Combined transformation and genetic technique verification of protein-protein interactions in the yeast two-hybrid system

The yeast two-hybrid system is frequently used to identify protein-protein interactions. The assay is based on the functional reconstitution of a transcriptional activator. Since an indirect phenotype of the positive clones is the basis for selection of positive interacting clones, the two-hybrid screens are vulnerable to false positives. Here we report a screening protocol based on the sequential use of the cotransformation approach followed by the genetic method for verifying true two-hybrid interactions. Using this procedure, we have screened a cDNA library and have been able to isolate true positives from the yeast two-hybrid screen.

C5a-stimulated human neutrophils use a subset of beta2 integrins to support the adhesion-dependent phase of superoxide production

Isolated human polymorphonuclear neutrophils (PMN) responded to human C5a with an immediate, transient release of superoxide lasting from 0.5 to 5 min. This was followed by a second release of superoxide, which began at 10 min after addition of C5a, was sustained for more than 30 min, and required ICAM-1 immobilized in the wells. F(ab')2 monoclonal antibody (mAb) preparations were used to dissect the role of individual beta2 integrins and to avoid the confounding effects of ligating Fc receptors. Anti-CD18 mAb treatment of the PMN had no effect on the immediate first phase but completely inhibited the second, adhesion-dependent phase of superoxide production. Anti-CR3 mAb only inhibited the adhesion phase of superoxide production partially, implying that other beta2 integrins were involved. A mixture of anti-CD11a, anti-CD11b, and anti-CD11c was not able to block superoxide production completely, suggesting a role for alphad/beta2. Surprisingly, blocking anti-LFA-1 mAb had no effect on superoxide production. Consistent with this observation, immobilized, purified ICAM-2, a specific counter-receptor for LFA-1, did not support the adhesion-dependent phase of-superoxide production. Thus, PMN treated with C5a used signals via CR3, P150/95, and alphad/beta2, but not LFA-1, to support superoxide production. LFA-1 has been shown by others to mediate most of the adhesion necessary for transendothelial migration in vivo. The inability of LFA-1 ligation to stimulate superoxide production may be an important means of preventing blood-vessel damage when PMN migrate across the endothelium.

Wavelength-shifting molecular beacons

We describe wavelength-shifting molecular beacons, which are nucleic acid hybridization probes that fluoresce in a variety of different colors, yet are excited by a common monochromatic light source. The twin functions of absorption of energy from the excitation light and emission of that energy in the form of fluorescent light are assigned to two separate fluorophores in the same probe. These probes contain a harvester fluorophore that absorbs strongly in the wavelength range of the monochromatic light source, an emitter fluorophore of the desired emission color, and a nonfluorescent quencher. In the absence of complementary nucleic acid targets, the probes are dark, whereas in the presence of targets, they fluoresce-not in the emission range of the harvester fluorophore that absorbs the light, but rather in the emission range of the emitter fluorophore. This shift in emission spectrum is due to the transfer of the absorbed energy from the harvester fluorophore to the emitter fluorophore by fluorescence resonance energy transfer, and it only takes place in probes that are bound to targets. Wavelength-shifting molecular beacons are substantially brighter than conventional molecular beacons that contain a fluorophore that cannot efficiently absorb energy from the available monochromatic light source. We describe the spectral characteristics of wavelength-shifting molecular beacons, and we demonstrate how their use improves and simplifies multiplex genetic analyses.

Intercellular adhesion molecule 1 and beta2 integrins in C1q-stimulated superoxide production by human neutrophils: an example of a general regulatory mechanism governing acute inflammation

OBJECTIVE

To investigate the role of intercellular adhesion molecule 1 (ICAM-1) and beta2 integrins in the production of superoxide (O2-) by C1q-stimulated human polymorphonuclear leukocytes (PMN).

METHODS

PMN were pretreated with F(ab')2 fragments of monoclonal antibodies (mAb) that blocked or did not block beta2 integrin-mediated adhesion. The cells were added to wells coated with C1q, and the production of O2- was monitored kinetically as a color change due to reduction of cytochrome c. In some experiments, C1q was co-immobilized with purified ICAM-1.

RESULTS

Blocking mAb to the shared beta2 integrin subunit, CD18, completely inhibited the O2- response triggered by immobilized C1q, while blocking mAb to the alpha subunits of the beta2 integrins each partially blocked the O2- response. PMN treated with C1q were found to activate the beta2 integrins lymphocyte function-associated antigen 1 and CR3 for binding to ICAM-1. Co-immobilization of ICAM-1 with C1q cooperatively triggered O2- production by PMN.

CONCLUSION

beta2 integrin binding to an ICAM provided an essential costimulatory signal for O2-production triggered by C1q in PMN. Our findings suggest a model for PMN activation in which 2 stimuli are required for O2- production: a first signal that also activates PMN beta2 integrins, followed by a second, beta2 integrin-mediated signal, which occurs physiologically upon PMN binding to ICAM-1. The requirement for this dual signal for PMN generation of O2- would serve as a regulatory mechanism to limit the production of O2- to a tissue environment where C1q, or some other stimulus, is colocalized with stromal cells bearing up-regulated ICAM-1. This mechanism may explain why all tissues can express ICAM-1 and may explain in part why inhibitors of tumor necrosis factor alpha, a major physiologic stimulus of ICAM-1 up-regulation, are potent antiinflammatory agents.

Rapid identification of Candida dubliniensis using a species-specific molecular beacon

Candida dubliniensis is an opportunistic fungal pathogen that has been linked to oral candidiasis in AIDS patients, although it has recently been isolated from other body sites. DNA sequence analysis of the internal transcribed spacer 2 (ITS2) region of rRNA genes from reference Candida strains was used to develop molecular beacon probes for rapid, high-fidelity identification of C. dubliniensis as well as C. albicans. Molecular beacons are small nucleic acid hairpin probes that brightly fluoresce when they are bound to their targets and have a significant advantage over conventional nucleic acid probes because they exhibit a higher degree of specificity with better signal-to-noise ratios. When applied to an unknown collection of 23 strains that largely contained C. albicans and a smaller amount of C. dubliniensis, the species-specific probes were 100% accurate in identifying both species following PCR amplification of the ITS2 region. The results obtained with the molecular beacons were independently verified by random amplified polymorphic DNA analysis-based genotyping and by restriction enzyme analysis with enzymes BsmAI and NspBII, which cleave recognition sequences within the ITS2 regions of C. dubliniensis and C. albicans, respectively. Molecular beacons are promising new probes for the rapid detection of Candida species.

A DNA damage signal is required for p53 to activate gadd45

We provide direct evidence that overexpression of p53 is not sufficient for robust p53-dependent activation of the endogenous gadd45 gene. When p53 was induced in TR9-7 cells in the absence of DNA damage, waf1/p21 and mdm2 mRNA levels were increased, but a change in gadd45 mRNA was barely detectable. Activation of the gadd45 gene was observed when camptothecin was added to cells containing p53 in the absence of a further increase in the p53 level. Phosphorylation of p53 at serine 15 and acetylation at lysine 382 were detected after drug treatment. It has been suggested that p53 posttranslational modification is critical during activation. However, inhibition of these modifications by wortmannin was not sufficient to block the transactivation of gadd45. Interestingly, after camptothecin treatment, increased DNase I sensitivity was detected at the gadd45 promoter, suggesting that an undetermined DNA damage signal is involved in inducing chromatin remodeling at the gadd45 promoter while cooperating with p53 to activate gadd45 transcription.

Percutaneous transluminal angioplasty for stenosis of the aorta due to aortic arteritis in children

Percutaneous transluminal balloon angioplasty for stenosis of the aorta due to aortic arteritis was attempted on 45 lesions in 41 children (age range, 4-14 years; mean, 9.9+/-4.2 years) presenting with symptoms of hypertension, severe congestive heart failure, and lower limb claudication. Balloon dilatation was technically successful in 38 (92.7%) patients for 41 stenotic lesions (91.1%). The mean peak systolic pressure gradient (PSG) decreased from 71.7 +/- 23.9 mmHg to 23.2 +/- 17.5 mmHg (p < 0.001) and the diameter of the stenosed segment increased from 3.3 +/- 1.1 mm to 7.5 +/- 2.2 mm (p < 0.001) immediately after angioplasty. Patients with short-segment (<3 cm) stenosis had a lower residual gradient (17.9 +/- 11.1 mmHg vs 30.5 +/- 22.6 mmHg; p < 0.05) and a wider diameter of the aorta (8.8 +/- 1.1 mm vs 7.5 +/- 2.2 mm; p < 0.02) compared to patients with long-segment (>/=3 cm) stenosis. Four patients required stent implantation; 2 for flow-limiting dissection, 1 for failure to reduce PSG by >50%, and 1 for recurrent restenosis. There was marked hemodynamic and angiographic improvement in these 4 patients. Hemodynamic and angiographic restudy in 21 of the 41 patients at mean follow-up period of 6.2 +/- 4.2 months (range, 3-24 months) showed restenosis in 4 (19%) patients. Restenosis was more common in patients with long-segment stenosis than those with short-segment stenosis (30% vs 9.1%). Late restudy in 8 patients, done at 3-7 years after first restudy, showed no recurrence of aortic narrowing. On clinical follow-up of 38 patients for a mean of 58.8 +/- 36.0 months (range, 8-146 months) there was marked improvement in symptoms. Hypertension was cured in 11 (29%), improved in 24 (63%), and persisted in 3 (8%). Six patients with associated severe renal artery stenosis showed further improvement in hypertension after successful renal angioplasty. Severe congestive heart failure improved in 21 (95.4%) of 22 patients. Mean left ventricular ejection fraction improved from 0.32 +/- 0.08 to 0. 48 +/- 0.10 (p < 0.001) at a mean follow-up of 28.7 +/- 8.4 months in these patients. Hemodynamic restudy in 10 of these patients showed improvements in left ventricular end-diastolic pressure from a mean 37 +/- 9 mmHg (range, 25-55 mmHg) to 16.4 +/- 6.2 mmHg (range, 6-25 mmHg) (p < 0.001). Lower limb claudication improved in all 4 patients. Our results suggest that percutaneous transluminal balloon angioplasty in children is safe and highly effective in relieving stenosis of the aorta due to aortic arteritis, with marked clinical improvement, and should be the treatment of choice particularly for discrete stenosis.

Endovascular stenting for unsuccessful angioplasty of the aorta in aortoarteritis

PURPOSE

The efficacy and safety of endovascular stent implantation to correct dissection or a suboptimal result after percutaneous transluminal angioplasty (PTA) was evaluated in patients suffering from aortic stenosis due to aortoarteritis.

METHODS

Twelve children and young adults [aged (mean +/- SD) 18.2 +/- 8.7 years] underwent stent implantation after PTA of the aorta, seven for obstructive dissection, four for ineffective balloon dilatation, and one for recurrent restenosis. Nine patients underwent implantation of self-expandable stents and three received balloon-expandable Palmaz stents.

RESULTS

Stent implantation could be successfully performed in all 12 patients. After stent implantation, the peak systolic pressure gradient decreased from 91 +/- 33.5 mmHg to 12.4 +/- 12.5 mmHg (p < 0.001). The diameter of the stenosed segment increased from 4.6 +/- 0.8 mm to 11.1 +/- 1.9 mm (p < 0.001). The dissection was completely covered in all seven patients with dissection. Except for epigastric pain with vomiting in one patient, there was no complication. On follow-up, over 12-57 months (mean 26.8 +/- 10.8 months), 11 patients (91.6%) had marked improvement in their blood pressure. Patients with congestive heart failure and claudication also showed improvement. Repeat catheterization in five patients, between 6-30 months (mean 16.8 +/- 9.1 months) after stent implantation, showed sustained improvement in four and a fusiform, long segment, intrastent restenosis after 30 months in one child. The stenosis was safely redilated.

CONCLUSION

Endovascular aortic stent implantation is safe and provides good immediate relief in patients with unsatisfactory results after balloon angioplasty. Improvement is sustained in most patients on intermediate-term follow-up.

Race-specific HIV-1 disease-modifying effects associated with CCR5 haplotypes

Genetic variation in CC chemokine receptor 5 (CCR5), the major HIV-1 coreceptor, has been shown to influence HIV-1 transmission and disease progression. However, it is generally assumed that the same CCR5 genotype (or haplotype) has similar phenotypic effects in different populations. To test this assumption, we used an evolutionary-based classification of CCR5 haplotypes to determine their associated HIV-1 disease-modifying effects in a large well-characterized racially mixed cohort of HIV-1-seropositive individuals. We demonstrate that the spectrum of CCR5 haplotypes associated with disease acceleration or retardation differs between African Americans and Caucasians. Also, we show that there is a strong interactive effect between CCR5 haplotypes with different evolutionary histories. The striking population-specific phenotypic effects associated with CCR5 haplotypes emphasize the importance of understanding the evolutionary context in which disease susceptibility genes are expressed.

Changing trends in acute poisoning in Chandigarh zone: a 25-year autopsy experience from a tertiary care hospital in northern India

A 25-year autopsy study (1972-1997) of acute poisoning deaths from a tertiary care hospital in northern India (Postgraduate Institute of Medical Education and Research, Chandigarh) revealed a steep increase in the incidence of acute poisoning since 1987. The majority (68%) of subjects were between the ages of 14 and 30 years, and there was a male preponderance (69%). The main victims were students and unemployed youths, followed by agricultural workers and domestic workers. The proportion of urban victims increased from 45% in the period from 1972 to 1977 to 72% in the period from 1992 to 1997. The proportion of suicidal deaths increased from 34% in the period from 1972 to 1977 to 77% in the period from 1992 to 1997, whereas accidental deaths decreased from 63% to 17% in the same period. Barbiturates (37%) and copper sulfate (22%) were the most common poisons causing mortality between 1972 and 1977; organophosphates (46%) became the most common between 1977 and 1982. Since 1982, aluminum phosphide (65%) has been the most common poison.

Expression of the Na+/H+ and Cl-/HCO-3 exchanger isoforms in proximal and distal human airways

Recent studies have indicated the presence of Na+/H+ and Cl-/HCO-3 exchange activities in lung alveolar and tracheal tissues of various species. To date, the identity of the Na+/H+ (NHE) and Cl-/HCO-3 (AE) exchanger isoforms and their regional distribution in human airways are not known. Molecular species of the NHE and AE gene families and their relative abundance in the human airway regions were assessed utilizing RT-PCR and the RNase protection assay, respectively. Organ donor lung epithelia from various bronchial regions (small, medium, and large bronchi and trachea) were harvested for RNA extraction. Gene-specific primers for the human NHE and AE isoforms were utilized for RT-PCR. Our results demonstrated that NHE1, AE2, and brain AE3 isoforms were expressed in all regions of the human airways, whereas NHE2, NHE3, AE1, and cardiac AE3 were not detected. RNase protection studies for NHE1 and AE2, utilizing glyceraldehyde-3-phosphate dehydrogenase as an internal standard, demonstrated that there were regional differences in the NHE1 mRNA levels in human airways. In contrast, the levels of AE2 mRNA remained unchanged. Differential expression of these isoforms in the human airways may have functional significance related to the airway absorption and secretion of electrolytes.

Thermodynamic basis of the enhanced specificity of structured DNA probes

Molecular beacons are DNA probes that form a stem-and-loop structure and possess an internally quenched fluorophore. When they bind to complementary nucleic acids, they undergo a conformational transition that switches on their fluorescence. These probes recognize their targets with higher specificity than probes that cannot form a hairpin stem, and they easily discriminate targets that differ from one another by only a single nucleotide. Our results show that molecular beacons can exist in three different states: bound to a target, free in the form of a hairpin structure, and free in the form of a random coil. Thermodynamic analysis of the transitions between these states reveals that enhanced specificity is a general feature of conformationally constrained probes.

Multiplex detection of four pathogenic retroviruses using molecular beacons

We describe a multiplex nucleic acid assay that identifies and determines the abundance of four different pathogenic retroviruses (HIV-1, HIV-2, and human T-lymphotrophic virus types I and II). Retroviral DNA sequences are amplified in a single, sealed tube by simultaneous PCR assays, and the resulting amplicons are detected in real time by the hybridization of four differently colored, amplicon-specific molecular beacons. The color of the fluorescence generated in the course of amplification identifies which retroviruses are present, and the number of thermal cycles required for the intensity of each color to rise significantly above background provides an accurate measure of the number of copies of each retroviral sequence that were present originally in the sample. Fewer than 10 retroviral genomes can be detected. Moreover, 10 copies of a rare retrovirus can be detected in the presence of 100, 000 copies of an abundant retrovirus. Ninety-six samples can be analyzed in 3 hr on a single plate, and the use of a closed-tube format eliminates crossover contamination. Utilizing previously well characterized clinical samples, we demonstrate that each of the pathogenic retroviruses can be identified correctly and no false positives occur. This assay enables the rapid and reliable screening of donated blood and transplantable tissues.

Stenting of the aorta for recurrent, long stenosis due to Takayasu's arteritis in a child

Balloon angioplasty followed by stenting of the thoracic aorta is reported in a 5-year-old girl with Takayasu's arteritis, who presented with severe hypertension and congestive heart failure. Her aortogram showed severe long segment stenosis of the descending thoracic aorta, which was successfully treated by balloon angioplasty on two occasions, but developed recurrences after 6 and 7 months of angioplasty. Balloon dilatation of the stenosed aorta, followed by sequential implantation of three 30-mm long Palmaz stents in tandem, bridging the full segment of the angioplastied aorta were performed successfully without any complications. The aortic diameter increased from 3.3 mm to 7.7 mm and the peak systolic pressure gradient decreased from 75 mmHg to 3 mmHg. There was no recurrence on clinical follow-up of 13 months.

Multiplex detection of single-nucleotide variations using molecular beacons

We demonstrate that single-nucleotide differences in a DNA sequence can be detected in homogeneous assays using molecular beacons. In this method, the region surrounding the site of a sequence variation is amplified in a polymerase chain reaction and the identity of the variant nucleotide is determined by observing which of four differently colored molecular beacons binds to the amplification product. Each of the molecular beacons is perfectly complementary to one variant of the target sequence and each is labeled with a different fluorophore. To demonstrate the specificity of these assays, we prepared four template DNAs that only differed from one another by the identity of the nucleotide at one position. Four amplification reactions were prepared, each containing all four molecular beacons, but each initiated with only one of the four template DNAs. The results show that in each reaction a fluorogenic response was elicited from the molecular beacon that was perfectly complementary to the amplified DNA, but not from the three molecular beacons whose probe sequence mismatched the target sequence. The color of the fluorescence that appeared in each tube during the course of the amplification indicated which nucleotide was present at the site of variation. These results demonstrate the extraordinary specificity of molecular beacons. Furthermore, the results illustrate how the ability to label molecular beacons with differently colored fluorophores enables simple multiplex assays to be carried out for genetic analysis.

Differential expression of 10 sigma factor genes in Mycobacterium tuberculosis

The ability of Mycobacterium tuberculosis to adapt to different environments in the infected host is essential for its pathogenicity. Consequently, this organism must be able to modulate gene expression to respond to the changing conditions it encounters during infection. In this paper we begin a comprehensive study of M. tuberculosis gene regulation, characterizing the transcript levels of 10 of its 13 putative sigma factor genes. We developed a real-time RT-PCR assay using a family of novel fluorescent probes called molecular beacons to quantitatively measure the different mRNAs. Three sigma factor genes were identified that have increased mRNA levels after heat shock, two of which also responded to detergent stress. In addition, we also identified a sigma factor gene whose mRNA increased after mild cold shock and a second that responded to conditions of low aeration.

Early and long-term results of subclavian angioplasty in aortoarteritis (Takayasu disease): comparison with atherosclerosis

PURPOSE

To compare the early and long-term outcomes of subclavian artery angioplasty in patients with aortoarteritis and atherosclerosis.

METHODS

Sixty-one subclavian artery angioplasties were performed in 55 consecutive patients with aortoarteritis (n = 32) and atherosclerosis (n = 23) between 1986 and 1995. An arch aortogram followed by a selective subclavian artery angiogram was done to profile the site and extent of the lesion, its relation to the vertebral artery, and the distal circulation. Percutaneous transluminal angioplasty (PTA) was performed via the femoral route for 56 stenotic lesions and 5 total occlusions.

RESULTS

PTA was successful in 52 (92.8%) stenotic lesions and 3 (60%) total occlusions. Three patients (5.4%) had complications, that could be effectively managed nonsurgically. Compared with atherosclerosis, patients with aortoarteritis were younger (27.4 +/- 9.3 years vs 54.5 +/- 10.5 years; p < 0.001), more often female (75% vs 17.4%; p < 0.001), gangrene was uncommon (0% vs 17.4%; p < 0.05), and diffuse involvement was seen more often (43.8% vs 4.4%; p < 0.001). The luminal diameter stenoses were similar before PTA (88.6 +/- 9.7% vs 89.0 +/- 9.1%; p = NS). Higher balloon inflation pressure was required to dilate the lesions of aortoarteritis (9.9 +/- 4.6 ATM vs 5.5 +/- 1.0 ATM; p < 0.001). This group had more residual stenosis (15.5 +/- 12.4% vs 8.3 +/- 9.4%; p < 0.05) after PTA. There were no neurological sequelae, even in PTA of prevertebral lesions. On 3-120 months (mean 43.3 +/- 28.9 months) follow-up of 40 patients, restenosis was more often observed in patients with aortoarteritis, particularly in those with diffuse arterial narrowing. These lesions could be effectively redilated. Clinical symptoms showed marked improvement after successful angioplasty.

CONCLUSION

Subclavian PTA is safe and can be performed as effectively in aortoarteritis as in atherosclerosis, with good long-term results. Long-term follow-up shows that it provides good symptomatic relief.

Tissue culture of wild-type, interspecific genome/plastome hybrids and plastome mutants of evening primrose (Oenothera): controlled morphogenesis and transformation

A favourable combination of genetic features in the genus Oenothera offers access to fundamental biological aspects that are not readily approached with other materials. We have developed protocols for cell and tissue culture as well as for transformation, in order to establish the basis for a comprehensive cell and molecular biology of Euoenothera species, their genome/plastome hybrids and plastome mutants. Regeneration of plants from excised seedling parts (roots, hypocotyl, cotyledons, shoot tips) and leaf explants was optimal on NT medium containing 1 mg ⋅ l^-1 6-benzylaminopurine and 3 mg ⋅ l^-1 α-naphtalene acetic acid. This medium also proved to be efficient in the propagation of various wild-type genotypes, interspecific hybrids and plastome mutants. Using Ti-based approaches we also succeeded in generating transgenic Oenothera plants with relatively high efficiency.

Molecular beacon sequence analysis for detecting drug resistance in Mycobacterium tuberculosis

We developed a new approach to DNA sequence analysis that uses fluorogenic reporter molecules--molecular beacons--and demonstrated their ability to discriminate alleles in real-time PCR assays of genomic DNA. A set of overlapping molecular beacons was used to analyze an 81-bp region of the Mycobacterium tuberculosis rpoB gene for mutations that confer resistance to the antibiotic rifampin. In a blinded study of 52 rifampin-resistant and 23 rifampin-susceptible clinical isolates, this method correctly detected mutations in all of the resistant strains and in none of the susceptible strains. The assay was carried out entirely in sealed PCR tubes and was simple to perform and interpret. This approach can be used to analyze any DNA sequence of moderate length with single base pair accuracy.

Molecular beacons: a new approach for semiautomated mutation analysis

Molecular beacons are oligonucleotide probes that become fluorescent upon hybridization. We designed molecular beacons to detect a point mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, a mutation that has been related to an increased risk for cardiovascular disease and neural tube defects. The application of molecular beacons enables fast, semiautomated, accurate mutation detection. Moreover, the procedure is performed in a closed tube system, thereby avoiding carryover contamination. We believe these probes will find their way into nucleic acid research and diagnostics.

Use of recombinant pemphigus vulgaris antigen in development of ELISA and IB assays to detect pemphigus vulgaris autoantibodies

AIM/OBJECTIVE

The objectives of this study are: (1) to measure the titers of pemphigus vulgaris (PV) autoantibody in the sera of patients with active disease, using three different assays: (a) Indirect immunofluorescence (IIF) using monkey esophagus as a substrate, (b) immunoblot (IB) and, (c) enzyme-linked immunosorbent assay (ELISA) using recombinant PV antigen (rPVA). (2) To compare the sensitivity of these three assays.

BACKGROUND

The titer of PV autoantibodies and disease severity and extent do not always correlate. This could be due to the lack of consistency and specificity of the substrate. Different results are obtained using different substrates. A standard substrate with uniformly controlled source of antigen would be more useful and clinically beneficial.

METHODS

In this study we studied 25 PV patients, six each with bullous pemphigoid (BP), ocular cicatricial pemphigoid (OCP), mucous membrane pemphigoid (MMP), and herpes gestationis (HG), and sera from 16 normal subjects. IIF was used to determine the PV autoantibody using monkey esophagus. IB assay was used according to standard protocol using normal human epidermis and rPVA as substrates. ELISA was performed using rPVA as antigens expressed in E. coli.

RESULTS

Sera of all 25 PV patients showed binding to the rPVA, normal human sera and the sera from the six BP, six OCP, six MMP, and six HG patients did not show any binding. In addition, we used antisera from rabbits immunized with PVA peptides (Bos-1, Bos-6) which also showed binding to rPVA, whereas normal rabbit sera did not show any reactivity. ELISA and IB titers in all the patients were 2.5 to 160 times higher than with the conventionally used IIF assay. The titers of the PV specific autoantibody measured using the rPVA did not show statistically significant differences between the ELISA and IB assays.

CONCLUSIONS

IB and ELISA are superior to IIF in evaluating the antibody levels in PV patients. ELISA is more practical and is preferable to IB and is recommended for clinical use.

Multicolor molecular beacons for allele discrimination

Molecular beacons are hairpin-shaped oligonucleotide probes that report the presence of specific nucleic acids in homogenous solutions. When they bind to their targets they undergo a conformational reorganization that restores the fluorescence of an internally quenched fluorophore. We found that their hairpin conformation enables the use of a wide variety of differently colored fluorophores. Using several molecular beacons, each designed to recognize a different target and each labeled with a different fluorophore, we demonstrate that multiple targets can be distinguished in the same solution, even if they differ from one another by as little as a single nucleotide. A comparison of "hairpin probes" with corresponding "linear probes" confirms that the presence of the hairpin stem in molecular beacons significantly enhances their specificity.

Messenger RNA release from ribosomes during 5'-translational blockage by consecutive low-usage arginine but not leucine codons in Escherichia coli

In '5'-translational blockage', significantly reduced yields of proteins are synthesized in Escherichia coli when consecutive low-usage codons are inserted near translation starts of messages (with reduced or no effect when these same codons are inserted downstream). We tested the hypothesis that ribosomes encountering these low-usage codons near the translation start prematurely release the mRNA. RNA from polysome gradients was fractionated into pools of polysomes and monosomes and a ribosome-free pool. New hybridization probes, called 'molecular beacons', and standard slot blots were used to detect test messages containing either consecutive low-usage AGG (arginine) or synonymous high-usage CGU insertions near the 5' end. The results show an approximately twofold increase in the ratio of free to bound mRNA when the low-usage codons were present in the message compared with when high-usage codons were present. In contrast, there was no difference in the ratio of free to bound mRNA when consecutive low-usage CUA or high-usage CUG (leucine) codons were inserted or when the arginine codons were inserted near the 3' end. These data indicate that at least some mRNA is released from ribosomes during 5'-translational blockage by arginine but not leucine codons, and they support proposals that premature termination of translation can occur in some conditions in vivo in the absence of a stop codon.

Fine-needle aspiration diagnosis of carotid body tumor: report of a case and review of experience with cytologic features in four cases

A 45-yr-old female presented with a left upper cervical swelling of 4 yr duration. The clinical suspicion of carotid body tumor (CBT) was confirmed by imaging findings, fine-needle aspiration (FNA) cytology, and histology of the resected tumor. Review of our experience with four cases including the present one during 10 yr (1984-1994) showed that the age of the patients ranged from 35 to 45 yr with a mean of 40.8 yr. All four cases were females and had left-sided upper cervical swelling. Clinically one case was diagnosed as cervical lymphadenopathy and there was clinical suspicion of CBT in two cases. Findings of digital subtraction angiogram in four cases and ultrasonography including Doppler ultrasound vascular imaging in three cases were consistent with CBT. The cytodiagnosis was CBT in three cases and inadequate (blood only) in one case. The analysis of detailed cytologic features in three cases revealed blood-rich aspirate with poor to moderate cellularity, indistinct cell outline, and acinar formation. Giant bare nuclei, spindle-shaped tumor cells, and cytoplasmic granulations were observed in two cases each. Histopathology of the resected tumors in two cases confirmed the cytodiagnosis of CBT. FNA cytology played a useful role in arriving at a tissue diagnosis of this rare neoplasm.

Anaesthetic management of patients undergoing surgery for tachyarrhythmias. Initial experience with 16 patients

Sixteen patients suffering from various cardiac arrhythmias were treated surgically. Intraoperative computerised electrophysiologic mapping was used in 14. Thirteen patients were suffering from Wolff-Parkinson-White syndrome. They underwent surgical division or cryoablation of accessory pathways. Two patients who had rheumatic mitral stenosis with left atrial clot underwent "Maze III" procedure with open mitral commissurotomy and clot removal. One patient with paroxysmal refractory ventricular tachycardia and a left ventricular aneurysm had an aneurysmectomy with subendocardial resection of the arrhythmic focus. All antiarrhythmic medications were discontinued preoperatively. Morphine was the principal anaesthetic agent, supplemented with halothane. Muscle relaxation was provided with pancuronium bromide. The various problems encountered included hypotension and arrhythmia during placement of epicardial band array for mapping (4 patients), ventricular tachycardia during internal jugular vein cannulation (1 patient) and continuance of delta wave after cryoablation in 2 patients. Halothane may have interfered with electrophysiologic mapping and accurate localization of accessory pathway leading to persistence of delta wave. The choice of anaesthetic agents should be guided by the electrophysiologic effects and potential influence of these agents on the accessory pathways.

Percutaneous transluminal angioplasty for renovascular hypertension in children: initial and long-term results

OBJECTIVE

To evaluate the efficacy and safety of percutaneous transluminal renal angioplasty (PTRA) in children.

METHODS

We performed aortography and attempted PTRA in 35 consecutive children (age 5 to 14 years, mean 10.8 +/- 2.5 years) with severe hypertension having > or = 75% renal artery stenosis (RAS).

RESULTS

The stenosis was caused by aortoarteritis in 31 (88.6%) cases and by juvenile idiopathic fibromuscular disease (FMD) in four (11.4%) cases. Twenty-seven (77.1%) patients, including three having RAS of solitary functioning kidney with total occlusion of contralateral renal artery, had bilateral RAS and eight (22.9%) had unilateral RAS. PTRA was technically successful in 54 (91.5%) of 59 stenotic lesions in 31 (88.6%) of 35 patients. Both aortoarteritis and FMD patients had significant decrease in RAS after PTRA. One patient had acute reocclusion of one renal artery after bilateral PTRA, which could be successfully opened by reangioplasty. Postangioplasty angiographic restudy performed in 18 patients at 4 to 72 months (mean 23.1 +/- 27.9 months) after successful angioplasty showed restenosis in 8 (25.8%) of 31 lesions initially dilated and de novo lesions of aorta in two patients. All seven restenotic renal artery lesions attempted and both stenosis of aorta were successfully dilated. Twenty-nine of 31 patients with successful PTRA have been followed up from 4 to 108 months (mean 41.0 +/- 29.3 months). Mean systolic blood pressure decreased from 185.1 +/- 27.4 to 120.6 +/- 19.2 mm Hg and mean diastolic blood pressure decreased from 118.4 +/- 13.2 to 84.6 +/- 10.4 mm Hg after PTRA. Twenty seven (93.1%) of these 29 patients had benefical blood pressure response. Seventeen (58.6%) patients improved, 10 (34.5%) were cured, although 2 (6.9%) patients failed to respond to PTRA. Blood pressure response was better in FMD as compared to aortoarteritis group. Patients with unilateral RAS, discrete stenosis, and post-PTRA stenosis < or = 20% also identified good blood pressure response.

CONCLUSION

Aortoarteritis is the most common cause of renovascular hypertension in South Asian children. PTRA is safe and highly effective and therefore should be the treatment of choice in pediatric renovascular hypertension.

Ocular cicatricial pemphigoid antigen: partial sequence and biochemical characterization

Ocular cicatricial pemphigoid (OCP) is an autoimmune disease that affects mainly conjunctiva and other squamous epithelia. OCP is histologically characterized by a separation of the epithelium from underlying tissues within the basement membrane zone. Immunopathological studies demonstrate the deposition of anti-basement membrane zone autoantibodies in vivo. Purified IgG from sera of patients with active OCP identified a cDNA clone from a human keratinocyte cDNA library that had complete homology with the cytoplasmic domain of beta 4-integrin. The sera recognized a 205-kDa protein in human epidermal, human conjunctiva, and tumor cell lysates that was identified as beta 4-integrin by its reaction with polyclonal and monoclonal antibodies to human beta 4-integrin. Sera from patients with bullous pemphigoid, pemphigus vulgaris, and cicatricial pemphigoid-like diseases did not recognize the 205-kDa protein, indicating the specificity of the binding. These data strongly implicate a role for human beta 4-integrin in the pathogenesis of OCP. It should be emphasized that multiple antigens in the basement membrane zone of squamous epithelia may serve as targets for a wide spectrum of autoantibodies observed in vesiculobullous diseases. Molecular definition of these autoantigens will facilitate the classification and characterization of subsets of cicatricial pemphigoid and help distinguishing them from bullous pemphigoid. This study highlights the function and importance of beta 4-integrin in maintaining the attachment of epithelial cells to the basement membrane.

A decade of subclavian angioplasty: aortoarteritis versus atherosclerosis

The therapeutic outcome of percutaneous transluminal angioplasty (PTA) for subclavian steno-occlusive disease performed over the last 10 years was assessed in 60 consecutive patients of aortoarteritis (n = 35) and atherosclerosis (n = 25). Sixty lesions were stenotic and 6 short segment total occlusions. Twenty-five lesions were prevertebral and 41 postvertebral. PTA was successful in 56 (primary success rate 93.3%) stenotic lesions and 3 (50%) total occlusions. In comparison to atherosclerosis, patients with aortoarteritis were younger (27.7 +/- 9.1 versus 54.7 +/- 10.7 years; p < 0.001), more often female (75% versus 20%; p < 0.001), gangrene was uncommon (0% versus 16%; p < 0.05) and diffuse involvement was more often seen (42.9% versus 4.0%; p < 0.001). The luminal diameter stenosis was similar before PTA (88.6 +/- 9.7% versus 89.0 +/- 9.1%; p = NS); however, aortoarteritis group had more residual stenosis (15.7 +/- 12.5% versus 8.3 +/- 9.6%; p < 0.05) after PTA. Higher balloon inflation pressure was required to dilate the lesions of aortoarteritis (9.9 +/- 4.6 versus 5.5 +/- 1.0 atm; p < 0.001). Three (5%) patients had complications which could be effectively managed nonsurgically. There were no neurological sequelae, even in PTA of prevertebral lesions. On clinical follow-up over a period of 4-120 (43.7 +/- 29.6) months in 45 of the 60 (75%) patients, higher restenosis rate (20.8% versus 4.8%; p = NS) was observed in aortoarteritis group, particularly in those patients with diffuse arterial narrowing. These lesions could be effectively redilated. Successful PTA resulted in marked improvement in symptoms on long-term follow-up. In conclusion, subclavian PTA is safe and can be as effectively performed in aortoarteritis as in atherosclerosis with good long-term results.

Coeliac artery aneurysm: a case report

Coeliac artery aneurysms are rare. A case of coeliac artery aneurysm treated successfully by endoaneurysmorrhaphy is presented. Although excision with arterial reconstruction is usually recommended, endoaneurysmorrhaphy can also be considered in selected cases.

Vortex or whorl formation of cultured human corneal epithelial cells induced by magnetic fields

The terms 'vortex keratopathy' and 'hurricane keratopathy' describe two similar conditions affecting the corneal surface. In the former, a vortex or whorl pattern is seen on the corneal surface and is due to the deposition of substances such as pigment, iron or drugs in the epithelial cells. In the latter, a similar pattern is presented by migrating epithelial cells but, unlike the former, the pattern is rendered more visible by fluorescein staining. Both represent the migratory pattern of normal epithelial cells which is otherwise not visible due to the slow rate of epithelial turnover and migration. The whorl pattern has a clockwise predisposition in the majority of cases and is hypothesised to be due to the influence of ocular electro-magnetic fields on the migrating epithelial cells. In this study we tested in vitro the effect of static magnetic fields on corneal epithelial cells. We were able to reproduce dramatic vortex or whorl patterns in response to magnetic fields, but without preferential migration towards the North or South Pole.

Balloon dilatation of inferior vena cava stenosis in Budd-Chiari syndrome

Percutaneous balloon angioplasty was used to dilate inferior vena cava (IVC) stenosis in 12 patients with Budd Chiari syndrome. There were seven men and five women, aged 32.8 +/- 8.5 years. Angioplasty was performed using balloon 18-20 mm in diameter. In eleven (91.6%) patients, IVC could be successfully dilated. In these eleven patients, the caval diameter at the site of stenosis increased from 2.3 +/- 1.5 to 13.1 +/- 2.8 mm (p < 0.001), the mean IVC pressure decreased from 28.2 +/- 4.1 to 10.5 +/- 3.4 mmHg (p < 0.001) and the gradient across the stenosis decreased from 23.1 +/- 2.2 to 4.2 +/- 1.9 mmHg (p < 0.001). There was appreciable clinical improvement after angioplasty. On a mean followup of 10.8 (3-18) months four (36.4%) patients had restenosis which could be successfully dilated again. These results suggest that balloon dilatation of inferior vena cava stenosis is safe and effective, however, recurrence is common and needs redilatation.

Extremely sensitive, background-free gene detection using binary probes and beta replicase

We have developed a specific and sensitive nucleic acid amplification assay that is suitable for routine gene detection. The assay is based on a novel molecular genetic strategy in which two different RNA probes are hybridized to adjacent positions on a target nucleic acid and then ligated to form an amplifiable reporter RNA. The reporter RNA is then replicated up to a hundred billion-fold in a 30-min isothermal reaction that signals the presence of the target. The assay can detect fewer than 100 nucleic acid molecules; it provides quantitative results over a wide range of target concentrations and it employs a universal format that can detect any infectious agent.

Molecular beacons: probes that fluoresce upon hybridization

We have developed novel nucleic acid probes that recognize and report the presence of specific nucleic acids in homogeneous solutions. These probes undergo a spontaneous fluorogenic conformational change when they hybridize to their targets. Only perfectly complementary targets elicit this response, as hybridization does not occur when the target contains a mismatched nucleotide or a deletion. The probes are particularly suited for monitoring the synthesis of specific nucleic acids in real time. When used in nucleic acid amplification assays, gene detection is homogeneous and sensitive, and can be carried out in a sealed tube. When introduced into living cells, these probes should enable the origin, movement, and fate of specific mRNAs to be traced.

Novel, ligation-dependent PCR assay for detection of hepatitis C in serum

A simple, sensitive, and specific ligation-dependent PCR (LD-PCR) method for the detection of hepatitis C virus (HCV) RNA in serum is described. The assay uses two DNA capture probes for RNA isolation and two DNA hemiprobes for subsequent PCR. Each capture probe has a 3' sequence complementary to the conserved 5' untranslated region of HCV RNA and a biotin moiety at the 5' end capable of interacting with streptavidin-coated paramagnetic beads. Each hemiprobe contains a sequence complementary to the 5' untranslated region in juxtaposition to one another and a common sequence for PCR primer binding. In guanidinium thiocyanate solutions, the capture probes and the hemiprobes form a hybrid with their target, and the hybrid can be isolated from serum by the binding of the capture probes to the paramagnetic beads in the presence of a magnetic field. The hemiprobes can then be linked to each other by incubation with T4 DNA ligase to form a full probe that serves as a template for a PCR. When serial 10-fold dilutions of synthetic HCV RNA (10(7) to 10 molecules) were tested, there was a good correlation between the amount of PCR product and the initial number of RNA molecules, with a sensitivity of 100 HCV RNA molecules per reaction. Twenty-four specimens that had been tested by either a branched DNA probe (bDNA) assay (13 specimens) or a reverse transcription PCR (RT-PCR) assay (11 specimens) were also analyzed by LD-PCR. The results showed a good correlation among LD-PCR, RT-PCR, and the bDNA assay. However, both LD-PCR and RT-PCR were more sensitive than the bDNA assay when the HCV titer was low.

Percutaneous rotational atherectomy in peripheral vascular disease for lesions unsuitable for balloon angioplasty

Percutaneous rotational atherectomy (Rotablator), a high speed (> 140,000 RPM) rotational burr was used to relieve 90-99 percent obstruction in 3 superficial femoral and 2 axillary arteries. These patients had severe claudication in respective extremities. In 4 patients, the lesion was considered to be unsuitable for balloon angioplasty and one patient underwent rotational atherectomy after failure to cross the lesion with balloon catheter. The burr size used ranged from 1.5 to 2.5 mm. After rotablation, the stenosis was reduced from 94.6 +/- 4.5 percent to 42 +/- 8.4 percent. The residual narrowing was further reduced by adjunctive balloon angioplasty to 14 +/- 5.5 percent (p < 0.001). Except for hemoglobinuria in one patient, there were no complications. All patients had good distal pulsations and were relieved of their claudication. On follow-up of 5-18 months, there has been no restenosis. Thus, our preliminary experience suggests that rotational atherectomy is safe and produces gratifying results in patients with peripheral vascular disease having lesions unsuitable for primary balloon angioplasty.

Calcium transport mechanism in human colonic apical membrane vesicles

BACKGROUND & AIMS

Recent studies have shown the role of human colon in the absorption of calcium, especially in the presence of severe disease or resection of the small bowel. The aim of the current study was to explore the mechanism(s) of calcium uptake by the purified human colonic apical membrane vesicles.

METHODS

Apical membrane vesicles were purified from mucosal scrapings of colons from organ donors, and 45Ca uptake was measured using a rapid filtration technique.

RESULTS

The majority of the 45Ca associated with vesicles represented uptake into closed intravesicular space, whereas the remaining 45Ca uptake represented binding to the vesicles. Ca2+ uptake was found to be dependent on time, pH, temperature, and ionic strength of the incubation medium and inhibitable by ruthenium red, La3+, and ethylene glycol-bis(beta-amino-ethyl ether)-N,N,N',N'-tetraacetic acid. Experiments of the effects of membrane potential generated by K+/valinomycin or anion substitutions on Ca2+ uptake showed that the Ca2+ uptake process was potential insensitive. Calcium uptake was unaffected by outwardly directed H+, K+, and Na+ gradients. Ca2+ uptake showed saturation kinetics with no significant differences in Michaelis constant and maximum velocity values of this transporter between proximal and distal colonic segments.

CONCLUSIONS

The uptake of Ca2+ by human colonic apical membranes involves predominantly a carrier-mediated transport mechanism.

Laser assisted balloon angioplasty in lower extremity occlusive disease

Percutaneous transluminal laser angioplasty was used as an adjunct to balloon angioplasty in 36 occluded lower extremity artery segments in 32 patients. Indications for intervention were severe claudication in 25 (78.1%) and rest pain or gangrene in 7 (21.9%) patients. Neodymium-yttrium-aluminium-garnet laser heated probe was used to recanalize the iliac artery in 19, femoral artery in 9, both iliac and femoral arteries in 2, and popliteal and tibial arteries in 2 patients. Patients with successful laser recanalization underwent balloon angioplasty to further widen the lumen. Initial angiographic success was achieved in 28 (87.5%) patients with recanalization of 32 (88.9%) of 36 occlusions. Three patients had extra-axial catheter/guide wire passage and 1 patient had acute thrombosis of the recanalized artery which was successfully reperfused by thrombolytic therapy. At discharge the Doppler ankle-arm pressure index had increased from 0.46 +/- 0.15 to 0.84 +/- 0.12 (p < 0.001) in 29 patients with recanalized arteries. There was marked clinical improvement in these patients. On 6-47 (mean = 23.4 +/- 7.5) months follow up of 28 successfully treated patients 26 (92.9%) showed sustained clinical improvement. Thus laser assisted balloon angioplasty appears to be a safe and useful adjunct in recanalization of lower extremity occlusive disease.