Comparative disposition of dimethylaminoethanol and choline in rats and mice following oral or intravenous administration.

Dimethylaminoethanol (DMAE) and its salts have been used to treat numerous disorders in humans and hence safety of its use is a concern. DMAE is a close structural analog of choline, an essential nutrient. Exposure to DMAE may affect choline uptake and synthesis. The current investigation characterizes: 1) the absorption, distribution, metabolism, and excretion (ADME) of DMAE in Wistar Han rats and B6C3F1 mice following a single gavage or intravenous (IV) administration of 10, 100 or 500 mg/kg [14C]DMAE, and 2) the ADME of [14C]choline (160 mg/kg) and the effect on its disposition following pre-treatment with DMAE (100 or 500 mg/kg). In both rats and mice, following gavage administration, DMAE was excreted in urine (16-69%) and as exhaled CO2 (3-22%). The tissue retention was moderate (21-44%); however, the brain concentrations were low and there was no accumulation. Serum choline levels were not elevated following administration of DMAE. The DMAE metabolites in urine were DMAE N-oxide and N,N-dimethylglycine; the carcinogen, N-N-dimethylnitrosamine, was not detected. The pattern of disposition of [14C]choline following gavage administration was similar to that of [14C]DMAE. Prior treatment with DMAE had minimal effects on choline disposition. The pattern of disposition of [14C]DMAE and [14C]choline following IV administration was similar to gavage administration. There were minimal dose-, sex- or species-related effects following gavage or IV administration of [14C]DMAE or [14C]choline. Data from the current study did not support previous reports that: 1) DMAE alters choline uptake and distribution, or 2) that DMAE is converted into choline in vivo.

Disposition of fullerene C60 in rats following intratracheal or intravenous administration.

Fullerene C60 is used in a variety of industrial and consumer capacities. As part of a comprehensive evaluation of the toxicity of fullerene C60 by the National Toxicology Program, the disposition following intratracheal (IT) instillation and intravenous (IV) administration of 1 or 5 mg/kg b.wt. fullerene C60 was investigated in male Fischer 344 rats. Following IT instillation, fullerene C60 was detected in the lung as early as 0.5 h post-exposure with minimal clearance over the 168 h period; the concentration increased ≥20-fold with a 5-fold increase in the dose. Fullerene C60 was not detected in extrapulmonary tissues. Following IV administration, fullerene C60 was rapidly eliminated from the blood and was undetectable after 0.5 h post-administration. The highest tissue concentrations of fullerene C60 occurred in the liver, followed by the spleen, lung and kidney. Fullerene C60 was cleared slowly from the kidney and the lung with estimated half-lives of 24 and 139 h, respectively. The liver concentration of fullerene C60 did not change much with time; over 90% of the fullerene C60 remained there over the study duration up to 168 h. Fullerene C60 was also not detected in urine or feces. These data support the hypothesis that fullerene C60 accumulates in the body and therefore has the potential to induce detrimental health effects following exposure.

Environmental chemical exposure may contribute to uterine cancer development: studies with tetrabromobisphenol A.

Tetrabromobisphenol A (TBBPA), a widely used flame retardant, caused uterine tumors in rats. In this study, TBBPA was administered to male and female Wistar Han rats and B6C3F1/N mice by oral gavage in corn oil for 2 years at doses up to 1,000 mg/kg. TBBPA induced uterine epithelial tumors including adenomas, adenocarcinomas, and malignant mixed Müllerian tumors (MMMTs). In addition, endometrial epithelial atypical hyperplasia occurred in TBBPA-treated rats. Also found to be related to TBBPA treatment, but at lower incidence and at a lower statistical significance, were testicular tumors in rats, and hepatic tumors, hemangiosarcomas (all organs), and intestinal tumors in male mice. It is hypothesized that the TBBPA uterine tumor carcinogenic mechanisms involve altered estrogen levels and/or oxidative damage. TBBPA treatment may affect hydroxysteroid-dehydrogenase-17ß (HSD17ß) and/or sulfotransferases, enzymes involved in estrogen homeostasis. Metabolism of TBBPA may also result in the formation of free radicals. The finding of TBBPA-mediated uterine cancer in rats is of concern because TBBPA exposure is widespread and endometrial tumors are a common malignancy in women. Further work is needed to understand TBBPA cancer mechanisms.

N,N-dimethyl-p-toluidine, a component in dental materials, causes hematologic toxic and carcinogenic responses in rodent model systems.

Because of the potential for exposure to N,N-dimethyl-p-toluidine (DMPT) in medical devices and the lack of toxicity and carcinogenicity information available in the literature, the National Toxicology Program conducted toxicity and carcinogenicity studies of DMPT in male and female F344/N rats and B6C3F1/N mice. In these studies, a treatment-related macrocytic regenerative anemia characterized by increased levels of methemoglobin and Heinz body formation developed within a few weeks of DMPT exposure in rats and mice. DMPT induced nasal cavity, splenic, and liver toxicity in rats and mice at 3 months and 2 years. DMPT carcinogenic effects were seen in the liver of male and female rats and mice, the nasal cavity of male and female rats, and the lung and forestomach of female mice. In rodents, DMPT is distributed to many of the sites where toxic and carcinogenic effects occurred. DMPT-induced oxidative damage at these target sites may be one mechanism for the treatment-related lesions. Methemoglobinemia, as seen in these DMPT studies, is caused by oxidation of the heme moiety, and this end point served as an early alert for other target organ toxicities and carcinogenic responses that followed with longer term exposure.

Adeno-associated virus serotype 9 efficiently targets ischemic skeletal muscle following systemic delivery.

Targeting therapeutic gene expression to the skeletal muscle following intravenous (IV) administration is an attractive strategy for treating peripheral arterial disease (PAD), except that vector access to the ischemic limb could be a limiting factor. As adeno-associated virus serotype 9 (AAV-9) transduces skeletal muscle at high efficiency following systemic delivery, we employed AAV-9 vectors bearing luciferase or enhanced green fluorescent protein (eGFP) reporter genes to test the hypothesis that increased desialylation of cell-surface glycans secondary to hindlimb ischemia (HLI) might help offset the reduction in tissue perfusion that occurs in mouse models of PAD. The utility of the creatine kinase-based (CK6) promoter for restricting gene expression to the skeletal muscle was also examined by comparing it with the cytomegalovirus (CMV) promoter after systemic administration following surgically induced HLI. Despite reduced blood flow to the ischemic limbs, CK6 promoter-driven luciferase activities in the ischemic gastrocnemius (GA) muscles were ∼34-, ∼28- and ∼150-fold higher than in the fully perfused contralateral GA, heart and liver, respectively, 10 days after IV administration. Furthermore, luciferase activity from the CK6 promoter in the ischemic GA muscles was ∼twofold higher than with CMV, while in the liver CK6-driven activity was ∼42-fold lower than with CMV, demonstrating that the specificity of ischemic skeletal muscle transduction can be further improved with the muscle-specific promoters. Studies with Evans blue dye and fluorescently labeled lectins revealed that vascular permeability and desialylation of the cell-surface glycans were increased in the ischemic hindlimbs. Furthermore, AAV9/CK6/Luc vector genome copy numbers were ∼sixfold higher in the ischemic muscle compared with the non-ischemic muscle in the HLI model, whereas this trend was reversed when the same genome was packaged in the AAV-1 capsid (which binds sialylated, as opposed to desialylated glycans), further underscoring the importance of desialylation in the ischemic enhancement of transduction displayed by AAV-9. Taken together, these findings suggest two complementary mechanisms contributing to the preferential transduction of ischemic muscle by AAV-9: increased vascular permeability and desialylation. In conclusion, ischemic muscle is preferentially targeted following systemic administration of AAV-9 in a mouse model of HLI. Unmasking of the primary AAV-9 receptor as a result of ischemia may contribute importantly to this effect.

Knowing the entire story - a focus group study on patient experiences with chronic Lyme-associated symptoms (chronic Lyme disease).

BACKGROUND: Healthcare providers frequently struggle to provide effective care to patients with chronic Lyme-associated symptoms (chronic Lyme disease, CLD), potentially causing these patients to feel misunderstood or neglected by the healthcare system. This study is the first to use a combined medical and communication science approach, and aims to assess patients' experiences with CLD & CLD-related care, identify themes and repertories in these patients' narrations, and provide potential ways to improve communication with them. METHODS: Informed by the principles of 'clean language', we conducted focus groups with self-identified CLD patients (N = 15). We asked participants about their experiences with CLD and CLD-related healthcare. We performed thematic analyses using a bottom-up approach based in discourse analysis. We also sought to identify specific types of verbalizations (repertoires) across themes. RESULTS: Participants thematised a heterogeneous set of CLD-associated symptoms, which they frequently labelled as 'invisible' to others. Their illness significantly affected their daily lives, impacting their work, social activities, relationships with loved ones, hobbies and other means of participating in society. Negative experiences with healthcare providers were near-universal, also in patients with short-lived CLD-associated symptoms. Verbalizations were notable for frequent use of communicative modes that implicitly create common ground between participants and that give a certain validity to personal experiences (impersonal 'you' and other forms of presupposition). CONCLUSION: Central themes found in CLD patients' communication are 1. the experience of significant symptoms, 2. for which adequate relief is only rarely found from conventional medical practitioners, and 3. that are largely invisible to the outside world. Verbalizing these themes, patients use various repertoires for their shared experiences, such as a feeling of abandonment or not being heard by the medical system, feelings of loss with respect to their previous health, and the idea that they might have been better off had they been diagnosed sooner. Working with these repertoires will enable healthcare providers to establish a shared perspective with their CLD patients, thus engaging in more fruitful doctor-patient communication. We hypothesize that these findings are not unique to CLD, but may also be applicable to other conditions with an uncertain aetiology, such as Long COVID.

Carcinogenesis studies of cresols in rats and mice.

Cresols, monomethyl derivatives of phenol, are high production chemicals with potential for human exposure. The three isomeric forms of cresol are used individually or in mixtures as disinfectants, preservatives, and solvents or as intermediates in the production of antioxidants, fragrances, herbicides, insecticides, dyes, and explosives. Carcinogenesis studies were conducted in groups of 50 male F344/N rats and 50 female B6C3F1 mice exposed to a 60:40 mixture of m- and p-cresols (m-/p-cresol) in feed. Rats and mice were fed diets containing 0, 1500, 5000, or 15,000 ppm and 0, 1000, 3000, or 10,000 ppm, respectively. Survival of each exposed group was similar to that of their respective control group. Mean body weight gains were depressed in rats exposed to 15,000 ppm and in mice exposed to 3000 ppm and higher. A decrease of 25% over that of controls for the final mean body weight in mice exposed to 10,000 ppm appeared to be associated with lack of palatability of the feed. A marginally increased incidence of renal tubule adenoma was observed in the 15,000-ppm-exposed rats. The increased incidence was not statistically significant, but did exceed the range of historical controls. No increased incidence of hyperplasia of the renal tubules was observed; however, a significantly increased incidence of hyperplasia of the transitional epithelium associated with an increased incidence of nephropathy was observed at the high exposure concentration. The only significantly increased incidence of a neoplastic lesion related to cresol exposure observed in these studies was that of squamous cell papilloma in the forestomach of 10,000-ppm-exposed mice. A definitive association with irritation at the site-of-contact could not be made because of limited evidence of injury to the gastric mucosa at the time of necropsy. However, given the minimal chemical-related neoplastic response in these studies, it was concluded that there was no clear evidence of carcinogenicity in male rats or female mice exposed to the cresol mixture.

Immune tolerance therapy utilizing factor VIII/von Willebrand factor concentrate in haemophilia A patients with high titre factor VIII inhibitors.

Factor VIII (FVIII) inhibitors remain a serious complication of treatment for patients with haemophilia A. Immune tolerance induction (ITI) can eliminate inhibitors in the majority of patients, but there are major concerns related with this therapy. Investigators have raised the possibility that the use of FVIII/von Willebrand factor (FVIII/VWF) concentrates may improve the success rate of ITI and may shorten the duration of therapy necessary to attain tolerance. This retrospective study describes 25 patients at five institutions in the USA, who were treated with FVIII/VWF concentrate as part of their ITI. These were all patients who were considered poor prognosis because of clinical and laboratory characteristics, which made ITI less likely to be successful or because of a poor response to initial ITI with a monoclonal/recombinant FVIII concentrate. Overall success (complete tolerization) was 32% with another 40% attaining partial tolerization, but not complete tolerization. Of those patients attaining only partial tolerization, two patients ultimately discontinued ITI and had return of their high titre inhibitors. Eight percent of patients failed to attain either partial or complete tolerization and discontinued ITI. Another 24% are continuing with ITI but have titres of >10 BU. This study adds further retrospective data to the information regarding the use of FVIII/VWF concentrate in ITI.

LPP expression during in vitro smooth muscle differentiation and stent-induced vascular injury.

Lipoma preferred partner (LPP) has been identified as a protein highly expressed in smooth muscle (SM) tissues. The aim of the present study was to determine mechanisms that regulate LPP expression in an in vitro model of SM cell (SMC) differentiation and in stent-induced pig coronary vessel injury. All trans-retinoic acid treatment of A404 cells induced a strong increase in LPP, as well as SM alpha-actin, SM myosin heavy chain, and smoothelin mRNA levels, in a Rho kinase (ROK)-dependent manner. Adenovirus mediated overexpression of myocardin in A404 cells significantly increased LPP mRNA expression. Interestingly, inactivation of RhoA with C3-exoenzyme or treatment with ROK inhibitors strongly inhibited myocardin mRNA expression in retinoic acid-treated A404 cells or human iliac vein SMCs. LPP silencing with short interfering RNA significantly decreased SMC migration. LPP expression was also markedly decreased in focal adhesion kinase (FAK)-null cells known to have impaired migration but rescued with inducible expression of FAK. LPP expression in FAK-null fibroblasts enhanced cell spreading. In stented pig coronary vessels, LPP was expressed in the neointima of cells lacking smoothelin and showed expression patterns identical to those of SM alpha-actin. In conclusion, LPP appears to be a myocardin-, RhoA/ROK-dependent SMC differentiation marker that plays a role in regulating SMC migration.

Complementary DNA for the folate binding protein correctly predicts anchoring to the membrane by glycosyl-phosphatidylinositol.

Membrane bound and soluble forms of a high-affinity folate binding protein have been found in kidney, placenta, serum, milk, and in several cell lines. The two forms have similar binding characteristics for folates, are immunologically cross-reactive and based upon limited amino acid sequence data, are nearly identical. Based upon pulse-chase experiments, a precursor-product relationship has been suggested. The membrane form has been shown to mediate the transport of folate in cells grown in physiological concentrations of folate. A function for the soluble form has not yet been identified. We constructed a cDNA library from a human carcinoma cell line, Caco-2, which expresses the membrane form abundantly. The library was screened and a near full-length cDNA for the folate binder was isolated. Transfection of COS cells with the cDNA inserted in an expression vector resulted in marked overexpression of a membrane-associated folate binder as assessed by direct binding of radiolabeled folate and by indirect immunofluorescence. The deduced amino acid sequence is not consistent with a typical membrane spanning domain but rather with a signal for anchoring via a glycosyl-phosphatidylinositol linkage. Release of the binder with a phosphatidylinositol-specific phospholipase C strongly supports this hypothesis.

Isolation and characterization of two types of MDCK epithelial cell clones based on glycosphingolipid pattern.

The Madin-Darby canine kidney (MDCK) epithelial cell line was shown previously to be heterogeneous with marked differences reported between low-passage (strain I) and high-passage (strain II) cultures (Richardson, J.C.W., Scalera, V. and Simmons, N.L. (1981) Biochim. Biophys. Acta 673, 26-36). This report describes major differences in the glycolipids of the two subpopulations of cells that comprise strain I and strain II cultures. The majority of strain II cells were strongly positive for the Forssman glycolipid antigen, while strain I cells were Forssman-deficient. Upon finding that strain I cells were contaminated with mycoplasma, we rescued Forssman-deficient cells from strain II using an anti-Forssman plus complement lysis procedure. Clones of surviving cells consisted of two distinct cell types. The first were Forssman-deficient, non-ciliated, spindle-shaped cells which generated negative (apical to basolateral) transepithelial potential differences. Clones of the second type were strongly Forssman-positive, ciliated, and formed island-shaped clusters of cuboidal cells. These latter clones generated positive potential differences and grew more slowly than the spindle-shaped clones. Spindle cells were enriched in fucolipids, while cuboidal cells contained higher levels of sulfated glycolipids. These two types of clones should provide excellent model systems in which to study the processing and polarity of glycolipids in epithelial cells.

Selective alpha(v)beta(3)-receptor blockade reduces macrophage infiltration and restenosis after balloon angioplasty in the atherosclerotic rabbit.

BACKGROUND: alpha(v)beta(3)-Integrin receptors are upregulated in atherosclerotic arteries and play a key role in smooth muscle cell and possibly inflammatory cell migration. We hypothesized that after balloon angioplasty (BA) of atherosclerotic arteries, selective inhibition of the alpha(v)beta(3)-receptor by XT199, a small-molecule, non-peptide-selective alpha(v)beta(3)-receptor antagonist, would reduce restenosis. METHODS AND RESULTS: After induction of focal atherosclerosis, rabbits underwent femoral BA and received XT199 (2.5 mg/kg IV bolus plus 2.5 mg. kg(-1). d(-1) IV; n=19) or vehicle (n=20) for 14 days. At 28 days after BA, the XT199 group had a larger lumen (0.75+/-0.26 versus 0.57+/-0.20 mm(2), P=0.03) and a smaller neointimal area (0.49+/-0.18 versus 0.68+/-0.25 mm(2), P=0.01) than the vehicle group. Angiographic analysis confirmed a 30% to 40% reduction in restenosis. Arteries harvested at 28 days after BA did not show a reduction in intima plus media smooth muscle cell content but did show a 50% reduction in macrophage cell density in the XT199 group (716+/-452 versus 1458+/-989 cells/mm(2), P<0.006). Neovessel density at 28 days was also reduced (23+/-42 versus 58+/-46 vessel cross sections/mm(2), P<0.02). Early after BA (ie, 3 to 7 days), there was a decrease in intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression, indicative of a reduction in vascular cell activation. CONCLUSIONS: Selective alpha(v)beta(3)-receptor blockade for 14 days after BA in the focally atherosclerotic rabbit significantly reduced restenosis and limited macrophage infiltration and neovascularization in the vessel wall.

Differential expression of CYP1A, 2B, and 3A genes in the F344 rat following exposure to a polybrominated diphenyl ether mixture or individual components.

Polybrominated diphenyl ethers (PBDEs), used as flame retardants, have been detected in the environment and in mammalian tissues and fluids. Evidence indicates that PBDE mixtures induce CYPs through aryl hydrocarbon receptor (AhR)-dependent and -independent pathways. The present work has investigated the effects of individual components of a commercial PBDE mixture (DE71) on expression of CYP1A1, a biomarker for activation of the AhR (dioxin-like), and CYP2B and CYP3A, biomarkers for activation of the constitutive androstane and pregnanexreceptors (CAR and PXR), respectively, in the rat. Male F344 rats were dosed orally on three consecutive days with either DE71, PBDE components, 2,2',4,4'-tetraBDE (BDE47), 2,2',4,4',5-pentaBDE (BDE99), 2,2',4,4',5,5'-hexaBDE (BDE153), representative polybrominated dibenzofurans (PBDFs) present in DE71, or reference PCBs. Differential expression of target genes was determined in liver 24 h after the last dose. Quantitative PCR analysis indicated up-regulation of CYP1A1 by DE71; however, the response was weak compared to that for dioxin-like PCB126. Individual PBDE components of DE71 up-regulated CYP1A1 only at the highest administered dose (100 micromol/kg/day). Representative PBDFs efficiently up-regulated CYP1A1; therefore, they, along with other PBDFs and polybrominated dibenzodioxins detected in DE71 and individual PBDE components, may be responsible for most, if not all, dioxin-like properties previously observed for PBDEs. Conversely, PBDEs appear capable of up-regulating CYP2B and CYP3A in rats at doses similar to that for non-dioxin-like PCB153. These results indicate that in vivo PBDE-mediated toxicity would be better categorized by AhR-independent mechanisms, rather than the well-characterized AhR-dependent mechanism associated with exposure to dioxin-like chemicals.

Adenosine A(2A) receptor stimulation reduces inflammation and neointimal growth in a murine carotid ligation model.

Endothelial activation and leukocyte recruitment are early events in atherosclerosis and the vascular response to injury. Adenosine has anti-inflammatory effects on leukocytes and endothelial cells mediated through its A(2A) receptor. We tested the hypothesis that A(2A) activation would reduce inflammation and neointimal formation in a murine carotid ligation model. Before injury, mice were randomized to a 7-day subcutaneous infusion of a specific A(2A) receptor agonist (ATL-146e, 0.004 microg/kg per minute), vehicle control, ATL-146e plus ZM241385 (a selective A(2A) antagonist), or ZM241385 alone. Leukocyte recruitment and adhesion molecule expression were assessed at early time points, and the neointimal area was measured at 14 and 28 days after injury. Compared with control mice, ATL-146e-treated mice had significantly less neutrophil and macrophage recruitment and vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and P-selectin expression in the first 7 days after injury. Neointimal area was markedly and persistently reduced by 80% at 14 and 28 days, despite termination of ATL infusion at 7 days. ATL-146e+ZM241385-treated and ZM241385-treated animals had neointimal areas similar to those of control animals, confirming that the observed effects of ATL-146e were mediated specifically by the A(2A) receptor. These data demonstrate that novel stimulation of adenosine A(2A) receptors can inhibit early inflammatory processes that are important in neointimal formation after vascular injury.

Immunoassay of tryptase from human mast cells.

A sandwich ELISA was developed for the measurement of tryptase. The assay utilizes the mouse monoclonal anti-tryptase antibody, termed G5 (IgG2b kappa) in the solid phase and monospecific goat IgG anti-tryptase antibody together with tryptase in the fluid phase. The immunoassay will quantify 0.1 ng-5.6 ng of tryptase per 100 microliters of sample solution to within 0.1 ng. Intra-assay coefficients of variation were determined at 0.3 ng, 1.0 ng and 3.0 ng of tryptase per assay, respectively, to be 19%, 7% and 4% with buffer and 10%, 4%, and 4% in the presence of 20% plasma. Inter-assay coefficients of variation at the same respective levels of tryptase were 22%, 18% and 15% with buffer and 18%, 11% and 14% with 20% plasma. Net absorbance values obtained with a standard amount of tryptase in buffer alone and up to 50% (v/v) normal human citrate-treated plasma were within 10% of one another, indicating nearly complete detection of tryptase added to plasma. This represents the first sensitive immunoassay for a preformed mediator specific for human mast cells.

Antimalarials. 11. 2-Vinylogs of substituted 2-aryl-4-quinoline amino alcohols.

3-(P-Chlorobenzylidene)-5, 7-dimethyl-2, 3-dihydro-1H-cyclopenta[b]quinoline-9-(di-n-butylaminomethyl)methanol and 2-[beta-(p-chlorostyryl)]-6, 8-dimethylquinoline-4-(di-n-butylaminomethyl)methanol were synthesized from 6, -8-dimethyl-4-hydroxycarbostyril by 3, 3-dichlorination, dimethoxylation th the 3-ketal, basic hydrolysis to the glyoxal acetal, Pfitzinger condensation with cylopentanone or acetone to the 2, 3-trimethylene or 2-methylquinoline, condensation with p-ClPhCHO at the 2-methylene or 2-methyl group, hydrolysis to the 4-quinaldehyde, methylenation to the epoxide, and condensation with Bu2NH. Both were curative against P. berghei in mice. The first was the more effective: active at 10 mg/kg, completely curative at 40 mg/kg, and only mildly phototoxic in animals.

Antimalarials. 10. Substituted 3-halo- and 3-methoxy-2-aryl-4-quinoline(di-n-butylaminomethyl)methanols.

Four 2-aryl-4-quinoline(di-n-butylaminomethyl)methanols with Br, Cl, F, or OMe in position 3 were synthesized by modifications of standard reactions. The antimalarial activity decreased with increased size of the 3-substituent. The 3-F-4',6,8-Cl3 compound was the most active (at 2.5 mg/kg) and was completely curative at 80 mg/kg against P. berghei in mice.

5,6-Dihydropyran-2-ones possessing various sulfonyl functionalities: potent nonpeptidic inhibitors of HIV protease.

On the basis of previous SAR findings and molecular modeling studies, a series of compounds were synthesized which possessed various sulfonyl moieties substituted at the 4-position of the C-3 phenyl ring substituent of the dihydropyran-2-one ring system. The sulfonyl substituents were added in an attempt to fill the additional S(3)' pocket and thereby produce increasingly potent inhibitors of the target enzyme. Racemic and enantiomerically resolved varieties of selected compounds were synthesized. All analogues in the study displayed decent binding affinity to HIV protease, and several compounds were shown to possess very good antiviral efficacy and safety margins. X-ray crystallographic structures confirmed that the sulfonamide and sulfonate moieties were filling the S(3)' pocket of the enzyme. However, the additional substituent did not provide improved enzymatic inhibitory or antiviral activity as compared to the resolved unsubstituted aniline. The addition of the sulfonyl moiety substitution does not appear to provide favorable pharamacokinectic parameters. Selected inhibitors were tested for antiviral activity in clinical isolates and exhibited similar antiviral activity against all of the HIV-1 strains tested as they did against the wild-type HIV-1. In addition, the inhibitors exhibited good antiviral efficacies against HIV-1 strains that displayed resistance to the currently marketed protease inhibitors.

Driving safety and adolescent behavior.

Accidents, and mainly automotive accidents, are currently the leading cause of mortality and morbidity among young people. Understanding and addressing the issue of automotive accident prevention requires an awareness of the multiple psychodynamic, familial, and societal influences that affect the development and behavior of adolescents. Risk-taking behavior is the product of complex personal and environmental factors. As pediatricians, we have the obligation and the opportunity to improve the safety of our youth who drive and ride. This opportunity is available to us not only in our roles as counselors to youth and families, but also as we serve as role models, educators, and agents for change within our communities.

Recommended changes in pediatric education: the impact on pediatrician involvement in health care delivery to adolescents.

In an attempt to examine the extent of implementation of the recommendations issued by the Task Force on Pediatric Education for increased emphasis on adolescent medicine during residency training, pediatricians' perceptions of their skills and abilities to provide health care to adolescents were evaluated. A sample of 558 pediatricians selected at random and 385 members of the American Academy of Pediatrics' Section on Adolescent Health (SAH) completed a 41-item questionnaire. The physicians' perceived levels of skill in ten areas were analyzed while simultaneously assessing the impact of SAH membership, year of graduation from medical school, gender, and percentage of practice time devoted to adolescents on each issue. SAH members, as expected, ranked their levels of skill significantly higher than did the other pediatricians in all areas surveyed. A significant percentage of the SAH pediatricians, however, indicated that their skills were acquired through postresidency fellowship training. There was an increasing trend among all pediatricians in their perceived levels of skill to deliver health care to adolescents during the past several decades, but there has been no appreciable increase in such perceived skill levels since the task force issued its recommendations. In fact, pediatricians graduating from medical school in the decade prior to 1976 who are not SAH members ranked their skills higher than did non-SAH pediatricians who graduated in the past 10 years. These data lead to the conclusion that the recommendations of the Task Force on Pediatric Education have not been adequately implemented.