Exploiting Metabolic Defects in Glioma with Nanoparticle Encapsulated NAMPT Inhibitors

The treatment of primary central nervous system (CNS) tumors is challenging due to the blood-brain barrier and complex mutational profiles, which is associated with low survival rates. However, recent studies have identified common mutations in gliomas (IDH-WT and mutant, WHO grades II-IV; with grade IV tumors referred to as glioblastomas; GBMs). These mutations drive epigenetic changes, leading to promoter methylation at the NAPRT gene locus, which encodes an enzyme involved in generating NAD+. Importantly, NAPRT-silencing introduces a therapeutic vulnerability to inhibitors targeting another NAD+ biogenesis enzyme, NAMPT, rationalizing a treatment for these malignancies. Multiple systemically-administered NAMPTis have been developed and tested in clinical trials, but dose-limiting toxicities-including bone marrow suppression and retinal toxicity-have limited their efficacy. Here, we report a novel approach for the treatment of NAPRT-silenced GBMs using nanoparticle-encapsulated (NP) NAMPT inhibitors (NAMPTis) administered by convection-enhanced delivery (CED). We demonstrate that GMX1778 (a NAMPTi) can be formulated in degradable polymer NPs with retention of potency for NAMPT inhibition and anticancer activity in vitro, plus sustained drug release in vitro and in vivo. Direct injection of these drugs via CED into the brain is associated with reduced retinal toxicity compared with systemic administration. Finally, we show that CED of NP-encapsulated GMX1778 to NAPRT-silenced intracranial GBM xenografts in mice exhibit significant tumor growth delay and extends survival. These data support an approach to treat gliomas harboring defects in NAD+ metabolism using CED of NP-encapsulated NAMPTis to greatly improve the therapeutic index and treatment efficacy for this class of drugs.

Abstract P059: Exploiting mutant PPM1D-induced metabolic defects with nanoparticle-encapsulated NAMPT inhibitors

Diffuse Intrinsic Pontine Glioma (DIPG) is a leading cause of death in pediatric cancer, with an abysmal <1% 5-year survival rate due to lack of effective treatment options. A significant effort is needed to understand the genetic landscape of this disease to develop novel therapeutic strategies and modalities. Recently, the Bindra laboratory found that a truncation mutation in the gene PPM1D, found in ~30% of DIPG cases, causes global epigenetic alterations that lead to therapeutic vulnerabilities. They found that mutant PPM1D activity results in loss of the NAD+ biogenesis protein NAPRT that can be therapeutically targeted by inhibitors of another protein in the NAD+ biogenesis pathway NAMPT (NAMPTi), providing a viable therapeutic strategy for these cancers. Some NAMPTis have been FDA-approved for clinical usage, but present with systemic and retinal toxicity. Moreover, while there are few NAMPTis that can pass the blood brain barrier through systemic delivery, studies show diminished concentrations at the target site. Together, current studies show that the use of NAMPTis for precision targeting of CNS cancers such as DIPG with mutant PPM1D status is a promising therapeutic strategy, but impractical given the limitations of these drugs. However, recent developments in drug delivery systems offer a chance to overcome these issues. Tools such as nanoparticle (NP) drug delivery and unique injection set-ups such as convection-enhanced delivery (CED) allow for drugs such as NAMPTis to be reconsidered for clinical usage. To circumvent the challenges presented by these drugs, we have developed and characterized nanoparticles that encapsulate NAMPTis (NAMPTi-NP) and use CED for sustained intratumoral delivery. Thus far, we have fabricated and optimized PLA-PEG copolymeric nanoparticles capable of encapsulating the NAMPTi, GMX-1778. We characterized these nanoparticles based on (1) hydrodynamic diameter, (2) zeta potential, and (3) stability within an artificial cerebrospinal fluid solution. We have performed both in vitro and in vivo assays to determine the functionality of the NAMPTi-NPs through (1) cellular uptake studies via immunofluorescence, (2) functional analysis via NAD+ quantification, (3) short- and long-term cell viability assays to determine sensitivity to the NAMPTi-NP, and (4) in vivo biodistribution studies to assess sustained retention of NAMPTi-NP with CED intracranial injections. We find that NAMPTi-NPs have immediate and sustained cellular uptake, loss of NAD+ post-treatment indicating effective targeting, and enhanced sensitivity in long-term viability studies in mutant PPM1D models. Lastly, these NAMPTi-NP display prolonged retention in brain tissue compared to free drug injection over time. With further in vivo validation, this NP-based strategy will be a powerful tool for targeting mutant PPM1D DIPG and other cancers.

Citation Format: Matthew A. Murray, Yazhe Wang, Ranjini Sundaram, Jason Beckta, Mark Saltzman, Ranjit Bindra. Exploiting mutant PPM1D-induced metabolic defects with nanoparticle-encapsulated NAMPT inhibitors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P059.

A whole-animal platform to advance a clinical kinase inhibitor into new disease space

Synthetic tailoring of approved drugs for new indications is often difficult, as the most appropriate targets may not be readily apparent, and therefore few roadmaps exist to guide chemistry. Here, we report a multidisciplinary approach for accessing novel target and chemical space starting from an FDA-approved kinase inhibitor. By combining chemical and genetic modifier screening with computational modeling, we identify distinct kinases that strongly enhance ('pro-targets') or limit ('anti-targets') whole-animal activity of the clinical kinase inhibitor sorafenib in a Drosophila medullary thyroid carcinoma (MTC) model. We demonstrate that RAF-the original intended sorafenib target-and MKNK kinases function as pharmacological liabilities because of inhibitor-induced transactivation and negative feedback, respectively. Through progressive synthetic refinement, we report a new class of 'tumor calibrated inhibitors' with unique polypharmacology and strongly improved therapeutic index in fly and human MTC xenograft models. This platform provides a rational approach to creating new high-efficacy and low-toxicity drugs.

Autophagic clearance of proteasomes in yeast requires the conserved sorting nexin Snx4

Turnover of the 26S proteasome by autophagy is an evolutionarily conserved process that governs cellular proteolytic capacity and eliminates inactive particles. In most organisms, proteasomes are located in both the nucleus and cytoplasm. However, the specific autophagy routes for nuclear and cytoplasmic proteasomes are unclear. Here, we investigate the spatial control of autophagic proteasome turnover in budding yeast (Saccharomyces cerevisiae). We found that nitrogen starvation-induced proteasome autophagy is independent of known nucleophagy pathways but is compromised when nuclear protein export is blocked. Furthermore, via pharmacological tethering of proteasomes to chromatin or the plasma membrane, we provide evidence that nuclear proteasomes at least partially disassemble before autophagic turnover, whereas cytoplasmic proteasomes remain largely intact. A targeted screen of autophagy genes identified a requirement for the conserved sorting nexin Snx4 in the autophagic turnover of proteasomes and several other large multisubunit complexes. We demonstrate that Snx4 cooperates with sorting nexins Snx41 and Snx42 to mediate proteasome turnover and is required for the formation of cytoplasmic proteasome puncta that accumulate when autophagosome formation is blocked. Together, our results support distinct mechanistic paths in the turnover of nuclear versus cytoplasmic proteasomes and point to a critical role for Snx4 in cytoplasmic agglomeration of proteasomes en route to autophagic destruction.

A prospective randomized trial of cannulation technique in ERCP: effects on technical success and post-ERCP pancreatitis

BACKGROUND AND STUDY AIMS

Inadvertent injection of contrast agent into the pancreatic duct is believed to be an important contributor to pancreatitis occurring after endoscopic retrograde cholangiopancreatography (post-ERCP pancreatitis, PEP). Our aim was to examine whether primary deep biliary cannulation with a guide wire is associated with a lower rate of PEP than conventional contrast-assisted cannulation.

PATIENTS AND METHODS

From August 2003 to April 2006 all patients with an intact papilla who were referred for ERCP were eligible. Patients with pancreatic or ampullary cancer were excluded. Patients were randomized to undergo sphincterotomy biliary cannulation using either contrast injection or a guide wire. The ERCP fellow attempted initially for 5 minutes. If unsuccessful, the consultant attempted for 5 minutes using the same technique, followed by crossover to the other technique in the same sequence and then needle-knife sphincterotomy where appropriate. Patients were assessed clinically after the procedure, then followed up with telephone interviews after 24 hours and 30 days, and serum amylase and lipase tests after 24 hours.

RESULTS

Out of 1654 patients undergoing ERCP, 413 were included in the study. PEP occurred in 29/413 (7.0 %): 16 in the guide-wire arm, 13 in the contrast arm ( P = 0.48). The overall cannulation success rate was 97.3 %. Cannulation was successful without crossover in 323/413 patients (78.2 %): 167/202 (81.4 %) in the guide-wire arm and 156/211 (73.9 %) in the contrast arm ( P = 0.03). Multivariate analysis demonstrated female sex (OR = 2.7, P = 0.04), suspected sphincter of Oddi dysfunction (OR = 5.5, P = 0.01), and complete filling of the pancreatic duct with contrast agent (OR = 3.5, P = 0.02) to be independently associated with PEP. The risk of PEP increased incrementally with each attempt at the papilla (OR 1.4 per attempt, P = 0.04) to greater than 10 % after four or more attempts.

CONCLUSIONS

The guide-wire technique improves the primary success rate for biliary cannulation during ERCP but does not reduce the incidence of PEP compared to the conventional contrast technique. The incidence of PEP increases incrementally with each attempt at the papilla.

Argon plasma coagulation in the management of symptomatic gastrointestinal vascular lesions: experience in 100 consecutive patients with long-term follow-up

BACKGROUND

The long-term efficacy of argon plasma coagulation (APC) in the management of gastrointestinal vascular lesions has not been evaluated in a large and well-defined series. The impact of APC on transfusion requirements and hemoglobin, and technical parameters including complications and number of treatment sessions, is assessed in this series.

METHODS

Patients who underwent APC for bleeding gastrointestinal vascular lesions were identified via interrogation of an established endoscopic database, excluding patients with radiation proctitis, tumors, residual polypectomy tissue and acute ulcer bleeding. Follow-up data were collected via interview with patients and referring doctors, review of medical records, and follow-up blood tests.

RESULTS

One hundred patients were enrolled, males = 46, median age = 74 yr (range: 19-99 yr). Median follow-up time was 16 months (range: 4-47 months). Lesions treated were arteriovenous malformations (n = 74) and gastric antral vascular ectasia (n = 26). Fifty-three patients required transfusion. In this group, median hemoglobin improved from 66 g/L (range: 35-114) to 111 g/L (range: 55-155, p < 0.001). Median transfusion velocity fell from 2 units/month (range: 0.1-6) to 0 units/month (range: 0-4, p < 0.001). Transfusion requirement was abolished in 77%. In non-transfusion-requiring patients, median hemoglobin improved from 105 g/L (range: 58-143) to 123 g/L (range: 79-158, p < 0.001). No complications occurred.

CONCLUSIONS

APC is effective and safe in the management of gastrointestinal vascular lesions.

Sporadic duodenal adenoma is associated with colorectal neoplasia

OBJECTIVE

The objective of this study was to assess the association between colorectal neoplasia and sporadic duodenal adenoma.

METHODS

A retrospective case control study was conducted using the databases of two major teaching hospitals in Western Australia. The frequency of colorectal neoplasia in patients with sporadic duodenal adenomas was compared with that in a control group of patients presenting for endoscopies. The frequency of colorectal cancer in duodenal adenoma patients was also compared with the population incidence.

RESULTS

Of 56 sporadic duodenal adenoma patients, 34 (61%) had been colonoscoped. When comparing the findings between patients with sporadic duodenal adenoma and an endoscoped control group, all colorectal neoplasias were significantly more common in the duodenal adenoma group (56% v 33%; odds ratio (OR) 2.4 (95% confidence intervals (CI) 1.1-5.4)). Although finding either advanced colorectal adenoma or cancer was also more common in duodenal adenoma patients (38% v 19%; OR 2.3 (95% CI 1.0-5.2)), as was finding colorectal cancer alone (21% v 8%; OR 3.0 (95% CI 1.0-9.1)), the results were not statistically significant. However, the incidence of colorectal cancer was much greater in duodenal adenoma patients than in the population (p<0.001).

CONCLUSIONS

Sporadic duodenal adenoma has a clinically important association with colorectal neoplasia. Thus patients with duodenal adenomas should undergo colonoscopy to detect colorectal neoplasia.

Hospital efficiency and patient satisfaction

The objective of this study was to investigate the relationship between efficiency and patient satisfaction for a sample of general, acute care hospitals in Ontario, Canada. A measure of patient satisfaction at the hospital level was constructed using data from a province-wide survey of patients in mid-1999. A measure of efficiency was constructed using data from a cost model used by the Ontario Ministry of Health, the primary funder of hospitals in Ontario. In accordance with previous studies, the model also included measures of hospital size, teaching status and rural location. Based on the results of this study, at a 95% confidence level, there does appear to be evidence to suggest that an inverse relationship between hospital efficiency and patient satisfaction exists. However, the magnitude of the effect appears to be small. Hospital size and teaching status also appear to affect satisfaction, with lower satisfaction scores reported among non-teaching and larger hospitals. This study did not find any evidence to suggest that hospital location (rural versus urban) or religious affiliation contributed to reports of patient satisfaction in any way not explained by the other measures included in the study. The findings imply that low patient satisfaction cannot be explained by excessive management concentration on efficiency. Managers should analyse some of the underlying causes of patient dissatisfaction before reconfiguring resources. It may be beneficial in larger hospitals to study the aspects of care that patients have reported they prefer in small hospitals.

Comparison of external and internal pelvic measurements of Belgian Blue cattle from sample herds in Belgium and the United kingdom

Measurements describing pelvic conformation of pedigree Belgian Blue cows were obtained from a sample of nine herds in Flanders, Belgium, comprising 111 adult breeding cows, and from 11 herds in the United Kingdom comprising 108 similar cows. All herds in the Belgian sample (111 cows) managed parturition by elective caesarian section as did seven herds (56 cows) in the UK sample; the remainder of UK herds (52 cows) allowed cows the opportunity to calve naturally per vagina before resorting to caesarian section. The data described the external and internal measurements, and pelvic area characteristic of this breed, irrespective of the different selection pressures applied over a number of years to this breed through variation in farm management and market forces present in either country. From these data, generalized linear models were constructed to predict pelvic area; they correctly identified cows with either small or large pelvic areas. There were no significant differences in pelvic conformation between cattle bred either in Belgium or the UK, although those cows bred in herds where natural calving was allowed to take place had significantly larger internal pelvic height (p < 0.05) and area (p < 0.05) than other Belgian Blue cows. The correlation coefficients between internal pelvic height and width and external pelvic measurements were significant (p < 0.001). These results might facilitate the selection of breeding cows with larger pelvic area so that a higher proportion of cows can calve naturally than currently occurs. However, selection for other traits such as relatively low birth weight combined with higher weaning weight should be carried out at the same time.

Peptidyl diazomethyl ketones inhibit the human rhinovirus 3C protease: effect on virus yield by partial block of P3 polyprotein processing

The efficacy of a series of diazomethyl ketones (DMKs) was measured in rhinovirus-infected cultures and against the HRV14 3C protease. Their specificity and potency were confirmed against purified recombinant enzyme expressed in a yeast secretion system. An internally quenched fluorescent peptide substrate was used to assess the potency against the enzyme, obtaining a 50% inhibitory concentration (IC50) of 1 microM for both Z-L-F-Q-CHN2 and Z-V-L-F-Q-CHN2, while a lower affinity was observed for Z-F-Q-CHN2. The tripeptide Z-L-F-Q-CHN2 blocked viral replication with an IC50 value of 30 microM as judged by the reduction in viral induced cytopathy of HeLa-H1 cells, as well as a marked reduction in viral plaque formation (50% effective concentration=20 microM). Western blot analysis of viral proteins from infected cells indicates that this inhibitor works specifically by blocking viral polyprotein maturation, displaying a reduction of detectable 3C protease and an accumulation of the 3CD polypeptide. These results indicate that DMK inhibitors of the 3C protease have antiviral potency. Furthermore, the pattern of viral protein processing observed suggests that reducing the concentration of mature HRV 3C protease even in the presence of increased 3CD protein is sufficient to block proper viral processing and significantly reduce virus yield.

Systemic administration of adrenomedullin(27-52) increases bone volume and strength in male mice

Adrenomedullin is a 52-amino acid peptide first described in a human phaeochromocytoma but since been found to be present in many tissues, including the vascular system and bone. Because of its structural similarity to amylin and calcitonin gene-related peptide, both of which have actions on bone cells, we have previously assessed the effects of adrenomedullin on the skeleton, and found that it increases osteoblast proliferation in vitro and bone formation following local injection in vivo. The present study carries this work forward by assessing the effects on bone of the systemic administration of a fragment of this peptide lacking the structural requirements for vasodilator activity. Two groups of 20 adult male mice received 20 injections of human adrenomedullin(27-52) 8.1 microg or vehicle over a 4-week period and bone histomorphometry and strength were assessed. In the tibia, adrenomedullin(27-52) produced increases in the indices of osteoblast activity, osteoid perimeter and osteoblast perimeter (P<0.05 for both using Student's t-test). Osteoclast perimeter was not affected. There was a 21% increase in cortical width and a 45% increase in trabecular bone volume in animals treated with adrenomedullin(27-52) (P<0.002 for both). Assessment of bone strength by three-point bending of the humerus showed both the maximal force and the displacement to the point of failure were increased in the animals treated with adrenomedullin(27-52) (P<0.03 for both). There was also a significant increase in the thickness of the epiphyseal growth plate. No adverse effects of the treatment were noted. It is concluded that adrenomedullin(27-52) acts as an anabolic agent on bone. These findings may be relevant to the normal regulation of bone mass and to the design of agents for the treatment of osteoporosis.

Status migrainosus in children and adolescents

Data concerning status migrainosus in children and adolescents is sparse. The varied clinical presentations, diagnostic evaluation, and treatment modalities are discussed.

Hydrochlorothiazide reduces loss of cortical bone in normal postmenopausal women: a randomized controlled trial

PURPOSE

Thiazide diuretics reduce urine calcium excretion and might therefore reduce postmenopausal bone loss. In some, but not all, case-control studies, their use has been associated with a reduced incidence of hip fractures. We studied the effects of hydrochlorothiazide on bone loss in normal postmenopausal women.

SUBJECTS AND METHODS

We performed a randomized, double-blind, 2-year trial of the effects of hydrochlorothiazide (50 mg per day) and placebo on bone mineral density in normal postmenopausal women. Participants were not required to have either low bone mineral density or hypertension. Bone mineral density was measured using dual-energy x-ray absorptiometry.

RESULTS

One hundred eighty-five women entered the study, of whom 138 completed 2 years of follow-up. In an intention-to-treat analysis, hydrochlorothiazide produced significant benefits on bone mineral density of the total body (between-group difference at 2 years of 0.8%, 95% confidence interval [CI]: 0.3% to 1.3%, P <0.0001), legs (0.9%, 95% CI: 0.2% to 1.7%, P <0.0001), mid-forearm (1.2%, 95% CI: 0.2% to 2.2%, P = 0.02), and ultradistal forearm (1.7%, 95% CI: 0.1% to 3.2%, P = 0.04). There was no effect in the lumbar spine (0.5%, 95% CI: -0.5% to 1.6%) or femoral neck (0.2%, 95% CI: 1.3% to 1.7%). The between-group changes tended to be greatest during the first 6 months, except in the mid-forearm where there appeared to be a progressive divergence. An as-treated analysis produced similar results. Urine calcium excretion and indices of bone turnover decreased in the thiazide group, but parathyroid hormone concentrations did not differ between the groups. Treatment was tolerated well.

CONCLUSIONS

Hydrochlorothiazide (50 mg per day) slows cortical bone loss in normal postmenopausal women. It may act directly on bone as well as on the renal tubule. The small size of the effect suggests that thiazides may have a role in the prevention of postmenopausal bone loss, but that they are not an appropriate monotherapy for treating osteoporosis.

Evidence for a major gene for bone mineral density in idiopathic osteoporotic families

Although there have been a number of studies indicating a heritable component for osteoporosis in middle to late adulthood, the etiology of osteoporosis in young people is uncertain. The present study aims to evaluate the extent to which genetic factors influence familial resemblance for bone mineral density (BMD) in families ascertained on the basis of young osteoporotic probands. The sample comprises eight families (74 total individuals) that were identified through a proband under the age of 35 years with a history of two or more fractures and a spinal bone density of at least 2.5 SDs below the mean for age and sex (Z score). Secondary causes of osteoporosis were excluded in the probands. In total, 27% (18/66) of the probands' relatives had osteoporosis and an additional 30% (20/66) had osteopenia. Classical segregation analysis was performed to evaluate the extent to which a genetic etiology could account for familial resemblance in these families. The results indicate a major gene of codominant inheritance for spinal BMD. Model-fitting comparisons revealed no support for environmental effects or for polygenic inheritance.

Inhibitory effect of dibenzofuran and dibenzosuberol derivatives on rhinovirus replication in vitro; effective prevention of viral entry by dibenzosuberenone

A series of derivatives of dibenzofuran and dibenzosuberol block rhinovirus replication in vitro as judged by their ability to hinder the cytopathic effect in cells infected with HRV14 or HRV16. Both the number and the size of viral plaques were reduced effectively by treatment with these compounds in a dose-dependent fashion, thus affecting viral spread. The compound 2-hydroxy-3-dibenzofuran carboxylic acid was equally effective against HRV16 and HRV14, with IC50 values of 25 microM in cytopathy assays. Dibenzosuberenone showed minor differences in selectivity, with IC50 values of 10 and 30 microM for HRV16 and HRV14 cytopathy, respectively. Likewise, dibenzosuberenone effectively prevented the production of HRV16 proteins, viral RNA, and infectious virus particles when present at concentrations above 30 microM. Time-of-addition experiments show that compounds must be administered before or during the viral adsorption step in order to be effective antivirals. Dibenzosuberenone can block the adsorption of viral particles on to cells, preventing further steps in the replication cycle, but is not effective as a direct inactivating agent. These compounds likely interact with viral capsid proteins, affecting receptor interactions required for attachment and subsequent entry into cells.

Hormone replacement therapy causes a respiratory alkalosis in normal postmenopausal women

Menopause is associated with an increase in venous bicarbonate concentrations that is reversible with hormone replacement therapy (HRT). However, the mechanism underlying this effect is not known. To address this question, we studied the changes in acid-base indexes in the arterialized venous blood of normal postmenopausal women commencing conjugated equine estrogen (0.625 mg/day), medroxyprogesterone acetate (MPA; 5 mg/day), their combination, or placebo, in a double blind randomized controlled study over 3 months. Serum bicarbonate concentrations decreased significantly in the groups receiving either MPA or estrogen plus MPA (P = 0.008). This trend was apparent as early as 2 days and reached 2.7 and 2.3 mmol/L in the respective groups by 3 months. Similar changes were seen with partial pressure of carbon dioxide (P = 0.04); a change of -0.7 kPa occurred in the estrogen plus MPA group at 3 months. There were no changes in bicarbonate concentrations or partial pressure of carbon dioxide in those receiving estrogen alone or placebo. Accompanying changes in blood pH were apparent in the estrogen plus MPA group, where there was an upward trend at 1 week (P = 0.056) and a significant change from baseline (+0.013) at 3 months (P = 0.03). In the whole group, the changes in pH were inversely correlated with those in urinary excretion of hydroxyproline (r = -0.44; P = 0.01). We conclude that HRT using conjugated estrogens and MPA produces small, but sustained, changes in acid-base status. These may contribute to the effects of HRT and menopause on many tissues and disease processes, including the development of osteoporosis.

Evaluating expert systems: how to ensure an independent assessment

Evaluation of an expert system provides unique challenges in an organizational setting. Often the proposed system is provided by an independent supplier who is not in a position to provide an unbiased assessment of the effectiveness or merit of the system. Even when the system is developed by personnel within the same firm or by the users themselves, these individuals, being instrumental in the design and development of the system, lack the autonomy necessary to evaluate the system. This article describes one evaluation process which was applied by the authors. It is an adaptable approach which provides the needed independent assessment without being excessively cumbersome or difficult to administer.

Socioeconomic status and determinants of hemostatic function in healthy women

Hemostatic factors are reported to be associated with coronary heart disease (CHD). Socioeconomic status (SES) is 1 of the determinants of the hemostatic profile, but the factors underlying this association are not well known. Our aim was to examine determinants of the socioeconomic differences in hemostatic profile. Between 1991 and 1994, we studied 300 healthy women, aged 30 to 65 years, who were representative of women living in the greater Stockholm area. Fibrinogen, factor VII mass concentration (FVII:Ag), activated factor VII (FVIIa), von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1) were measured. Educational attainment was used as a measure of SES. Low educational level and an unfavorable hemostatic profile were both associated with older age, unhealthful life style, psychosocial stress, atherogenic biochemical factors, and hypertension. Levels of hemostatic factors increased with lower educational attainment. Independently of age, the differences between the lowest (mandatory) and highest (college/university) education in FVII:Ag levels were 41 microg/L (95% confidence interval [CI], 15 to 66 microg/L, P=0.001), 0.26 g/L (95% CI, 0.10 to 0.42 g/L, P=0.001) in fibrinogen levels, and 0.11 U/mL (95% CI, 0.09 to 0.12 U/mL, P=0.03) in levels of vWF. The corresponding differences in FVIIa and PAI-1 were not statistically significant. With further adjustment for menopausal status, family history of CHD, marital status, psychosocial stress, lifestyle patterns, biochemical factors, and hypertension, statistically significant differences between mandatory and college/university education were observed in FVII:Ag (difference=34 microg/L; 95% CI, 2 to 65 microg/L, P=0.05) but not in fibrinogen (difference=0.03 g/L; 95% CI, -0.13 to 0.19 g/L, P=0.92) or in vWF (difference=0.06 U/mL; 95% CI, -0.10 to 0.22 U/mL, P=0.45). An educational gradient was most consistent and statistically significant for FVII:Ag, fibrinogen, and vWF. Age, psychosocial stress, unhealthful life style, atherogenic biochemical factors, and hypertension mediated the association of low educational level with elevated levels of fibrinogen and vWF. Psychosocial stress and unhealthful life style were the most important contributing factors. There was an independent association between education and FVII:Ag, which could not be explained by any of these factors.

A genome-wide search for chromosomal loci linked to mental health wellness in relatives at high risk for bipolar affective disorder among the Old Order Amish

Bipolar affective disorder (BPAD; manic-depressive illness) is characterized by episodes of mania and/or hypomania interspersed with periods of depression. Compelling evidence supports a significant genetic component in the susceptibility to develop BPAD. To date, however, linkage studies have attempted only to identify chromosomal loci that cause or increase the risk of developing BPAD. To determine whether there could be protective alleles that prevent or reduce the risk of developing BPAD, similar to what is observed in other genetic disorders, we used mental health wellness (absence of any psychiatric disorder) as the phenotype in our genome-wide linkage scan of several large multigeneration Old Order Amish pedigrees exhibiting an extremely high incidence of BPAD. We have found strong evidence for a locus on chromosome 4p at D4S2949 (maximum GENEHUNTER-PLUS nonparametric linkage score = 4.05, P = 5. 22 x 10(-4); SIBPAL Pempirical value <3 x 10(-5)) and suggestive evidence for a locus on chromosome 4q at D4S397 (maximum GENEHUNTER-PLUS nonparametric linkage score = 3.29, P = 2.57 x 10(-3); SIBPAL Pempirical value <1 x 10(-3)) that are linked to mental health wellness. These findings are consistent with the hypothesis that certain alleles could prevent or modify the clinical manifestations of BPAD and perhaps other related affective disorders.

Stickler syndrome without eye involvement is caused by mutations in COL11A2, the gene encoding the alpha2(XI) chain of type XI collagen

Eye involvement has been considered a principal component feature in Stickler syndrome. However, families lacking eye involvement have been reported. We describe such a family and show that their phenotype is due to a heterozygous 27 basepair deletion in the gene COL11A2, which encodes the alpha2(XI) chain of type XI collagen. This is the second family in whom a COL11A2 mutation has been found to cause Stickler syndrome without eye involvement. This result confirms the role of COL11A2 in the etiopathogenesis of this disorder.

Determination of the genome composition of influenza virus reassortants using multiplex reverse transcription-polymerase chain reaction followed by fluorescent single-strand conformation polymorphism analysis

The influenza virus genome is composed of eight negative-strand RNA segments. In cells coinfected with two or more influenza strains, the genomic RNAs reassort at random, resulting in progeny viruses (reassortants) that contain genes derived from each parent. Genetic reassortment among influenza viruses occurs naturally and plays an important role in viral epidemiology and pathogenicity. The reassortment process is also utilized for the annual production of influenza vaccines. Each year, the two gene segments that encode the major surface antigens of the current virulent, wild-type viruses are reassorted with the remaining six gene segments of a laboratory-derived vaccine or "master donor" strain. As the gene reassortment appears to be random, identifying a progeny virus with the desired gene constellation can be labor-intensive. We developed a streamlined, cost-effective method to genotype influenza viruses that combines multiplex reverse transcription-polymerase chain reaction (RT-PCR) and fluorescent single-strand conformation polymorphism (SSCP) analysis. This method utilizes oligonucleotide primers labeled with one of three fluorescent dyes to generate RT-PCR products for each gene segment in a multiplex configuration. The RT-PCR products of the reassortants, wild-type, and master donor viruses are then electrophoresed under SSCP conditions. The viral origin of each gene segment can be identified by fluorescence and mobility shift patterns of the corresponding RT-PCR products. We demonstrate the utility of this method in differentiating the genes of a master donor strain, several wild-type viruses, and vaccine reassortants.

Quality improvement in family practice. Program for Pap smears

PROBLEM BEING ADDRESSED

With the increasing emphasis on quality improvement, we need programs for improving office practice.

OBJECTIVE OF PROGRAM

To demonstrate a simple and inexpensive program that resulted in improvement in the quality of Papanicolaou smears in a family practice teaching clinic. The performance measure was the proportion of smears containing endocervical components.

MAIN COMPONENTS OF PROGRAM

The program involved annual feedback on the performance of the physicians in the clinic. Feedback was given to physicians at a regular group meeting; brief discussion of the findings also occurred at that time. There were no other interventions.

CONCLUSIONS

A program involving straightforward feedback and discussion for less than 1 hour contributed to a 7% improvement in the proportion of Pap smears with endocervical components. This "low tech" approach should be tested in other settings and with other procedures and treatments.

Developing microcomputer-based quality assurance systems for health care

Points out some important issues that must be dealt with when developing microcomputer-based QA systems for health care. While no single solution to the problems associated with quality assurance (QA) system development exists, the first step towards an efficient and effective approach is problem identification and commitment to developing a strategy which addresses the issues discussed in this paper. Examines potential solution alternatives and associated pitfalls, and gives an example of designing a QA system, including a database management system with suggestions for spreadsheet templates.

Changing distributions of extracellular matrix components during early wing morphogenesis in Drosophila

A new monoclonal antibody, specific to an epitope in the carboxyl terminus of the Drosophila collagen IV molecule (basement membrane collagen) was identified. The distributions of collagen IV, laminin, and an additional extracellular molecule, the 2G2 antigen (2G2-Ag), were followed immunocytochemically during early wing development. In late third instar larvae, collagen IV and laminin surround the entire wing disc, whereas the 2G2-Ag is limited to the region of the future wing pouch. For the first few hours following eversion of the disc, all three ECM components line the basal surfaces of all epithelial cells in the wing pouch, both those destined to line the wing veins and those destined to become tightly apposed in the large intervein regions. Collagen IV and laminin persist on these cells during the two initial rounds of apposition of dorsal and ventral wing surfaces; later, they become restricted to the cells lining the veins. The 2G2-Ag disappears completely quite early in the pupal period. Collagen IV appears to be synthesized at least twice, once in the larva and a second time in the pupa; in between it is enzymatically cleaved and may be eliminated, probably by hemocytes. In an extreme allele of blistered the wing is ballooned to form a single internal space. Collagen IV and laminin line all basal wing cell surfaces early in pupal development as they do in the wild type. Later, however, they continue to line the entire cavity of the mutant wing rather than assuming a restricted distribution. In a completely veinless wing (rhomboidveinletvein), collagen IV and laminin are also present generally on basal surfaces at early times, but are completely absent between the tightly apposed wing layers later. The ECM distributions both in wild type wings and in mutants suggest that the matrix plays a role in the establishment of the wing venation pattern. One possibility, strengthened by recent findings regarding ECM receptors in Drosophila, is their involvement in dorsal-ventral wing layer adhesion. Our findings also lead us to suggest that certain sets of features which distinguish vein from intervein cells may be linked during cell differentiation and thus help to define these cell phenotypes. The features include cytoskeletal specializations and certain cell surface and ECM molecules.

The German health care system: structure and changes

The German health care system has often been viewed by American policy makers as a model for a system that controls costs and provides coverage to virtually all of its citizens, while maintaining a private market for the delivery of most services. Nevertheless, German policy makers are as concerned as their American counterparts about the increasing share of national income devoted to health care. To control rising health care costs, the German government, after two decades of cost control interventions, has enacted a major health care reform aimed at reducing structural deficits of the current system and enhancing competition within the system. We review the general structure of the German health care system and analyze its specific problems. We also discuss its accomplishments and present the recently enacted health care reform.

Global budgeting in Germany: lessons for the United States

In 1993 Germany implemented significant health reform legislation that, among other things, strengthened the global budgeting of physicians and instituted global budgeting of pharmaceutical expenditures. German physician expenditures are now capped at the growth in income of members of the sickness funds, in contrast to prior years, in which some growth above a targeted level was allowed. For the first time, dental services also are subject to the budget cap. The new reform legislation also limits growth in pharmaceutical expenditures by increasing the level of copayments and by placing physicians as a group at financial risk for growth over the limit. This paper examines the effect of these reforms during the first year and offers lessons for reform of the U.S. system.

Expression of insulin-like growth factor binding protein-4 (IGFBP-4) by rat neural cells--comparison to other IGFBPs

We recently isolated and characterized the 24 kDa and N-glycosylated 28 kDa insulin-like growth factor binding protein-4 (rIGFBP-4) from the B104s rat neuronal cell line (Endocrinology, 129 (1991) 1009-1115). To examine the prevalence of IGFBP-4 secretion by cells of neural origin, we assessed the expression of IGFBP-4 in different neural cell types using ligand blotting, immunoblotting and blot hybridization with relevant cDNAs. A specific IGFBP-4 antibody raised against a synthetic 20 amino acid peptide was used for immunologic recognition. In all the neural cells tested (B104s, C6 astrocytoma, primary neonatal astrocytes and primary fetal neurons), IGFBP-4 was definitively identified by immunoblotting. Blot hybridization using a rat cDNA probe revealed expression of IGFBP-4 mRNA transcripts by all these cells. Using a combination of the same techniques, expression of IGFBP-1, -2, and -3 were also examined. The B104s cells secreted primarily IGFBP-4; C6 cells secreted predominantly IGFBP-3 and small amount of IGFBP-4; both primary neonatal astrocytes and fetal neurons secreted IGFBP-2 as the major IGFBP accompanied by a small quantity of IGFBP-4. IGFBP-1 was not identified in any of the cell media. When probed with the respective IGFBP cDNAs, the mRNA abundance generally reflected the media IGFBP content. The expression of IGFBP-4 mRNA in vivo was examined as well and compared to that of IGFBP-1 and IGFBP-2. Transcripts for both IGFBP-2 and IGFBP-4 were found in all gross anatomical divisions of the rat brain from embryonic day 15 until adulthood, whereas IGFBP-1 was not detected at any time. IGFBP-4 mRNA tended to be more abundant at the youngest ages whereas IGFBP-2 increased during development. These data indicate that IGFBP-4 is produce by a variety of neural cell types and suggest that it may play a role in brain development.

Epidermal growth factor stimulates insulin-like growth factor-binding protein-1 expression in the neonatal rat

Insulin-like growth factors (IGFs) and the IGF-binding proteins (IGFBPs) appear to be important in the regulation of perinatal growth. We have shown previously that administration of epidermal growth factor (EGF) to newborn rat pups inhibits growth and decreases serum IGF-I concentrations. The experiments described here were designed to investigate the effect of EGF on the IGFBPs using ligand blots of serum and Northern analysis of hepatic RNA. EGF administration caused a rapid (within 2 h) 2-fold increase in the serum IGFBP-1 concentration. Hepatic IGFBP-1 mRNA increased even more rapidly, was increased at least 2-fold at 2 h, and remained elevated 4 h after EGF. The response to EGF was specific to IGFBP-1; IGFBP-2 hepatic mRNA content was not increased over the control value, and serum IGFBP-3 and -4 concentrations were not changed by ligand blot analysis. The IGFBP-1 response to EGF was most dramatic in the first few days of life. Although EGF lowered circulating insulin levels, EGF stimulated IGFBP-1 secretion in the presence of exogenously administered insulin. Thus, the increase in IGFBP-1 did not appear to be mediated by changes in serum insulin. These results demonstrate that EGF increases serum IGFBP-1 concentrations, probably by stimulating synthesis. The association of decreased growth and increased IGFBP-1 concentrations after EGF treatment suggests that elevated IGFBP-1 concentrations may restrict IGF bioactivity in the neonatal rat.

Development and organization of glial cells in the peripheral nervous system of Drosophila melanogaster

We have used enhancer trap lines as markers to recognize glial cells in the wing peripheral nervous system of Drosophila melanogaster. Their characterization has enabled us to define certain features of glial differentiation and organization. In order to ask whether glial cells originate within the disc or whether they migrate to the wing nerves from the central nervous system, we used two approaches. In cultured wing discs from glial-specific lines, peripheral glial precursors are already present within the imaginal tissue during the third larval stage. Glial cells differentiate on a wing nerve even in mutants in which that nerve does not connect to the central nervous system. To assess whether peripheral glial cells originate from ectoderm or from mesoderm, we cultured discs from which the mesodermally derived adepithelial cells had been removed. Our findings indicate that peripheral glial cells originate from ectodermally derived cells. As has already been shown for the embryonic central nervous system, gliogenesis in the periphery is an early event during adult development: glial cells, or their precursors, are already present at stages when neurons are still differentiating. Finally, our results also suggest that peripheral glial cells may not display a stereotyped arrangement.

Are physicians changing the way they practise obstetrics?

OBJECTIVE

To examine trends in obstetric interventions in women at low risk over approximately 3 years. It was postulated that there would be a general reduction in most intervention rates.

DESIGN

Retrospective review of hospital records.

SETTING

Three downtown hospitals of the University of Toronto, in which academic and nonacademic family physicians and obstetricians practised.

PATIENTS

A total of 2365 women in phase 1 (April 1985 to March 1986) and 1277 in phase 2 (May to September 1988) met the inclusion criteria for grade A (pregnancy at no predictable risk) of the Ontario Antenatal Record at the time of admission to hospital.

OUTCOME MEASURES

Rates of artificial rupture of the membranes, induction, augmentation, epidural anesthesia, continuous electronic fetal monitoring (EFM), instrumental delivery, episiotomy and cesarean section.

RESULTS

The family physicians and the obstetricians had significant decreases (p < 0.01) over time in the rates of episiotomy, especially mediolateral, and low forceps delivery. The rate of epidural anesthesia decreased significantly in the obstetrician group. The rates of artificial rupture of the membranes, induction and continuous EFM increased in the two physician groups; the increased rate of EFM was significant in the obstetrician group (p < 0.01). There was no significant change in the rates of augmentation, midforceps delivery, vacuum extraction or cesarean section. All of the trends were found to hold when the intervention rates were analysed according to the women's parity.

CONCLUSIONS

Some of the findings reflect recommendations and trends reported in the literature, whereas others are not supported by clear medical evidence. The unpredictable nature of the trends suggests that further study is warranted of the reasons for obstetric trends and for the changes in physicians' practice patterns.

Effects of acute hypoxemia on insulin-like growth factors and their binding proteins in fetal sheep

It has been proposed that insulin-like growth factor I (IGF-I) regulates fetal growth and differentiation. Plasma IGF-I concentrations correlate positively with fetal nutrient availability and newborn birth weights. To explore the hypothesis that hypoxemia decreases fetal growth by decreasing fetal IGF-I availability, we instrumented 14 fetal sheep with vascular catheters. At least 4 days after surgery, 10 fetuses were made acutely hypoxemic by infusing nitrogen into the maternal trachea for 3 h. Fetal blood oxyhemoglobin saturation decreased from 53 +/- 6 (SD) to 31 +/- 9%. Concomitantly, plasma IGF-I concentrations decreased from 91 +/- 11 to 67 +/- 10 ng/ml and IGF-I binding protein-1 concentration increased significantly, as assessed by ligand and Western blot analysis. Fetal IGF-I concentrations remained below control values throughout a subsequent recovery period (68 +/- 12 ng/ml at 6 h). In four control fetuses and in the ewes, plasma IGF-I concentrations were not significantly different from control values (97 +/- 18 and 181 +/- 18 ng/ml, respectively). These data support the hypothesis that decreases in fetal oxygen availability may decrease fetal growth by decreasing IGF-I production and availability.

Effect of protein kinase C inhibitors on endothelin- and vasopressin-induced constriction of the rat basilar artery

The goal of this study was to determine whether inhibitors of protein kinase C (PKC) attenuate constrictor responses of the basilar artery in vivo to endothelin and arginine vasopressin. In anesthetized rats, the diameter of basilar arteries was measured through a cranial window [control diameter 218 +/- 3 (SE) microns]. Vessel diameter was measured during topical application of agonists and antagonists. Sphingosine (10(-6) M), a PKC inhibitor that binds to the regulatory site of PKC, attenuated vasoconstriction in response to endothelin (10(-9), 10(-8), and 10(-7) M) and vasopressin (10(-9) and 10(-8) M). H-7 (10(-9) M), a PKC inhibitor that binds to the catalytic site of PKC, also inhibited vasoconstriction in response to endothelin and vasopressin. Sphingosine and H-7 did not affect baseline diameter and did not attenuate vasoconstriction in response to prostaglandin (PG) F2 alpha. The V1 antagonist [d(CH2)5Tyr(Me)]arginine vasopressin (10(-8) M) significantly inhibited constriction in response to vasopressin (10(-9) and 10(-8) M) but not PGF2 alpha (10(-6) M). These observations suggest that activation of PKC may contribute to endothelin-induced constriction of the basilar artery in vivo and that PKC may also be a mediator of V1-receptor-mediated constriction of the basilar artery in response to vasopressin.

Episiotomy: Differences in practice between family physicians and obstetricians

A review of 2188 records compared the numbers and types of episiotomies and tears in low-risk women delivered by family physicians and obstetricians. Family physicians performed significantly fewer episiotomies and were more likely to rely on the mediolateral procedure; obstetricians varied episiotomy type more often. The rates of third-degree tears and intact perineum were very similar.

Signal transduction pathways in constriction of the basilar artery in vivo

We examined effects of a putative myosin light chain kinase inhibitor in the cerebral circulation in vivo. In anesthetized rats, diameter of basilar arteries was measured through a cranial window (control, 232 +/- 10 microns, mean +/- SEM). Vessel diameter was measured during topical application of agonists and antagonists. ML-7, which has been reported to compete with adenosine triphosphate for binding to the catalytic site on myosin light chain kinase, attenuated vasoconstriction in response to prostaglandin F2 alpha (10(-6) M; -22 +/- 1% before versus -14 +/- 1% and -3 +/- 2% during ML-7, 10(-7) and 10(-6) M, respectively; p less than 0.05). ML-7 (10(-6) M) did not affect baseline diameter. Responses to serotonin (10(-8) M) and phorbol 12,13-dibutyrate (10(-8) M) were not attenuated by ML-7. Thus, constriction of the basilar artery induced by prostaglandin F2 alpha in vivo is attenuated by an inhibitor of myosin light chain kinase.

Guidepost cells

Guidepost cells, as classically defined in the grasshopper embryo have only rarely been found in other systems. If the concept of guidepost cells is expanded, recognizing that any special role of specific cells in axon guidance is a function of the entire landscape in which axons are growing, and that growth cone--guidepost interactions may share mechanisms with many other cell--cell interactions, then numerous examples are found in both the peripheral and central nervous systems of many species.

Potassium channel activators and bronchial asthma

The cromakalim-like KCOs relax airways smooth muscle by an action that is associated with the opening of plasmalemmal K(+)-channels. The K(+)-channel involved may be analogous to the ATP-sensitive K(+)-channel identified in pancreatic beta-cells. It is unlikely to be open under normal circumstances and plays little role in determining the strong outward rectifying behaviour of the plasmalemma of the airways smooth muscle cell. K(+)-channel opening may cause relaxation of the airways smooth muscle cell by mechanisms additional to inhibition of Ca2+ influx through L-type VOCs. The cromakalim-like KCOs have bronchodilator activity in vivo and can depress NANC excitatory neuroeffector transmission in the lung at concentrations smaller than those required to relax airways smooth muscle. The mechanism of action of cromakalim in alleviating nocturnal asthma may not involve direct relaxation of airways smooth muscle. It is possible that cromakalim may instead act to inhibit the mechanisms underlying airway hyper-reactivity.

Role of protein kinase C in constrictor responses of the rat basilar artery in vivo

1. The goal of this study was to determine the effects of activation and inhibition of protein kinase C on the rat basilar artery in vivo. 2. The diameter of the basilar artery was measured through a craniotomy in rats anaesthetized with pentobarbitone sodium (50 mg kg-1, I.P., supplemented with 20 mg kg-1 h-1). Diameters were measured under control conditions and during topical application of various agonists, both alone and in the presence of antagonists. 3. Serotonin (5-HT) produced concentration-related constriction of the basilar artery (baseline diameter = 234 +/- 9 microns, mean +/- S.E.M.), which was inhibited by the 5-HT2 receptor antagonist LY53857. 4. Sphingosine (10(-6) M), a protein kinase C inhibitor which binds to the regulatory site of protein kinase C, inhibited the response to 10(-8) M-serotonin (-19 +/- 2% before vs. -3 +/- 2% during sphingosine, P less than 0.05). In contrast, constrictor responses to prostaglandin F2 alpha to (PGF2 alpha; 10(-6) M) were not inhibited by sphingosine (-16 +/- 2% before vs. -18 +/- 2% during sphingosine, P greater than 0.05). 5. H-7 (10(-9) M), another protein kinase C inhibitor, which binds to the catalytic site of protein kinase C, also inhibited constriction of the basilar artery in response to serotonin, but not prostaglandin F2 alpha. 6. Phorbol 12,13-dibutyrate (PDBu, 10(-8) M), which activates protein kinase C, produced slowly developing constriction of the basilar artery. PDBu-induced vasoconstriction (-33 +/- 2%) was attenuated by sphingosine (-11 +/- 4% during sphingosine, P less than 0.05) and H-7 (-1.5 +/- 5% during H-7, P less than 0.05). 7. In summary, activation of protein kinase C appears to mediate vasoconstrictor responses of the basilar artery to serotonin, but not PGF2 alpha.

Relationship of self-efficacy and binging to adherence to diabetes regimen among adolescents

OBJECTIVE

To test the hypothesis that poorer adherence to diabetes care is related to four variables associated with self-concept in adolescents with diabetes: self-esteem, self-efficacy, depression, and binging behavior. In addition, we expected adolescent females to be less adherent to diabetes care.

RESEARCH DESIGN AND METHODS

We recruited 193 consecutive patients (aged 13-18 yr) with insulin-dependent diabetes mellitus during their regular quarterly visit to a diabetes clinic in a large urban hospital. Participants completed the Rosenberg Self-Esteem Scale, the Children's Depression Inventory, an assessment of the frequency of binging in the past 3 mo, and parallel forms of an adherence scale and a self-efficacy scale that were developed for use in this study.

RESULTS

Adolescents who reported lower adherence tended to report lower self-esteem (r = 0.45, P less than 0.001) and self-efficacy (r = 0.57, P less than 0.001), more depressive symptoms (r = -0.50, P less than 0.001), more binging (r = -0.36, P less than 0.001), and had higher HbA1c (r = -0.24, P less than 0.001) than those with higher adherence scores. Together, the psychological variables accounted for 50% of the variance in adherence. There was no sex difference in reported binging, but, as expected, adolescent females reported less adherence overall (F[7,184] = 2.5, P = 0.018).

CONCLUSIONS

Treatment adherence in adolescents with insulin-dependent diabetes mellitus is associated with behavioral and psychological variables. These findings suggest that specific behavioral and cognitive interventions could be used to improve adherence in those individuals who lack confidence in their ability to perform diabetes-related tasks.

Guinea-pig isolated trachealis: the effects of charybdotoxin on mechanical activity, membrane potential changes and the activity of plasmalemmal K(+)-channels

1. A study has been made, in guinea-pig isolated trachealis, of the effects of charybdotoxin in modulating (a) the activity of large conductance K(+)-channels, (b) the spontaneous electrical activity of intact cells and (c) the mechanical effects of some bronchodilator drugs. 2. Single smooth muscle cells were isolated from guinea-pig trachealis by enzymic digestion and were studied by the patch clamp recording technique. Recordings were made from outside-out plasmalemmal patches when the medium bathing the external surface of the patches contained 1.2 mM Ca2+ and 6 mM K+ while that bathing the cytosolic surface contained 0.1 microM Ca2+ and 140 mM K+. Charybdotoxin (100 nM), applied to the external surface of patches held at 0 mV, abolished the unitary currents associated with the opening of large conductance K(+)-channels. 3. Opened segments of guinea-pig trachea were used for the simultaneous recording of membrane potential and tension changes. In these experiments charybdotoxin (100 nM) caused the conversion of spontaneous electrical slow waves into spike-like action potentials. This effect was accompanied by a very small reduction in resting membrane potential. 4. Tissue bath recording showed that charybdotoxin (100 nM) increased the spontaneous mechanical tone of the tissue, antagonized (2.8 fold in each case) the relaxant actions of isoprenaline and theophylline but did not antagonize the relaxant actions of cromakalim or RP 49356. 5. It is concluded that charybdotoxin is an effective inhibitor of large conductance K(+)-channels in guinea-pig trachealis cells. The ability of charybdotoxin to convert spontaneous slow waves into spike-like action potentials suggests that the large, charybdotoxin-sensitive, K+-channels play an important role in determining the strong outward rectifying behaviour of the cells. The ability of charybdotoxin to antagonize isoprenaline and theophylline, but not to antagonize cromakalim and RP 49356, suggests that opening of the large conductance, charybdotoxin-sensitive K+-channel is implicated in the action of the former but not the latter pair of bronchodilator drugs.

Role of protein kinase C in bradykinin-induced increases in microvascular permeability

The goal of this study was to determine whether protein kinase C mediates bradykinin-induced increases in microvascular permeability. Permeability of the hamster cheek pouch was evaluated using intravital fluorescent microscopy and fluorescein isothiocyanate (FITC)-dextran (MW 70,000). We examined effects of sphingosine, a protein kinase C inhibitor, on bradykinin-induced increases in permeability. Increases in permeability were quantitated by counting the number of leaky sites and calculating the clearance of FITC-dextran. During bradykinin (10(-6) M), leaky sites increased from 0 to 40 +/- 4 (mean +/- SEM) sites/0.11 cm2, and clearance increased from 1.7 +/- 1.0 to 22 +/- 9 ml/sec x 10(-6). The bradykinin type-2 receptor antagonist D-Arg,[Hyp3,Thi5,8,D-Phe7]-bradykinin virtually abolished formation of leaky sites in response to bradykinin. To determine whether changes in microvascular pressure contribute to the increase in leaky sites, venular pressure was measured using a micropipette and survo-null device. Increases in cheek pouch venular pressure were similar during application of bradykinin and adenosine, which increased permeability, and isoproterenol, which did not increase permeability in the cheek pouch. Thus, increases in permeability were not linked to changes in microvascular pressure. The protein kinase C inhibitor, sphingosine (10(-6) M), markedly attenuated responses to bradykinin. Leaky sites increased from 0 to only 2 +/- 1 sites/0.11 cm2, and clearance increased from 3.9 +/- 1.4 to only 6.7 +/- 2.2 ml/sec x 10(-6). To test the specificity of sphingosine, we examined effects of adenosine (10(-6) M). Sphingosine did not significantly alter increases in microvascular permeability in responses to adenosine. We also examined effects of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), another protein kinase C inhibitor, on responses to bradykinin and adenosine. H-7 greatly attenuated formation of leaky sites during stimulation with bradykinin and did not alter the number of leaky sites produced during adenosine. The findings suggest that protein kinase C may mediate increases in vascular permeability in response to bradykinin.

The influence of the high-risk care environment on the practice of low-risk obstetrics

This retrospective chart review compared the intervention rates in 2,365 low-risk obstetric patients at three urban teaching hospitals, two of which were high-risk, perinatal referral centers. The third cared for mostly low-risk patients. The hypothesis was that rates of intervention in low-risk pregnancies would be higher in the high-risk care environment. Family physicians at the perinatal referral centers performed significantly more artificial rupture of membranes, epidural blocks, augmentations of labor, and episiotomies on their low-risk patients than did those at the low-risk hospital. This trend was also found for obstetricians but did not reach statistical significance. Thus, the conclusion was drawn that caring for low-risk patients in a high-risk care environment is associated with a higher intervention rate by family physicians. Factors that may contribute to this finding are discussed.

Mechanical, biochemical and electrophysiological studies of RP 49356 and cromakalim in guinea-pig and bovine trachealis muscle

Experiments have been performed using guinea-pig and bovine trachealis in order to determine whether cromakalim and RP 49356 share the same relaxant action and to analyse the mechanisms underlying this action. RP 49356 was approximately 3 times less potent than cromakalim in suppressing the spontaneous tone of guinea-pig trachea and, like cromakalim, was antagonised by glibenclamide and by phentolamine. Biochemical studies showed that relaxant concentrations of cromakalim and RP 49356 did not alter the cAMP or cGMP content of guinea-pig trachealis muscle and did not inhibit cAMP or cGMP hydrolysis by tracheal homogenates. Like cromakalim, RP 49356 caused marked hyperpolarisation of guinea-pig trachealis cells. Patch clamp recording using inside-out membrane patches from bovine trachealis showed that cromakalim, RP 49356, glibenclamide and phentolamine were each without effect on the open state probability (Popen) of large conductance, Ca(2+)-activated K(+)-channels. We conclude that cromakalim and RP 49356 share a similar action in opening K(+)-channels in the trachealis cell membrane. This action probably does not involve the intracellular accumulation of cyclic nucleotides and the channel involved is not the large conductance, Ca(2+)-dependent K(+)-channel.

Self-predictions of emotional response patterns: age, sex, and situational determinants

A total of 407 males and females in 4 different age groups (M age = 8.0, 10.8, 15.2, and 20.3 years) completed questionnaires requiring self-ratings of 5 emotions (angry, happy, sad, fearful, and loving), on a 5-point scale, for 10 affect-laden sentences. Each of the 5 emotions was targeted as a key emotion by 2 sentences. The resulting patterns indicate that children as young as 8 can discriminate between affect-eliciting statements, differentially rate up to 5 concurrent emotional responses, and predict response patterns similar to those predicted by adults. Furthermore, sex differences occur during adolescence whereby males predict more varied but less intense secondary emotions, whereas females predict fewer but more intense secondary emotions.

Cerebral blood flow during fastigial pressor response in cats

We tested the hypotheses that electrical stimulation of the fastigial nucleus increases cerebral blood flow by a dilator mechanism, impairs autoregulation during increases in arterial pressure, and attenuates increases in cerebral blood flow during acute hypertension by activation of sympathetic nerves. Cerebral blood flow was measured with microspheres in anesthetized cats during control and moderate or severe hypertension produced by stimulation of the rostral fastigial nucleus. Cervical sympathetic nerves to one cerebral hemisphere were cut to compare responses in the innervated and denervated hemispheres. Fastigial stimulation at a level that raised arterial pressure from 94 +/- 10 (mean +/- SE) to 133 +/- 6 mmHg had no significant effect on cerebral blood flow. Autoregulation was preserved because cerebral vascular resistance increased approximately 40% during the fastigial pressure response. When mean arterial pressure was raised to 189 +/- 9 mmHg by stimulation of the fastigial nucleus, cerebral blood flow increased similarly in the denervated hemisphere and the hemisphere with intact sympathetic nerves. We conclude that stimulation of the fastigial nucleus in cats does not have a direct dilator effect on cerebral vessels, does not impair autoregulation during moderate hypertension, and does not attenuate increases in cerebral blood flow during severe hypertension by activation of sympathetic pathways.

Influence of functional impairment and social support on depressive symptoms in persons with diabetes

Tested the buffering model of social support among 158 adults with diabetes. We predicted that, among patients with higher levels of illness-related impairment, adequate social support would act as a buffer against depression. Measures included the Beck Depression Inventory; the Sickness Impact Profile; and an assessment of the adequacy of social support to enable the patient to deal with illness-related tasks, domestic chores, financial responsibilities, and emotional needs. Depressive symptoms correlated positively with functional impairment (r = .58, p less than .001) and negatively with the adequacy of social support (r = -.31, p less than .001). In addition, social support moderated depression in the face of greater impairment such that, among patients who reported the most illness-related functional disabilities, adequate support provided a relative protection from depression. The findings suggest that individuals with inadequate support are most at risk to become depressed when disability related to illness increases.

Cromakalim-induced relaxation of guinea-pig isolated trachealis: antagonism by glibenclamide and by phentolamine

1. Tested against the spontaneous tone of guinea-pig isolated trachealis, cromakalim (0.1-100 microM), isoprenaline (1 nM-1 microM) and theophylline (1 microM-1 mM) each produced concentration-dependent relaxation. 2. Glibenclamide (0.1-10 microM) did not itself alter the spontaneous tone of the trachea nor did it modify the relaxant actions of isoprenaline or theophylline. In contrast, glibenclamide (0.1 and 1 microM) caused a concentration-dependent rightward shift of the log concentration-effect curve of cromakalim. Glibenclamide (10 microM) reduced the slope of the log concentration-effect curve of cromakalim and moved the foot of the curve back towards the control position. 3. Phentolamine (1, 10 and 100 microm) did not itself alter the spontaneous tone of the trachea nor did it modify the relaxant actions of isoprenaline or theophylline. In contrast phentolamine caused concentration-dependent depression of the log concentration-effect curve of cromakalim. 4. Neither prazosin (1 microM) nor yohimbine (10 microM) modified the spontaneous tone of the trachea. Prazosin and yohimbine each failed to antagonise the effects of cromakalim, isoprenaline and theophylline. 5. Intracellular electrophysiological recording showed that glibenclamide (1 microM) and phentolamine (100 microM) caused minor change in the resting membrane potential of trachealis cells. Slow wave activity was slightly depressed by these agents. In contrast tetraethylammonium (TEA; 8 mM) caused marked depolarisation, and promoted the conversion of slow waves into regenerative action potentials. These electrical changes were accompanied by tonic tension development. 6. Phentolamine (100 microM) and glibenclamide (1 microM) reduced and reversed both the relaxation and the hyperpolarisation induced by cromakalim (10 microM). 7. It is concluded that glibenclamide and phentolamine each provide selective antagonism of the relaxant action of cromakalim in guinea-pig trachealis. These agents also inhibit the plasmalemmal hyperpolarisation induced by cromakalim. The effect of phentolamine is unrelated to the blockade of alpha 1- or alpha 2-adrenoceptors. If either glibenclamide or phentolamine act to block the K+ channels opened by cromakalim, then such channels are not identical to those which endow the trachealis plasmalemma with its powerful rectifying behaviour.

Differences in intrapartum obstetric care provided to women at low risk by family physicians and obstetricians

To determine differences in practice style and to examine maternal and neonatal outcomes, we reviewed the hospital charts of 1115 women admitted by family physicians and 1250 women admitted by obstetricians who gave birth at one of three teaching hospitals in Toronto between April 1985 and March 1986. All the women in the two groups were categorized retrospectively as being at low risk at the onset of labour on the basis of their prenatal records and their admission histories and physical examination results. There were higher proportions of younger women and women of lower socioeconomic status in the family physician group than in the obstetrician group (p less than 0.001). The rates of interventions, including artificial rupture of the membranes, induction, augmentation, low forceps plus vacuum extraction, episiotomy and epidural anesthesia, were all higher in the obstetrician group. The mean birth weight and the cesarean section rate were the same in the two groups. Differences in labour and delivery outcomes between the two groups, including a higher rate of spontaneous vaginal delivery for the family physicians, reflected a more "expectant" practice style by family doctors. However, there were no significant differences in the rates of maternal or neonatal complications. A practice style characterized by a higher rate of interventions was not associated with improved maternal or newborn outcome in this low-risk setting.

The guidance of axons from transplanted neurons through aneural Drosophila wings

The sensory neurons of the wing of Drosophila arise during the first 24 hr of metamorphosis, and their axons converge to form a stereotyped set of nerves projecting proximally from the peripherally located cell bodies through the wing and towards the CNS. To better characterize the cues guiding this stereotyped axon outgrowth, we have performed a series of transplantation studies in which neurons from a variety of sources (wing, eye, antenna, and leg disks) were placed into mutant, aneural wings. Axons growing from such implants in effect assay the host wing for the presence and location of guidance cues. Our results show, first, that such axons prefer to grow in the normal, proximal direction and, second, that they prefer to grow along the approximate site of one of the normal nerves, that of the third longitudinal vein. It therefore appears that the aneural wing epithelium contains cues capable of directing both the polarity and the location of axonal outgrowth. These cues are relatively non-specific, in that a variety of neuronal types are capable of responding to them.