1560. Pharmacokinetics–Pharmacodynamics (PK-PD) of Gepotidacin (GEP) Against Escherichia coli in Murine Pyelonephritis and Thigh Infection Models

Background

GEP, a first in class novel triazaacenaphthylene bacterial topoisomerase inhibitor, inhibits bacterial replication and has in vitro activity against key pathogens implicated in a range of infections, including drug-resistant strains of E. coli associated with acute cystitis.

Methods

PK and PD studies were conducted in murine (male CD-1 mice) thigh and kidney infections. The administered doses ranged from 1 to 200 mg/kg SC every 6 hours starting 1-hour post-infection. Infected tissues were evaluated for bacterial burden at 24-h post-infection (baseline controls at 1-hour post-infection). Plasma and tissue samples (kidney or thigh homogenates) were collected at 15, 30, 60, 120, 240 and 360 minutes. A population PK (PopPK) model was built in NONMEM using plasma exposures. Efficacy was determined against E. coli ALL, 997577, ATCC25922, IR5 and NCTC13441 (MICs of 1 to 4 µg/mL) in thigh-infected neutropenic (I-) mice and against E. coli ALL in kidney-infected immunocompetent (I+) and I- mice. The PopPK model was used to determine GEP exposures associated with efficacy. PK-PD analyses were conducted using Phoenix WinNonLin 6.3 (Pharsight). The change in log₁₀ colony-forming units (CFU) from baseline were correlated with free drug (f) AUC:MIC using an inhibitory model from the Phoenix library, and model parameter values for each isolate were used to calculate the plasma fAUC:MIC associated with stasis, 1- or 2-log₁₀ reductions in CFU.

Results

Plasma PK data were best fit by a 1-compartment IV model with first-order elimination and were similar in I+ vs. I- and thigh- vs. kidney-infected mice. The AUC_0-6 of GEP in kidney was approximately 4- to 5-fold higher than in plasma while the AUC_0-6 in thigh was approximately half of plasma. In the I- thigh model, median plasma fAUC:MIC ratios for stasis, 1- or 2-log₁₀ reductions in CFU were 11, 16, and 25 (ranges 3–17, 4–25 and 7–40), respectively. Efficacy vs. E. coli ALL was similar in I- mice infected in thigh or kidney. In I+ mice, the PK-PD target was reduced by half.

Conclusion

Median plasma fAUC:MIC targets ranged from 11 to 25. Higher drug levels in kidney vs. plasma or thigh did not translate into improved efficacy in pyelonephritis vs. thigh-infection models.

Disclosures

All authors: No reported disclosures.

Homozygous XYLT2 variants as a cause of spondyloocular syndrome

Spondyloocular syndrome (SOS) is a rare autosomal recessive, skeletal disorder. Two recent studies have shown that it is the result of biallelic sequence variants in the XYLT2 gene with pleiotropic effects in multiple organs, including retina, heart muscle, inner ear, cartilage, and bone. The XYLT2 gene encodes xylosyltransferase 2, which catalyzes the transfer of xylose (monosaccharide) to the core protein of proteoglycans (PGs) leading to initiating the process of PG assembly. SOS was originally characterized in 2 families A and B of Iraqi and Turkish origin, respectively. Using DNA from affected members of the same 2 families, we performed whole exome sequencing, which revealed 2 novel homozygous missense variants (c.1159C > T, p.Arg387Trp) and (c.2548G > C, p.Asp850His). Our findings extend the body of evidence that SOS is caused by homozygous variants in the XYLT2 gene. In addition, this report has extended the phenotypic description of SOS by adding follow-up data from 5 affected individuals in one of the two families, presented here.

Abstract P1-09-10: ICOSL anti-HER2 V-mAbs: Localizing engineered ICOSL costimulatory agonists to HER2+ tumors through trastuzumab

Background: The presence of tumor infiltrating lymphocytes (TILs) has been associated with improved prognosis in HER2+ breast cancer patients. Antigen specific TCR and costimulatory receptor signaling drive increases in TIL number, effector function, and tumor cytotoxicity. Improving the number and effector phenotype of tumor localized TILs has curative potential by enhancing the adaptive and memory immune response. Targeting HER2 with the monoclonal anti-HER2 antibody trastuzumabhas improved survival in HER2+ breast cancer patients and is known to increase peripheral type I immunity, which may be reflected by increased TILs.

The Immunoglobulin Superfamily (IgSF) includes a large, diverse family of immunotherapy targets expressed on immune cells and tumors. Transmembrane IgSF receptors,CD28 and inducible T cell co-stimulator (ICOS), related costimulatory molecules expressed on T cells, interact with CD80/CD86 and ICOS ligand (ICOSL), respectively, and play critical roles in T cell activation and adaptive immunity.The Alpine Immune Science's VIgDTM platform uses directed evolution to derive novel, therapeutically-applicable IgSF extracellular domains with tailored specificity and affinity. The vIgD platform has generated human ICOSL vIgDs capable of binding both ICOS and CD28, activating both pathways. To promote anti-tumor activity of TILs in HER2+ tumors, we developed trastuzumab-ICOSL “V-mAbs” consisting of trastuzumab fused to activating ICOSL vIgDs. These V-mAbs are designed to localize to HER2+ tumors and activate antigen-specific, resident T-cells through costimulatory receptor agonism.

Methods: V-mAbs were generated by fusing ICOSL vIgDs to either the N- or C- termini of the heavy and/or light chains of trastuzumab. V-mAb binding to CD28, ICOS or HER2 was measured by flow cytometric analysis of transfected cells or ForteBio analysis. V-mAb costimulatory activity was confirmed by immobilization in the presence of anti-CD3 in a primary human T cell assay. Finally, V-mAbs were co-cultured with HER2+ target cells and human T cells; T-cell activity was measured by proliferation, cytokine production, and target lysis.

Results: V-mAbs were successfully produced and bound to CD28, ICOS and HER2. In a plate bound costimulation assay, the V-mAbs increased the amount of IFN-gamma produced by T-cells stimulated with anti-CD3. When incubated with HER2+ target cells, V-mAbs promoted T-cell proliferation, cytokine secretion, and target cell lysis. Data from in vivo studies, to determine the impact of trastuzumab V-mAbs on HER2+ cancers, will be presented when available.

Conclusions: Trastuzumab-ICOSL V-mAbs are novel ICOS- and CD28-activating immunotherapies for HER2-positive tumors, promoting T-cell proliferation, cytokine secretion, and target cell lysis in a HER2 dependent fashion. The V-mAb platform has broad potential to enable tumor-localized immune modulation via the diverse array of IgSF members. Preclinical development of trastuzumab-ICOSL clinical therapeutics is in progress.

Citation Format: Rickel E, Evans L, Swanson R, Levin SS, Rixon M, Wolfson M, Bhandari J, MacNeil S, Hoover J, Kornacker M, Capuano I, Peng SL. ICOSL anti-HER2 V-mAbs: Localizing engineered ICOSL costimulatory agonists to HER2+ tumors through trastuzumab [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-09-10.

Efficacy of Cefiderocol against Carbapenem-Resistant Gram-Negative Bacilli in Immunocompetent-Rat Respiratory Tract Infection Models Recreating Human Plasma Pharmacokinetics

Cefiderocol (S-649266), a novel siderophore cephalosporin, shows potent activity against carbapenem-resistant Gram-negative bacilli. In this study, we evaluated the efficacy of cefiderocol against carbapenem-resistant Gram-negative bacilli (Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae) in immunocompetent-rat respiratory tract infection models recreating plasma pharmacokinetics (PK) profiles in healthy human subjects. A total of 6 clinical isolates (1 cephalosporin-susceptible P. aeruginosa isolate, 1 multidrug-resistant P. aeruginosa isolate, 2 multidrug-resistant A. baumannii isolates, and 2 carbapenem-resistant K. pneumoniae isolates) were evaluated. Four-day treatment with a human exposure of 1 g ceftazidime every 8 h as a 0.5-h infusion showed potent efficacy only against a ceftazidime-susceptible isolate, not against five ceftazidime-resistant isolates harboring carbapenemase. With cefiderocol, a human exposure of 2 g every 8 h as a 3-h infusion for 4 days produced a >3 log10 reduction in the number of viable cells of these carbapenem-resistant isolates in the lungs. When the infusion time was 1 h, bactericidal activity was also observed against all isolates tested, although for 2 of 5 carbapenem-resistant isolates, a 3 log10 reduction was not achieved. The difference in efficacy achieved by changing the infusion period from 1 h to 3 h was considered to be due to the higher percentage of the dosing interval during which free-drug concentrations were above the MIC (%fTMIC), as observed for β-lactam antibiotics. These results suggest the potential utility of cefiderocol for the treatment of lung infections caused by carbapenem-resistant P. aeruginosa, A. baumannii, and K. pneumoniae strains.

Novel cyclohexyl-amides as potent antibacterials targeting bacterial type IIA topoisomerases

As part of our wider efforts to exploit novel mode of action antibacterials, we have discovered a series of cyclohexyl-amide compounds that has good Gram positive and Gram negative potency. The mechanism of action is via inhibition of bacterial topoisomerases II and IV. We have investigated various subunits in this series and report advanced studies on compound 7 which demonstrates good PK and in vivo efficacy properties.

Novel amino-piperidines as potent antibacterials targeting bacterial type IIA topoisomerases

We have identified a series of amino-piperidine antibacterials with a good broad spectrum potency. We report the investigation of various subunits in this series and advanced studies on compound 8. Compound 8 possesses good pharmacokinetics, broad spectrum antibacterial activity and demonstrates oral efficacy in a rat lung infection model.

Use of the surgical wound infection model to determine the efficacious dosing regimen of retapamulin, a novel topical antibiotic

The effect of topically applied retapamulin ointment was evaluated using various dosing regimens in the Staphylococcus aureus and Streptococcus pyogenes wound infection model. Retapamulin (1%, wt/wt) was efficacious using twice-daily (b.i.d.) applications for 4 or 5 days. These data underpinned the decision to evaluate 1% retapamulin b.i.d. in clinical trials.

Comparative bacteriological efficacy of pharmacokinetically enhanced amoxicillin-clavulanate against Streptococcus pneumoniae with elevated amoxicillin MICs and Haemophilus influenzae

A new pharmacokinetically enhanced formulation of amoxicillin-clavulanate (2,000 mg of amoxicillin/125 mg of clavulanate twice a day; ratio 16:1) has been designed, with sustained-release technology, to allow coverage of bacterial strains with amoxicillin-clavulanic acid MICs of at least 4/2 mug/ml. The bacteriological efficacy of amoxicillin-clavulanate, 2,000/125 mg twice a day, ratio 16:1, was compared in a rat model of respiratory tract infection versus four other amoxicillin-clavulanate formulations: 8:1 three times a day (1,000/125 mg), 7:1 three times a day (875/125 mg), 7:1 twice a day (875/125 mg), and 4:1 three times a day (500/125 mg); levofloxacin (500 mg once a day); and azithromycin (1,000 mg on day 1 followed thereafter by 500 mg once a day). Bacterial strains included Streptococcus pneumoniae, with amoxicillin-clavulanic acid MICs of 2/1 (one strain), 4/2, or 8/4 microg/ml (three strains each), and Haemophilus influenzae, one beta-lactamase-positive strain and one beta-lactamase-negative, ampicillin-resistant strain. Animals were infected by intrabronchial instillation. Antibacterial treatment commenced 24 h postinfection, with doses delivered by computer-controlled intravenous infusion to approximate the concentrations achieved in human plasma following oral administration. Plasma concentrations in the rat corresponded closely with target human concentrations for all antimicrobials tested. Amoxicillin-clavulanate, 2,000/125 mg twice a day, ratio 16:1, was effective against all S. pneumoniae strains tested, including those with amoxicillin-clavulanic acid MICs of up to 8/4 microg/ml and against beta-lactamase-producing and beta-lactamase-negative ampicillin-resistant H. influenzae. These results demonstrate the bacteriological efficacy of pharmacokinetically enhanced amoxicillin-clavulanate 2,000/125 mg twice a day (ratio 16:1) against S. pneumoniae with amoxicillin-clavulanic acid MICs of at least 4/2 microg/ml and support clavulanate 125 mg twice a day as sufficient to protect against beta-lactamase in this rat model.

New bone formation with teriparatide [human parathyroid hormone-(1-34)] is not retarded by long-term pretreatment with alendronate, estrogen, or raloxifene in ovariectomized rats

With the ready availability of several osteoporosis therapies, teriparatide [human PTH-(1-34)] is likely to be prescribed to postmenopausal women with prior exposure to agents that prevent bone loss, such as bisphosphonates, estrogen, or selective estrogen receptor modulators. Therefore, we evaluated the ability of once daily teriparatide to induce bone formation in ovariectomized (Ovx) rats with extended prior exposure to various antiresorptive agents, such as alendronate (ABP), 17 alpha-ethinyl estradiol (EE), or raloxifene (Ral). Sprague Dawley rats were Ovx and treated with ABP (28 microg/kg, twice weekly), EE (0.1 mg/kg per d), or Ral (1 mg/kg per d) for 10 months before switching to teriparatide 30 microg/kg per d for another 2 months. Analysis of the proximal tibial metaphysis showed that all three antiresorptive agents prevented ovariectomy-induced bone loss after 10 months, but were mechanistically distinct, as shown by histomorphometry. Before teriparatide treatment, ABP strongly suppressed activation frequency and bone formation rate to below levels in other treatment groups, whereas these parameters were not different from sham values for EE or Ral. Trabecular area for ABP, EE, and Ral were greater than that in Ovx controls. However, the trabecular bone effects of ABP were attributed not only to effects on the secondary spongiosa, but also to the preservation of primary spongiosa, which was prevented from remodeling. After 2 months of teriparatide treatment, lumbar vertebra showed relative bone mineral density increases of 18%, 7%, 11%, and 10% for vehicle/teriparatide, ABP/teriparatide, EE/teriparatide, and Ral/teriparatide, respectively, compared with 10 month levels. Histomorphometry showed that trabecular area was increased by 105%, 113%, 36%, and 48% for vehicle/teriparatide, ABP/teriparatide, EE/teriparatide, and Ral/teriparatide, respectively, compared with 10 month levels. Teriparatide enhanced mineralizing surface, mineral apposition rate, and bone formation rate in all groups. Compression testing of vertebra showed that teriparatide improved strength (peak load) and toughness in all groups to a proportionately similar extent compared with 10 month levels. These data showed a surprising ability of the rat skeleton to respond to teriparatide despite extensive pretreatment with ABP, EE, or Ral. Therefore, the mature skeleton of Ovx rats remains highly responsive to the appositional effects of teriparatide regardless of pretreatment status in terms of cancellous bone area or rate of bone turnover.

Long-term islet graft survival in streptozotocin- and autoimmune-induced diabetes models by immunosuppressive and potential insulinotropic agent FTY720

BACKGROUND

Toxicity of current immunosuppressive agents to islet grafts is one of the major obstacles to clinical islet transplantation (Tx). This study was designed to assess the efficacy of FTY720, a novel immunomodulator with a unique mechanism of action, on islet graft survival and function in streptozotocin (STZ)- and autoimmune-induced diabetic recipients.

METHODS

Islet allograft from BALB/C mice or islet isografts were transplanted into STZ-induced diabetic CBA mice and autoimmune nonobese diabetic (NOD) mice. FTY720 was administered orally at 0.5 mg/kg per day in STZ diabetic recipients or 3 mg/kg per day in NOD recipients after Tx. Functional status of the islet graft was monitored by measuring blood glucose daily. Insulin secretion from mouse islets was measured with an insulin scintillation proximity assay.

RESULTS

Under the treatment of FTY720, long-term normoglycemia (>100 days) was achieved in 100% of STZ diabetic recipients and 50% of diabetic NOD recipients compared with a respective 11 and 7 days in untreated animals after allogeneic islet Tx. Normoglycemia persisted only temporarily (<4 weeks) in untreated NOD recipients of NOD islets, but was maintained for >100days with FTY720 treatment. Histologically, leukocyte infiltration observed in untreated animals was largely inhibited in FTY720-treated ones. Additionally, FTY720 stimulated insulin secretion from isolated islets by approximately twofold under both normoglycemic and hyperglycemic conditions.

CONCLUSIONS

FTY720 is highly effective in protecting allo- and autoimmune response-mediated islet graft destruction without direct toxicity to the islets. The effect is likely attributable to its action in preventing effector lymphocyte infiltration into the grafted tissue.

Treadmill and cycle ergometry testing in 5- to 6-year-old children

The primary purpose of this study was to determine the maximal cardiorespiratory responses of 48, 5- to 6-year-old children (24 girls and 24 boys), who were tested on a treadmill (TM) and an electronically braked cycle ergometer (CE). We also examined the percentage of boys and girls who were able to achieve the criteria for reaching maximal oxygen consumption (VO2max) on each testing mode. After an orientation period, each child was tested twice (once on the TM and once on the CE), with an interval of 1 week between tests. VO2max was measured during progressive, all out, continuous TM and CE tests using standardized procedures. A 2 x 2 analysis of variance test (genderxexercise mode) with Bonferroni adjustment revealed the following: (1) there were no gender differences in any of the measured dependent variables, (2) the children produced a significantly higher relative VO2max (ml x kg(-1) x min(-1) and a higher absolute VO2max (l x min(-1)) on the TM than on the CE (P < 0.001), (3) the children produced a higher heart rate on the TM than on the CE (P < 0.001), (4) the CE generated significantly higher values for respiratory exchange ratio (P < 0.001), (5) the criteria necessary to establish a maximal exercise effort were achieved on both the TM and the CE, and (6) all of the children reached two of the criteria associated with a maximal effort, while only 46% of the children reached three criterion measures. There were no significant differences in the attainment of criterion measures between the TM and the CE. The results of this study indicate a lack of gender differences in maximal exercise testing in 5- to 6-year-old children, and that both the CE and the TM are effective modes of maximal cardiorespiratory testing in this age group.

Colorectal cancer screening: video-reviewed flexible sigmoidoscopy by nurse endoscopists--a Canadian community-based perspective

BACKGROUND

Colorectal cancer (CRC) is the third most common incident cancer and the second most fatal cancer in Canada. Flexible sigmoidoscopy (FS) is one of the modalities under consideration for CRC screening. The present series reports on a screening program of FS performed by nonphysician endoscopists in a Canadian community setting, with video review of procedures by physicians and recommendation of follow-up colonoscopy where polyps are identified.

RESULTS

Five hundred twenty-five, average-risk, asymptomatic patients were examined. After exclusion of inappropriate referrals, 488 remained for analysis. The duration and extent of examination were comparable with those of previous studies elsewhere. Compliance with suggested follow-up was 97.3%. Polyps were identified at FS in 15.4% of examinees. In 8.2% of patients, the polyps were neoplastic at subsequent histology. Four malignant lesions were detected, all at an early stage. There were no complications of FS.

INTERPRETATION

This report shows that FS can be carried out safely and effectively by nonphysician personnel in a community setting in Canada. The manpower cost for nonphysician operators is considerably less than that for specialist physician endoscopists. This approach deserves consideration in cost effectiveness analyses of CRC screening.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Effects of environmentally relevant concentrations of 2,3,7,8-TCDD on domestic chicken immune function and CYP450 activity: F1 generation and egg injection studies

Domestic chickens (Gallus gallus) were used as a surrogate species for wild turkey to assess risk from environmental 2,3,7,8-TCDD exposure. Lymphocyte proliferation and CYP450 induction were assessed in adults exposed via i.m. injection, in F1 14-day old hatchlings, in F1 adults (30-weeks old), and in 14-day old hatchlings exposed via yolk sac injections. Hatchlings from injected eggs exhibited a dose-response in lymphocyte proliferation, IgM titers, EROD, and PROD endpoints. Exposed adults showed a significant dose-dependent increase in CYP450 induction. F1 14-day old chicks exhibited a significant dose-dependent suppression of B-cell proliferation and induction of CYP450 enzymes. F1 adult proliferative responses exhibited B-cell suppression, that was not statistically significant. Significant sex-dependent EROD and MROD induction was also observed in F1 adults, indicating mixed-function oxidase imprinting from maternal exposure.

Oral hygiene practices and oral health knowledge in a population of Mozambican adults

A study was carried out to assess the oral hygiene practices and dental knowledge by means of a questionnaire, in a group of 239 adults in Mozambique. Despite the relatively low educational status of the sample, the level of dental knowledge appeared satisfactory. However, there still exists a need for increasing the awareness of good oral hygiene in this population.

Accreditation of prior learning: is it worth it? An evaluation of a pilot scheme

Accreditation of Prior Learning (APL) is a relatively new process for both students and colleges of nursing and claims to offer many benefits (Open University 1990, Fox et al 1992). This paper describes the findings of a study undertaken to determine students' experiences of the APL process and their perceptions of how the APL process developed them. A sample of 14 students reported on the use of APL to obtain academic credit for a Level I Welsh National Board Framework Module. The results indicated both some difficulties and benefits associated with using the APL process. The majority of students experienced difficulty in reflecting on prior learning and practice. This seemed to be due in part to the students' reluctance to value their clinical learning experiences. Many of the sample also reported difficulty in maintaining motivation over the period of time allocated to complete the APL process. All the students undertook the process in their own time and had to submit the module summative assignment in addition to the APL evidence required. These factors may have further influenced motivational levels. Clear positive outcomes were that APL was felt to be a worthwhile process, even increasing self-esteem for some individuals. It also enabled students to develop reflective writing skills and to value clinical experience. Recommendations were made to both facilitate and enhance the APL experience for future students, and to promote critical reflection within the nursing profession as a whole.

Effect of agents used in perforation repair on osteoblastic cells

The effects of dental materials on osteoblastic responses in bone were measured using biosynthesis of matrix proteins, osteopontin (OPN), and osteocalcin (OCN) as indices. Materials used in perforation repair were standardly mixed and extracted in sterile water for 10 days. Extracts were added to the medium of osteoblastic ROS 17/2.8 cells and cultured for 48 h. Water incubated in parallel served as the vehicle/dilution control. 1,25-Dihydroxyvitamin D3, which increases biosynthesis of OPN and OCN, served as the positive control. After culture, total cellular RNA was isolated from individual monolayers, and Northern blotting was performed to quantitate mRNA levels encoding OCN and OPN. mRNA levels in treated samples were compared with controls, and significant differences were detected for several materials. Changes in matrix biosynthesis were modest (< 2-fold), compared with 1,25-dihydroxyvitamin D3 (6-fold). Materials used in perforation repair may produce small, but measurable effects on osteoblastic responses.

Continuously infused calcium hydroxide: its influence on hard tissue repair

To study the ability of calcium hydroxide to promote hard tissue repair, Alza Alzet Osmotic Pumps, implanted in Sprague-Dawley rats, were used to deliver either calcium hydroxide and glycerol, barium hydroxide and glycerol, tetracycline and glycerol, or glycerol only to a standardized round bur defect in a rat femur. The pumps infused one of the reagents into the defects continuously over a 4-wk experimental period. The effects of each reagent on the healing of the bony defects were compared by histological evaluation. The Alza Osmotic Pump proved to be an effective method to deliver an agent to an experimental site. Our preliminary findings from a limited sample size indicated that calcium hydroxide contributed to a more complete osseous repair than either barium hydroxide or tetracycline. Barium hydroxide with a sustained pH equivalent to calcium hydroxide showed no greater healing than the controls. Tetracycline results were also similar to controls.

Effect of chronobiological alteration of the circadian rhythm of prolactin and somatotropin release in the dairy cow

The objective of this study was to determine if a skeletal photoperiod administered at the appropriate time of a 24-h day could stimulate prolactin and somatotropin release in dairy cattle. Cows in mo 8 of gestation were exposed to either 12 to 13 h of continuous light or to three skeletal photoperiods consisting of a total of 8 h of light. Cows in the skeletal photoperiod light regimens received 6 h of light from 0500 to 1100 h and a 2-h light pulse at either 1500 to 1700 h, 1800 to 2000 h, or 2100 to 2300 h. Cows exposed to the light regimen pulse at 1800 to 2000 h exhibited a circadian rhythm of prolactin and somatotropin release. The mean prolactin and somatotropin concentrations were also higher in this treatment. It is concluded that a circadian rhythm with a photosensitive phase is present for prolactin and somatotropin release in the lactating dairy cow. The photosensitive phase for both hormones occurs between 13 and 15 h after subjective dawn. The expression of the circadian rhythm of these hormones depends on the photoperiod to which cows are exposed.

The prevalence of smokeless tobacco use in native children in northern Saskatchewan, Canada

We used a self-administered questionnaire to develop a profile of smokeless tobacco use among 1,170 Canadian native children aged 7 to 21 years attending schools situated in remote communities in northern Saskatchewan. Nearly 30% of the sample were current users of smokeless tobacco; more than 50% of users began to use these products before the age of 12 years. More males than females chewed tobacco or dipped snuff. The results revealed a relatively high prevalence of smokeless tobacco users among the present sample of native children and were found to be consistent with data from other studies of similarly aged native populations. The results also showed a prevailing pattern of addiction among the users of smokeless tobacco. It is suggested that educational programs aimed at preventing or reducing the use of tobacco products among native populations be intensified and as well, these programs would benefit from the active participation of trained native personnel.

Periodontal status in a Hutterite population

The periodontal status of a population of 117 adult Hutterites living in Saskatchewan, Canada, was assessed. Despite poor oral hygiene levels, and inadequate dental knowledge, the presence of periodontitis was low. The findings are in accordance with data obtained recently from other selected populations.

Histological and biomechanical assessment of articular cartilage from stored osteochondral shell allografts

Normal and stored articular cartilage from the medial tibial plateaus of mature canine knee joints were evaluated histologically and biomechanically. The medial plateaus from the right knee (control) were assessed fresh, while the left (stored) were preserved in culture media at 4 degrees C for 3, 7, 14, or 28 days and then evaluated. Biomechanically, confined compression tests were performed on all specimens to determine the aggregate modulus and apparent permeability of the articular cartilage. Histologically, Safranin O- and hematoxylin and eosin (H&E)-stained sections were evaluated. All stored cartilage specimens had an aggregate modulus on average lower than normal, but the differences were not significant (p greater than 0.10). The apparent permeability was on average higher than but also not significantly different from normal (p greater than 0.10). Time in storage (up to 28 days) did not have a significant effect on the biomechanical properties of stored cartilage normalized by control values (p greater than 0.50). Safranin O and H&E histological evaluation also showed no overall changes in cell appearance or staining of the stored cartilage when compared with control for the time periods studied.

Effect of estrogen/progestin potency on lipid/lipoprotein cholesterol

We studied 374 women taking oral contraceptives, 284 women taking estrogen preparations after menopause, and 1086 women taking no hormones, to determine the relation of plasma lipids and lipoprotein cholesterol concentrations to various types of estrogen/progestin formulations. Premenopausal women, using oral contraceptives containing a relatively low dose of estrogen combined with a medium or high dose of progestin (Norlestrin, Ovral, or Demulen) had a 24 per cent higher median concentration of low-density-lipoprotein cholesterol than did those not using hormones (P less than 0.05). Women using oral contraceptives that are high in estrogen and low in progestin (Enovid or Oracon) had significantly higher concentrations of high-density-lipoprotein cholesterol than did nonusers; those using Ovral, a low-estrogen and high-progestin formulation, had significantly lower levels of high-density-lipoprotein cholesterol. In postmenopausal women the use of estrogen was associated with concentrations of low-density-lipoprotein cholesterol that were 11 to 19 per cent below the levels in postmenopausal women who did not use hormones. The effects of estrogen-progestin balance on low-density and high-density lipoproteins may underlie the increased incidence of stroke and myocardial infarction in women of childbearing age who take oral contraceptives.

Association arrays for the study of familial height, weight, lipid, and lipoprotein similarity in three West Coast populations

A more refined understanding of familial similarity may be achieved through a collection of measures of dependence that is sensitive to a variety of nonlinear trends ans stochastic relationships between trait values. Parent-offspring, spouse, and sibling similarities are examined by association arrays that assess dependence between variables for appropriate classes of functions (e.g., the class of all increasing functions). The methodology is applied to height, weight, lipid, and lipoprotein variables collected in nuclear families at the Seattle, Stanford, and La Jolla Lipid Research Clinics. Among the results obtained using association arrays, there is the suggestion that spouse similarity for standardized weight is strongest for functions emphasizing the higher values of the wives' weight independent of the husbands' weight, and that sibling similarity for high density lipoprotein cholesterol concentrations appears strongest for functions emphasizing the higher values of the siblings. The results deduced from the method of association arrays are compared and contrasted with those obtained from standard correlations.

Alteration in blood pressures associated with combined alcohol and oral contraceptive use-the lipid research clinics prevalence study

Alterations in systolic and diastolic blood pressure levels associated with combined oral contraceptive (OC) and alcohol use were investigated in white women 20-49 years of age from 10 North American Lipid Research Clinics study populations. OC users had systolic pressures 2-3 mm Hg higher than non-users, but no difference was noted for diastolic pressures. Among non-OC users, both systolic and diastolic blood pressures were positively associated with reported alcohol consumption, though participants reporting no alcohol use had blood pressures slightly higher than those reporting minimal intake. The blood pressure correlates of OC's and alcohol appeared to be independent, and systolic pressures levels were over 8 mm Hg higher in those reporting heavier alcohol intake and OC use than among those reporting minimal alcohol intake and no OC use.

Alterations of plasma lipid and lipoprotein levels associated with benzodiazepine use--the LRC Program Prevalence Study

In a study of white adults from 10 North American Lipid Research Clinics populations, plasma lipid and lipoprotein levels in benzodiazepine (diazepam, chlordiazepoxide, flurazepam) users were compared to both the entire population of non-users and matched control non-users. Significantly higher plasma triglyceride and very low density lipoprotein cholesterol levels and by one method of analysis, lower high density lipoprotein cholesterol levels were noted in male benzodiazepine users. No significant differences were noted in total plasma cholesterol or low density lipoprotein cholesterol levels.

Alterations of plasma high-density lipoprotein cholesterol levels associated with consumption of selected medications. The Lipid Research Clinics Program Prevalence Study

From the 10 North American study populations of the Lipid Research Clinics Program, mean levels of plasma high-density (HDL) cholesterol were contrasted between users of eight categories of prescribed medications and a control group of nonusers of those categories matched for age, sex, study population and ponderosity. Women taking propranolol had a mean HDL cholesterol level 12 mg/dl lower than nonusers (p < 0.05). Men taking phenytoin had a mean HDL cholesterol level more than 18 mg/dl higher than nonusers (p < 0.05). Men taking benzodiazepine derivatives had a mean HDL cholesterol level 3.3 mg/dl lower than nonusers (p < 0.05). No significant differences were found between users and nonusers of thiazide diuretics, chlorthalidone, barbiturates, sympathomimetics or antihistamines.

Compliance from a patient's perspective

The non-compliant patient is a sub ject guaranteed to elevate the blood pressure of most diabetes health care professionals. But have you considered the frustration, the guilt, and the stigma of being labeled a non-compliant patient? It's an unfair burden to lay on someone who is already coping with this complex disease. For your sake, and that of your patient, we need a frank dis cussion of the reasons for non-com pliance. Then maybe we can treat the problem and not just its symp toms.