Child and adolescent COVID-19 vaccination coverage by educational setting, United States

OBJECTIVES

The COVID-19 pandemic changed the setting of education for many children in the U.S. Understanding COVID-19 vaccination coverage by educational setting is important for developing targeted messages, increasing parents' confidence in COVID-19 vaccines, and protecting all children from severe effects of COVID-19 infection.

STUDY DESIGN/METHODS

Using data from the Household Pulse Survey (n = 25,173) collected from December 9-19, 2022, January 4-16, 2023, and February 1-13, 2023, this study assessed factors associated with COVID-19 vaccination and reasons for non-vaccination among school-aged children 5-11 and adolescents 12-17 by educational setting.

RESULTS

Among children 5-11 years, COVID-19 vaccination coverage was higher among those who received in-person instruction (53.7%) compared to those who were homeschooled (32.5%). Furthermore, among adolescents 12-17 years, COVID-19 vaccination coverage was higher among those who received in-person instruction (73.5%) or virtual/online instruction (70.1%) compared to those who were homeschooled (51.0%). Children and adolescents were more likely to be vaccinated if the parental respondent had been vaccinated compared to those who had not. Among children and adolescents who were homeschooled, main reasons for non-vaccination were concern about side effects (45.4-51.6%), lack of trust in COVID-19 vaccines (45.0-50.9%), and lack of trust in the government (32.7-39.2%).

CONCLUSIONS

Children and adolescents who were home-schooled during the pandemic had lower vaccination coverage than those who attended school in person, and adolescents who were home-schooled had lower vaccination coverage than those who received virtual instruction. Based on the reasons for non-vaccination identified in this study, increasing parental confidence in vaccines, and reducing barriers to access are important for supporting COVID-19 vaccination for school-age children.

CBFA2T3-GLIS2-dependent pediatric acute megakaryoblastic leukemia is driven by GLIS2 and sensitive to navitoclax

Pediatric acute megakaryoblastic leukemia (AMKL) is an aggressive blood cancer associated with poor therapeutic response and high mortality. Here we describe the development of CBFA2T3-GLIS2-driven mouse models of AMKL that recapitulate the phenotypic and transcriptional signatures of the human disease. We show that an activating Ras mutation that occurs in human AMKL increases the penetrance and decreases the latency of CBF2AT3-GLIS2-driven AMKL. CBFA2T3-GLIS2 and GLIS2 modulate similar transcriptional networks. We identify the dominant oncogenic properties of GLIS2 that trigger AMKL in cooperation with oncogenic Ras. We find that both CBFA2T3-GLIS2 and GLIS2 alter the expression of a number of BH3-only proteins, causing AMKL cell sensitivity to the BCL2 inhibitor navitoclax both in vitro and in vivo, suggesting a potential therapeutic option for pediatric patients suffering from CBFA2T3-GLIS2-driven AMKL.

Study protocol for The GOAL Trial: comprehensive geriatric assessment for frail older people with chronic kidney disease to increase attainment of patient-identified goals-a cluster randomised controlled trial

BACKGROUND

An increasing number of older people are living with chronic kidney disease (CKD). Many have complex healthcare needs and are at risk of deteriorating health and functional status, which can adversely affect their quality of life. Comprehensive geriatric assessment (CGA) is an effective intervention to improve survival and independence of older people, but its clinical utility and cost-effectiveness in frail older people living with CKD is unknown.

METHODS

The GOAL Trial is a pragmatic, multi-centre, open-label, superiority, cluster randomised controlled trial developed by consumers, clinicians, and researchers. It has a two-arm design, CGA compared with standard care, with 1:1 allocation of a total of 16 clusters. Within each cluster, study participants ≥ 65 years of age (or ≥ 55 years if Aboriginal or Torres Strait Islander (First Nations Australians)) with CKD stage 3-5/5D who are frail, measured by a Frailty Index (FI) of > 0.25, are recruited. Participants in intervention clusters receive a CGA by a geriatrician to identify medical, social, and functional needs, optimise medication prescribing, and arrange multidisciplinary referral if required. Those in standard care clusters receive usual care. The primary outcome is attainment of self-identified goals assessed by standardised Goal Attainment Scaling (GAS) at 3 months. Secondary outcomes include GAS at 6 and 12 months, quality of life (EQ-5D-5L), frailty (Frailty Index - Short Form), transfer to residential aged care facilities, cost-effectiveness, and safety (cause-specific hospitalisations, mortality). A process evaluation will be conducted in parallel with the trial including whether the intervention was delivered as intended, any issue or local barriers to intervention delivery, and perceptions of the intervention by participants. The trial has 90% power to detect a clinically meaningful mean difference in GAS of 10 units.

DISCUSSION

This trial addresses patient-prioritised outcomes. It will be conducted, disseminated and implemented by clinicians and researchers in partnership with consumers. If CGA is found to have clinical and cost-effectiveness for frail older people with CKD, the intervention framework could be embedded into routine clinical practice. The implementation of the trial's findings will be supported by presentations at conferences and forums with clinicians and consumers at specifically convened workshops, to enable rapid adoption into practice and policy for both nephrology and geriatric disciplines. It has potential to materially advance patient-centred care and improve clinical and patient-reported outcomes (including quality of life) for frail older people living with CKD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04538157. Registered on 3 September 2020.

Every child, every day, back to play: the PICUstars protocol - implementation of a nurse-led PICU liberation program

BACKGROUND

As admissions to paediatric intensive care units (PICU) rise and mortality rates decline, the focus is shifting from survival to quality of survivorship. There is paucity of internationally accepted guidelines to manage complications like over-sedation, delirium, and immobility in the paediatric setting. These have a strong adverse impact on PICU recovery including healthcare costs and long-term functional disability. The A2F bundle (ABCDEF), or ICU Liberation, was developed to operationalise the multiple evidence-based guidelines addressing ICU-related complications and has been shown to improve clinical outcomes and health-care related costs in adult studies. However, there is little data on the effect of ICU Liberation bundle implementation in PICU.

METHODS

PICU-STARS will be a single centre before-and-after after trial and implementation study. It is designed to evaluate if the multidimensional, nurse-led ICU Liberation model of care can be applied to the PICU and if it is successful in minimising PICU-related problems in a mixed quaternary PICU. In a prospective baseline measurement, the present practises of care in the PICU will be assessed in order to inform the adaptation and implementation of the PICU Liberation bundle. To assess feasibility, implementation outcomes, and intervention effectiveness, the implementation team will use the Consolidated Framework for Implementation Research (CIFR) and process assessment (mixed methods). The implementation process will be evaluated over time, with focus groups, interviews, questionnaires, and observations used to provide formative feedback. Over time, the barriers and enablers for successful implementation will be analysed, with recommendations based on "lessons learned." All outcomes will be reported using standard descriptive statistics and analytical techniques, with appropriate allowance for patient differentials in severity and relevant characteristics.

DISCUSSION

The results will inform the fine-tune of the Liberation bundle adaptation and implementation process. The expected primary output is a detailed adaptation and implementation guideline, including clinical resources (and investment) required, to adopt PICU-STARS in other children's hospitals.

PATIENT AND PUBLIC INVOLVEMENT STATEMENT

The authors thank the PICU education and Liberation Implementation team, and our patients and families for their inspiration and valuable comments on protocol drafts. Results will be made available to critical care survivors, their caregivers, relevant societies, and other researchers.

TRIAL REGISTRATION

ACTRN, ACTRN382863 . Registered 19/10/2021 - Retrospectively registered.

STUDY STATUS

recruiting.

[The association between aeroallergenic structures and allergic rhinitis: a study on northern Vietnam]

Recently, there has been an increase in the number of patients with allergic rhinitis (AR) and the number of publications devoted to this problem is increasing. The main etiological factors of AR are pollen of trees, meadow and weeds, as well as mold spores, household allergens and epidermis of animals. Epidemiological studies have found that the prevalence and structure of AR are influenced by regional characteristics, such as the climatic and geographical and social characteristics of the region, and successively therapeutic and preventive algorithms in AR are also different.

AIM

To examine the phenotype of the incidence of AR in connection with the characteristics of aeroallergens under the influence of climatic and geographical conditions in northern Vietnam, to make a new contribution to knowledge about AR in Asia and to increase the effect of treatment and prevention in this territory.

MATERIALS AND RESEARCH METHODS

The study was conducted in the period from 06.2018 to 09.2018 on the basis of the ENT department of Thainguyen Central Hospital, Vietnam. A total of 556 patients with pathology of ENT organs aged 18 to 70 years were examined, 158 cases of chronic rhinitis were revealed. Among data from 158 patients, 64 patients were diagnosed with AR. We used otorhinolaryngological examination, a standard specific allergological examination and carried out aeropolyneological research in the city of the northern Vietnam, from 06.2018 to 06.2019.

RESULT

The aerobiological spectrum is dominated by pollen from the families Moraceae, Urticaceae, Poaceae, Acacia, Artemisia, fern spores and fungal spores from the genus Alternaria. Among patients with chronic rhinitis, 40% were diagnosed with AR, 98.44% of them year-round or perennial AR, with predominant sensitization to house dust mites and molds, much more often to plant pollen. Among 9 (14.06%) patients diagnosed with a polyp of the nasal cavity, 6 (9.37%) patients had increased levels of specific IgE in the blood to a mixture of molds. Sensitization in patients with AR with hypertrophy of the mucous membrane of the nasal cavity is predominant on house dust.

CONCLUSION

Predominantly, AR in northern Vietnam was year-round. Especially the connection between the formation of a polyp of the nasal cavity and hypersensitivity to fungal spores has been indicated, which may also indicate the role of social factors in further recommendations for the diagnosis, treatment and prevention of AR in patients living in North Vietnam.

Effects of temperature and viscosity on miracidial and cercarial movement of Schistosoma mansoni: ramifications for disease transmission

Parasites with complex life cycles can be susceptible to temperature shifts associated with seasonal changes, especially as free-living larvae that depend on a fixed energy reserve to survive outside the host. The life cycle of Schistosoma, a trematode genus containing some species that cause human schistosomiasis, has free-living, aquatic miracidial and cercarial larval stages that swim using cilia or a forked tail, respectively. The small size of these swimmers (150-350 µm) dictates that their propulsion is dominated by viscous forces. Given that viscosity inhibits the swimming ability of small organisms and is inversely correlated with temperature, changes in temperature should affect the ability of free-living larval stages to swim and locate a host. By recording miracidial and cercarial movement of Schistosoma mansoni using a high-speed camera and manipulating temperature and viscosity independently, we assessed the role each factor plays in the swimming mechanics of the parasite. We found a positive effect of temperature and a negative effect of viscosity on miracidial and cercarial speed. Reynolds numbers, which describe the ratio of inertial to viscous forces exerted on an aquatic organism, were <1 across treatments. Q₁₀ values were <2 when comparing viscosity treatments at 20 °C and 30 °C, further supporting the influence of viscosity on miracidial and cercarial speed. Given that both larval stages have limited energy reserves and infection takes considerable energy, successful transmission depends on both speed and lifespan. We coupled our speed data with mortality measurements across temperatures and discovered that the theoretical maximum distance travelled increased with temperature and decreased with viscosity for both larval stages. Thus, our results suggest that S. mansoni transmission is high during warm times of the year, partly due to improved swimming performance of the free-living larval stages, and that increases in temperature variation associated with climate change might further increase transmission.

Determination of wild animal sources of fecal indicator bacteria by microbial source tracking (MST) influences regulatory decisions

Fecal indicator bacteria (FIB) are used to assess fecal pollution levels in surface water and are among the criteria used by regulatory agencies to determine water body impairment status. While FIB provide no information about pollution source, microbial source tracking (MST) does, which contributes to more direct and cost effective remediation efforts. We studied a watershed in Florida managed for wildlife conservation that historically exceeded the state regulatory guideline for fecal coliforms. We measured fecal coliforms, enterococci, a marker gene for avian feces (GFD), and a marker gene for human-associated Bacteroides (HF183) in sediment, vegetation, and water samples collected monthly from six sites over two years to: 1) assess the influence of site, temporal factors, and habitat (sediment, vegetation, and water) on FIB and MST marker concentrations, 2) test for correlations among FIB and MST markers, and 3) determine if avian feces and/or human sewage contributed to FIB levels. Sediment and vegetation had significantly higher concentrations of FIB and GFD compared to water and thus may serve as microbial reservoirs, providing unreliable indications of recent contamination. HF183 concentrations were greatest in water samples but were generally near the assay limit of detection. HF183-positive results were attributed to white-tailed deer (Odocoileus virginianus) feces, which provided a false indication of human sewage in this water body. FIB and GFD were positively correlated while FIB and HF183 were negatively correlated. We demonstrated that birds, not sewage, were the main source of FIB, thus avoiding implementation of a total maximum daily load program (TMDL). Our results demonstrate that the concomitant use of FIB and MST can improve decision-making and provide direction when water bodies are impaired, and provides a strategy for natural source exclusion in water bodies impacted by wild animal feces.

Expression of a mutant prohibitin from the aP2 gene promoter leads to obesity-linked tumor development in insulin resistance-dependent manner

A critical unmet need for the study of obesity-linked cancer is the lack of preclinical models that spontaneously develop obesity and cancer sequentially. Prohibitin (PHB) is a pleiotropic protein that has a role in adipose and immune functions. We capitalized on this attribute of PHB to develop a mouse model for obesity-linked tumor. We achieved this by expressing Y114F-PHB (m-PHB) from the aP2 gene promoter for simultaneous manipulation of adipogenic and immune signaling functions. The m-PHB mice develop obesity in a sex-neutral manner, but only male mice develop impaired glucose homeostasis and hyperinsulinemia similar to transgenic mice expressing PHB. Interestingly, only male m-PHB mice develop histiocytosis with lymphadenopathy, suggesting that metabolic dysregulation or m-PHB alone is not sufficient for the tumor development and that both are required for tumorigenesis. Moreover, ovariectomy in female m-PHB mice resulted in impaired glucose homeostasis, hyperinsulinemia and consequently tumor development similar to male m-PHB mice. These changes were not observed in sham-operated control m-Mito-Ob mice, further confirming the role of obesity-related metabolic dysregulation in tumor development in m-PHB mice. Our data provide a proof-of-concept that obesity-associated hyperinsulinemia promotes tumor development by facilitating dormant mutant to manifest and reveals a sex-dimorphic role of PHB in adipose-immune interaction or immunometabolism. Targeting PHB may provide a unique opportunity for the modulation of immunometabolism in obesity, cancer and in immune diseases.

Association between local indoor smoking ordinances in Massachusetts and cigarette smoking during pregnancy: a multilevel analysis

OBJECTIVE

To estimate the association between local clean indoor air ordinances and prenatal maternal smoking across 351 municipalities in Massachusetts before the 2004 statewide ban and to test the effect of time since ordinance adoption on the association.

METHODS

The authors linked 2002 birth certificate data of women who gave birth in the state and reported a Massachusetts residence (n=67,584) to a database of indoor smoking ordinances in all municipalities. Multilevel regression models accounting for individual- and municipality-level variables estimate the associations between the presence of local smoking ordinances, strength of the ordinances, time since ordinance adoption and prenatal smoking.

RESULTS

Compared with those living in municipalities with no ordinances, women living in municipalities with a smoking ordinance had lower odds of prenatal smoking (OR=0.72, CI=0.53 to 0.98). No effect was found for 100% smoke-free ordinances. For the analyses testing the effect of time, pregnant women living in municipalities with ordinances enacted >2 years were less likely to smoke than those in municipalities with more recent (<1 year) ordinances.

CONCLUSIONS

Preventing smoking among women of reproductive age is a public health priority. This study suggests that indoor smoking ordinances were associated with lower prenatal smoking prevalence and the favourable effect increased over time. Findings highlight the public health benefit of tobacco control policies.

Implementing a program for switching from i.v. to oral antimicrobial therapy

Management Case Studies describe approaches to real-life management problems in health systems. Each installment is a brief description of a problem and how it was dealt with. The cases are intended to help readers deal with similar experiences in their own work sites. Problem solving, not hypothesis testing, is emphasized. Successful resolution of the management issue is not a criterion for publication--important lessons can be learned from failures, too.

Juxtaposition of the atrial appendages: a clinical series of 22 patients

Because the outcome of a large clinical series of patients with juxtaposition of the atrial appendages (JAA) has not previously been reported, a retrospective study was performed on patients diagnosed with JAA at a tertiary medical center. Patients with JAA were identified through a computerized database search, and echocardiograms and medical records of patients with JAA were reviewed. Twenty-two patients with JAA were identified, with an overall incidence of 0.28%. All but 2 patients were diagnosed prospectively with JAA by echocardiography. The lesion-specific incidences and associated lesions were similar to those of large autopsy and surgical series. Abnormal conotruncal anatomy was more frequently seen with juxtaposition of the right atrial appendage (JRAA) vs juxtaposition of the left atrial appendage (JLAA) (14/15 vs 4/7), as was atrial outlet obstruction (6/15 vs 2/7). JLAA was more frequently associated with complex atrioventricular anatomy (3/7 vs 1/15). Patients with JAA underwent single ventricle palliation in 11/22 cases with 6 deaths; biventricular repair was performed in 8/22 cases with no deaths. Surgical outcomes for patients with JRAA and JLAA were similar, and survival was predominantly influenced by suitability for biventricular repair.

Evidence for antimuscarinic acetylcholine receptor antibody-mediated secretory dysfunction in nod mice

OBJECTIVE

Antibodies directed against general and specific target-organ autoantigens are present in the sera of human patients and animal models with autoimmune disease. The relevance of these autoantibodies to the disease process remains ambiguous in most cases. In autoimmune exocrinopathy (Sjögren's syndrome), autoantibodies to the intracellular nuclear proteins SSA/Ro and SSB/La, as well as the cell surface muscarinic cholinergic receptor (M3) are observed. To evaluate the potential role of these factors in the loss of secretory function of exocrine tissues, a panel of monoclonal and polyclonal antibodies was developed for passive transfer into the NOD animal model.

METHODS

Monoclonal antibodies to mouse SSB/La, rat M3 receptor, and a rabbit polyclonal antiparotid secretory protein antibody were obtained for this study. These antibody reagents were subsequently infused into NOD-scid mice. Saliva flow rates were subsequently monitored over a 72-hour period. Submandibular gland lysates were examined by Western blotting for alteration of the distribution of the water channel protein aquaporin (AQP).

RESULTS

Evaluation of the secretory response indicated that only antibodies directed toward the extracellular domains of the M3 receptor were capable of mediating the exocrine dysfunction aspect of the clinical pathology of the autoimmune disease. In vitro stimulation with a muscarinic agonist of submandibular gland cells isolated from mice treated with anti-M3 antibody, but not saline or the isotype control, failed to translocate AQP to the plasma membrane.

CONCLUSION

These findings define a clear role for the humoral immune response and the targeting of the cell surface M3 signal transduction receptor as primary events in the development of clinical symptoms of autoimmune exocrinopathy. Furthermore, the anti-M3 receptor activity may negatively affect the secretory response through perturbation of normal signal transduction events, leading to translocation of the epithelial cell water channel.

Stereospecific versus nonstereospecific assessments for the bioequivalence of two formulations of racemic chlorpheniramine

Chlorpheniramine (chlorphenamine, CPAM) is a racemic antihistaminic H1 drug containing two enantiomers. The aim of this study was to assess the bioequivalence of two formulations (reference and Vietnamese-tested formulation) of racemic chlorpheniramine combined with phenylpropanolamine in an open-labeled, randomized, crossover two-period study, after administration of 8 mg of racemic chlorpheniramine in 12 healthy Vietnamese subjects. First, dissolution of both formulations was tested in vitro according to USP requirements. Then the 12 subjects received both formulations after an overnight fast and a 7-day wash-out period. Plasma samples were collected up to 168 h. Plasma concentrations of total chlorpheniramine and its individual enantiomers were determined with a validated chiral HPLC method and pharmacokinetic parameters were estimated using model-independent analysis. For the reference formulation, Cmax and AUC values were higher for (+)S-chlorpheniramine ((+)S-CPAM) compared to (-)R-chlorpheniramine ((-)R-CPAM) (13.3 vs. 6.8 ng/ml and 409 vs. 222 ng/ml/h, respectively) while Clt/F and Vd/F were lower (9.8 vs. 17.6 l/h and 321 vs. 627 l, respectively). No difference was observed for Tmax, t(1/2), and MRT. Pharmacokinetic parameters were similar for the reference and the Vietnamese-tested formulation. Bioequivalence was assessed by Schuirmann test, as recommended by the current FDA and European Community criteria. Dissolution tests showed that both formulations were equivalent. A nonstereospecific, but not a stereospecific, approach indicated bioequivalence between the formulations.

Salivary epidermal growth factor levels decrease in patients receiving radiation therapy to the head and neck

OBJECTIVE

The objective of this study was to assess changes in salivary epidermal growth factor (EGF) in patients receiving radiation therapy to the head and neck and to determine whether salivary EGF levels correlate with the severity of radiation-induced oral mucositis.

STUDY DESIGN

Thirteen patients and 18 control subjects were enrolled in the study. Saliva was collected before, during (weekly), and after radiation therapy. Salivary total protein (TP) and EGF concentrations were measured and correlated with the severity of oral mucositis. The variability in normalized EGF (ngEGF/mgTP) values and mucositis scores were analyzed with analysis of covariance, and the adjusted correlation coefficient was calculated.

RESULTS

EGF levels decreased (P =.004), whereas TP levels increased over time (P =.039). A strong correlation was seen with decreasing normalized EGF values and more severe mucositis (P =. 0001).

CONCLUSION

A strong negative correlation between normalized EGF and mucositis severity suggests a possible role for EGF in the progression of radiation-induced mucosal breakdown.

Congenital Heart Surgery Nomenclature and Database Project: aortic valve disease

The extant nomenclature for aortic valve disease is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. Aortic valve disease has been subdivided into stenotic and regurgitant lesions. Stenotic lesions have been characterized by anatomic location: supravalvar, valvar, and subvalvar. Regurgitant lesions have been characterized as either congenital or acquired. A comprehensive database set is presented that is based on a hierarchical scheme. Data are entered at various levels of complexity and detail that can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented that will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Intra-articular IL-4 gene therapy in arthritis: anti-inflammatory effect and enhanced th2activity

Gene therapy has been explored as a potential method for treating chronic inflammatory diseases such as rheumatoid arthritis. To determine the efficacy of intra-articular IL-4 gene therapy in an animal model of arthritis using a retroviral vector, a retrovirus encoding rat IL-4 (DA-IL-4) was engineered, purified and concentrated to high titer (>/=109 CFU/ml). Infectivity and expression levels were demonstrated in vitro using cultured fibroblast-like synoviocytes. Efficacy was evaluated in the rat adjuvant arthritis model. DA-IL-4 or DA-beta-gal retrovirus was injected into the intra-articular joint space of the right ankle on day 12 after immunization. Three days after joint injection, the injected paw contained increased levels of IL-4 compared with control or with the contralateral uninjected paw, demonstrating successful transgene expression. Surprisingly, 8 days after treatment IL-4 levels continued to increase in the injected and contralateral paw compared with DA-beta-gal-treated animals. Serum IL-4 levels were also elevated in DA-IL-4-treated rats. RT-PCR studies demonstrated that the transgene was expressed in the injected ankle but not in the contralateral joint. IL-4 gene therapy resulted in a significant reduction in paw swelling and decreased radiographic evidence of bone destruction. This is the first demonstration of successful intra-articular retroviral gene treatment using a therapeutic gene. In addition to its anti-inflammatory effect, this study supports the potential application of intra-articular gene therapy as a method for enhancing systemic Th2 function.

Use of somatosensory evoked potentials for thoracic and thoracoabdominal aortic resections

BACKGROUND

Despite tremendous development in surgical and anesthetic techniques, resection of the thoracic and thoracoabdominal segments of the aorta remain associated with the risk of paralysis. Routine use of somatosensory-evoked potential (SEP) monitoring in patients undergoing surgery of the thoracic aorta has become a standard intra- and postoperative procedure at our institution since its first use in 1993.

METHODS

One hundred forty nine (149) thoracic aortic operations were performed during January 1993 through January 1998 using SEP-directed serial sacrifice of paired intercostal arteries. Full, partial, or no cardiovascular bypass was variably used, dictated by anatomy; 49 patients required deep hypothermic circulatory arrest (DHCA). Patients were monitored during both the intraoperative procedure as well for the post-anesthesia period until neurologic stability and/or ability to reproducibly demonstrate lower extremity neurologic competency was established. Postoperative neurologic function was compared to ischemic intervals, extent of aortic resection, number of intercostal arteries sacrificed, type of perfusion, and underlying aortic pathology.

RESULTS

Overall mortality in the group was 13 patients (8.7%), with no one cause predominating. Nine patients sustained permanent paraplegia, only 1 of whom lost SEPs during the procedure. Abnormal SEPs were seen in 19 patients, 14 of whom had normal neurologic function after awakening. Three of 19 (15.8%) developed late paraplegia that resolved with medical therapy. Eleven patients (7.4%) developed cerebrovascular accidents (CVA), with the majority (8) appearing in the group undergoing DHCA. The risk of CVA was significantly higher in DHCA patients (p < 0.01) than other patients. No patient with CVA had abnormal SEPs; 4 DHCA patients developed abnormal SEPs, 1 with permanent paralysis.

CONCLUSIONS

The routine use of SEP monitoring during thoracic and thoracoabdominal aortic surgery as well as during the postoperative period may be useful in decreasing the observed incidence of paraplegic events associated with these procedures.

Subtypes of acute aortic dissection

BACKGROUND

This series consists of a 12-year experience with a policy of identifying and replacing the aortic segment containing the primary intimal tear for repair of acute aortic dissection.

METHODS

Patients with type A dissection underwent urgent surgery. Patients with type B dissection were referred for surgery based on selective criteria, including aortic dilatation greater than 5 cm. A classification system for acute dissection is described that specifies the site of intimal tear while retaining the clinical relevance of the Stanford system.

RESULTS

Of 168 acute dissections, 139 were type A and 29 were type B. The site of intimal tear was as follows: ascending aorta, 83 cases; arch, 32 cases; descending aorta, 29 cases; multiple tears, 11 cases (10 included arch tears); no tear (intramural hematoma), 6 cases; not noted, 7 cases. Only 60% of acute type A dissections arose from solitary intimal tears in the ascending aorta, whereas 30% had arch tears. Hospital mortality for type A dissection was 13.7% (18.8% for arch tears, NS) and 0% for type B. False lumen patency was 57.1% for type A dissection and 18.8% for type B dissection (p = 0.002), yet survival was similar for these groups. Ten-year survival for type A dissection with arch tear (0.51 +/- 0.12) was lower than 10-year survival for type A dissection with ascending tear (0.74 +/- 0.05; p = 0.77), and significantly lower than for type A dissection with descending tear (0.88 +/- 0.12; p = 0.029).

CONCLUSIONS

Systematic resection of the primary tear yielded similar hospital mortality, 5-year survival, and aorta-related event-free survival rates for subtypes of acute type A dissection. Excellent results were obtained with a selective approach to type B dissection.

Natural history of descending thoracic and thoracoabdominal aneurysms

BACKGROUND

A review of 165 patients with chronic dissecting and degenerative aneurysms of the descending thoracic and thoracoabdominal aorta initially managed nonoperatively was carried out to ascertain factors associated with a high risk of rupture.

METHODS

Changes in the aneurysms were followed with three-dimensional reconstructions of computed tomograph scans. Risk factors were compared in patients with dissecting and nondissecting aneurysms who experienced rupture, in whom operation was recommended during the course of follow-up, and in those without rupture or operation.

RESULTS

Nondimensional variables associated with an enhanced risk of rupture include age, the presence of chronic obstructive pulmonary disease, and even uncharacteristic continued pain. Patients with rupture of dissections had significantly higher blood pressures than survivors, and significantly smaller maximal descending thoracic aortic diameters (median 5.4 cm) than patients with rupture of degenerative aneurysms (median 5.8 cm). The extent of the aneurysm, as reflected by the maximal abdominal aortic diameter, was a significant risk factor for rupture only in nondissecting aneurysms. Mortality from rupture was significantly higher in patients with chronic dissections than in patients with nondissecting aneurysms: 9/10 vs 26/34 (p = 0.004).

CONCLUSIONS

Almost 20% of patients followed nonoperatively succumbed to rupture, suggesting that a more aggressive surgical approach toward patients with chronic aneurysms of the descending thoracic and thoracoabdominal aorta is warranted. An individualized risk of rupture within 1 year can now be calculated, and patients whose operative risk is lower than their calculated risk should be offered elective surgery.

Excessive synthesis of matrix metalloproteinases in exocrine tissues of NOD mouse models for Sjögren's syndrome

OBJECTIVE

Matrix metalloproteinases (MMP) and their substrates, components of the extracellular matrix, regulate environmental signals for cellular differentiation and tissue function. Changes in the levels of these enzymes may influence cell survival as well as pathology involving ectopic apoptosis. Using the non-obese diabetic (NOD) mouse model for Sjögren's syndrome, we evaluated the synthesis and expression of MMP in the exocrine target tissues of autoimmunity.

METHODS

NOD, immunodeficient NOD-scid, and nondiabetic NOD.B10.H2b mice were evaluated for MMP activity in their saliva and exocrine gland lysates by gelatin zymography and reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, changes in protein content of saliva and gland lysates were determined by specific Western blot and by enzymatic activity of amylase and cysteine proteases. Mice continuously treated with the MMP inhibitor GM6001 were evaluated from 7 to 20 weeks of age for the contribution of MMP activity to development of these hallmark biochemical markers of Sjogren's syndrome-like disease of NOD mice.

RESULTS

Gelatin zymography of whole saliva and gland lysates indicated the presence of increased proteolytic activity, corresponding to proteins with a molecular mass ranging from 50 to 95 kDa, in the saliva of older (> 20 weeks of age) NOD mice as well as NOD.B10.H2b and NOD-scid mice compared to BALB/c controls. Elevated steady state levels of mRNA transcripts for the gelatinases MMP-2 and MMP-9 were detected in total RNA extracted from parotid and submandibular glands by RT-PCR. Despite prophylactic injection of the broad spectrum MMP inhibitor GM6001 into mice beginning at 7 weeks of age and continuing to 20 weeks, development of the autoimmune exocrinopathy was neither stopped nor retarded.

CONCLUSION

These observations suggest that excessive MMP activity is associated with autoimmune Sjögren's syndrome-like disease in NOD mice. However, a possible contribution by increased MMP activity in initiation and progression of this autoimmune disease is yet to be elucidated.

The outcome of cardiac operations in infants weighing two kilograms or less

OBJECTIVE

A review of our recent experience of operating on infants weighing 2 kg or less who had congenital heart disease was performed to determine the outcome of early surgical repair or palliation.

METHODS

A retrospective review of hospital records was performed for infants who weighed 2 kg or less and who were identified to have undergone cardiac operation at our institution January 1992 to June 1997. The data collected included age, weight, gestational age, cardiac diagnosis, surgical procedure, and outcome measures such as length of stay, morbidity, and mortality rate. Outpatient charts were reviewed for follow-up survival and cardiac status.

RESULTS

Thirty-three operations were performed on 30 patients. Median age at operation was 19.5 days (1 to 140 days), and median weight was 1.8 kg (1.1 to 2.0 kg). Cardiac diagnoses varied, with coarctation of the aorta and tetralogy of Fallot most common. Twenty-four patients were born at 37 or fewer weeks' gestation. Hospital survival was 83% with no difference in mortality rates based on age, weight, or type of surgical procedure. Premature infants tended to have worse hospital survival. Median postoperative length of stay was 39 days (6 to 122 days). Median duration of mechanical ventilation in survivors was 6 days (2 to 24 days). Neurologic complications were documented in eight patients. Of the 25 hospital survivors, 20 (80%) are alive with good cardiac status at a mean follow-up of 13 months.

CONCLUSION

Cardiac operations in a selected group of infants weighing 2 kg or less can provide acceptable hospital survival. In most instances, complete repair is possible with good medium-term outcome in the survivors. Investigation into neurologic outcomes in these patients is warranted.

Changes in the expression of extracellular matrix (ECM) and matrix metalloproteinases (MMP) of proliferating rat parotid acinar cells

Tissue morphogenesis, development, and maintenance of function are mediated by signals generated through the composition of the extracellular matrix. The regulation of the composition of matrix is determined by enzymes specific for their degradation, the matrix metalloproteinases. Chronic injections of the beta-adrenergic receptor agonist, isoproterenol, result in a non-neoplastic hypertrophy and hyperplasia of the rat parotid gland. The activity of matrix metalloproteinases, as measured by gelatin zymography and enzymatic digestion of Azocoll substrates by gland lysates, decreased significantly (P < 0.05) following 24 hrs of agonist treatment, and slowly recovered to control values by 6 days of treatment. Daily administration of the broad-spectrum matrix metalloproteinase inhibitor Galardin for 3 days in combination with isoproterenol resulted in enhanced gland hypertrophy compared with that produced by isoproterenol alone. Given alone, Galardin also caused hypertrophy. The relative abundance of mRNA for the extracellular matrix molecules, collagens I and III and fibronectin, declined rapidly following the initiation of beta-agonist treatment in vivo, while laminin B1 and B2 mRNA levels increased initially before declining below control levels. These changes in patterns of mRNA levels also were observed in the concentrations of glandular protein when Western dot blot analysis of collagens I and III and laminin, respectively, was used. The importance of laminin, in vivo, was demonstrated by coinjection of anti-laminin antibody along with isoproterenol, which resulted in the inhibition of beta-agonist-induced parotid gland hypertrophy and hyperplasia. These data suggest that modulation of the ECM is associated with isoproterenol-induced salivary gland hypertrophy and hyperplasia. It is likely that this modulation of the ECM takes place through transcriptional regulation of some ECM genes and regulation of matrix-degrading enzyme activity.

Direct synovial gene transfer with retroviral vectors in rat adjuvant arthritis

OBJECTIVE

To evaluate the feasibility of direct in vivo gene transfer in an animal model of arthritis using a retroviral vector.

METHODS

The timing and dose of retroviral vector was examined using very high titer retroviral vector (> or = 10(9) CFU) in rat adjuvant arthritis. Retroviral vector expressing beta-galactosidase (beta-gal) or vehicle alone was injected into the right ankle of rats with adjuvant arthritis. Ankles were injected either on Day 7 (pre-arthritis), Day 10 (early arthritis), Day 15 (accelerating arthritis), or Day 28 (chronic arthritis) after adjuvant immunization. Joints were harvested 3 days later and extracts were assayed for beta-gal activity.

RESULTS

Synovial beta-gal expression was minimal in the Day 7 group and elevated in the Day 10, Day 15, and Day 28 groups. Gene transfer with retroviral vector did not exacerbate the local inflammatory response. Minimal or no beta-gal expression was observed in the contralateral uninjected paw or in the spleen, lung, liver, and kidneys. Frozen sections of retroviral vector injected joints were stained with X-gal and revealed transduced cells in the lining and superficial sublining layers. To determine the longevity of gene expression, ankle joints were injected with vector on Day 15 post-adjuvant, harvested, and assayed for beta-gal activity for up to 49 days after injection. Expression of the enzyme peaked from Day 3 to 7 and was still readily detected up to 49 days after retrovirus infection.

CONCLUSION

This is the first report of successful direct in vivo gene transfer in the rat adjuvant arthritis model using a retroviral vector. Appropriate timing of administration and very high titer retroviral vector preparations are key determinants of adequate gene transduction.

Elevated salivary EGF levels stimulated by periodontal surgery

Previous studies have shown epidermal growth factor (EGF) to be involved in oral wound healing as well as gastric cytoprotection. EGF functions with hormone-like properties to stimulate epithelial cells by binding to the EGF receptor which ultimately leads to proliferation via signal transduction mechanisms. Salivary glands are a major source of EGF The purpose of this study was to determine if intra-oral wounding by periodontal surgery stimulated increased salivary EGF levels. Salivary EGF levels were determined for 12 systemically healthy individuals (ages 27 to 70 years old) presurgically and postsurgically at 6, 12, 18, 24, 30, 36, and 42 hours and 2 and 6 weeks. Three ml of unstimulated whole saliva was obtained at each time point to allow immunoassay quantitation. Age and gender matched unoperated patients served as controls. Salivary samples were incubated with monoclonal and polyclonal EGF antibodies in these "sandwich" enzyme immunoassays. Quantitation was obtained by spectrometric analysis at OD 450 nm after addition of 200 microl of colorimetric substrate. Mean EGF levels ranged from 2441 pg/ml presurgically to 3349 pg/ml at 18 hours postsurgically and 1207 pg/ml at 6 weeks postsurgically. Repeated measures analysis of variance indicated statistically significant differences in 18 hours postsurgical salivary EGF levels when compared to controls and to postsurgical levels from 36 hours forward (P < 0.01). A second smaller rise in EGF was detected at 30 hours. These results suggest a transient increase in salivary EGF levels in response to intra-oral wounding.

Assessment of bromhexine as a treatment regimen in Sjögren's syndrome-like disease in the NOD (non-obese diabetic) mouse

OBJECTIVE

Bromhexine has been reported to alleviate the xerostomia and xerophthalmia associated with secondary Sjögren's syndrome. The aim of this study was to determine if it might prove useful in the treatment of Sjögren's syndrome-like disease of the NOD mouse model for autoimmune sialoadenitis.

METHODS

Groups of mice were divided into sets receiving 60 mg/kg bromhexine in drinking water and control pair-fed animals. The efficacy of drug treatment was assessed by weekly measurement of stimulated saliva volumes, protein concentration, and amylase activity. At termination (20 weeks) submandibular and lacrimal glands were removed to assess the levels of lymphocytic infiltration by histological evaluation under light microscopy.

RESULTS

Control and bromhexine-treated groups of mice showed no difference in the loss or rate of reduction in stimulated saliva flow over the 12 weeks of treatment. No differences were noted in the protein concentration and amylase loss with increasing age of the animals. Similar temporal changes in total protein profiles and aberrant expression of the 20 kDa parotid secretory protein isoform were observed by SDS-polyacrylamide gel profiles and Western bolt analysis. Histological evaluation of exocrine gland sections failed to detect any reduction in focal lymphocyte infiltration.

CONCLUSION

Bromhexine therapy did not alter the development or severity of Sjögren's syndrome-like disease in the NOD mouse model for autoimmune sialoadenitis.

Prospective study of the natural history of thoracic aortic aneurysms

BACKGROUND

The decision whether or not to recommend resection of moderately large descending thoracic and thoracoabdominal aneurysms requires weighing the relatively high mortality and significant risk of paraplegia associated with operation against the likelihood that the aneurysm will rupture spontaneously, with an almost invariably fatal outcome. To better define the risk of aneurysm rupture, we undertook a prospective study of patients who had not had operation on their moderately large descending thoracic and thoracoabdominal aneurysms.

METHODS

Patients were enrolled at the time of their second computed tomographic scans: three-dimensional computer-generated reconstructions allowed determination of several dimensional parameters for each study, including diameters and cross-sectional areas at the site of maximal dilatation in the descending aorta and in the abdomen as well as total thoracoabdominal surface area. Comparisons of serial studies permitted calculation of yearly rates of change in these dimensions.

RESULTS

Of 114 patients, 8 died of causes unrelated to the aneurysm, 26 died of rupture, 20 met previously determined criteria for operation, and 60 survived without operation or rupture. Multivariate regression analysis identified maximal diameter in the descending and in the abdominal aorta as independent risk factors for rupture, as well as older age, the presence of even uncharacteristic pain, and a history of chronic obstructive pulmonary disease. A piecewise exponential model enabled construction of an equation allowing calculation of rate of rupture in patients in whom the values of the risk factors are known, and also of the probability of rupture in a given individual over a specified time interval.

CONCLUSIONS

Because using this equation--based on easily determined risk factors (age, pain, chronic obstructive pulmonary disease, maximal thoracic and maximal abdominal aortic diameter)--allows the risk of aneurysm rupture within a given interval to be estimated fairly accurately for each individual patient, it is our current practice to recommend operation when the calculated risk of rupture within 1 year exceeds the anticipated mortality of elective operation, rather than relying on general operative guidelines based almost exclusively on aneurysm size.

PSP expression in murine lacrimal glands and function as a bacteria binding protein in exocrine secretions

Nonobese diabetic (NOD) mice, an animal model for type I autoimmune diabetes and autoimmune sialoadenitis, abnormally express parotid secretory protein (PSP) in the submandibular glands (Robinson, C. P., H. Yamamoto, A. B. Peck, and M. G. Humphreys-Beher. Clin. Immunol. Immunopathol. 79: 50-59, 1996). To evaluate possible PSP gene dysregulation in the NOD mouse, we have examined a number of organs and tissues for PSP mRNA transcripts and protein expression. Results indicate that PSP is produced in the lacrimal glands of NOD mice as well as most laboratory mouse strains. Although purified salivary PSP from C3H/HeJ or BALB/c mice fails to affect amylase enzyme activity in in vitro assays, PSP bound to whole bacteria in a Zn2+-dependent manner. Additionally, radiolabeled protein bound to specific bacterial membrane proteins using a ligand binding assay. PSP gene transcription, but not protein production, was observed in the heart and pancreas from NOD mice, indicating abnormal transcription of the PSP gene. Sequence analysis of PSP cDNA from NOD mice revealed numerous base differences (compared with the published PSP sequence) capable of leading to significant amino acid substitutions, suggestive of strain-specific differences for the protein in mice. Together these results suggest that there exists in the NOD mouse a dysregulation of PSP transcription in various tissues. However, except for C3H/HeJ mice, PSP appears as a normal product of the lacrimal glands where, as in saliva, it may function as a nonimmune antimicrobial agent in the protection of tissue surfaces exposed to the external environment.

The Bentall procedure in patients with Marfan's syndrome

From 1985 to 1996, 18 patients with Marfan's syndrome underwent the Bentall procedure at Mount Sinai Hospital. They are compared with 38 patients aged < 40 without Marfan's syndrome who also underwent composite valve-graft replacement of the ascending aorta. The mean age of the non-Marfan group was 33 while that of the Marfan group was 29. Nearly three-quarters of each group were male. Aortic dissection was present in 33% of the Marfan group but only in 18% of the other group. Seventy-eight percent of the Marfan patients and 89% of the non-Marfan patients had aortic regurgitation. Twenty-one percent of the patients in the control group nevertheless had gross aortic pathology suggestive of Marfan's syndrome and may have had variants of the syndrome; 26% of the non-Marfan group had a bicuspid aortic valve. A modification of the Bentall procedure with implantation of coronary artery buttons was performed in the majority of the patients in both groups. Three patients, all in the group with Marfan's syndrome, required a concomitant mitral valve procedure. There was one death in each group. Two non-Marfan patients required reoperation; neither had dissection. Four patients with Marfan's syndrome underwent reoperation for distal disease in the aorta; they comprised one third of the Marfan patients who had aortic dissection. Three late complications occurred in the group with Marfan's syndrome: progressive cardiomyopathy; myocardial infarction; and late tamponade. There were also two late sudden deaths in the group with Marfan's syndrome, which may have been the consequence of aortic rupture. No difference in immediate operative mortality following the Bentall procedure was noted between patients with and without Marfan's syndrome, but young patients without Marfan's syndrome seem to have better event-free and long-term survival. In patients with Marfan's syndrome, the presence of acute dissection makes reoperation more likely, and sudden death from rupture still occurs despite careful postoperative surveillance. A higher incidence of severe mitral valve disease was found among young patients with Marfan syndrome than in controls.

Use of hypothermic circulatory arrest for cerebral protection during aortic surgery

Optimal use of hypothermic circulatory arrest during aortic surgery requires understanding of its physiology. Research in laboratory animals and clinical observations have now documented that considerable residual cerebral metabolism remains with cooling to levels of 15-18 degrees C, especially if cooling intervals are short, reflected by persistent jugular venous desaturation. Cooling should be continued to below 15 degrees C if the duration of HCA is expected to exceed 20 minutes, and continued until jugular venous saturations exceed 95%. There is considerable laboratory evidence that even short durations of HCA are followed by a prolonged interval of increased cerebral vascular resistance during which cerebral metabolism is maintained at normal levels by markedly increased oxygen extraction. Clinical observations have now confirmed that considerable jugular venous desaturation is present in patients following HCA: it is more pronounced with prolonged HCA, and is still present as late as six hours after the start of rewarming. This reinforces the concept of a prolonged postoperative vulnerable interval following HCA, during which any compromise in oxygen delivery has the potential for producing cerebral injury. Several adjunctive measures have been shown to improve outcome following HCA. The simplest and most important is topical hypothermia: packing the head in ice during the interval of HCA. Retrograde cerebral perfusion (RCP) has also been shown to improve EEG recovery as well as histological and behavioral outcome in laboratory animals following prolonged HCA, but some of its effect may be secondary to its efficacy in keeping the brain cold, since RCP provides very low rates of flow and supports metabolism at a much lower level than antegrade perfusion at the same temperature. But despite the clear superiority of antegrade perfusion, and the documentation of some benefits of RCP in laboratory measures of cerebral protection, clinical results using RCP and ACP have not yet demonstrated the superiority of these methods over use of HCA alone, perhaps because these modalities are usually employed in patients with unusually high risk of neurological injury: those with dissection or with clot or atheroma in the aorta. Nevertheless, recent years have seen considerable reduction in mortality following aortic surgery, especially in older patients, and a trend toward a lower incidence of permanent neurologic dysfunction. The presence of preoperative rupture or hemodynamic compromise, and of clot or atheroma in the aorta, remain the most significant risk factors both for death and occurrence of stroke.

Severe sore throat as a presenting symptom of adult onset Still's disease: a case series and review of the literature

We describe our experience with 3 cases and a literature review examining whether sore throat is an early manifestation of adult onset Still's disease (AOSD). From our review of 341 cases in the English literature we noted that 69% of all reported patients displayed sore throat early in the disease course. We propose that sore throat be considered an important early diagnostic manifestation of AOSD because it appears useful in identifying patients in their first month of illness.

Identification of risk factors in patients undergoing thoracoabdominal aneurysm repair

Developments and advances in surgical and anesthetic techniques have lead to increased survival in patients undergoing complex thoracic aortic aneurysm repairs. The decision to operate, however, continues to be based in a large degree on the clinical impression of the patient's ability to withstand the rigors of the procedure. As part of the ongoing effort of our department to further elucidate those parameters that impart added risk to patients, the diameters and volumes of CT-imaged aortas were determined for 67 surgical and nonoperatively managed patients. Significant differences were found between those patients not requiring surgery, and both those undergoing operation and those that died of rupture. Similarly, the average yearly increase in volume in surgical and rupture patients was higher than that of nonoperatively managed patients. Those patients who smoked also were found to have a significant yearly increase in size of their aortas relative to those patents that did not. An algorithm for managing patients presenting with thoracoabdominal aneurysms based upon size at initial presentation, change in annual diameter and volume, and estimated risk for paraplegia is presented.

Cell cycle control in isoproterenol-induced murine salivary acinar cell proliferation

The eukaryotic cell cycle is a summary of a complex network of signal transduction pathways resulting in both DNA replication and cell division. Cyclin-dependent kinases (CDKs) control the cell cycle in all eukaryotes, whereas other proteins, known as cyclins, act as their regulatory subunits. Chronic injection with isoproterenol (ISO) can induce acinar cell proliferation in rodent salivary glands. Cyclins and CDK proteins from control and ISO-treated murine parotid acinar cells were detected by using Western blotting techniques. By comparing the expression of these cell cycle regulatory kinases in the parotid acinar cell transition from a quiescent state to a hypertrophic state, we found rapid increases in the protein levels of all CDKs, cyclin D and proliferating cell nuclear antigen (PCNA). The highest protein levels for CDKs and cyclins appeared at about 72 hr of ISO stimulation and were coincident with the highest rate of increase in gland wet weight. After 72 hr, the increase of both cell cycle protein and gland wet weight began to subside. By using a co-immunoprecipitation method, the following cell cycle regulators (CDK-cyclin complexes) were detected, CDK4-cyclin D, CDK2-cyclin E, CDK2-cyclin A, and cdc2-cyclin B, along with an increase in kinase activity over control untreated animals. Additionally, we detected significant decreases in the newly isolated CDK inhibitor (CKI) p27kip but not Wee 1 kinase. The increased levels of CKI correlated with a decrease in kinase activity of CDK/cyclin complexes by 144 hr of chronic isoproterenol treatment. Our data suggest that the holoenzymes for cell cycle control (cyclin-CDK complexes) function as a final regulatory mechanism leading to salivary gland acinar cell proliferation. The gradual decline in protein levels of the CDKs and cyclins after 3 days of chronic treatment further indicates that ISO-induced proliferation of parotid acinar cells is self-limiting and non-tumorigenic.

Is vitrification involved in depression of the phase transition temperature in dry phospholipids?

Recent literature has suggested that the depression of the phase transition temperature (Tm) in dry phospholipids by sugars may be ascribed to vitrification of the stabilizing solute, rather than by the direct interaction between sugar and phospholipid we have proposed. Koster et al. ((1994) Biochim. Biophys. Acta 1193, 143-150) claim that the only necessity is that the glass transition (Tg) for the sugar exceed Tm for the lipid. Evidence is presented in the present paper that this is not sufficient. Based on the vitrification hypothesis of Koster et al., the predicted order of effectiveness in depressing Tm in dry dipalmitoylphosphatidylcholine (DPPC) is dextran > or = hydroxyethyl starch > stachyose > raffinose > trehalose > sucrose > glucose. In fact, the opposite order was seen. The effect of raffinose, sucrose, or trehalose on Tm in dry DPPC depends on the thermal history of the sample, as we have reported previously. When DPPC dried with trehalose is heated for the first time, Tm is about 55 degrees C, but on the second and subsequent heating scans Tm falls to about 25 degrees C. Koster et al. suggest that this effect is due to heating the sample above Tg rather than to melting the hydrocarbon chains. We present evidence here that all that is required is for the chains to be melted. Further, we show that retention of residual water by DPPC dried with trehalose depends on the drying temperature, but is independent of drying temperature with glucose, a finding that is consistent with direct interaction. We conclude that vitrification is not in itself sufficient to depress Tm in dry phospholipids.

Alterations in the secretory response of non-obese diabetic (NOD) mice to muscarinic receptor stimulation

Salivary gland secretion in non-obese diabetic (NOD) and BALB/c mice was evaluated following stimulation with the muscarinic receptor agonist pilocarpine. Both saliva flow rates and total protein were similar in BALB/c and prediabetic NOD mice. With diabetes onset in NOD mice, the saliva flow rate and protein concentration were dramatically reduced. The level of cyclic AMP (cAMP) generated 10 min following agonist injection was similar for the parotid gland of BALB/c and prediabetic and diabetic NOD mice but was reduced in diabetic NOD mice. In the submandibular gland both prediabetic and diabetic NOD mice showed a reduced potential for the generation of cAMP compared with BALB/c mice. The parotid gland from NOD mice had elevated levels of basal and muscarinic receptor agonist (carbachol)-stimulated concentrations of inositol phosphate intermediates in in vitro assays compared with BALB/c animals, while in the submandibular gland of NOD mice, basal and agonist-stimulated concentrations of inositol phosphate intermediates were reduced relative to BALB/c. An evaluation of muscarinic receptor density showed a reduction with diabetes onset for the parotid gland, while a similar level was observed in prediabetic NOD and BALB/c mice. The receptor density was decreased for both the prediabetic and diabetic NOD submandibular glands compared with BALB/c animals. Sera from diabetic NOD but not BALB/c mice immunoprecipitated radiolabeled muscarinic receptor, indicating the presence of autoantibody to the receptor in diabetic mice. Thus, the reduction of muscarinic agonist response in NOD mice may be due, in part, to a generalized reduction in signal transduction components most evident in the prediabetic and diabetic submandibular gland and to a less certain degree in the parotid gland from diabetic NOD mice as a consequence of autoantibodies directed against cell surface antigens.

Absorption of insulin in the peritoneal cavity in a diabetic animal model

This study was conducted to determine if different anatomical sites within the peritoneal cavity have different capacities for portal insulin absorption. Diabetic male Sprague-Dawley rats were studied. They were anesthetized and injected with streptozotocin. Blood glucose was measured before and after insulin (1 U/kg) was applied directly to the omentum, serosal surface of cecum, or parietal peritoneum or injected subcutaneously. In a control group, blood glucose was measured at intervals without administering insulin. In addition, insulin labeled with radioactive iodine (125I) was applied to the same three locations in the peritoneal cavity or injected intravenously. Animals were sacrificed at 1, 5, 15, or 30 mins, and radioactivity was measured in excised livers and in blood samples. Blood glucose in the omental group responded to insulin with a greater hypoglycemic effect than in the peritoneal and control groups. The percentage of radioactivity recovered in liver was significantly higher in the omental than in the serosal and peritoneal groups at 1 and 5 mins. The ratio of liver-to-blood radioactivity was also significantly higher in omental than in serosal and peritoneal groups and higher in the serosal than in the peritoneal group at 5 mins. The data suggest that, in this model, the omentum is a better site for insulin absorption than serosa or parietal peritoneum and that significant portal venous absorption of insulin occurs.