Diabetic ketoacidosis diagnosis in a hospital setting

CONTEXT

Diabetic ketoacidosis (DKA) is an endocrine emergency that can occur in people with diabetes. Its incidence is estimated to be 220,340 hospital admissions each year. Treatment algorithms include fluid resuscitation, intravenous (IV) insulin infusion, and scheduled electrolyte and glucose monitoring. The misdiagnosis of DKA in the setting of hyperglycemic emergencies results in overtreatment and unnecessary increases in healthcare utilization and costs.

OBJECTIVES

The aims of this study were to determine how often DKA is overdiagnosed in the context of other acute hyperglycemic emergencies, to describe the baseline characteristics of patients, to determine the hospital treatments for DKA, and to identify the frequency of endocrinology or diabetology consultation in the hospital setting.

METHODS

A retrospective chart review was conducted utilizing charts from three different hospitals within a hospital system. Charts were identified utilizing ICD-10 codes for admissions to the hospital for DKA. If the patient was over 18 and had one of the diagnostic codes of interest, the chart was reviewed for further details regarding the criteria for DKA diagnosis as well as admission and treatment details.

RESULTS

A total of 520 hospital admissions were included for review. DKA was incorrectly diagnosed in 28.4 % of the hospital admissions reviewed, based on a review of the labs and DKA diagnostic criteria. Most patients were admitted to the intensive care unit (ICU) and treated with IV insulin infusion (n=288). Consultation of endocrinology or diabetology occurred in 40.2 % (n=209) of all hospital admissions, and 128 of those consults occurred in ICU admissions. The diagnosis of DKA was incorrect in 92 of the patients admitted to the medical surgical unit (MSU) and in 49 of patients admitted to the ICU.

CONCLUSIONS

Almost one third of hospital admissions for hyperglycemic emergencies were misdiagnosed and managed as DKA. DKA diagnostic criteria are specific; however, other diagnoses like hyperosmolar hyperglycemic syndrome (HHS), hyperglycemia, and euglycemic DKA can make an accurate diagnosis more complicated. Education directed at improving the diagnostic accuracy of DKA among healthcare providers is needed to improve diagnostic accuracy, ensure the appropriate use of hospital resources, and potentially reduce costs to the healthcare system.

Targeting lung macrophages for fungal and parasitic pulmonary infections with innovative amphotericin B dry powder inhalers

The incidence of fungal pulmonary infections is known to be on the increase, and yet there is an alarming gap in terms of marketed antifungal therapies that are available for pulmonary administration. Amphotericin B (AmB) is a highly efficient broad-spectrum antifungal only marketed as an intravenous formulation. Based on the lack of effective antifungal and antiparasitic pulmonary treatments, the aim of this study was to develop a carbohydrate-based AmB dry powder inhaler (DPI) formulation, prepared by spray drying. Amorphous AmB microparticles were developed by combining 39.7 % AmB with 39.7 % γ-cyclodextrin, 8.1 % mannose and 12.5 % leucine. An increase in the mannose concentration from 8.1 to 29.8 %, led to partial drug crystallisation. Both formulations showed good in vitro lung deposition characteristics (80 % FPF < 5 µm and MMAD < 3 µm) at different air flow rates (60 and 30 L/min) when used with a DPI, but also during nebulisation upon reconstitution in water.

Resident opinions of diabetes management in training: a survey

CONTEXT

Primary care physicians need a strong foundation in diabetes management, as they are the first line of care for patients with this complex disease, which is increasing in frequency in the United States. This foundational training begins in medical school, but its applications become more important during residency.

OBJECTIVES

To quantify osteopathic and allopathic family medicine residents' amount of exposure to diabetes in residency training, investigate referral patterns related to diabetes management, and assess comfort levels with various diabetes treatment modalities.

METHODS

An 18-item cross sectional survey was sent via email using Qualtrics to program directors and chief residents of 16 different training programs located in seven different health systems and four different states; the programs were focused on family medicine, internal medicine, pediatrics, and combined internal medicine/pediatrics programs. The link was also posted on Twitter using specific "handles" to "tag" professional associations and groups related to primary care. Emails and tweets were initiated on October 15, 2018 and responses were collected through April 15, 2019. Data collection was reinitiated via email only from May 1, 2020 through July 31, 2020 due to low initial response rate. The study, which included multiple choice and Likert scale questions with some skip logic, was designed by study investigators. Data was exported from Qualtrics to an Excel spreadsheet and analyzed using descriptive statistics, which are reported as percentages.

RESULTS

A total of 61 residents responded to the survey, with most (52; 85.2%) enrolled in family medicine or internal medicine programs. Residents were mostly located in rural (28; 45.9%) and suburban (25; 41.0%) areas. Respondents reported being extremely comfortable with metformin (45; 73.8%), basal insulin (24; 39.3%), and healthy lifestyle education (32; 52.5%) for the treatment of diabetes. They reported being least comfortable with diabetes technology, with 51 (83.6%) uncomfortable or extremely uncomfortable with insulin pumps and 43 (70.5%) uncomfortable with continuous glucose monitoring systems for diabetes treatment. Referral rates to endocrinologists were low, with 47 (77%) reporting referral of diabetes patients 10-15% of the time. Residents reported interest in workshops and online continuing medical education for further training opportunities, but interest in additional formal training was low (3; 4.9%).

CONCLUSIONS

Residents in this study reported confidence in diabetes management and referral rates among this group were low. However, reported comfort levels with treatment modalities beyond metformin and lifestyle changes were not strong. Referral rates may have been low due to the low number of endocrinologists in rural areas and therapeutic inertia. Diabetes fellowships could increase resource availability for patient referral. Utilization of diabetologists in primary care programs may also add benefit and improve skills among trainees including more familiarity with diabetes technology and use of newer medications used in diabetes management.

Development and characterization of ibuprofen co-crystals granules prepared via fluidized bed granulation in a one-step process - a design of experiment approach

OBJECTIVE

The focus of this study was to investigate the possibility of producing ibuprofen-nicotinamide (IBU-NIC) and ibuprofen-isonicotinamide (IBU-INA) cocrystal-containing granules, using a one-step fluidized bed dryer granulation manufacturing process, and evaluate their mechanical properties.

SIGNIFICANCE

Pharmaceutical cocrystals represent a suitable strategy to improve properties of active pharmaceutical ingredients (APIs), such as solubility and processability. Ibuprofen (IBU) is a small molecule API which can form cocrystals with different coformers, including NIC and INA. An improvement in mechanical properties for IBU-NIC cocrystals relative to IBU was previously reported but, to date, the formulation of IBU cocrystals in a solid dosage form has not been investigated.

METHODS

In situ cocrystallization and granulation were achieved concurrently by processing in a lab-scale fluidized bed granulator following a design of experiment (DoE) approach using a two-level factorial design with both process and formulation variables. Solid-state, micrometric, dissolution, and mechanical (tabletability) characteristics of granules were assessed post-processing.

RESULTS

Granules containing cocrystals were successfully prepared for 11 of 16 DoE runs. Parameters with a significant effect on granule drug loading, flow function, porosity, and size could be identified from the DoE model. Process yield was increased by using a high inlet temperature at high solution feed rate. To avoid the formation of sticky particles, caking and over-wetting of the powder during the process, the utilization of high inlet temperature, low API + coformer:filler ratio, low API concentration in solution and low solution feed rate were suggested by the model.

CONCLUSION

The multivariable model developed enables accurate optimization of the granulation process for IBU cocrystals.

Primary Care Diabetes Fellowship Programs: Developing National Standards

The rapid and constant increase in the number of people living with diabetes has outstripped the capacity of specialists to fully address this chronic disease alone. Furthermore, although most people with diabetes are treated in the primary care setting, most primary care providers feel under-prepared and under-resourced to fully address the needs of their patients with diabetes. Addressing this care gap will require a multifaceted approach centering on primary care training in diabetes and its complications. One-year diabetology fellowship programs are well situated to provide this training. Previous research has shown that the higher the diabetes-specific volume of patients seeing a primary care physician was, the better the quality outcomes were across six quality indicators (eye examinations, LDL cholesterol testing, A1C testing, prescriptions for ACE inhibitors or angiotensin receptor blockers, prescriptions for statins, and emergency department visits for hypoglycemia or hyperglycemia). Primary care diabetes fellowships have existed for many years, but the number of fellowships and fellowship positions has recently grown dramatically. This article proposes a standardized curriculum for such programs and makes the case for increasing their number in the United States.

High Prevalence of Diabetes Distress in a University Population

Context

Diabetes distress is an affective condition that addresses an individual's frustrations, worries, and concerns about living with diabetes. It is associated with fewer self-care behaviors, suboptimal glycemic control, and lower quality of life (QOL). For these reasons, diabetes care guidelines recommend routine assessment of diabetes distress.

Objective

To assess diabetes distress in a university population.

Methods

This study was conducted using a descriptive, cross-sectional design. Researchers assessed diabetes distress and other psychosocial factors via an electronic anonymous survey among students, faculty, and staff at a large university in the Midwest.

Results

A total of 173 participants completed the survey (mean [SD] age, 35.1 [16.7] years), with 108 [62.4%] female and 142 [82.1%] white participants). Eighty-five participants had type 1 diabetes mellitus (T1DM), and 88 had type 2 diabetes mellitus (T2DM). Of the 85 T1DM participants, 23 (27.4%) reported high diabetes distress, and 27 (30.7%) T2DM participants reported high diabetes distress. Sixteen T1DM (18.8%) and 15 T2DM (17.0%) participants screened positive for severe depression. Severe depression was associated with high distress for both T1DM and T2DM participants (T1DM: χ2=28.845, P<.001; T2DM: χ2=20.679, P<.001). Participants with T1DM reported more frequent self-care behaviors (mean [SD], 62.3 [17.1] vs 52.2 [19.2]; P<.001), but lower diabetes QOL (63.3 [14.1] vs 68.5 [15.5]; P=.021) compared with T2DM participants. No differences were observed in depressive symptoms, diabetes self-efficacy, and coping styles. Linear regression models showed that high diabetes distress scores (standardized β=.323, P=.025; standardized β=.604, P<.001) were independently associated with higher hemoglobin A1C levels and lower diabetes QOL after controlling for depressive symptoms, age, and gender in T1DM participants. Similarly, high diabetes distress scores (standardized β=.434, P<.001) were associated with lower diabetes QOL in T2DM participants after controlling for the same variables.

Conclusion

High diabetes distress levels were associated with lower diabetes QOL for both T1DM and T2DM participants. These findings suggest that attending or working at a university may be associated with high diabetes distress scores and lower diabetes QOL. Additional research with a larger, more diverse sample from multiple universities is needed to confirm these findings.

A Design of Experiment (DoE) approach to optimise spray drying process conditions for the production of trehalose/leucine formulations with application in pulmonary delivery

The present study evaluates the effect of L-leucine concentration and operating parameters of a laboratory spray dryer on characteristics of trehalose dry powders, with the goal of optimizing production of these powders for inhaled drug delivery. Trehalose/L-leucine mixtures were spray dried from aqueous solution using a laboratory spray dryer. A factorial design of experiment (DoE) was undertaken and process parameters adjusted were: inlet temperature, gas flow rate, feed solution flow rate (pump setting), aspiration setting and L-leucine concentration. Resulting powders were characterised in terms of particle size, yield, residual moisture content, and glass transition temperature. Particle size was mainly influenced by gas flow rate, whereas product yield and residual moisture content were found to be primarily affected by inlet temperature and spray solution feed rate respectively. Interactions between a number of different process parameters were elucidated, as were relationships between different responses. The leucine mass ratio influenced the physical stability of powders against environmental humidity, and a high leucine concentration (30% w/w) protected amorphous trehalose from moisture induced crystallization. High weight ratio of leucine in the formulation, however, negatively impacted the aerosol performance. Thus, in terms of L-leucine inclusion in a formulation designed for pulmonary delivery, a balance needs to be found between physical stability and deposition characteristics.

Diabetes Fellowship in Primary Care: A Survey of Graduates

Context

The diabetes pandemic has outpaced the US supply of diabetes specialists and has overwhelmed primary care providers (physicians, physician assistants, and nurse practitioners). Primary care diabetes fellowships can be used to address this workforce shortage.

Objectives

To determine the skills obtained during 2 diabetes fellowship programs, the barriers encountered in practice, the impact of the programs on career paths, and perceived acceptance by patients and colleagues.

Methods

A Qualtrics link to a 26-item survey was sent via email to all graduates of the Ohio University Heritage College of Osteopathic Medicine and East Carolina University Brody School of Medicine diabetes fellowship programs. Items included demographic information, comfort level with different clinical diabetes skills, and current system barriers encountered in their practices.

Results

Of 39 graduates, 36 completed the survey. The most beneficial skills acquired during the fellowship were insulin pump management (13 [36%]), insulin management (10 [29%]), and diabetes pharmacology (6 [17%]). The most common barrier was the lack of board certification as a diabetologist, which affected time with patients and insurance reimbursement. The perceived acceptance by patients was high (25 [69%]), and the perceived receptiveness by colleagues was mostly neutral (7 [19%]) or positive (10 [29%]). The most common postfellowship career path was primary care medicine (15) followed by hospitalist (7) and diabetologist (5).

Conclusion

Physicians who completed the diabetes fellowship training reported high comfort levels with treating patients with diabetes, but they also reported the barriers faced in an unrecognized specialty.

A comparative study between hot-melt extrusion and spray-drying for the manufacture of anti-hypertension compatible monolithic fixed-dose combination products

The purpose of this work was to investigate the application of different advanced continuous processing techniques (hot melt extrusion and spray drying) to the production of fixed-dose combination (FDC) monolithic systems comprising of hydrochlorothiazide and ramipril for the treatment of hypertension. Identical FDC formulations were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD) and modulated differential scanning calorimetry (mDSC). Drug dissolution rates were investigated using a Wood's apparatus, while physical stability was assessed on storage under controlled temperature and humidity conditions. Interestingly both drugs were transformed into their amorphous forms when spray dried, however, hydrochlorothiazide was determined, by PXRD, to be partially crystalline when hot melt extruded with either polymer carrier (Kollidon® VA 64 or Soluplus®). Hot melt extrusion was found to result in significant degradation of ramipril, however, this could be mitigated by the inclusion of the plasticizer, polyethylene glycol 3350, in the formulation and appropriate adjustment of processing temperature. The results of intrinsic dissolution rate studies showed that hot-melt extruded samples were found to release both drugs faster than identical formulations produced via spray drying. However, the differences were attributable to the surface roughness of the compressed discs in the Wood's apparatus, rather than solid state differences between samples. After a 60-day stability study spray dried samples exhibited a greater physical stability than the equivalent hot melt extruded samples.

Endocrinologists' Opinions of Diabetology as a Primary Care Subspecialty

IN BRIEF This study was conducted to ascertain the opinions of endocrinologists about diabetes care as it relates to the health care provider workforce. A survey was administered to endocrinologists in the Planning Research in Inpatient Diabetes and Planning Research in Outpatient Diabetes (PRIDE/PROUD) group and given to attendees of the American Diabetes Association (ADA) Scientific Sessions special interest group whose focus was primary care. The majority of respondents agreed that there is a need for more providers to be trained to take care of patients with diabetes and that more trained providers are needed, and almost half agreed that primary care providers (PCPs) with advanced training in diabetes should be part of the workforce for managing the diabetes pandemic. Expanding diabetes fellowship programs for PCPs remains an important potential solution for addressing workforce development needs in diabetes care.

The Time Is Now: Diabetes Fellowships in the United States

PURPOSE OF REVIEW

Diabetes is a complex and costly chronic disease that is growing at an alarming rate. In the USA, we have a shortage of physicians who are experts in the care of patients with diabetes, traditionally endocrinologists. Therefore, the majority of patients with diabetes are managed by primary care physicians. With the rapid evolution in new diabetes medications and technologies, primary care physicians would benefit from additional focused and intensive training to manage the many aspects of this disease. Diabetes fellowships designed specifically for primary care physicians is one solution to rapidly expand a well-trained workforce in the management of patients with diabetes.

RECENT FINDINGS

There are currently two successful diabetes fellowship programs that meet this need for creating more expert diabetes clinicians and researchers outside of traditional endocrinology fellowships. We review the structure of these programs including funding and curriculum as well as the outcomes of the graduates. The growth of the diabetes epidemic has outpaced current resources for readily accessible expert diabetes clinical care. Diabetes fellowships aimed for primary care physicians are a successful strategy to train diabetes-focused physicians. Expansion of these programs should be encouraged and support to grow the cadre of clinicians with expertise in diabetes care and improve patient access and outcomes.

On the Autistic Spectrum Disorder concordance rates of twins and non-twin siblings

Using the Interactive Autism Network Research Database, the Autistic Spectrum Disorder concordance rates for twins and non-twin siblings were calculated. For males, females and both genders together, the concordance rate for dizygotic twins is approximately twice that of non-twin siblings. We also determined that the concordance rate for non-twin siblings decreases as the interval between pregnancies increases. Our results appear to indicate that the uterine environment may contribute to autism concordance rates.

Hydrodynamic simulation (computational fluid dynamics) of asymmetrically positioned tablets in the paddle dissolution apparatus: impact on dissolution rate and variability

The aim of this work was to investigate the dissolution rate from both the curved and planar surfaces of cylindrical compacts of benzoic acid, which were placed centrally and non-centrally at the base of the vessel of the paddle dissolution apparatus. The effect of fixing the compacts to a particular position on the variability of dissolution results was also examined. In addition, computational fluid dynamics (CFD) was used to simulate fluid flow around compacts in the different positions in the vessel, and the relationship between the local hydrodynamics in the region of the compacts and the dissolution rate determined. The dissolution rate was found to increase from the centre position to the off-centre positions for each surface examined. There was a corresponding increase in maximum fluid velocities calculated from the CFD fluid flow simulations at a fixed distance from the compact. There was less variability in dissolution from compacts fixed to any of the positions compared with those that were not fixed. Fluid flow around compacts in different positions could be successfully modelled, and hydrodynamic variability examined, using CFD. The effect of asymmetric fluid flow was evident visually from the change in shape of the eroded compacts.

Milk amyloid A: Correlation with cellular indices of mammary inflammation in cows with normal and raised serum amyloid A

This study compared concentrations of amyloid A in bovine milk with the cell-based indicators of intramammary inflammation, somatic cell count and California Mastitis Test. Mammary quarter data pertaining to 180 cows were categorised according to concentrations of serum amyloid A in the cow of origin. Ranked correlation, ranked regression and receiver operator characteristics all demonstrated acceptable agreement between milk amyloid A concentrations and cell-based indices. There were some indications of reduction in this agreement, in cows with raised concentrations of serum amyloid A. However, there were also indications that serum amyloid A did not significantly influence milk amyloid A. The results of the current study indicate that milk amyloid A exhibits good correlation with established cell-based indicators of intramammary inflammation.

A Study of Dry Cow Therapy and Effects on SCC in 10 Irish Dairy Herds

Somatic cell count (SCC) data for 480 cows in 10 Irish dairy herds from January 2001 until June 2002 were analysed. Herds were selected on the basis of a recent or ongoing history of clinical or subclinical mastitis. An individual cow SCC of 200 000 cells per ml was used as the threshold for elevation of SCC. The duration of elevated SCC prior to drying-off and the magnitude of the elevation in SCC were found to have an impact on the response to dry cow therapy (DCT). A trend also emerged indicating that increasing parity had a negative influence on the response to DCT.

Sensitivity of dissolution rate to location in the paddle dissolution apparatus

The aim of the present study was to determine the apparent diffusion boundary layer and dissolution rate constant for various surfaces of compacts and at various locations in the USP paddle dissolution apparatus. Benzoic acid compacts were coated with paraffin wax leaving only the surface under investigation free for dissolution. The dissolution rates for various surfaces at varying locations in the paddle dissolution vessel were determined from the slope of the dissolution profile (amount dissolved (mg) versus time (min)). The apparent diffusion boundary layer and dissolution rate constant were calculated and were found to vary depending on the surface of the compact from which dissolution took place and also on the location and size of the compact. It may be concluded that, in developing models to describe the dissolution from solid dosage forms, it is not accurate to assume constant hydrodynamics and mass transfer rates at all surfaces of the system, or in different locations within the test device. A more exact description of the hydrodynamics would be necessary in order to precisely model drug dissolution in the paddle dissolution apparatus.

Gas 6 promotes Axl-mediated survival in pulmonary endothelial cells

We examined Gas 6-Axl interactions in human pulmonary artery endothelial cells (HPAEC) and in Axl-transduced HPAEC to test Gas 6 function during endothelial cell survival. We identified the 5.0-kb Axl, 4.2-kb Rse, and 2.6-kb Gas 6 mRNAs in HPAEC. Immunoprecipitation and Western blotting confirmed the presence of these proteins. Gas 6 is present in cell-associated and secreted fractions of growth-arrested HPAEC, independent of cell density. In addition, the Axl receptor is constitutively phosphorylated in growth-arrested cultures, and exogenous Gas 6 enhanced Axl phosphorylation threefold. Gas 6 added to growth-arrested HPAEC resulted in a significant increase in cell number (1.5 nM Gas 6 increased cell number 35%). Flow cytometry revealed that Gas 6 treatment resulted in 28% fewer apoptosing cells. Transduction of a full-length Axl cDNA into HPAEC resulted in 54% fewer apoptosing cells after Gas 6 treatment. Collectively, the data demonstrate antiapoptotic activities for Gas 6 in HPAEC and suggest that Gas 6 signaling may be relevant to endothelial cell survival in the quiescent environment of the vessel wall.

Nuclear import of arachidonate 5-lipoxygenase

Leukotrienes are lipid messenger molecules that are secreted by leukocytes to orchestrate a rapid and prolonged immune response. The enzyme 5-lipoxygenase catalyzes the rate-limiting first two steps in the synthesis of leukotrienes from arachidonic acid. Although it has long been known that 5-lipoxygenase moves from the cytoplasm to a membrane following activation, it has only recently been recognized that the enzyme may shuttle into and out of the nucleus before activation. The regulation of this movement of soluble 5-lipoxygenase between the cytoplasm and the nucleoplasm, as well as its impact on 5-lipoxygenase action, leukotriene synthesis and cell function, is only now being elucidated. This review details the state of our understanding of the nuclear import of 5-lipoxygenase and its potential importance in immunity.

VEGF is deposited in the subepithelial matrix at the leading edge of branching airways and stimulates neovascularization in the murine embryonic lung

We used whole lung cultures as a model to study blood vessel formation in vitro and to examine the role that epithelial-mesenchymal interactions play during embryonic pulmonary vascular development. Mouse lungs were isolated at embryonic day 11.5 (E11.5) and cultured for up to 4 days prior to blood vessel analysis. Platelet endothelial cell adhesion molecule-1 (PECAM/CD31) and thrombomodulin (TM/CD141) immunolocalization demonstrate that vascular development occurs in lung cultures. The vascular structures identified in lung cultures first appear as a loosely associated plexus of capillary-like structures that with time surround the airways. To investigate the potential role of vascular endothelial cell growth factor (VEGF) during pulmonary neovascularization, we immunolocalized VEGF in embryonic lungs. Our data demonstrate that VEGF is uniformly present in the airway epithelium and the subepithelial matrix of E11.5 lungs. At later time points, E13.5 and E15.5, VEGF is no longer detected in the proximal airways, but is restricted to the branching tips of airways in the distal lung. RT-PCR analysis reveals that VEGF(164) is the predominant isoform expressed in lung cultures. Grafting heparin-bound VEGF(164) beads onto lung explants locally stimulates a marked neovascular response within 48 hr in culture. Semi-quantitative RT-PCR reveals an 18% increase in PECAM mRNA in VEGF(164)-treated whole lung cultures as compared with untreated cultures. The restricted temporal and spatial expression of VEGF suggests that matrix-associated VEGF links airway branching with blood vessel formation by stimulating neovascularization at the leading edge of branching airways.

Congenital arthrogryposis: an inherited limb deformity in pedigree Suffolk lambs

Thirty of 52 pedigree Suffolk lambs (58 per cent) were born with arthrogryposis characterised by bilateral flexion rigidity of the metacarpophalangeal and carpal joints. The recent introduction of a breeding ram was identified as the only significant risk factor in the flock, and embryo transfer was used to test the hypothesis that the arthrogryposis was an inherited disorder associated with the introduction of this ram. Two adult ewes that had previously produced lambs with arthrogryposis by the ram and four of its affected daughters were available as donors, and 20 crossbred ewes were used as recipients. Ten Suffolk-crossed ewes that had no known familial relationship with the ram were also mated by the ram as controls and they produced 10 normal lambs. Following embryo transfer, 19 lambs were born, of which seven were stillborn; arthrogryposis was evident in 10 of the 12 live lambs. Analysis of the data suggested that in the population under study, arthrogryposis was inherited as an autosomal recessive condition.

Identification of a bipartite nuclear localization sequence necessary for nuclear import of 5-lipoxygenase

5-Lipoxygenase catalyzes the synthesis of leukotrienes from arachidonic acid. This enzyme can reside either in the cytoplasm or the nucleus; its subcellular distribution is influenced by extracellular factors, and its nuclear import correlates with changes in leukotriene synthetic capacity. To identify sequences responsible for the nuclear import of 5-lipoxygenase, we transfected NIH 3T3 cells and RAW 264.7 macrophages with expression vectors encoding various 5-lipoxygenase constructs fused to green fluorescent protein. Overexpression of wild type 5-lipoxygenase with or without fusion to green fluorescent protein resulted in a predominantly intranuclear pattern of fluorescence, similar to the distribution of native 5-lipoxygenase in primary alveolar macrophages. Within the 5-lipoxygenase protein is a sequence (Arg(638)-Lys(655)) that closely resembles a bipartite nuclear localization signal. Studies using deletion mutants indicated that this region was necessary for nuclear import of 5-lipoxygenase. Analysis of mutants containing specific amino acid substitutions within this sequence confirmed that it was this sequence that was necessary for nuclear import of 5-lipoxygenase and that a specific arginine residue was critical for this function. As nuclear import of 5-lipoxygenase may regulate leukotriene production, natural or induced mutations in this bipartite nuclear localization sequence may also be important in affecting leukotriene synthesis.

IL-1beta mediates induction of hepatic type 1 plasminogen activator inhibitor in response to local tissue injury

Type 1 plasminogen activator inhibitor (PAI-1), a major physiological inhibitor of plasminogen activation, is an important component of the hepatic acute phase response. We studied the acute phase regulation of murine hepatic PAI-1 in response to systemic toxicity and local tissue injury in both wild-type mice and in mice in which the interleukin (IL)-1beta gene had been inactivated by gene targeting. Endotoxin induced plasma PAI-1 antigen levels and PAI-1 mRNA accumulation in liver to the same extent in both wild-type and IL-1beta-deficient mice. In contrast, turpentine increased plasma PAI-1 and hepatic PAI-1 mRNA accumulation in wild-type mice but not in IL-1beta-deficient mice. Intraperitoneal injection of murine IL-1beta rapidly increased plasma PAI-1 and hepatic PAI-1 mRNA in both wild-type and IL-1beta-deficient mice. These results suggest that IL-1beta is a critical inducer of hepatic PAI-1 gene expression during the acute phase response to local tissue injury. In situ hybridization studies revealed that hepatocytes are the cells primarily responsible for the hepatic expression of the PAI-1 gene induced by lipopolysaccharide and turpentine.

Intravascular coagulation activation in a murine model of thrombomodulin deficiency: effects of lesion size, age, and hypoxia on fibrin deposition

We consecutively inactivated both alleles of the thrombomodulin (TM) gene in murine embryonic stem (ES) cells and generated TM-deficient (TM-/-) chimeric mice. Quantitation of an ES-cell marker and protein C cofactor activity indicates that up to 50% of pulmonary endothelial cells are ES-cell derived and therefore TM deficient. Infusions of 125I-fibrinogen into mice show a significant increase (fourfold, P <.005) in radiolabeled cross-linked fibrin in TM-/- chimeric mouse lung as compared with wild-type mice. However, only chimeric mice that exhibit at least a 30% reduction in protein C cofactor activity and are at least 15 months old display this phenotype. Immunocytochemical localization of TM in chimeras shows a mosaic pattern of expression in both large and small blood vessels. Colocalization of cross-linked fibrin and neo (used to replace TM) reveals that fibrin is deposited in TM-/- regions. However, the fibrin deposits were largely restricted to pulmonary vessels with a lumenal area greater than 100 micrometer2. The hypercoagulable phenotype can be induced in younger chimeric mice by exposure to hypoxia, which causes a fivefold increase in beta-fibrin levels in lung. Our findings show that TM chimerism results in spontaneous, intravascular fibrin deposition that is dependent on age and the magnitude of the TM deficiency.

A targeted point mutation in thrombomodulin generates viable mice with a prethrombotic state

The activity of the coagulation system is regulated, in part, by the interaction of thrombin with the endothelial cell receptor thrombomodulin with subsequent generation of activated protein C and suppression of thrombin production. Our previous investigation demonstrated that ablation of the thrombomodulin gene in mice causes embryonic lethality before the assembly of a functional cardiovascular system, indicating a critical role for the receptor in early development. In the current study, we show that a single amino acid substitution in thrombomodulin dissociates the developmental function of the receptor from its role as a regulator of blood coagulation. Homozygous mutant mice with severely reduced capacity to generate activated protein C or inhibit thrombin develop to term, and possess normal reproductive performance. The above animals exhibit increased fibrin deposition in selected organs, which implies tissue specific regulation of the coagulation system that is supported by further evidence from the examination of mice with defects in fibrinolysis. The thrombomodulin-deficient animals provide a murine model to examine known or identify unknown genetic and environmental factors that lead to the development of thrombosis.

Heat shock and proinflammatory stressors induce differential localization of heat shock proteins in human monocytes

Heat shock (HS) proteins (HSP) are a family of molecular chaperones induced by environmental stresses such as oxidative injury, and contribute to protection from and adaptation to cellular stress. We investigated in human monocytes the expression and subcellular distribution of hsp70 and hsc70 after HS and inflammation-related stresses leading to generation of reactive oxygen species by these cells, such as the phorbol ester PMA and erythrophagocytosis (E phi). By combining immunofluorescent staining and Western blot on subcellular fractions, we found that all three stress factors resulted in an increased hsp70 expression, however the subcellular distribution pattern was different depending on the type of stress. While HS induced a rapid translocation of hsp70 into the nucleus, no nuclear translocation of hsp70 was observed after PMA or E phi. Neither of the examined stresses induced membrane expression of hsp70. The observed differences in subcellular distribution pattern might relate to distinct regulation and specific functions of hsp70 in inflammation.

Cervico-thoracic vertebral osteomyelitis in 14 calves

Fourteen cases of cervico-thoracic (C-T) vertebral osteomyelitis in calves were investigated over a 6 year period. The onset of clinical signs was between 2 and 9 weeks of age. There was no breed or sex predisposition. The clinical history prior to referral extended from 5 days to 8 weeks (mean 20 days). The most common clinical presentation was difficulty in rising with a tendency to knuckle or kneel on the forelimbs which displayed hypotonia and hyporeflexia. In over half the cases pain could be elicited on manipulation of the neck. The lesion in all cases involved one or more of the vertebrae from C6 to T1. The diagnosis was confirmed by radiology and/or at post mortem. Four animals were discharged after treatment, 10 animals were humanely destroyed. Salmonella dublin was isolated from the vertebral lesion in eight of the 10 calves at post mortem.

Absence of the blood-clotting regulator thrombomodulin causes embryonic lethality in mice before development of a functional cardiovascular system

We have targeted the murine thrombomodulin (TM) gene in embryonic stem cells and generated embryos as well as mice with TM deficiency. The heterozygous TM-deficient (TM+/-) mice as compared to wild-type (TM+/+) littermates exhibit 50% reductions in the levels of TM mRNA and TM protein. However, TM+/- mice appear normal and are free of thrombotic complications. The homozygous TM-deficient (TM-/-) embryos die before embryonic day 9.5. An overall retardation in growth and development of TM-/- embryos is first evident on embryonic day 8.5 (8-12 somite pairs). However, no specific pathologic abnormalities are observed. These initial changes take place at a time when TM is normally expressed in the parietal yolk sac. The removal of embryonic day 7.5 TM-/- embryos from maternal decidua and their subsequent culture in vitro allow development to proceed to stages not observed in vivo (13-20 somite pairs) with the appearance of normal blood vessels in the visceral yolk sac and embryo. The results of our studies suggest that the failure of TM-/- embryos to survive at mid-gestation is a consequence of dysfunctional maternal-embryonic interactions caused by the absence of TM in the parietal yolk sac and demonstrate that the receptor is necessary for normal embryonic development in utero.

Induction of plasminogen activator inhibitor-1 in HepG2 human hepatoma cells by mediators of the acute phase response

The liver plays a central role in the systemic acute phase response of an organism to injury. Plasminogen activator inhibitor-1 (PAI-1), a major regulator of fibrinolysis, is an important component of the acute phase response in humans. The source of plasma PAI-1 has been a matter of controversy, but recent in situ hybridization experiments have demonstrated that human hepatocytes express the PAI-1 gene in vivo. However, little is known about regulation of human hepatic PAI-1 gene expression by mediators of the acute phase response. We have analyzed the regulation of PAI-1 mRNA accumulation by interleukin (IL)-1, IL-6, and dexamethasone, known mediators of the acute phase response, in HepG2 cells, a highly differentiated human hepatoma cell line that produces a broad spectrum of acute phase proteins including PAI-1. Incubation of HepG2 cells with IL-1 resulted in a rapid and transient 40-fold induction of the 3.2-kilobase PAI-1 mRNA and a 30-fold induction of the 2.2-kilobase PAI-1 mRNA. Although IL-6 alone had only a modest effect on PAI-1 expression, in combination with IL-1, it caused a synergistic induction of PAI-1 mRNA accumulation. Dexamethasone alone did not increase PAI-1 mRNA accumulation but enhanced it in combination with IL-1. Using nuclear run-on experiments, we determined that the mechanism by which IL-1 alone, or in combination with IL-6, induced PAI-1 mRNA accumulation was to cause a 10-15-fold, transient stimulation of PAI-1 gene transcription. We found no evidence of an effect of these cytokines on PAI-1 mRNA stability. These data demonstrate that mediators of the acute phase response induce the accumulation of PAI-1 mRNA in human hepatoma cells by rapidly and transiently increasing the transcription of the PAI-1 gene.

Morbidity and mortality in a large Irish feedlot; microbiological and serological findings in cattle with acute respiratory disease

A survey of morbidity and mortality was undertaken in a slatted unit containing 6399 beef cattle over a 6 month period. The mortality rate was 0.78% and the morbidity rate was 12.7%. The interval from arrival to morbidity was 25.5 days +/- 0.9. Significantly more sick cattle were identified on either Mondays or Tuesdays than were seen on Saturdays or Sundays (P < 0.005). The mean interval to mortality (all diseases) was 48.5 days +/- 7.4. Respiratory disease was the most frequently recorded disease and was responsible for 62% of morbidity and 58% of mortality. Samples from 133 cattle, taken as they presented with acute onset respiratory disease, contained antibodies to Bovine Herpes Virus -1(BHV-1) (14.3%), Bovine Viral Diarrhoea Virus (BVDV) (78%), Bovine Respiratory Syncytial Virus (BRSV) (94%) and Parainfluenza type 1 Virus (P13V) (99%). When the same cattle were resampled 4 to 6 weeks later antibodies were found for BHV-1 (93.2%), BVDV (99.2%), BRSV (100%) and P13V (100%). Eleven of 27 bronchoalveolar lavage samples taken from the above group of cattle exhibited positive fluorescence for BHV-1 but all 27 samples were negative for BVDV, BRSV and P13V. Pasteurella multocida was isolated from eight of the 27 lavage samples and Pasteurella haemolytica from one sample.

Preparation of fluorescent basic fibroblast growth factor: localization in living retinal microvascular endothelial cells

A biologically active fluorescent derivative of recombinant human basic fibroblast growth factor (bFGF) was prepared by immobilization on heparin-Sepharose 4B (HS) and derivatization with the fluorophore, Texas Red (TR). TR-bFGF was separated from free dye and carrier protein by elution from HS using 1.5 M NaCl. TR-bFGF contained an average of two dye molecules bound per bFGF, retained its mitogenic activity and was visible using a fluorescence microscope equipped with silicon intensified target camera (SIT). TR-bFGF stimulated the growth of bovine aortic endothelial cells (BAEC), microvessel endothelial cells (MVEC) and BHK-21 cells grown in culture. BAEC, MVEC and BHK-21 cells treated with 20 ng ml-1 (1 nM) TR-bFGF for 72 hr were stimulated over serum controls by 87, 26 and 6%, respectively. TR-bFGF stimulated EC growth was inhibited in a dose-dependent fashion when cells were coincubated with microM chloroquine. When EC were treated with TR-bFGF at 4 degrees C and then monitored at 37 degrees C, bright, focal, cytoplasmic spots were observed, which accumulated as punctate, perinuclear fluorescence. EC internalization of TR-bFGF was inhibited 80% by the addition of 100-fold molar excess unlabeled bFGF or by maintaining cultures at 4 degrees C. TR-bFGF colocalized with an EC lysosomal marker, but TR-bFGF was not detected in the nucleus. Results of these localization studies suggest that TR-bFGF stimulates EC proliferation without entering the nucleus.

Density-dependent accumulation of basic fibroblast growth factor in the subendothelial matrix

Recent evidence indicates that basic fibroblast growth factor (bFGF), which lacks a conventional signal recognition sequence, is a component of the subendothelial matrix. However, the molecular mechanisms regulating its cellular release and subsequent matrix deposition remain equivocal. To examine the cellular and subcellular mechanisms regulating bFGF release and subendothelial sequestration, we generated polyclonal antibodies against a chemically cross-linked bFGF. We then used anti-bFGF IgG in conjunction with 3T3 cell [3H]thymidine incorporation assays, enzyme immunoassays and immunofluorescence to learn whether bFGF accumulation in the subendothelial matrix is dependent upon endothelial cell (EC)-cell contact, which coincides with growth arrest. In contrast to subconfluent cultures, which lacked any detectable extracellular matrix bFGF localization, bovine aortic and microvascular EC plated at confluent densities displayed a punctate extracellular staining pattern that was abolished when EC were pretreated with 10 micrograms/ml cycloheximide. Additionally, when EC were treated with either 1 mM beta-D xyloside, an inhibitor of proteoglycan assembly, or 100 micrograms/ml heparin, there was a 40% reduction in matrix-associated bFGF (quantified by image analysis of antibody stained cultures). 3T3 [3H]thymidine incorporation assays indicated that the beta-D xyloside-induced reduction of matrix-associated bFGF coincided with a significant increase in bFGF activity in the conditioned media. Neither sparsely-plated nor confluent EC cultures possessed specific bFGF localization of the nuclear compartment when cells were fixed using cold methanol; however, when EC were fixed in formaldehyde and lysed in isotonic buffers containing 0.1% Triton X-100 or absolute acetone, there was a marked decrease in anti-bFGF staining of the postconfluent extracellular matrix and a concomitant increase in nuclear fluorescence. Because bFGF-stimulated vascular cell growth has been implicated in controlling neointimal cell proliferation, we screened normal and atherosclerotic coronary blood vessels for bFGF, but we were unable to detect it either in lesioned or normal intima. In contrast, significant bFGF levels were observed in association with the EC and mesangial cells of the renal corpuscle, where heparan sulfate accumulates within the glomerular basement membrane. Our in vitro results suggest that bFGF accumulates within the proteoglycan-containing subendothelial matrix concomitant with the formation of cell-cell contacts. In situ, the composition of the microvascular matrix and the cellular phenotype may facilitate the selective accumulation of bFGF that we observed. This, in turn, may influence vascular morphogenesis and remodeling during angiogenesis.

CDC55, a Saccharomyces cerevisiae gene involved in cellular morphogenesis: identification, characterization, and homology to the B subunit of mammalian type 2A protein phosphatase

Microscopic screening of a collection of cold-sensitive mutants of Saccharomyces cerevisiae led to the identification of a new gene, CDC55, which appears to be involved in the morphogenetic events of the cell cycle. CDC55 maps between CDC43 and CHC1 on the left arm of chromosome VII. At restrictive temperature, the original cdc55 mutant produces abnormally elongated buds and displays a delay or partial block of septation and/or cell separation. A cdc55 deletion mutant displays a cold-sensitive phenotype like that of the original isolate. Sequencing of CDC55 revealed that it encodes a protein of about 60 kDa, as confirmed by Western immunoblots using Cdc55p-specific antibodies. This protein has greater than 50% sequence identity to the B subunits of rabbit skeletal muscle type 2A protein phosphatase; the latter sequences were obtained by analysis of peptides derived from the purified protein, a polymerase chain reaction product, and cDNA clones. An extragenic suppressor of the cdc55 mutation lies in BEM2, a gene previously identified on the basis of an apparent role in bud emergence.

A sequence that directs transcriptional initiation in yeast

While RNA polymerase II of the yeast Saccharomyces cerevisiae initiates transcription at discrete sites, these sites are located over a wide range of distances from the TATA box for different genes. This variability has led to a number of proposals for consensus sequences located at the initiation site which, in conjunction with the TATA box, would direct initiation. We tested this hypothesis via oligonucleotide-directed mutagenesis, by placing the sequence CAAG, a member of one of these consensus sequences, upstream of the coding sequence of the CYC7 gene at a site at which initiation does not occur. The distance between the TATA sequence and this putative initiation site was varied by inserting it into the wild-type gene and three deletion mutants. The results demonstrated that this sequence can serve as an initiation site when located 49, 77, or 106 bp from the TATA sequence, but not when located 30 bp away.

1,25-Dihydroxyvitamin D3 induces collagen binding to the human monocyte line U937

Interactions of cells with components of the extracellular matrix can modulate cellular functions. We measured binding of a major matrix protein to U937 cells, a human promonocytic line. Radioiodinated type I or type III human collagen was bound only to U937 cells differentiated to a more mature phenotype with 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). Binding was observed at 4 degrees C and was saturable; Scatchard analysis of the binding to 1,25-(OH)2D3-pretreated U937 cells indicated a single class of high-affinity binding sites. Preincubation of U937 cells with interferon gamma did not induce collagen binding. Collagen binding did not appear to be dependent on fibronectin binding. Surface proteins of U937 cells were 125I labeled and cell membrane proteins resolved by affinity chromatography on collagen-Sepharose. Major specifically labeled bands of 180, 155, and 125 kD were identified in membrane fractions from 1,25-(OH)2D3-pretreated U937 cells only. 1,25-(OH)2D3 appears to specifically regulate collagen binding to monocyte precursors.

Sequences required for transcriptional initiation of the Saccharomyces cerevisiae CYC7 genes

A series of BAL 31 deletions were constructed in the upstream region of the Saccharomyces cerevisiae CYC7 gene to determine sequences required for transcriptional initiation. These deletions identified the TATA box as an alternating A-T sequence at -160 and the initiation sequences as well as the spatial relationship between them. The TATA box was necessary for wild-type levels of expression of the CYC7 gene. Decreasing the distance between the TATA sequence and the initiation site did not alter gene expression, but the site of transcription was shifted 3'-ward. In most cases, transcription initiated at a number of sites, the 5'-most of which was the first suitable site greater than 45 base pairs 3' of the TATA sequence, suggesting a spatial relationship between these sequences. Consensus sequences previously proposed for initiation sites were evaluated with respect to the start sites identified in this study as well as the start sites of other yeast genes.

Hormone 1 alpha,25-dihydroxyvitamin D3 modulates heat shock response in monocytes

Monocytes, which play a central role in inflammatory reactions, are exposed to elevated temperatures in febrile states or to potential cellular toxins (e.g., reactive oxygen species, immune mediators). We analyzed the heat shock (HS) response in human peripheral blood monocytes and the monocytic line U937 compared with that in dermal fibroblasts. After HS, U937 cells and fibroblasts synthesized mainly the 70- and 83-kDa HS proteins (HSPs), whereas the spectrum of HSPs synthesized by monocytes varied over the range 41-45 degrees C. Incubation with hydrogen peroxide induced synthesis of the 70-kDa HSP in monocytes only. The hormone 1 alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] that protects monocytes from thermal injury had similar effects on the HS response in U937 cells, increasing synthesis of HSPs and levels of HSP 70 mRNA and partially preventing the decrease in normal protein synthesis, whereas interferon-gamma had no effect. 1,25-(OH)2D3 did not modify the HS response in fibroblasts, although these cells contained cellular receptors for 1,25-(OH)2D3. 1,25-(OH)2D3 could play a specific role in modulating the HS response in monocytes and related cells.

1,25-Dihydroxyvitamin D3 maintains adherence of human monocytes and protects them from thermal injury

Adherence to a substratum is a characteristic feature of monocyte-macrophages which may be required for several effector functions. Human peripheral blood monocytes selected by adherence were found to readhere preferentially at 1 h to fibronectin or to a biological matrix. There was then a progressive decrease in the number of adherent cells, and by 48 h only 8-20% of monocytes remained adherent. This loss of adherence occurred while monocytes remained viable by criteria such as exclusion of trypan blue or release of lactate dehydrogenase. 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) maintained the adherence of cultured monocytes to tissue culture plastic as well as to the biological matrix. This effect was concentration- and time-dependent, and suppressed by inhibitors of protein synthesis. Cellular proteins were labeled after incubation with [35S]methionine. Analysis by two-dimensional gel electrophoresis revealed increased labeling of several distinct proteins in 1,25-(OH)2D3-treated monocytes compared with control monocytes. The increased loss of adherence and decreased overall protein synthesis observed in monocytes incubated at 45 degrees C was partially prevented by preincubation of the cells with 1,25-(OH)2D3. We further evaluated the effects of thermal stress and 1,25-(OH)2D3 on protein synthesis by monocytes, and found that 1,25-(OH)2D3 increased the synthesis of heat shock proteins, protected normal protein synthesis, and increased the rate of recovery of normal protein synthesis after the thermal stress. These observations suggest that 1,25-(OH)2D3 influences monocytes by preserving the synthesis of proteins, including those critical for the maintenance of cell adherence.