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J King

Publications and source records attributed to J King.

At least 199 records · Page 11Linked to original sources
PubMed1994

Local rule-based theory of virus shell assembly.

A local rule-based theory is developed which shows that the self-assembly of icosahedral virus shells may depend on only the lower-level interactions of a protein subunit with its neighbors--i.e., on local rules rather than on larger structural building blocks. The local rule theory provides a framework for understanding the assembly of icosahedral viruses. These include both viruses that fall in the quasiequivalence theory of Caspar and Klug and the polyoma virus structure, which violates quasi-equivalence and has puzzled researchers since it was first observed. Local rules are essentially templates for energetically favorable arrangements. The tolerance margins for these rules are investigated through computer simulations. When these tolerance margins are exceeded in a particular way, the result is a "spiraling" malformation that has been observed in nature.

Bacteriophage P22↗
PubMed1994

In vitro and ribosome-bound folding intermediates of P22 tailspike protein detected with monoclonal antibodies.

It remains unclear whether polypeptide chains renaturing in vitro from strong denaturants proceed through the same folding pathway as chains released from ribosome within cells. Folding intermediates formed both in vivo and in vitro have been examined using three monoclonal antibodies shown previously to recognize different epitopes of the native P22 tailspike protein (Friguet, B., Djavadi-Ohaniance, L., Haase-Pettingell, C. A., King J., and Goldberg, M. E. (1990) J. Biol. Chem. 265, 10347-10351). The tailspike protein was reconstituted from polypeptide chains unfolded by urea as described by Fuchs et al. (Fuchs, A., Seiderer, C., and Seckler, R. (1991) Biochemistry 30, 6598-6604), and the appearance of immunoreactive forms during the refolding was monitored. The three antibodies discriminated intermediates at different stages in the folding pathway. On the basis of the reconstitution pathway determined from spectroscopic and hydrodynamic measurements by Fuchs et al. (1991), monoclonal antibody (mAb) 236-3 recognized partially folded monomers, mAb 155-3 recognized folded protomers in a protrimer species, and mAb 33-2 recognized the native trimer. The kinetics of appearance of the immunoreactive forms during the in vitro refolding of the protein in crude extracts of phage-infected cells was similar to that observed with the pure tailspike. Thus, the antibodies provided probes for the chain folding and association pathway in vivo. The conformation of the ribosome-bound tailspike polypeptide chains of the infected cells was analyzed with the three antibodies. The antibodies recognizing native trimer and the protrimer did not bind chains associated with the ribosomes. Antibody 236-3, which recognized structured monomers in vitro, bound to the polypeptide chains still associated with ribosomes. This result suggests that steps that take place in solution during in vitro refolding may occur in a ribosome-bound state in vivo.

Amino Acid Sequence↗
PubMed1994

Bioresorbable screws for facial bone reconstruction: a pilot study in rabbits.

Rigid fixation using plates and screws is an accepted mode of repair for facial fractures and osteotomies. To avoid potential complications associated with metal implants, bioresorbable implants are being developed. A study was performed to assess the strength over time of three bioresorbable polymeric screws for facial bone reconstruction. Screws of each polymer type and a titanium control were implanted in the periorbital bones of eight rabbits. Rabbits were euthanized at various time intervals. Pull-out testing and histological analysis were performed. Results showed varying degrees of resorption and screw pull-out strength dependent on time and polymer type, and no change in the control. This study demonstrates that bioresorbable screws can be used in bone, although the optimal choices for human implantation are yet to be determined.

Animals↗
PubMed1994

Intragenic recombination in the CSR1 locus of Arabidopsis.

Four classes of herbicides are known to inhibit plant acetolactate synthase (ALS). In Arabidopsis, ALS is encoded by a single gene, CSR1. The dominant csr1-1 allele encodes an ALS resistant to chlorsulfuron and triazolopyrimidine sulfonamide while the dominant csr1-2 allele encodes an ALS resistant to imazapyr and pyrimidyl-oxy-benzoate. The molecular distance between the point mutations in csr1-1 and csr1-2 is 1369 bp. Here we used multiherbicide resistance as a stringent selection to measure the intragenic recombination frequency between these two point mutations. We found this frequency to be 0.008 +/- 0.0028. The recombinant multiherbicide-resistant allele, csr1-4, provides an ideal marker for plant genetic transformation.

Acetolactate Synthase↗
PubMed1994

Pressure denaturation of the bacteriophage P22 coat protein and its entropic stabilization in icosahedral shells.

The pressure stability of bacteriophage P22 coat protein in both monomeric and polymeric forms under hydrostatic pressure was examined using light scattering, fluorescence emission, polarization, and lifetime methodology. The monomeric protein is very unstable toward pressure and undergoes significant structural changes at pressures as low as 0.5 kbar. These structural changes ultimately lead to denaturation of the subunit. Comparison of the protein denatured by pressure to that in guanidine hydrochloride suggests that pressure results in partial unfolding, perhaps by a domain mechanism. Fluorescence lifetime measurements indicate that at atmospheric pressure the local environments of the tryptophans are remarkably similar, suggesting they may be clustered. In contrast to the monomeric protein subunit, the protein when polymerized into procapsid shells is very stable to applied pressure and does not dissociate with pressure up to 2.5 kbar. However, under applied pressure the procapsid shells are cold-labile, suggesting they are entropically stabilized. The significance of these results in terms of virus assembly are discussed.

Bacteriophage P22↗
PubMed1994

Morphometric quantitation of stroma in human benign prostatic hyperplasia.

OBJECTIVES: Human benign prostatic hyperplasia (BPH) consists of three major histologic components: stroma, epithelium, and luminal space. For the relief of bladder outlet obstruction caused by BPH, quantitation of the histologic composition of BPH may aid in selecting treatment. To investigate variation between patients in the stromal percentage of BPH, we performed quantitative morphometry on specimens from patients with clinically significant bladder outlet obstruction obtained by three procedures: open prostatectomy, transurethral resection of the prostate (TURP), and prostate needle biopsy (PNB) just prior to TURP. METHODS: Ten specimens obtained by each surgical procedure were analyzed. Specimens were stained with antibody to muscle-specific actin to mark the stroma; quantitation of stroma was accomplished by computer image analysis. RESULTS: The percentage of stroma in all BPH cases ranged from 49.9% to 76.7% (mean, 65.4%, SD = 7.4). No significant difference was observed when comparing samples obtained by the three procedures (p = 0.70). Smooth muscle stromal composition was also quantified in PNB specimens. For these samples, a significant inverse relationship was found between the percentage stroma in the biopsy and the percentage of stroma composed of smooth muscle (r2 = 0.49; p = 0.021). CONCLUSIONS: The data demonstrated that the largest component of BPH was stroma, which comprised approximately 50% to 75% of the total hyperplastic tissue. The mean and range of stromal percentage were similar whether investigating large tissue samples from open prostatectomies or small samples from needle biopsies. PNB data indicated that an increased percentage of stroma may be due to increased nonmuscular elements in the stroma.

Antibodies, Monoclonal↗
PubMed1994

Genetic properties of temperature-sensitive folding mutants of the coat protein of phage P22.

Temperature-sensitive mutations fall into two general classes: those generating thermolabile proteins; and those generating defects in protein synthesis, folding or assembly. Temperature-sensitive mutations at 17 sites in the gene for the coat protein of Phage P22 are of the latter class, preventing the productive folding of the polypeptide chain at restrictive temperature. We show here that, though the coat subunits interact intimately to form the viral shell, these temperature-sensitive folding (TSF) mutations were all recessive to wild type. The mutant polypeptide chains were not rescued by the presence of wild-type polypeptide chains. Missense substitutions in multimeric proteins frequently exhibit intragenic complementation; however, all pairs of coat protein TSF mutants tested failed to complement. The recessive phenotypes, absence of rescue and absence of intragenic complementation are all accounted for by the TSF defect, in which destabilization of a folding intermediate at restrictive temperature prevents the mutant chain from reaching the conformation required for subunit/subunit recognition. We suggest that absence of intragenic complementation should be a general property of TSF mutations in genes encoding multimeric proteins. The spectra of new loci identified by isolating second-site suppressors and synthetic lethals of temperature sensitive mutants will also differ depending on the nature of the defect. In the case of TSF mutations, where folding intermediates are defective rather than the native molecule, the spectra of other genes identified should shift from those whose products interact with the native molecule to those whose products influence the folding process.

Bacteriophage P22↗
PubMed1994

CEA reduction after cryotherapy for liver metastases from colon cancer predicts survival.

Serum carcinoembryonic antigen (CEA) levels in 33 Australian patients with hepatic metastases from colorectal cancer were measured before and after treatment with hepatic cryotherapy and intra-arterial chemotherapy. Pre-operative and monthly postoperative CEA measurements were made and the lowest postoperative reading was recorded as a percentage fall from the pre-operative level. There was a highly significant association between the maximum percentage fall in CEA and survival. A 50% increase in the maximum percentage fall in CEA level was associated with one-tenth the risk of death (95% CI RR 0.03 to 0.32, Cox regression). It is estimated that an increase in the maximum percentage fall in CEA of 50% from 25 to 75% was associated with an increase in the median survival from 240 days to over 2 years.

Antineoplastic Agents↗
PubMed1994

Influence of socioeconomic status, ethnicity and an educational brochure on compliance with a postal faecal occult blood test.

The study aimed to determine if socioeconomic status and ethnicity affect compliance with postal faecal occult blood test screening, and if compliance can be increased by adding an educational brochure. A pilot intervention study was used in socioeconomically defined postcodes and defined census collection districts of the Southern Sydney Area Health Service. The study population of men and women aged 45 to 75 years was selected from general practice lists in the defined postcodes. Samples were comparable for age, sex, and socioeconomic indices. Compliance, using a general practitioner letter alone, was: for the Australian middle-socioeconomic status sample, 65.8 per cent (95 per cent confidence interval (CI) 59.5 to 72.1), the Australian low-socioeconomic status sample, 63.9 per cent (CI 57.3 to 70.5), the Arabic low-socioeconomic status sample, 33.3 per cent (CI 27.2 to 39.4). With the general practitioner letter plus brochure, compliance was: Australian middle-socioeconomic status sample, 67.0 per cent (CI 60.5 to 73.5), Australian low-socioeconomic status sample, 62.1 per cent (CI 55.3 to 68.9) and Arabic low-socioeconomic status sample, 36.8 per cent (CI 30.6 to 43.0). Compliance was higher in all Australian samples than in Arabic samples. A brochure, designed to increase compliance with testing, had no significant effect in Australian samples. Australian samples of different socioeconomic status complied almost equally. Results suggest that advice from the local doctor is very effective in motivating patients to screen with faecal occult blood testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Parish nursing--a conceptual framework.

Parish nursing is a current nursing care delivery model that practices holistic health care. Parish nurses provide care to a faith community, emphasizing the relationship between faith and health. Specific nursing activities address physical, emotional, and spiritual health and well-being, closely attending to the inseparability of these dimensions. Parish nurses may assume one or more roles associated with this practice to accomplish parish nursing activities and achieve the holistic health and well-being of individuals, families, and groups within the faith community. The five broad categories of client, health, nurse, environment, and nursing process provide a framework for organizing the concept of parish nursing for future nursing theory, research, and practice.

Christianity↗
PubMed1994

Efficacy of albuterol in the management of bronchiolitis.

OBJECTIVE: To examine the efficacy of albuterol (0.15 mg/kg per dose) in the management of bronchiolitis. DESIGN: Randomized, double-blind, placebo-controlled outpatient clinical trial utilizing four study groups: neubulized albuterol, nebulized saline, oral albuterol, and oral placebo. SETTING: Pediatric emergency department and outpatient clinic at University of Maryland in Baltimore. PATIENTS: Eighty-eight infants (median age 5.5 months) being treated for their first episode of wheezing were randomly assigned to nebulized albuterol (n = 22), nebulized saline (n = 23), oral albuterol (n = 19), oral placebo (n = 24). INTERVENTIONS: The nebulized groups received two nebulizations 30 minutes apart, whereas the oral groups received one oral dose. MAIN OUTCOME MEASURES: Respiratory and heart rates, clinical score, oxygen saturation (Spo2), and the infant's state, ie, asleep, awake, or feeding, were recorded at baseline and at 30 and 60 minutes after treatment. RESULTS: Randomization produced equivalent groups in terms of demographics and baseline measures. There were no statistically significant differences in any outcomes among the four treatments, except for oral albuterol, which produced an increase in heart rate (15 beats per minute, P = .005). No differences in the need for additional treatment or hospitalization were observed. Change in the state of the infant during the trial had significant effects on respiratory rate and clinical score. CONCLUSIONS: Albuterol is as effective as oral placebo in the management of bronchiolitis. Past studies supporting the use of albuterol did not control for effects of change in state of the infant and did not use a truly inactive placebo group. This study underscores the importance of these design components in measuring the efficacy of albuterol in infants.

Administration, Inhalation↗
PubMed1993

Inhibition of viral capsid assembly by 1,1'-bi(4-anilinonaphthalene-5-sulfonic acid).

The precursor shells of dsDNA bacteriophages are assembled by the polymerization of competent states of coat and scaffolding subunits. The fluorescent dye 1,1'-bi(4-anilinonaphthalene-5-sulfonic acid) (bisANS) binds to both the coat and scaffolding proteins from the Salmonella typhimurium bacteriophage P22. It displays little affinity for the polymerized forms of the proteins. The subunits with bound bisANS are incapable of assembling into procapsids. The binding constants of bisANS for both coat and scaffolding protein monomers have been measured and are 7 and 6 microM, respectively. Binding of bisANS to coat protein has little effect on the conformation as determined by circular dichroism and susceptibility to proteolysis. Binding of bisANS to scaffolding protein induces a change in the secondary structure consistent with a loss of alpha-helix, and an altered susceptibility to proteolysis. We suggest that the bisANS is probably binding at sites responsible for intersubunit interactions and thereby inhibiting capsid assembly.

Anilino Naphthalenesulfonates↗