postoperative analgesia.

PURPOSE: The purpose of this study was to compare morphine with ketamine to morphine alone in a double-blind investigation of postsurgical pain control. METHODS: Forty-two ASA 1 and 2 patients undergoing elective microdiscectomy were administered either 1 mg.ml-1 of morphine (n = 20) or 1 mg.ml-1 of both morphine and ketamine (n = 22) via iv patient controlled analgesia (IVPCA). Pain relief and side effects were assessed at 24 hr after surgery. RESULTS: The mean (SD) visual analogue scale (VAS) pain rating of 2.3 (1.67) for patients receiving morphine with ketamine was lower (P < 0.001) than the VAS scores of patients receiving only morphine 4.5 (1.54). Patients receiving morphine and ketamine also had less difficulty with side effects, reporting less nausea (P < 0.05), pruritus (P < 0.001), and urinary retention (P < 0.05). Although dysphoria is reported to be a common side effect of ketamine, complaints of dysphoria were rare in both groups, with only one subject (5%) in the morphine with ketamine group and three (15%) subjects receiving morphine alone reporting this side effect. CONCLUSION: IVPCA ketamine in combination with morphine provides superior postsurgical pain relief at lower dosage and with fewer side effects than morphine alone.

Multidimensional Pain Inventory profile classifications and psychopathology.

The Multidimensional Pain Inventory (MPI) and the MMPI have been used widely to assess chronic pain patients. This study examined the relationship between patient profile classifications generated by the MPI and psychopathology as measured by the MMPI. MPI Dysfunctional and Interpersonally Distressed means were significantly different than the MPI Adaptive Coper means on scales 4, 6, 7, and 8 of the MMPI. The Dysfunctional and Adapative Coper means were also significantly different on MMPI scale 2. MMPI profiles for 79% classified as Dysfunctional and 62% classified as Interpersonally Distressed displayed psychopathology as defined by significant two-point scale elevations. Only 23% of those classified as Adaptive Copers had significant two-point MMPI scale elevations.

Subcutaneous recombinant human erythropoietin in children with renal anemia on continuous ambulatory peritoneal dialysis.

Subcutaneous recombinant human erythropoietin (rHuEpo) treatment of renal anemia was performed in four boys and eight girls on CAPD, aged 0.8-12.5 (mean 7.4) years. In contrast to previous studies, our therapeutic goal was not set with a hematocrit of 30% but with full correction of anemia. Following a maximum weekly rHuEpo dosage of median 120 (range 100-240) IU/kg body weight, hematocrit increased in 10 children from 24 (14-29)% within 12 (4-17) weeks to 40.1 (33.5-48.4)%. The weekly increase in hematocrit was 1.27 (0.5-3.1)%. The corrected reticulocyte count increased from 1.3 (0.7-1.8)% to 2.3 (1.4-3.9)% within 4 (2-6) weeks. Eight children fulfilled the protocol; six with an uncomplicated course were able to maintain a hematocrit of 37.1 (35.1-42.7)% with only one sc medication per week of approximately two-thirds of their highest weekly rHuEpo dosage. No serious adverse effect of rHuEpo therapy was observed.

Hemoglobin E and codon 17 nonsense: two beta-globin gene mutations common in Southeast Asia detected by the use of ARMS.

Hemoglobin E (codon 26 GAG-->AAG) and codon 17 nonsense (AAG-->TAG), two clinically important mutations of the beta-globin gene, are common in Southeast Asia. The detection of these mutations using allele-specific PCR is described. Together with the previously reported method for the detection of the common Southeast asian codon 41-42 frameshift mutation (del CTTT), it is possible to identify the vast majority of clinically important beta-globin gene mutations in Southeast Asian populations by means of nonradioactive methods.

Identification of the mitochondrial receptor complex in Saccharomyces cerevisiae.

Mitochondrial protein import involves the recognition of preproteins by receptors and their subsequent translocation across the outer membrane. In Neurospora crassa, the two import receptors, MOM19 and MOM72, were found in a complex with the general insertion protein, GIP (formed by MOM7, MOM8, MOM30 and MOM38) and MOM22. We isolated a complex out of S. cerevisiae mitochondria consisting of MOM38/ISP42, the receptor MOM72, and five new yeast proteins, the putative equivalents of N. crassa MOM7, MOM8, MOM19, MOM22 and MOM30. A receptor complex isolated out of yeast cells transformed with N. crassa MOM19 contained the N. crassa master receptor in addition to the yeast proteins. This demonstrates that the yeast complex is functional, and provides strong evidence that we also have identified the yeast MOM19.

Pediatric and perinatal reference intervals for immunoglobulin light chains kappa and lambda.

In routine analysis for immunoglobulin light chains in pediatric diagnostics, the age-related reference intervals for serum kappa (kappa) and lambda (lambda) light chains were evaluated in 1543 healthy subjects (newborns to age 16 years, including 168 premature infants). Light-chain analysis was performed by rate nephelometry. IgG, IgA, and IgM were measured simultaneously, and heavy- and light-chain differences were calculated for control purposes. Results for IgG, IgA, and IgM generally agreed with reference intervals reported in the literature. kappa showed age-related changes comparable with changes in IgG concentrations, whereas lambda showed moderate fluctuations. The kappa/lambda ratio showed an almost linear increase with age, starting with 0.97 at four months and reaching the highest value of 2.21 at 15 years (mean values). Preterm infants presented with markedly low serum concentrations of IgG and corresponding light chains but with adult-type kappa/lambda ratios because of the maternal-origin IgG.