Therapeutic strategies to correct malfunction of CFTR

Cystic fibrosis (CF) is a systemic autosomal recessive inherited disorder that results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Although the gene was cloned 11 years ago, there still is no definitive treatment to correct the functional deficit. Current treatment strategies focus on pancreatic enzyme replacement and control of pulmonary inflammation and infection. This review examines novel strategies still in preclinical development or phase 1 clinical trials. Gene therapy is an evolving area of study that offers the potential for a cure for cystic fibrosis. CF lung disease is a significant barrier to effective gene delivery and transfer, but new vectors show promise in overcoming these limitations. There are also new pharmacological therapies aimed at correcting defects in CFTR processing and function. These are tailored to the specific class of mutation but may offer therapeutic benefit to many patients. They include phenylbutyrate, flavonoids, aminoglycosides and xanthines.

Skp2 is oncogenic and overexpressed in human cancers

Skp2 is a member of the F-box family of substrate-recognition subunits of SCF ubiquitin-protein ligase complexes that has been implicated in the ubiquitin-mediated degradation of several key regulators of mammalian G(1) progression, including the cyclin-dependent kinase inhibitor p27, a dosage-dependent tumor suppressor protein. In this study, we examined Skp2 and p27 protein expression by immunohistochemistry in normal oral epithelium and in different stages of malignant oral cancer progression, including dysplasia and oral squamous cell carcinoma. We found that increased levels of Skp2 protein are associated with reduced p27 in a subset of oral epithelial dysplasias and carcinomas compared with normal epithelial controls. Tumors with high Skp2 (>20% positive cells) expression invariably showed reduced or absent p27 and tumors with high p27 (>20% positive cells) expression rarely showed Skp2 positivity. Increased Skp2 protein levels were not always correlated with increased cell proliferation (assayed by Ki-67 staining), suggesting that alterations of Skp2 may contribute to the malignant phenotype without affecting proliferation. Skp2 protein overexpression may lead to accelerated p27 proteolysis and contribute to malignant progression from dysplasia to oral epithelial carcinoma. Moreover, we also demonstrate that Skp2 has oncogenic potential by showing that Skp2 cooperates with H-Ras(G12V) to malignantly transform primary rodent fibroblasts as scored by colony formation in soft agar and tumor formation in nude mice. The observations that Skp2 can mediate transformation and is up-regulated during oral epithelial carcinogenesis support a role for Skp2 as a protooncogene in human tumors.

Noise-Enhanced Measurement of Weak Doublet Spectra with a Fourier-Transform Spectrometer and a 1-Bit Analog-to-Digital Converter

We demonstrate an efficient noise dithering procedure for measuring the power spectrum of a weak spectral doublet with a Fourier-transform spectrometer in which the subthreshold interferogram is measured by a 1-bit analog-to-digital converter without oversampling. In the absence of noise, no information is obtained regarding the doublet spectrum because the modulation term s(x) of its interferogram is below the instrumental detection limit B, i.e., |s(x)| < B, for all path difference x values. Extensive numerical experiments are carried out concerning the recovery of the doublet power spectrum that is represented by s(x) = (s(0)/2)exp(-pi(2)x(2)/beta)[cos(2pif(1)x) + cos(2pif(2)x)], where s(0) is a constant, beta is the linewidth factor, and ?f? = (f(1) + f(2))/2. Different values of ?f?, s(0), and beta are considered to evaluate thoroughly the accuracy of the procedure to determine the unknown values of f(1) and f(2), the spectral linewidth, and the peak values of the spectral profiles. Our experiments show that, even for short observation times, the resonant frequencies of s(x) could be located with high accuracy over a wide range of ?f? and beta values. Signal-to-noise ratios as high as 50 are also gained for the recovered power spectra. The performance of the procedure is also analyzed with respect to another method that recovers the amplitude values of s(x) directly.

Changes in the biomechanical properties of neutrophils and endothelial cells during adhesion

This study examined changes in the biomechanical properties of cultured pulmonary microvascular endothelial cells (ECs) and neutrophils induced by adhesion of neutrophils to these ECs. The biomechanical properties of cells were evaluated using magnetic twisting cytometry, which measures the angular rotation of ferromagnetic beads bound to cells through antibody ligation on application of a specified magnetic torque. Adhesion of neutrophils to 24-hour tumor necrosis factor-alpha (TNF-alpha)-treated ECs, but not to untreated ECs, induced an increase in EC stiffness within 2 minutes, which was accompanied by an increase and a reorganization of F-actin in ECs. A cell-permeant, phosphoinositide-binding peptide attenuated the EC stiffening response, suggesting that intracellular phosphoinositides are required. The stiffening response was not inhibited by ML-7, a myosin light-chain kinase inhibitor, or BAPTA, an intracellular Ca2+ chelator. Moreover, the phosphorylation pattern of the regulatory myosin light chains was unaltered within 15 minutes of neutrophil adherence. These data suggested that the EC stiffening response appeared not to be mediated by myosin light-chain-dependent mechanisms. Concomitantly, neutrophil adhesion to 24-hour TNF-alpha-treated ECs also induced changes in the biomechanical properties of neutrophils compared to neutrophils bound to untreated ECs. Taken together, these results demonstrated that neutrophil adhesion to TNF-alpha-treated ECs induces changes in the biomechanical properties of both cell types through actin cytoskeletal remodeling. These changes may modulate neutrophil transmigration across the endothelium during inflammation.

Optical-feedback semiconductor laser Michelson interferometer for displacement measurements with directional discrimination

An optical-feedback semiconductor laser Michelson interferometer (OSMI) is presented for measuring microscopic linear displacements without ambiguity in the direction of motion. The two waves from the interferometer arms, one from the reference mirror and the other from the reflecting moving target, are fed back into the lasing medium (lambda = 830 nm), causing variations in the laser output power. We model the OSMI into an equivalent Fabry-Perot resonator and derive the dependence of the output power (and the junction voltage) on the path difference between the two interferometer arms. Numerical and experimental results consistently show that the laser output power varies periodically (period, lambda/2) with path difference. The output power variation exhibits an asymmetric behavior with the direction of motion, which is used to measure, at subwavelength resolution, the displacement vector (both amplitude and direction) of the moving sample. Two samples are considered in the experiments: (i) a piezoelectric transducer and (ii) an audio speaker.

New selectable marker/auxotrophic host strain combinations for molecular genetic manipulation of Pichia pastoris

We describe the isolation and characterization of three new biosynthetic genes-ARG4, ADE1, and URA3-from the methylotrophic yeast Pichia pastoris. The predicted products of the genes share significant sequence similarity to their Saccharomyces cerevisiae counterparts, namely argininosuccinate lyase, PR-aminoimidazolesuccinocarboxamide synthase, and orotidine-5'-phosphate decarboxylase, respectively. Along with the previously described HIS4 gene, each gene was incorporated as the yeast selectable marker into a set of shuttle vectors designed to express foreign genes in P. pastoris. In addition, we have constructed a series of host strains containing all possible combinations of ade1, arg4, his4, and ura3 auxotrophies to be used with these new vectors.

Identification, characterization, and mapping of expressed sequence tags from an embryonic zebrafish heart cDNA library

The generation of expressed sequence tags (ESTs) has proven to be a rapid and economical approach by which to identify and characterize expressed genes. We generated 5102 ESTs from a 3-d-old embryonic zebrafish heart cDNA library. Of these, 57.6% matched to known genes, 14.2% matched only to other ESTs, and 27.8% showed no match to any ESTs or known genes. Clustering of all ESTs identified 359 unique clusters comprising 1771 ESTs, whereas the remaining 3331 ESTs did not cluster. This estimates the number of unique genes identified in the data set to be approximately 3690. A total of 1242 unique known genes were used to analyze the gene expression patterns in the zebrafish embryonic heart. These were categorized into seven categories on the basis of gene function. The largest class of genes represented those involved in gene/protein expression (25.9% of known transcripts). This class was followed by genes involved in metabolism (18.7%), cell structure/motility (16.4%), cell signaling and communication (9.6%), cell/organism defense (7.1%), and cell division (4.4%). Unclassified genes constituted the remaining 17.91%. Radiation hybrid mapping was performed for 102 ESTs and comparison of map positions between zebrafish and human identified new synteny groups. Continued comparative analysis will be useful in defining the boundaries of conserved chromosome segments between zebrafish and humans, which will facilitate the transfer of genetic information between the two organisms and improve our understanding of vertebrate evolution.

Generation and structural analysis of soluble oligomeric gp140 envelope proteins derived from neutralization-resistant and neutralization-susceptible primary HIV type 1 isolates

We generated DNA constructs expressing soluble truncated forms of the envelope of SF162, a neutralization-resistant primary human immunodeficiency virus type 1 isolate, and SF162AV2, a neutralization-susceptible virus derived from SF162 after the deletion of 30 amino acids from the V2 loop. The constructs express the entire gp120 subunit and the extracellular region of the gp41 subunit, with either the presence ("cleaved" forms, designated gp140C) or the absence ("fused" forms, designated gp140F) of the gp120-gp41 cleavage site. Both gp140 forms derived from SF162 and SF162deltaV2 are secreted in the cell medium and are recognized by the oligomer-specific anti-gp41 MAb T4. As is the case for the corresponding virion-associated envelope molecules, the CD4-binding region is occluded within both gp140F and gp140C forms. However, structural differences exist between these two forms. The gp140F proteins are less efficiently recognized than the gp140C proteins by antibodies present in the sera of HIV-infected patients with neutralizing activities against SF162 and SF162AV2. Also, the V3 loop is more exposed on gp140F than gp140C. As is the case for intact virions, on CD4 binding both the gp140F and gp140C proteins undergo conformational changes that result in the exposure of the epitope recognized by MAb 17b, which has been implicated in coreceptor binding. In contrast, during these structural changes the exposure of specific V3 loop epitopes is not increased on either gp140C or gp140F. Taken together, our data indicate that although these gp140 forms differ structurally from the native envelope, their similarities, in particular that of gp140C, outweigh their differences.

Global experience in cervical carotid artery stent placement

The purpose of this article is to review and update the current status of carotid artery stent placement in the world. Surveys to major interventional centers in Europe, North and South America, and Asia were initially completed in June 1997. Subsequent information from these 24 centers in addition to 12 new centers has been obtained to update the information. The survey asked the various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 5,210 procedures involving 4,757 patients. There was a technical success of 98.4% with 5,129 carotid arteries treated. Complications that occurred during the carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 134 transient ischemic attacks (TIAs) for a rate of 2.82%. Based on the total patient population, there were 129 minor strokes with a rate of occurrence of 2.72%. The total number of major strokes was 71 for a rate of 1.49%. There were 41 deaths within a 30-day postprocedure period resulting in a mortality rate of 0.86%. The combined minor and major strokes and procedure-related death rate was 5.07%. Restenosis rates of carotid stenting have been 1.99% and 3.46% at 6 and 12 months, respectively. The rate of neurologic events after stent placement has been 1.42% at 6-12-month follow-up. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative for vascular surgery, especially for patients that are high risk for standard carotid endarterectomy. The periprocedure risks for major and minor strokes and death are generally acceptable at this early stage of development and have not changed significantly since the first survey results. Cathet. Cardiovasc. Intervent. 50:160-167, 2000.

Vibrational population relaxation of carbon monoxide in the heme pocket of photolyzed carbonmonoxy myoglobin: comparison of time-resolved mid-IR absorbance experiments and molecular dynamics simulations

The vibrational energy relaxation of carbon monoxide in the heme pocket of sperm whale myoglobin was studied by using molecular dynamics simulation and normal mode analysis methods. Molecular dynamics trajectories of solvated myoglobin were run at 300 K for both the delta- and epsilon-tautomers of the distal His-64. Vibrational population relaxation times of 335 +/- 115 ps for the delta-tautomer and 640 +/- 185 ps for the epsilon-tautomer were estimated by using the Landau-Teller model. Normal mode analysis was used to identify those protein residues that act as the primary "doorway" modes in the vibrational relaxation of the oscillator. Although the CO relaxation rates in both the epsilon- and delta-tautomers are similar in magnitude, the simulations predict that the vibrational relaxation of the CO is faster in the delta-tautomer with the distal His playing an important role in the energy relaxation mechanism. Time-resolved mid-IR absorbance measurements were performed on photolyzed carbonmonoxy hemoglobin (Hb(13)CO). From these measurements, a T(1) time of 600 +/- 150 ps was determined. The simulation and experimental estimates are compared and discussed.

Overexpression of hypoxia-inducible factor 1alpha in common human cancers and their metastases

Neovascularization and increased glycolysis, two universal characteristics of solid tumors, represent adaptations to a hypoxic microenvironment that are correlated with tumor invasion, metastasis, and lethality. Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding glucose transporters, glycolytic enzymes, and vascular endothelial growth factor. HIF-1 transcriptional activity is determined by regulated expression of the HIF-1alpha subunit. In this study, HIF-1alpha expression was analyzed by immunohistochemistry in 179 tumor specimens. HIF-1alpha was overexpressed in 13 of 19 tumor types compared with the respective normal tissues, including colon, breast, gastric, lung, skin, ovarian, pancreatic, prostate, and renal carcinomas. HIF-1alpha expression was correlated with aberrant p53 accumulation and cell proliferation. Preneoplastic lesions in breast, colon, and prostate overexpressed HIF-1alpha, whereas benign tumors in breast and uterus did not. HIF-1alpha overexpression was detected in only 29% of primary breast cancers but in 69% of breast cancer metastases. In brain tumors, HIF-1alpha immunohistochemistry demarcated areas of angiogenesis. These results provide the first clinical data indicating that HIF-1alpha may play an important role in human cancer progression.

Induction of immunity to prostate cancer antigens: results of a clinical trial of vaccination with irradiated autologous prostate tumor cells engineered to secrete granulocyte-macrophage colony-stimulating factor using ex vivo gene transfer

Vaccination with irradiated granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting gene-transduced cancer vaccines induces tumoricidal immune responses. In a Phase I human gene therapy trial, eight immunocompetent prostate cancer (PCA) patients were treated with autologous, GM-CSF-secreting, irradiated tumor vaccines prepared from ex vivo retroviral transduction of surgically harvested cells. Expansion of primary cultures of autologous vaccine cells was successful to meet trial specifications in 8 of 11 cases (73%); the yields of the primary culture cell limited the number of courses of vaccination. Side effects were pruritus, erythema, and swelling at vaccination sites. Vaccine site biopsies manifested infiltrates of dendritic cells and macrophages among prostate tumor vaccine cells. Vaccination activated new T-cell and B-cell immune responses against PCA antigens. T-cell responses, evaluated by assessing delayed-type hypersensitivity (DTH) reactions against untransduced autologous tumor cells, were evident in two of eight patients before vaccination and in seven of eight patients after treatment. Reactive DTH site biopsies manifested infiltrates of effector cells consisting of CD45RO+ T-cells, and degranulating eosinophils consistent with activation of both Th1 and Th2 T-cell responses. A distinctive eosinophilic vasculitis was evident near autologous tumor cells at vaccine sites, and at DTH sites. B-cell responses were also induced. Sera from three of eight vaccinated men contained new antibodies recognizing polypeptides of 26, 31, and 150 kDa in protein extracts from prostate cells. The 150-kDa polypeptide was expressed by LNCaP and PC-3 PCA cells, as well as by normal prostate epithelial cells, but not by prostate stromal cells. No antibodies against prostate-specific antigen were detected. These data suggest that both T-cell and B-cell immune responses to human PCA can be generated by treatment with irradiated, GM-CSF gene-transduced PCA vaccines.

Receptor-mediated gene transfer to cells of hepatic origin by galactosylated albumin-polylysine complexes

To study whether we could enhance the liver targeting of DNA delivery via asialoglycoprotein receptors using a complex of poly-L-lysine (PLL)-condensed DNA and galactosylated bovine serum albumin (GalBSA) (GPD complex), DNA was first combined with PLL and then with GalBSA via charge interaction (GalBSA: PLL: DNA=3:0.5:1, w/w/w). This vector was characterized by dynamic laser light scattering, gel retardation assay, and electron microscopy to determine the particle size, electrostatic charge interaction, and 3-D structure. An electron micrography of GPD complex, where GalBSA: PLL: DNA=3:0.5:1 (w/w/w), showed a structure of spherical particles with a mean diameter of 145+/-24.2 nm, and the complex was positively charged. The complex was tested for specificity and efficiency of gene transfer in cultured human hepatoblastoma cell line Hep G2 and mouse fibroblast cells NIH/3T3 in vitro. Cellular uptake was specifically dependent on the abundance of galactose receptors on target cells. Hep G2 cells transfected with GPD complexed with the fusogenic peptide KALA (WEAKLAKALAKALAKHLAKALAKALKACEA) showed a significantly higher reporter gene activity than those transfected with GPD complex alone or free DNA-KALA complex. The efficiency of gene transfer mediated by GPD-KALA complex was not affected by the presence of serum in the transfection medium. The reporter gene activity in NIH/3T3 cells transfected with GPD complex was very low regardless of the presence of KALA and almost the same as that transfected with bovine serum albumin (BSA)-PLL-DNA complex (BPD complex). This gene transfer formulation may find potential applications for the gene therapy of liver diseases.

The two-dimensional IR nonlinear spectroscopy of a cyclic penta-peptide in relation to its three-dimensional structure

A form of two-dimensional (2D) vibrational spectroscopy, which uses two ultrafast IR laser pulses, is used to examine the structure of a cyclic penta-peptide in solution. Spectrally resolved cross peaks occur in the off-diagonal region of the 2D IR spectrum of the amide I region, analogous to those in 2D NMR spectroscopy. These cross peaks measure the coupling between the different amide groups in the structure. Their intensities and polarizations relate directly to the three-dimensional structure of the peptide. With the help of a model coupling Hamiltonian, supplemented by density functional calculations, the spectra of this penta-peptide can be regenerated from the known solution phase structure. This 2D-IR measurement, with an intrinsic time resolution of less than 1 ps, could be used in all time regimes of interest in biology.

Protein fluctuations are sensed by stimulated infrared echoes of the vibrations of carbon monoxide and azide probes

The correlation functions of the fluctuations of vibrational frequencies of azide ions and carbon monoxide in proteins are determined directly from stimulated photon echoes generated with femtosecond infrared pulses. The asymmetric stretching vibration of azide bound to carbonic anhydrase II exhibits a pronounced evolution of its vibrational frequency distribution on the time scale of a few picoseconds, which is attributed to modifications of the ligand structure through interactions with the nearby Thr-199. When azide is bound in hemoglobin, a more complex evolution of the protein structure is required to interchange the different ligand configurations, as evidenced by the much slower relaxation of the frequency distribution in this case. The time evolution of the distribution of frequencies of carbon monoxide bound in hemoglobin occurs on the approximately 10-ps time scale and is very nonexponential. The correlation functions of the frequency fluctuations determine the evolution of the protein structure local to the probe and the extent to which the probe can navigate those parts of the energy landscape where the structural configurations are able to modify the local potential energy function of the probe.

Tumor-derived EMMPRIN (extracellular matrix metalloproteinase inducer) stimulates collagenase transcription through MAPK p38

EMMPRIN (extracellular matrix metalloproteinase inducer) stimulates fibroblast metalloproteinases (MMP) 1, 2 and 3 (Kataoka et al. (1993) Cancer Res. 53, 3154-3158). Here we focus on MMP-1, showing that in lung tumors, MMP-1's cognate mRNA is strongly expressed in stromal fibroblasts adjacent to EMMPRIN-expressing tumor cells. In vitro, EMMPRIN upregulates MMP-1 mRNA expression in a concentration-dependent manner, with a peak accumulation at 24 h. The response is genistein-sensitive, suggesting it is dependent on tyrosine kinase activity. Analysis of tyrosine phosphorylation-dependent MAP kinases ERK 1/2, SAPK/JNK, and p38 showed that the activity of p38 but not that of the other 2 kinases was elevated in response to EMMPRIN. That p38 activity was required for EMMPRIN stimulation of MMP-1 was evident from results showing that the p38 inhibitor SB203580 blocked this response. This is the first available information regarding the mechanism by which tumor-associated molecules upregulate MMP synthesis in stromal fibroblasts.

Class restriction of cephalosporin use to control total cephalosporin resistance in nosocomial Klebsiella

CONTEXT

Resistance to most or all cephalosporin antibiotics in Klebsiella species has developed in many European and North American hospitals during the past 2 decades.

OBJECTIVE

To determine if restriction of use of the cephalosporin class of antibiotics would reduce the incidence of patient infection or colonization by cephalosporin-resistant Klebsiella.

DESIGN

A before-after comparative 2-year trial.

SETTING

A 500-bed, university-affiliated community hospital in Queens, NY.

PATIENTS

All adult medical and surgical hospital inpatients.

INTERVENTION

A new antibiotic guideline excluded the use of cephalosporins except for pediatric infection, single-dose surgical prophylaxis, acute bacterial meningitis, spontaneous bacterial peritonitis, and outpatient gonococcal infection. All other cephalosporin use required prior approval by the infectious disease section.

MAIN OUTCOME MEASURE

Incidence of patient infection or colonization by ceftazidime-resistant Klebsiella during 1995 (control period) compared with 1996 (intervention period).

RESULTS

An 80.1% reduction in hospital-wide cephalosporin use occurred in 1996 compared with 1995. This was accompanied by a 44.0% reduction in the incidence of ceftazidime-resistant Klebsiella infection and colonization throughout the medical center (P<.01), a 70.9% reduction within all intensive care units (P<.001), and an 87.5% reduction within the surgical intensive care unit (P<.001). A concomitant 68.7% increase in the incidence of imipenem-resistant Pseudomonas aeruginosa occurred throughout the medical center (P<.01). All such isolates except one were susceptible to other antibiotics.

CONCLUSION

Extensive cephalosporin class restriction significantly reduced nosocomial, plasmid-mediated, cephalosporin-resistant Klebsiella infection and colonization. This occurred at the price of increased imipenem resistance in P aeruginosa, which remained susceptible to other agents. Thus, an overall reduction in multiply-resistant pathogens was achieved within 1 year.

Current global status of carotid artery stent placement

Our purpose was to review the current status of carotid artery stent placement throughout the world. Surveys were sent to major interventional centers in Europe, North and South America, and Asia. Information from peer-reviewed journals was also included and supplemented the survey. The survey asked various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. Of the centers which were sent surveys, 24 responded. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 2,048 cases, with a technical success of 98.6%. Complications that occurred during carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 63 minor strokes, with a rate of occurrence of 3.08%. The total number of major strokes was 27, for a rate of 1.32%. There were 28 deaths within a 30-day postprocedure period, resulting in a mortality rate of 1.37%. Restenosis rates of carotid stenting have been 4.80% at 6 mo. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative to vascular surgery, especially for patients that are at high risk for standard carotid endarterectomy. The periprocedural risks for major and minor strokes and death are generally acceptable at this early stage of development.

Mycobacterium tuberculosis specimen contamination revisited: the role of laboratory environmental control in a pseudo-outbreak

OBJECTIVE

To investigate suspected pseudo-outbreaks of Mycobacterium tuberculosis (MTB) during August 1994 and July 1995 among patients who did not have clinical findings consistent with tuberculosis.

DESIGN

Retrospective and prospective surveys of all clinical and laboratory data using standard epidemiological tools and DNA fingerprinting.

SETTING

A university-affiliated community hospital.

PATIENTS

Those with positive MTB cultures during periods when we noted that the number of MTB positive cultures greatly outnumbered the usual monthly average (retrospective analysis, 1994) and patients with positive MTB cultures without clinical findings consistent with tuberculosis (prospective survey, 1995).

RESULTS

Epidemiological and molecular studies revealed specimen cross-contamination in the laboratory due to a faulty exhaust hood. Improvement in laboratory ventilation and change of the implicated hood prevented further specimen contamination.

CONCLUSIONS

The identification of positive MTB cultures from patients without clinical evidence of tuberculosis should be a signal to suspect laboratory contamination and implement control measures. These should include a thorough epidemiological investigation, DNA fingerprint analysis, and an environmental inspection.

Hepatitis G virus encodes protease activities which can effect processing of the virus putative nonstructural proteins

The genome of a recently identified virus, hepatitis G virus (HGV), shows considerable homology to hepatitis C virus (HCV). Two HGV proteases similar to nonstructural proteins NS2 and NS3 of HCV were identified, and their cleavage site specificity was investigated. Amino acids essential for the protease activities were determined by mutation analysis. NS4A of HGV was demonstrated to be a cofactor for NS3-mediated proteolysis, with a region critical for activity residing between Leu1561, and Ala1598.

The effect of PTH antagonist BIM-44002 on serum calcium and PTH levels in hypercalcemic hyperparathyroid patients

BIM-44002, a pure competitive antagonist of parathyroid hormone (PTH), has a high affinity for the PTH/PTHrP receptor in vitro, and can completely inhibit the actions of a PTH agonist in rats in vivo. Toxicology studies in rats and dogs showed BIM-44002 to be devoid of any adverse effects. Therefore we undertook an investigation to evaluate the potential utility of BIM-44002 in lowering elevated serum calcium in three patients with primary hyperparathyroidism. BIM-44002 was administered by continuous intravenous infusion at dosages of 100 microg/hour (370 nmol/hour) for 12 hours, followed by 200 microg/hour for 12 hours, followed by 400 microg/hour for 12 hours. Vital signs and serum ionized and total calcium were monitored hourly and for 3 hours after cessation of the infusion. Blood for PTH determinations was obtained at the same time points. Serum calcium and PTH did not change during and after the infusion of the antagonist. No subject experienced any adverse reactions to the infusion of the antagonist. We conclude that although the PTH antagonist BIM-44002 was effective both in vitro and in vivo in animals, and it was safe in humans, it was not able to lower serum calcium in patients with hyperparathyroidism. Possible reasons for lack of clinical efficacy are discussed.

Phylogenetic relationship of the complete Rauscher murine leukemia virus genome with other murine leukemia virus genomes

We report the complete nucleotide sequence of the genome of Rauscher murine leukemia virus (R-MuLV), the replication-competent helper virus present in the Rauscher virus complex, and its phylogenetic relationship with other murine leukemia virus genomes. An overall sequence identity of 97.6% was found between R-MuLV and the Friend helper virus (F-MuLV), and the two viruses were closely related on the phylogenetic trees constructed from either gag, pol, or env sequences. Moloney murine leukemia virus (Mo-MuLV) was the next closest relative to R-MuLV and F-MuLV on all trees, followed by Akv and radiation leukemia virus (RadLV). The most distantly related helper virus was Hortulanus murine leukemia virus (Ho-MuLV). Interestingly, Cas-Br-E branched with Mo-MuLV on the gag and pol trees, whereas on the env tree, it revealed the highest degree of relatedness to Ho-MuLV, possibly due to an ancient recombination with an Ho-MuLV ancestor. In summary, a phylogenetic analysis involving various MuLVs has been performed, in which the postulated close relationship between R-MuLV and F-MuLV has been confirmed, consistent with the pathobiology of the two viruses.

Nature of the 5' residue in the M2 domain affects function of the human alpha 1 beta 1 GABAA receptor

The effects on the functional properties of the alpha 1 beta 1 GABAA receptor when the 5' (alpha 1 Val260; beta 1 Ile255) hydrophobic amino acids in the second transmembrane (M2) region were changed to threonine were examined. In response to a saturating concentration of GABA, the current evoked in mutant receptors showed a decreased rate of desensitization and at equilibrium was a greater fraction of the peak current than in wild-type receptors. The half-saturation concentration of the peak current response to GABA in mutant receptors was comparable to that in wild-type receptors, but the Hill coefficient was reduced to less than one. It was concluded that the 5' amino acids in the M2 region have a role in the conformational changes that occur within the alpha 1 beta 1 GABAA receptor in response to GABA.

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in reactive and neoplastic lymphoid cells

We have studied the expression of gelatinase A, gelatinase B, interstitial collagenase, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in reactive lymphoid cells, as well as in a series of cell lines derived from neoplasms of B- and T-cell lineage. Using both Northern blot analysis and zymography, gelatinase B activity was detected by zymography in two Burkitt cell lines and in a tonsillar cell suspension, while gelatinase A and interstitial collagenase activities were not detected by either method. TIMP-1 expression was demonstrated by Northern blot analysis in the multipotential neoplastic K-562 cell line, the high grade Burkitt's B-cell lymphoma lines, isolated tonsillar B cells and at low levels in peripheral blood T cells, but was not expressed in any of the neoplastic T-cell lines or isolated peripheral blood B cells. In contrast, TIMP-2 expression was restricted to tissues containing cells of T-cell lineage with high levels being observed in the neoplastic T-cell lines and lower levels in normal peripheral blood T cells and hyperplastic tonsil. Expression of TIMP-1 and TIMP-2 was confirmed at the protein level by reverse zymography and immunofluorescence assays using antihuman TIMP polyclonal antibodies. Expression of gelatinase B by the high grade B-cell Burkitt's lymphoma cell lines is consistent with previous findings in large cell immunoblastic lymphomas and indicates that this enzyme may play an important role in high grade non-Hodgkin's lymphomas. TIMP expression correlated with cell lineage in that TIMP-1 was primarily observed in B cells and TIMP-2 was restricted to T cells.

Ultrafast rotation and trapping of carbon monoxide dissociated from myoglobin

The nature of ligand motion within proteins has been investigated by measuring femtosecond time-resolved infrared (IR) spectra of CO photodissociated from the haem of myoglobin. Upon dissociation, the CO rotates approximately 90 degrees and becomes trapped within a ligand docking site located near the binding site. Two trajectories, distinguished spectroscopically and kinetically with time constants of 0.20 +/- 0.05 ps and 0.52 +/- 0.10 ps, lead to CO located within the docking site with opposite orientations. The protein reorganizes about the "docked' CO with a time constant of 1.6 +/- 0.3 ps and quickly establishes an energetic barrier that inhibits the reverse rebinding process.

Sudden cardiac death in cardiac transplant recipients

BACKGROUND

Sudden cardiac death (SCD) remains a significant cause of mortality in the general population. Its role in cardiac transplant patients-including its incidence, mechanism, potential risk factors, or influence on survival in this patient population-has not been well described.

METHODS AND RESULTS

We undertook a retrospective analysis of the clinical and autopsy records of 257 patient deaths. SCD was analyzed in relation to severity and frequency of rejection episodes, clinical history of arrhythmias, coronary artery disease (CAD), hypertension, diabetes, left ventricular dysfunction, and clinical history of premorbid symptoms. A total of 25 patients were identified as having died of SCD, an incidence of 9.7%: 20% died < or = 12 months after transplantation, 80% died after > 12 months, and 20% died after > or = 60 months. Patient survival ranged from 2.5 to 138 months (mean, 45.7 months). The mean number of rejection episodes per patient was 2.6, most occurring within 12 months after transplantation. Echocardiography or multigated acquisition scan revealed an ejection fraction (EF) > or = 50% in 68% of patients; however, the presence of arrhythmias, primarily atrial, was evident in 68% of patients and was equally distributed between patients with EFs > or = 50% and EFs < 50%. CAD was present in 53% of patients (10 of 19) whose angiograms were available, and the appearance of CAD after transplantation was between 29 and 85 months (mean, 51.4 months). Of the 9 patients with normal cardiac catheterization studies, 6 with available autopsy reports had documented CAD. Autopsy data in 13 of 25 patients revealed CAD in 92% and rejection in 15% (International Society for Heart and Lung Transplantation grade > 3A). Of the deaths, 64% occurred within 3 months of the last endomyocardial biopsy, 96% had normal biopsies, and the only rejection was without hemodynamic compromise.

CONCLUSIONS

SCD occurs relatively frequently in the cardiac transplant population, and CAD is present in most of the patients. Because the frequency of arrhythmias is relatively high in this group, more aggressive antiarrhythmic therapy may be beneficial for patients with allograft CAD in the prevention of SCD.

Effects of diminished and conflicting sensory information on balance in patients with cerebellar deficits

We studied the effects of altered sensory information on standing balance in 25 patients with cortical cerebellar atrophy (CCA), nine patients with olivoponto-cerebellar atrophy (OPCA), and 10 normal subjects. The total sway path and its components, the anteroposterior (AP) sway path and the lateral sway path, were measured under six conditions: (1) standing on a fixed platform with the eyes open and visual surroundings fixed, (2) standing on a fixed platform with the eyes closed, (3) standing on a fixed platform with the eyes open and visual surroundings AP sway referenced, (4) standing on an AP sway-referenced platform with the eyes open and visual surroundings fixed, (5) standing on an AP sway-referenced platform with the eyes closed, and (6) standing on an AP sway-referenced platform with the eyes open and visual surroundings AP sway referenced. Patients swayed more than normal subjects during normal stance (condition 1), when the visual information was absent (condition 2) or distorted (condition 3), and when the proprioceptive information from the ankles was distorted (condition 4). Patients swayed much more than normal, and most fell, when two sensory modalities were affected under condition 5 (proprioceptive information distorted and visual information absent) and condition 6 (both proprioceptive information and visual information distorted). When the patients' sway was normalized to that of the first condition, however, only their lateral sway was greater than the sway in normal subjects. Unlike in normal subjects, the patients' lateral sway varied with the AP sway to approximately the same degree in each condition for conditions 1-5. Clinical ratings of gait and balance were highly correlated with the sway measures. Quantitative testing of standing balance with altered sensory information has better sensitivity than normal stance testing.

Denture plaque distribution and the effectiveness of a perborate-containing denture cleanser

Formation of plaque on the surfaces of dentures is a common problem among denture wearers. A study was conducted to determine the distribution of plaque on dentures. The plaque material was disclosed with a dye solution and measured with a modified Quigley-Hein scale. A photographic method was used to determine the distribution of plaque on the dentures of a group of complete-denture wearers. The effectiveness of a perborate soak-type cleanser was also measured by studying the precleaned and postcleaned states of the denture. Denture plaque was more evident on the fitting surfaces of the dentures than on areas of the flange, teeth, and palate. The use of the soak-type cleanser alone may not be completely effective for the control of heavy plaque.

Maternal congenital heart disease and pregnancy outcome

OBJECTIVE

To study the obstetrics and neonatal outcome of women with congenital heart disease.

METHOD

This is a retrospective study of 85 women with congenital cardiac disease. Data collected include maternal characteristics, New York Heart Association Class, cardiac complications and obstetric and neonatal outcome.

RESULTS

The maternal and neonatal outcomes were excellent with no maternal and perinatal mortality. The main cardiac lesions were mitral valve prolapse (60.8%), atrial septal defect (8.6%), ventricle septal defect (6.5%) and aortic regurgitation (4.3%) and 2.1% each of tricuspid regurgitation, pulmonary regurgitation, Ebstein's anomaly, coarctation of aorta, patent ductus arteriosus, and Eisenmenger's syndrome. Six deliveries were associated with New York Heart Association deterioration. Compared to the general obstetric population, more women in the study group were primigravida, had pregnancy induced hypertension, underwent instrumental vaginal deliveries and caesarean sections and had more babies with lower birth weights.

CONCLUSION

Despite potential difficulties and complications associated with congenital heart disease, careful cardiac and obstetric management in a tertiary referal centre resulted in good maternal and fetal outcomes.

C4 and 21-hydroxylase gene deletions in nasopharyngeal carcinoma among the Chinese

Deletions around the C4 and 21-hydroxylase (21-OH) gene region occur among the Chinese, and C4B together with 21-OHA deletion is the most common. This deletion was found to be strongly associated with human leucocyte antigen (HLA) B58 DRB1*0301, particularly with DRB1*0301. The initial observation of a high frequency of this deletion in nasopharyngeal carcinoma (NPC) was secondary to the B58 DR3 association with NPC. A deletion of 21-OHA alone was observed to be associated with HLA B13 DRB1*1501.

Upregulation of the 72-kDa type IV collagenase in epithelial and stromal cells during rat tracheal gland morphogenesis

Submucosal glands secrete most of the mucus that lubricates the tracheal surface and protects it from irritants and infection. These glands develop postnatally in the rat, permitting convenient study of the mechanisms controlling this process. One such mechanism involves degradation of the supportive connective tissue matrix at the front of the growing glands. We recently showed that tracheal gland cell invasion of collagen gels in vitro is dependent on secretion of a 72-kDa type IV collagenase. In the present study, we show that the activity of this enzyme (also referred to as matrix metalloproteinase-2 or gelatinase A) is elevated at the time of gland development in vivo. That this increase is at least partly mediated at the level of steady-state mRNA was indicated by semiquantitative PCR analysis of gland-enriched, microdissected tissue samples. Immunohistochemistry revealed that the enzyme was present at the interface between the glands and extracellular matrix. In situ hybridization revealed that the cognate mRNA was present in epithelial cells of glands undergoing morphogenesis (particularly Postnatal Day 7) but not in those of adult glands or the surface epithelium. At all ages, stromal cells below the surface epithelium were labeled; labeling intensity was highest at the time and location of gland morphogenesis. These findings suggest that the 72-kDa type IV collagenase is developmentally regulated in gland and stromal cells at the level of steady-state mRNA and plays a role in the degradation of extracellular matrix during tracheobronchial gland morphogenesis.

Binding of CO to myoglobin from a heme pocket docking site to form nearly linear Fe-C-O

The relative orientations of carbon monoxide (CO) bound to and photodissociated from myoglobin in solution have been determined with time-resolved infrared polarization spectroscopy. The bound CO is oriented < or = 7 degrees from the heme normal, corresponding to nearly linear FE-C-O. Upon dissociation from the Fe, CO becomes trapped in a docking site that orientationally constrains it to lie approximately in the plane of the heme. Because the bound and "docked" CO are oriented in nearly orthogonal directions CO binding from the docking site is suppressed. These solutions results help to establish how myoglobin discriminates against CO, a controversial issue dominated by the misconception that Fe-C-O is bent.

Comparison of techniques for transscleral diode photocoagulation in the rabbit

PURPOSE

To assess the optimum probe design and treatment parameters for transscleral diode laser retinopexy.

METHODS

Transscleral diode photocoagulation was performed on the eyes of Dutch-belted rabbits using three different transscleral probes: a straight, 400-microns diameter probe; a prism-tipped 400-microns diameter probe; and a prism-tipped 900-microns diameter probe.

RESULTS

Transscleral diode photocoagulation with all three probe types was an effective method of ablating the retina and creating chorioretinal adhesions. Both the burn diameter and the mean radiant output energy requirement increased as the burn duration and probe aperture diameter was increased. Explosive retinal holes were encountered in 12% of the burns created with the straight probe. The use of the prism-tipped probes significantly reduced the incidence of retinal holes to < 4% (P < 0.005). Histopathologically, all burns were grade III in intensity with severe choroidal injury. In many of the burns, there was histopathologic evidence of thermal injury to the inner sclera. The frequency of these inner scleral changes was reduced with a long burn duration (5 seconds).

CONCLUSION

This study confirms that diode transscleral photocoagulation is a feasible method of thermal retinopexy. The use of the prism-tipped probes and long duration burns resulted in the fewest adverse reactions.

Differential susceptibility of plasma proteins to oxidative modification: examination by western blot immunoassay

Plasma proteins are exposed to oxidants in a variety of circumstances in vivo, such as during tissue injury and inflammation. In this report, the relative susceptibility of each of the major plasma proteins to oxidative modification was assessed by exposing whole plasma to a metal-catalyzed radical generating system and detecting oxidation (protein carbonyl groups) using a novel Western blot immunoassay. Proteins were derivitized with dinitrophenylhydrazine, separated by SDS-gel electrophoresis, and screened with antibodies against dinitrophenyl groups. As little as 1 pmol of protein-associated carbonyls could be detected (100 ng of a 50 kD protein containing 0.5 mol carbonyl/mol protein). Individual plasma proteins were identified by their comigration with standards, crossreactivity with specific antibodies, and by comparison of plasma to serum. Using this approach, we found that plasma fibrinogen was much more susceptible to oxidative modification compared to the other major plasma proteins, albumin, immunoglobulins, and transferrin. The results emphasize the utility of this method for studying oxidation of proteins in cell extracts and tissues and indicate that experiments on the effects of oxidation on fibrinogen function are merited.

Diet measurement in Vietnamese youth: concurrent reliability of a self-administered food frequency questionnaire

Dietary patterns of Asian Americans change with increasing acculturation, leading to increased consumption of Western foods including those high in fat. Strategies to preserve the healthy aspects of traditional diets need to be developed and dietary assessment methods evaluated. Little is known about reliability of brief dietary measures in the general population or among minority youth. The concurrent reliability of a brief food frequency questionnaire (FFQ) was determined among Vietnamese youth using diet reports. Students in a bilingual high school program were given a FFQ. Students then completed daily diet reports one day each week over seven weeks. The data from the FFQ were compared to the daily food reports. The reliability of the FFQ was highest for frequently eaten food types like rice (r = 0.626, P < 0.01), fruit (r = 0.513, P < 0.01), meat (r = 0.525, P < 0.01) and vegetables (r = 0.474, P < 0.01) and was lower for less commonly eaten types including fish/shellfish (r = 0.227, P = 0.20) and fried foods (r = 0.310, P = 0.07). These results suggest that a few simple FFQ items, particularly for indicator foods such as rice, are reliable for dietary assessment in this population.

Phase 1 clinical trial of chimeric monoclonal anti-CD4 antibody in multiple sclerosis

We conducted an open trial of cM-T412, a chimeric monoclonal anti-CD4 antibody, in 29 patients with MS. This antibody caused a prompt and long-lasting depletion of circulating CD4 (helper/inducer) lymphocytes. The mean (+/- SE) CD4 count for the group decreased from 870 (+/- 66) cells/mm3 at baseline to 76 (+/- 11) 3 hours after treatment, and then increased to 425 (+/- 38) at 1 month after treatment and 475 (+/- 39) at 6 months after treatment. Numbers of CD8 (cytotoxic/suppressor) lymphocytes, B lymphocytes, granulocytes, and monocytes changed transiently but showed no significant long-term effects. The most common side effects were headache, nausea, myalgia, fever, and tachycardia occurring in the first few hours after treatment. No serious or unexpected infections or other significant adverse effects occurred. Kurtzke EDSS scores remained stable, and MRI scans showed less contrast enhancement 1 week after treatment. We conclude that treatment of MS patients with cM-T412 chimeric anti-CD4 antibody is well tolerated at the doses tested and produces a long-lasting, selective depletion of CD4 lymphocytes.

Tine test cards for TB screening: rates of return and associated factors

OBJECTIVE

Screening for tuberculosis in children can be done with the multiple-puncture Tine test. Determination of the extent of induration following the test may be reported by a child's caregiver via a mailed Tine card. We report the rate of return of these cards, and factors associated with return, in a family medicine health center.

METHODS

Retrospective review of the medical charts of 152 mother and child pairs seen in the health center over a two-year period.

RESULTS

Of the 98 children who had received a Tine test by age one, 16.3% of their Tine cards were returned to the health center. Children whose delivery was insured by Medicaid were less likely to have a Tine card returned than were those without Medicaid (OR for non-return = 4.3, 95% CI = 1.2, 15.4). Physicians often documented a tuberculosis screening result without a Tine card.

CONCLUSIONS

Given the low return rates, health care professionals responsible for tuberculosis screening should be cautious when relying on caregivers to interpret, record and return tuberculosis screening results, particularly in the most disadvantaged populations. More valid data are likely to be obtained from a clinical reading of tuberculosis tests.

Nonexponential protein relaxation: dynamics of conformational change in myoglobin

The picosecond evolution of the tertiary conformation of myoglobin (Mb) after photodissociation of MbCO was investigated at room temperature by probing band III, a weak iron-porphyrin charge-transfer transition near 13,110 cm-1 (763 nm) that is sensitive to the out-of-plane displacement of the iron. Upon photolysis, the iron moves out of the plane of the porphyrin, causing a blue-shift of band III and a concomitant change in the protein conformation. The dynamics for this functionally important motion are highly nonexponential, in agreement with recent molecular dynamics simulations [Kuczera, K., Lambry, J.-C., Martin, J.-L. & Karplus, M. (1993) Proc. Natl. Acad. Sci. USA 90, 5805-5807]. The conformational change likely affects the height of the barrier to ligand rebinding and may explain nonexponential NO rebinding.

A prospective randomised study of local versus general anaesthesia for cataract surgery

One hundred and sixty-nine patients (aged 65-98 years) were randomised to receive either local or general anaesthesia for cataract surgery. Cognitive function was assessed using a battery of psychometric tests performed pre-operatively, and at 24 h, 2 weeks and 3 months postoperatively. Oxygen saturation, blood pressure and heart rate were monitored and the results recorded throughout the anaesthetic and immediate recovery period. In the general anaesthetic group, 19% of patients experienced at least one episode of oxygen desaturation during the procedure compared with none in the local anaesthetic group. Pulse rate and blood pressure were stable in the local anaesthetic group compared with the general anaesthetic group where marked fluctuations were noted; 61% of patients in the general anaesthetic group experienced falls in systolic blood pressure greater than 30% of the pre-induction value. No evidence of long-term postoperative cognitive dysfunction was detected and there was no significant difference between the performances of the two groups.

A review of patients with a 'normal' coronary angiogram over a 3-year period

Over a period of 36 months, we detected 54 patients with normal coronary arteries or non-critical coronary artery stenosis within our study series of coronary angiography. We studied these patients to determine their clinical, electrocardiographic, stress testing and angiocardiographic characteristics. We detected among them a preponderance of female sex and a higher incidence of ethnic Indians. The majority of the patients studied had one or more coronary risk factors. 52% had a normal resting ECG. In those with a positive stress test and reports available for review, there is a near equal distribution of horizontal and J-type ST depression. Those patients with a positive treadmill tend to have a higher left ventricular end diastolic pressure (LVEDP) at cardiac catheterization. We also noted in this group of patients a higher proportion with a small distal left anterior descending artery. These patients also tend to have higher LVEDP even in the presence of normal left ventriculogram. Our current series suggests the possibility of raised left ventricular end-diastolic pressure and the presence of a "small distal left anterior descending artery" syndrome in association with patients with a 'false positive' treadmill test.

Overestimation of severity of mitral stenosis during cardiac catheterization due to a large left atrial thrombus

We report a case of mitral stenosis with a large left atrial thrombus which was obstructing pulmonary venous inflow where the conventional use of the pulmonary capillary wedge pressure as an approximation of the left atrial pressure during diagnostic cardiac catheterisation led to the over-estimation of the severity of mitral stenosis.

[Postspinal headache. A comparison of the 24G Sprotte syringe and a 29G Quincke needle]

PATIENTS AND METHODS

A randomised study was performed to compare the frequency of postdural puncture headache in 56 patients who underwent spinal anaesthesia for extra-corporeal shockwave lithotripsy using either a Sprotte 24 G (n = 28) or Vygon 29 G or Quincke type needle (n = 28). Frequency of headache was recorded in a similar group of 28 patients who received general anaesthesia.

RESULTS

Dural puncture was easier with the Sprotte 24 G cannula than with the less stable Quincke needle, as documented by a significantly shortened time for insertion of the cannula (4.6 +/- 2.6 vs 8.6 +/- 6.3 min, P less than 0.005). The total frequency of post-operative headache was 57% in the Vygon 29 G group and 25% in the Sprotte 24 G group; 21% of patients in the general anaesthesia group complained of headache. Frequency of postdural puncture headache, classified as being posture-related, was 25% in the 29 G Vygon group, compared with 11% in the 24 G Sprotte group (P = 0.148). When only moderate and severe postdural puncture headache was considered, there was a significant difference (25% vs. 4%; P = 0.026) in favour of the Sprotte cannula.

DISCUSSION AND CONCLUSIONS

Thus, the 24 G Sprotte needle was at least as effective as the 29 G Vygon needle, and there is a suggestion that the former is more effective in minimising the incidence of moderate or severe postdural puncture headache.