Taking action on teen smoking. Texas physicians back tobacco regulations, counsel teens

This article describes how a staff group adapted to a change in students' learning requirements. Using the principles outlined in the nursing model being adopted by their college (Peplau 1980), the staff attempted to link their clinical environment with the students' objectives. The author concludes that by responding positively to the change, students and staff benefited from the new approach.     

The diagnostic value of discography

BACKGROUND: Conjunctival cyst formation following enucleation may occur in 3% to 7% of patients receiving orbital implants, especially secondary implants. We present a patient with a giant epithelial inclusion cyst of the anophthalmic orbit 50 years after enucleation without orbital implant. PATIENT: A 54-year-old male presented with increasing proptosis of the ocular prosthesis, shallowing of the inferior fornix, a palpable orbital mass, and difficulty in retaining the ocular prosthesis. At the age of 1 year enucleation of the right eye without orbital implant was performed following perforating ocular trauma. Results of examination of the other eye were unremarkable. Transillumination of the orbital mass was possible. The clinical diagnosis of an epithelial inclusion cyst was confirmed using ultrasonography and CT scan. An incision of conjunctiva and cyst wall and subsequent marsupialization were performed. Nine months postoperatively there was no evidence of recurrence of the cyst. The ocular prosthesis was well in place. CONCLUSION: Conjunctival cyst formation following enucleation may rarely occur in patients receiving orbital implants, especially secondary implants. The presentation of a conjunctival cyst formation following enucleation without orbital implant 50 years after surgery is noteworthy in comparison to implantation cysts which are known to occur more commonly within the first two years following secondary orbital implants.     

Practical applications of snake venom toxins in haemostasis

Snake venom toxins have an established role in the coagulation laboratory for the assay of haemostatic parameters and a potential role for therapeutic treatment of thrombotic disorders. In the laboratory, snake venom thrombin-like enzymes (SVTLEs) are used for the assay of fibrinogen and detection of fibrinogen breakdown products and dysfibrinogenaemias. Importantly, because SVTLEs are not inhibited by heparin, they can be used for assaying antithrombin III and other parameters in samples which contain heparin. Prothrombin activators occur in many snake venoms and these have become established in the assay of prothrombin, in the study of dysprothrombinaemias and in the preparation of meizothrombin and non enzymic forms of prothrombin. Russell's viper (Daboia russelli) venom contains a number of useful compounds including toxins which can be used to assay blood clotting factors V, VII, X, platelet factor 3 and lupus anticoagulants (LA). More recently, activators from the taipan, Australian brown snake and saw-scaled viper have been used to assay LA. Proteins C and S can be measured by means of protac, a fast acting inhibitor from Southern copperhead snake venom and von Willebrand factor can be studied with botrocetin from Bothrops jararaca venom. The disintegrins, a large family of Arg-Gly-Asp (RGD)-containing proteins found in snake venoms, show great potential for the study of platelet glycoprotein receptors, notably, GPIIb/IIIa and Ib, and in the treatment of arterial thrombotic disease. Established SVTLEs used in clinical practice include ancrod and defibrase although success with these agents has been limited. A further group of enzymes under consideration as thrombolytic agents are the fibrinogenases.     

Bacterially preexposed T cells impair bacterial elimination by non-Th1/Th2 cell mechanisms in a model of intra-abdominal infection

BACKGROUND: Escherichia coli preexposure in mice results in impaired elimination of subsequent intra-abdominal infections by a CD+4 T cell-dependent process. Certain gram-negative infections have been shown to induce T-helper-(Th)2 type CD4+ T-cell differentiation, which correlates with impaired elimination of infection and death. We hypothesized that E coli preexposure impairs subsequent bacterial elimination as a consequence of Th2 differentiation and that interleukin-12 (IL-12) treatment could reverse this differentiation and minimize the effects of E coli preexposure. METHODS: After preexposure to E coli or other species, BALB/c mice or interferon-gamma (INF-gamma)-deficient mice, treated with or without IL-12, were given a standard intra-abdominal infection (E coli, Bacteroides fragilis, and adjuvant). Cohorts were killed for abscess quantification, in vitro T-cell proliferative responsiveness, and cytokine secretory profiles. Splenic lymphocytes preexposed in vivo to other types of bacteria were transferred to naive mice before intra-abdominal infection to determine whether preexposure, eliciting the lymphocyte-dependent response, was species specific. RESULTS: E coli preexposure alone caused no Th1 or Th2 shift; increased the proliferative responses of T cells; and, in combination with IL-12 therapy, caused markedly decreased IL-2 and IL-4 responses and an increased IFN-gamma response. IL-12 therapy did not change the response to intra-abdominal infection despite its ability to cause marked Th1 polarization. IFN-gamma-deficient mice responded to E coli preexposure no differently than did wild-type mice. Transfer of lymphocytes preexposed to Pseudomonas aeruginosa, Klebsiella pneumoniae, and hemolytic E coli but not other types of nosocomial pathogens caused the development of more abscesses just as transfer of E coli preexposed lymphocytes had. CONCLUSIONS: CD4+ T cells responsive to E coli preexposure regulate subsequent intra-abdominal abscess formation by a mechanism not explained by the Th1/Th2 paradigm. Preexposure to hemolytic E coli and other Enterobacteriaceae alters responses to intra-abdominal infection.     

Influence of grapefruit juice on caffeine pharmacokinetics and pharmacodynamics

The influence of grapefruit juice (GFJ) on caffeine's metabolism and the hemodynamic effects of this potential food interaction were studied in 10 normotensive volunteers. In this crossover study, caffeine (3.3 mg/kg) and water or caffeine and GFJ were given to participants. Nine serum caffeine concentrations were determined within 24 hours of each phase. In another phase of this study, caffeine was given with multiple GFJ doses to 6 of the 10 participants. Ambulatory blood pressure (BP) monitors were used for 12 hours to assess treatment hemodynamic effects. The mean area under the serum caffeine concentration-time curve (AUC0-infinity) values +/- SD for the caffeine with water group, caffeine with GFJ group, and caffeine with multiple GFJ group were 47.0 +/- 10.8, 48.7 +/- 15.2, and 49.6 +/- 7.0 micrograms/ml.hr, respectively (NS). There was no significant difference on the ambulatory systolic BP, diastolic BP, percentage of the time with a diastolic BP greater than 90 mm Hg, or heart rate area under the effect curves. We conclude that grapefruit juice had no effect on caffeine pharmacokinetics or hemodynamic effects.     

Identification of the principal proteoglycan-binding site in LDL. A single-point mutation in apo-B100 severely affects proteoglycan interaction without affecting LDL receptor binding

The subendothelial retention of LDLs through their interaction with proteoglycans has been proposed to be a key process in the pathogenesis of atherosclerosis. In vitro studies have identified eight clusters of basic amino acids in delipidated apo-B100, the protein moiety of LDL, that bind the negatively charged proteoglycans. To determine which of these sites is functional on the surface of LDL particles, we analyzed the proteoglycan-binding activity of recombinant human LDL isolated from transgenic mice. Substitution of neutral amino acids for the basic amino acids residues in site B (residues 3359-3369) abolished both the receptor-binding and the proteoglycan-binding activities of the recombinant LDL. Chemical modification of the remaining basic residues caused only a marginal further reduction in proteoglycan binding, indicating that site B is the primary proteoglycan-binding site of LDL. Although site B was essential for normal receptor-binding and proteoglycan-binding activities, these activities could be separated in recombinant LDL containing single-point mutation. Recombinant LDL with a K3363E mutation, in which a glutamic acid had been inserted into the basic cluster RKR in site B, had normal receptor binding but interacted defectively with proteoglycans; in contrast, another mutant LDL, R3500Q, displayed defective receptor binding but interacted normally with proteoglycans. LDL with normal receptor-binding activity but with severely impaired proteoglycan binding will be a unique resource for analyzing the importance of LDL- proteoglycan interaction in atherogenesis. If the subendothelial retention of LDL by proteoglycans is the initial event in early atherosclerosis, then LDL with defective proteoglycan binding may have little or no atherogenic potential.     

Electrochemical oxidation of N-acyldopamines and regioselective reactions of their quinones with N-acetylcysteine and thiourea

Affinity selection from peptide libraries is a powerful tool that has been used for determining the sequence specificities of a number of enzymes and protein binding domains, including protein kinases, src homology 2 domains, and PDZ domains. We have extended this approach to protein tyrosine phosphatases using peptide libraries containing a nonhydrolyzable phosphotyrosine analog, difluorophosphonomethylphenylalanine. A size-exclusion method is used to separate enzyme-peptide complexes from free peptide, providing several advantages over the traditional immobilized protein affinity column approach. In addition, the feasibility of using mass spectrometric detection to quantitate peptides rapidly and reproducibly is demonstrated as an alternative to quantitation by peptide sequencing. The validity of this analysis is demonstrated by synthesizing individual peptides and comparing their affinity for enzyme with the predictions from the affinity selection process. As a model for these studies the protein tyrosine phosphatase PTP1B is used, providing additional insights into the sequence specificity of this enzyme. In particular, a selection for aromatic amino acids at the pY - 1 position (immediately N-terminal to the phosphotyrosine), as well as a broad pY + 1 selectivity, is observed in addition to the general preference for acidic residues N-terminal to the phosphotyrosine. The approach described here should prove applicable to protein tyrosine phosphatases in general as well as for the study of nonpeptidyl combinatorial libraries.