Mapping the auxin-binding site of auxin-binding protein 1

Auxin-binding protein 1 (ABP1) is a putative receptor for the class of plant growth hormones designated auxins of which indole-3-acetic acid (IAA) is the predominant endogenous member. ABP1 is a homodimeric glycoprotein consisting of subunits of 163 amino acid residues. We have performed a structural study of ABP1 that has localized a region along its primary sequence that is involved in hormone binding. We have used the photoaffinity labeling agent, 5-[7-3H]azidoindole-3-acetic acid (5-[3H]N3IAA), an active auxin analog, to covalently label residues that are within, or near, the auxin-binding site. Photolabeled ABP1 was digested to completion with trypsin, and the resulting peptides were purified by reverse phase high performance liquid chromatography. When 5-[3H]N3IAA was used at a concentration of 0.5 microM (one order of magnitude below the Kd for 5-N3IAA) only one peptide was labeled at a high specific activity. Labeling was blocked by the presence of 50 microM IAA, indicating that the interaction is specific. Sequence analysis determined that this tryptic fragment was derived from Ile130 to Leu145 of ABP1. We suggest that residue Asp134 is the specific target of the photolabeling and is within 1.48 A of the postulated hydrophobic platform of the auxin-binding site. We propose that Trp136 may serve as this hydrophobic platform in the binding site for the aromatic rings of auxins.

Health, addiction, social interaction and the decision to quit smoking

The decision to quit smoking is treated as a choice under uncertainty in an empirical model that incorporates health, medical advice, addiction, and social interaction. Probit models are estimated for attempts and success in quitting with data from the Health and Lifestyle Survey. The results show a clear role for addiction, social interaction and current health status. The evidence on the effectiveness of medical advice is ambiguous.

Fuel Alcohol Production: Optimization of Temperature for Efficient Very-High-Gravity Fermentation

The time required to end ferment wheat mash decreased as the temperature was increased from 17 to 33°C, but it increased as the concentration of dissolved solids was raised from 14.0 to 36.5 g/100 ml. Ethanol yield was not appreciably affected. Over the range of fermentation temperatures tested, the addition of urea accelerated the rate of fermentation, decreased the time required to complete fermentation at all dissolved-solid concentrations, and stimulated the production of slightly more ethanol than was produced by the corresponding unsupplemented control mashes. The optimum temperature for maximum ethanol production in urea-supplemented very-high-gravity wheat mash was 27°C. These data are important for the industrial assessment of very-high-gravity fermentation technology.

Mutation detection in the X-linked agammaglobulinemia gene, BTK, using single strand conformation polymorphism analysis

The gene defective in X-linked agammaglobulinemia (XLA) has recently been isolated and identified as btk, a non-receptor protein tyrosine kinase. We have utilized the technique of single strand conformation polymorphism (SSCP) analysis for the btk gene to identify mutations in XLA patients. The btk gene in affected boys from 10 families was analysed and mutations were identified in eight cases; seven of these were point mutations and one was a small insertion. The mutations were found throughout the gene coding region. Six of the patients have classical XLA and two have less severe forms of the disease. We have also identified a polymorphism at nucleotide position 2031. This technique will allow us to provide more accurate diagnoses of the disease and to determine the nature of the functional defects in the btk gene in these families.

Paradoxical reconstitution of complement activity following plasma transfusion of an individual with deficiency of the seventh component of complement

A subject deficient in the seventh component of complement (C7) was plasmapheresed with 660 ml C7-sufficient plasma. The expected reconstitution of C7 activity, followed by exponential decay, was not observed. During day 1, serum haemolytic C7 and total haemolytic complement were undetectable and C7 levels were very low by C7 ELISA. However, low levels of circulating fluid phase terminal complement complex (TCC) were detected. On day 2 about microgram C7/ml serum was detected and this rose to 6 micrograms/ml by day 17. Functional complement activity was also present. At day 28 the serum C7 and total haemolytic complement had dropped to pretransfusion levels. A low level of C5b6 was present in pretransfusion serum and this increased markedly immediately following transfusion when the patient's serum also acquired C7 consuming activity. Throughout the study low levels of anti-C7 antibodies were present but there was no evidence that antibody was directly responsible for the C7 consumption. Nevertheless antibody-antigen interactions could have generated circulating C5b6. C5b6 has been shown previously to have the capacity to inhibit C7 activity in vitro. Investigations of the C7 circulating on days 2-17 demonstrated normal molecular weight, functionally active C7. The donor sera and the recirculating C7 allotyped C7-1 by isoelectric focusing; however, the recirculating C7 showed additional weak bands with C7 functional activity, suggesting a possible genetic or acquired abnormality. Although the disappearance of C7 immediately post-transfusion may be explained by the presence of C5b6, there is no satisfactory explanation for the rising C7 levels on days 2-17 and we cannot exclude temporary C7 secretion by the patient.

Psychiatric presentation of a third ventricular colloid cyst in a mentally handicapped woman

A 42-year-old mentally handicapped woman presented with symptoms of affective disorder which resolved completely on excision of a colloid cyst of the third ventricle.

Subunit interactions in the carboxy-terminal domain of phytochrome

We have produced defined fragments of the oat PhyA AP3 protein using an in vitro translation system and analyzed the quaternary structure of these fragments by size exclusion chromatography. Sequences between amino acids S599 and L683 are shown to dimerize by this in vitro assay and by a lambda repressor-based in vivo assay. A subset of this dimerization region, V623-S673, which has previously been identified as being involved in interdomain interactions on the basis of the behavior of overlapping constructs in a lambda repressor assay for protein-protein interaction, is shown by both assays to be necessary but insufficient for dimerization. Sequences between L685 and R815, which are unable to dimerize by themselves, are shown to interact with sequences between S599 and L683. Sequences E1069-Q1129, also previously suggested to be involved in dimerization, are shown here not to be required for phytochrome dimerization. These results based on an in vitro assay have confirmed some of the results previously obtained using an in vivo assay and extend these earlier results by revealing new protein-protein interactions. This dissection of sequences involved in phytochrome dimerization taken together with previous work has enabled us to propose a model for the behavior of the dimerization region where the core structure involved in dimerization is located on both sides of a region around residue 750 found at the surface.

The effect of hypoxia on acquired drug resistance and response to epidermal growth factor in Chinese hamster lung fibroblasts and human breast-cancer cells in vitro

Prolonged hypoxia induced transient drug resistance in Chinese hamster lung fibroblasts. Previously hypoxic cells were resistant to adriamycin and resistant to etoposide. Complete recovery of etoposide sensitivity was observed following reaeration for 24 hr. A change in P-glycoprotein expression was unlikely to contribute to the resistance caused by hypoxia, since adriamycin resistance was not reversed by verapamil. However, alteration in the plasma membrane structure may be involved, since previously hypoxic cells were resistant to extracellular superoxide radical generated by the addition of xanthine/xanthine oxidase. In contrast, adriamycin sensitivity was not altered by hypoxia in 3 human breast-cancer cell lines. MDA-468 and MCF-7/Adr differed in their response to EGF, independent of the presence of hypoxia. These results suggest that hypoxic-stress-induced drug resistance is not generalized.

Physical mapping in the region of human Xq12-21.1 using pulsed field gel electrophoresis

A number of human disease genes have been localised to Xq12-21.1. A genetic map of this region has previously been constructed using family linkage studies and has been complemented by physical mapping studies using hybrid and deletion cell lines. We have constructed a preliminary long-range physical map of the region, which incorporates thirteen polymorphic and non-polymorphic probes, using pulsed field gel electrophoresis. The order of loci that can be inferred from all the genetic and physical mapping data is: cen-DXS133-[DXS153, DXS159]-DXS132-DXS135-[DXS131, DXS162]-[DXS325, DXS-347, DXS441]-PGK1-DXS447-DXS72-tel. The detection of several large non-overlapping MluI fragments by these probes implies that the minimum extent of the genomic DNA containing these loci is 16 Mb. This information should be useful in the eventual identification and isolation of the genes responsible for diseases that map to this region.

In vivo suppression of phytochrome aggregation by the GroE chaperonins in Escherichia coli

When expressed in Escherichia coli, a truncated form of phytochrome (oat PHYA AP3 residues 464-1129) self associates to form a series of products ranging in size from monomers to aggregates of greater than 20 subunits. When these same phytochrome sequences are coexpressed with the chaperonins GroEL and GroES, the truncated phytochrome migrates as a native-like dimer in size exclusion chromatography and no higher-order aggregates were detected. GroEL and GroES inhibition of phytochrome aggregation in E. coli presumably occurs via the suppression of folding pathways leading to incorrectly folded phytochrome.

Natural history, duplex characteristics, and histopathologic correlation of arterial injuries in a canine model

The treatment of patients with penetrating extremity trauma in proximity to major arteries as well as the nonoperative treatment of clinically occult arterial injuries remain controversial. Duplex ultrasonography (DUS) has recently been advocated in this setting. We therefore studied experimentally induced arterial injuries in dogs to correlate the natural history, duplex findings, and histopathologic condition of different injuries and to help define criteria for operation. Fifty-two canine femoral and carotid arteries were randomized to have surgically created intimal flaps (n = 15), crush injuries (n = 15), or lacerations (n = 15) or to be controls (n = 7). An experienced sonographer, blinded to the presence or type of injury, evaluated the vessels every 10 days for 1 month. Histopathologic study was performed 1 month after injury when the arteries were retrieved. The sensitivity (96.5%), specificity (86.4%), and accuracy (95.1%) of DUS in evaluating arterial injuries at 1 month correlated well with histopathologic evaluation. All arteries subjected to crush injuries showed abnormal duplex findings. These findings correlated well with the histologic picture of severe injury (arterial wall thickness = 2.72 x +/- 0.23 x control; intramural hemorrhage, 93%; mural thrombus, 60%). DUS and histologic study revealed healing of intimal flaps in 27% of the arteries. Other intimal flaps deteriorated (stenoses, 47%; dilation, 13%; occlusion, 13%). Most lacerations (86%) revealed duplex evidence of healing within 10 days of injury. This was confirmed by histologic study at 1 month in 73% of lacerated arteries. This study confirms the accuracy of DUS in diagnosing various arterial injuries and shows that the natural history of these injuries varies with the mechanism of injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Initial characterization of a pea mutant with light-independent photomorphogenesis

We have identified a mutant of pea cultivar Alaska that has many of the characteristics normally associated with light-grown seedlings even when grown in complete darkness. We have designated this mutant lip1, for light independent photomorphogenesis. Etiolated wild-type pea seedlings are white to slightly yellow in color and have a distinct morphology characterized by elongated epicotyls and buds containing unexpanded leaves with small, undifferentiated cells. In contrast, mutant seedlings grown under the same conditions are yellow in color and have short epicotyls and expanded leaves showing clear cellular differentiation. Transmission electron microscopy revealed partially developed, agranal plastids in the dark-grown mutant, unlike wild-type seedlings that contain etioplasts with prolamellar bodies. The mutant also exhibits a much shorter lag period for chlorophyll accumulation when etiolated seedlings are transferred from darkness to white light. The dark-grown mutant has 10-fold less spectrally detectable phytochrome, which can be attributed to a 10-fold reduction in the level of the PHYA polypeptide. Cab, Fed1, and RbcS transcripts are present in dark-grown mutant seedlings at levels comparable to those produced in light-grown material. The levels of these transcripts show a normal decrease when green plants grown for 15 days in a light/dark cycle are transferred to continuous darkness. However, transcript levels remain high during dark treatment of seedlings grown for 9 days in continuous light, indicating that the dark adaptation response in this mutant is developmentally plastic. The lip1 mutant has several features in common with the deetiolated Arabidopsis mutants det1, det2, and cop1. However, there are also several important differences, including varying effects on phytochrome levels, organ-specific gene expression, plastid development, and response to dark adaptation.

Antibodies to meningococcal class 1 outer membrane proteins in South African complement-deficient and complement-sufficient subjects

Inhibition assays were used to investigate human serum antibodies to the meningococcal class 1 outer membrane proteins. We adapted the whole-cell enzyme-linked immunosorbent assay technique to determine the ability of sera to inhibit the binding of murine subtyping monoclonal antibodies. Serum samples from 33 South African subjects with a deficiency in the sixth component of complement as well as serum samples from various groups of complement-sufficient subjects were investigated. Subjects were subdivided according to whether they were (i) convalescent from Neisseria meningitidis infections, (ii) nonconvalescent, or (iii) controls. Preliminary subtyping investigations had shown that P1.2 was present on 36% of meningococcal clinical isolates from Cape Province, South Africa. Assays with the anti-P1.2 antibodies showed the presence of high antibody levels in many deficient sera and moderately elevated levels in some sera from the complement-sufficient convalescent patients. P1.2, P1.4, P1.15, and P1.16 are epitopes situated on loop 4 of the class 1 outer membrane proteins, whereas P1.7 is on loop 1. Inhibition assays showed that human sera that inhibited binding by P1.2 monoclonal antibodies tended to inhibit the other monoclonal antibodies directed to loop 4 epitopes. This suggests that the epitopes recognized by the human antibodies are not exactly the same as the epitopes recognized by the murine monoclonal antibodies and raises the possibility of the importance of other epitopes.

An apparently allosteric effect involving N2O with the nitrous oxide reductase from Wolinella succinogenes

It was shown that kcat for the benzyl viologen cation (BV+)-N2O oxidoreductase activity of nitrous oxide reductase from Wolinella succinogenes was 2-3 times greater at high N2O concentrations than at low. This effect of N2O on kcat exhibited a titration curve implicating a single secondary binding site for N2O with a Kd of 130-200 microM (Km with respect to N2O is about 2.5 microM). This work represents the first evidence of an apparently allosteric kinetic effect among nitrous oxide reductases. Its possible cause is discussed. BV+ was generated in these kinetic studies by addition of sub-stoichiometric amounts of dithionite. This means of reduction proved to be superior to the photochemical generation of BV+ that had been used previously with the enzyme. Mass spectrometric measurements suggested that the M(r) of the subunit of the enzyme is about 95,500 rather than 88,000.

Indium-111 monoclonal antibody B72.3 scintigraphy in colorectal cancer. Correlation with computed tomography, surgery, histopathology, immunohistology, and human immune response

As part of an open-labeled nonrandomized multi-institutional Phase III study, the authors compared the results of In-111 (In-111) B72.3 glycyl-tyrosyl-n-diethylenetriaminepentaacetic acid lysine (GYK-DTPA) monoclonal antibody scintigraphy with computed tomography (CT), surgery, histopathology, immunohistology, and human antibody response in 23 patients with primary colorectal carcinoma. There were no significant adverse reactions to 1 mg of In-111-labeled antibody. Planar imaging identified 16 of 23 primary colon lesions, whereas single photon emission computer tomography (SPECT) imaging identified 21. SPECT also correctly identified lymphatic involvement in four patients. (There were two false-positive results.) Liver metastases were identified with SPECT imaging. Twenty-six percent of patients developed human anti-mouse antibody (HAMA). These preliminary results demonstrate that In-111 B72.3 GYK-DTPA is a safe monoclonal antibody conjugate that has a high sensitivity for identifying primary colorectal cancer. Regional lymphatic and distant liver metastases also can be imaged, but false-positive results can occur.

Nonoperative management of herniated nucleus pulposus: patient selection by the extension sign. Long-term follow-up

We have previously reported that the ability of patients with herniated nucleus pulposus (HNP) and radiculopathy to achieve full passive lumbar extension (negative extension sign) is a useful predictor of favorable response to conservative management. Of 154 patients with back pain and radiculopathy seen between 1979 and 1985, 73 were selected for conservative management based on this criterion. We also reviewed results of electromyography (EMG), computed tomography (CT), myelography, straight leg raise, crossed straight leg raise, deep tendon reflex, and dermatomal-sensory and motor deficits. Ninety-four percent of the subjects achieved full extension within 5 days of hospital admission. Although some patients who had full extension on admission subsequently underwent chemonucleolysis or surgery, none of those who could not extend initially and who later gained full lumbar extension required surgery. Of the 33 patients who were available for long-term follow-up, 94% were satisfied with the results, 82% were able to resume working, 73% required no analgesics, and 9% later required chemonucleolysis or surgery. Positive findings on admission EMG (5 of 7 patients), myelography (5 of 8 patients), or CT (9 of 11) did not preclude good results with conservative management. Female patients without complaint at follow-up (53%) outnumbered their male counterparts (25%). Patients (19 of 33) whose extension sign was initially positive on admission and became negative within 5 days of hospitalization (average, 1.6 days) had better outcomes with 95% satisfied, 90% without job changes, 74% not requiring analgesia, and none requiring surgery. At long-term follow-up, the extension sign effectively predicted a favorable response to nonoperative therapy of HNP in 91% of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of protein-protein interactions between subunits of phytochrome

We have used a novel assay based on protein fusions with lambda repressor to identify two small regions within phytochrome's carboxy-terminal domain that are capable of mediating dimerization. Using an in vivo assay, fusions between the DNA binding, amino-terminal domain of lambda repressor and fragments from oat PhyA phytochrome have been assayed for increased repressor activity, an indicator of dimerization. In this assay system, regions of oat phytochrome between amino acids V623-S673 and N1049-Q1129 have been shown to increase repressor activity. These short spans are highly conserved between proteins belonging to the phytochrome PhyA family. Embedded within these sequences are four segments that could potentially form amphipathic alpha helices. Two of the segments are well conserved between PhyA phytochrome and phytochromes encoded by the phyB and phyC genes, suggesting that heterodimers might form by way of subunit interaction at these sites.

Unsuspected preexisting saphenous vein disease: an unrecognized cause of vein bypass failure

Our prior anecdotal experience with unsuspected preexisting saphenous vein disease prompted us to study its incidence, its relation to graft failure, and to identify techniques for its detection. Thick-walled, postphlebitic sclerotic occluded, postphlebitic sclerotic recanalized, calcified, and varicose vein lesions were detected in 63 (12%) of 513 infrainguinal vein bypasses. In 13 (2% to 5%) cases, severe saphenous vein disease precluded use of the vein. In the remaining 50 cases, the entire vein or a portion thereof, with minimal or unsuspected disease, was used for bypass. Early graft failures occurred in 10 (20%) of the 50 cases. The cumulative primary patency rate at 30 months for bypasses performed with diseased veins was 32%. This was significantly less than the 73% cumulative primary patency rate for bypasses with veins without detectable disease (p less than or equal to 0.001). Retrospective evaluation of preoperative duplex ultrasonography (n = 21) originally used to evaluate saphenous vein length and diameter correctly identified thick-walled, occluded, calcified, and varicose veins in 62% of cases. Intraoperative methods of vein evaluation included inspection, palpation, irrigation, catheter or valvulotome insertion to identify obstruction, and intraoperative arteriography. Histologic examination of diseased veins demonstrated a spectrum of disease with thickening of the intima and media, vein wall calcification, and luminal recanalization. We conclude that (1) unsuspected preexisting saphenous vein disease occurs in approximately 12% of cases and results in both early and late graft failures; (2) detection, in some cases, is possible with duplex ultrasonography and intraoperative techniques; and (3) diseased veins that are recanalized, calcified, or thick-walled should not be used if an alternative vein is available.

Contracting for visitation with families

Visitation in adult critical care units is an important aspect of patient care, and thus should be incorporated into the patient's plan of care. There is no longer a question as to whether visitation should be liberalized or restricted; instead, visitation is individualized in each situation to best meet the patient's needs. One method of incorporating visitation into the care plan is by contracting with patients and family members.

Enumeration of Flexibacter canadensis in environmental samples by using a bacteriophage isolated from soil

The denitrifier Flexibacter canadensis, in the presence of sulfide, can reduce N2O in the presence of concentrations of C2H2 which normally inhibit N2O reduction. Most-probable-number estimates of naturally occurring F. canadensis populations in various soils and sediments were made with a bacteriophage which is active against and specific for a strain of denitrifying F. canadensis (Is-11). Our survey suggests that F. canadensis is common in the natural environment.

Putative receptor for the plant growth hormone auxin identified and characterized by anti-idiotypic antibodies

The molecular mechanism of action of auxins, which are an important class of plant growth regulators, is not known. While they are thought to influence cellular processes such as gene expression and membrane hyperpolarization by binding to specific receptors, no receptor mediating these processes has been unambiguously identified. We describe the identification of a putative auxin receptor by using anti-idiotypic antibodies. We have demonstrated that a 65-kilodalton protein found in a wide range of plants specifically binds auxins. Furthermore, since it is localized to the nucleus, it is a candidate for an auxin receptor that mediates some nuclear process.