Acute phase reaction to lipopolysaccharide-induced mastitis in early lactation dairy cows fed nitrogenic, glucogenic, or lipogenic diets

The availability of certain macronutrients is likely to influence the capacity of the immune system. Therefore, we investigated the acute phase response to intramammary (i.mam.) lipopolysaccharide (LPS) in dairy cows fed a nitrogenic diet (n = 10) high in crude protein, a glucogenic diet (n = 11) high in carbohydrates and glucogenic precursors, or a lipogenic diet (n = 11) high in lipids. Thirty-two dairy cows were fed one of the dietary concentrates directly after calving until the end of trial at 27 ± 3 days in milk (mean ± standard deviation). In wk 3 of lactation, 20 µg of LPS was i.mam. injected in one quarter, and sterile NaCl (0.9%) in the contralateral quarter. Milk samples of the LPS-challenged and control quarter were taken hourly from before (0 h) until 9 h after LPS challenge and analyzed for milk amyloid A (MAA), haptoglobin (HP), and IL-8. In addition, blood samples were taken in the morning, and composite milk samples at morning and evening milkings, from 1 d before until 3 d after LPS challenge, and again on d 9, to determine serum amyloid A (SAA) and HP in blood, and MAA and HP in milk. The mRNA abundance of various immunological and metabolic factors in blood leukocytes was quantified by quantitative reverse-transcription PCR from samples taken at -18, -1, 6, 9, and 23 h relative to LPS application. The dietary concentrates did not affect any of the parameters in blood, milk, and leukocytes. The IL-8 was increased from 2 h, HP from 2 to 3 h, and MAA from 6 h relative to the LPS administration in the milk of the challenged quarter and remained elevated until 9 h. The MAA and HP were also increased at 9 h after LPS challenge in whole-udder composite milk, whereas HP and SAA in blood were increased only after 23 h. All 4 parameters were decreased again on d 9. Similar for all groups, the mRNA abundance of HP and the heat shock protein family A increased after the LPS challenge, whereas the mRNA expression of the tumor necrosis factor α and the leukocyte integrin β 2 subunit (CD18) were decreased at 6 h after LPS challenge. The glucose transporter (GLUT)1 mRNA abundance decreased after LPS, whereas that of the GLUT3 increased, and that of the GLUT4 was not detectable. The mRNA abundance of GAPDH was increased at 9 h after LPS and remained elevated. The acute phase protein response was detected earlier in milk compared with blood indicating mammary production. However, immunological responses to LPS were not affected by the availability of specific macronutrients provided by the different diets.

Medication Holds in CKD During Acute Volume-Depleting Illnesses: A Randomized Controlled Trial of a "Sick-Day" Protocol

Rationale & Objective

Some drugs prescribed for chronic kidney disease (CKD) may become hazardous on sick days with volume depletion by increasing the risk of acute kidney injury (AKI) and kidney function loss; however, the risks and benefits of their use during intercurrent illness is unknown.

Study Design

6-month pragmatic trial examining a sick-day protocol to determine if withholding prespecified drugs during a volume-depleting illness reduces the incidence AKI or kidney function loss in CKD.

Setting & Participants

315 veterans with stage 3-5 CKD, treated with a renin-angiotensin-aldosterone inhibitor blocker, diuretic, nonsteroidal anti-inflammatory drug, or metformin were randomized into the study with n = 159 and n = 156 in sick-day protocol and usual care groups, respectively.

Intervention

Sick-day protocol administered via interactive voice response system (IVRS) or usual care with 6-month follow-up.

Outcomes

The outcomes of the study are as follows: (1) Change in kidney function, (2) incidence of AKI based on International Classification of Diseases, Tenth Revision codes and ambulatory laboratory testing, (3) urgent service utilizations, and (4) sick days.

Results

The mean age was 70.1 ± 7.4 and 69.2 ± 8.1 years, with a mean baseline glomerular filtration rate (GFR) of 43.1 ± 13.1 and 43.8 ± 13.0 mL/min/1.73 m2, and 112 (70%) and 100 (64%) of participants with diabetes in the sick-day protocol and usual care groups, respectively. The mean change in GFR in the sick-day protocol and usual care groups from baseline to 6-month follow-up, adjusting for baseline GFR, was -0.71 (95% CI, -2.11 to 0.69) and -0.72 (95% CI, -2.12 to 0.68), respectively, with no significant difference, P = 0.99. Hospitalizations in the sick-day protocol and usual care groups were 11.5/100 and 8.4/100 events per person-months, respectively, with the adjusted rate ratio not significantly increased (prevalence ratio, 1.30; 95% CI, 0.96-1.76). Participants interacted with the IVRS in 81% of expected weeks and 19 had one or more qualifying events. In 33 true sick days, participants correctly followed the protocol in only 14.

Limitations

Low incidence of sick days over the 6-month period of the study.

Conclusions

The sick-day protocol was not associated with a significant reduction in AKI episodes or kidney function loss in a high-risk CKD population. Engagement with the IVRS was high, but successful implementation of the sick-day protocol was not optimal.

Trial Registration

ClinicalTrials.gov; NCT03141905.

Effect of different dietary regimens at dry-off on performance, metabolism, and immune system in dairy cows

Concentrate withdrawal and feed restriction are commonly used to reduce milk production and to facilitate dry-off, but may impair immune function in dairy cows. We investigated the effect of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses, as well as on leukocyte function before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in crude protein (nitrogenic, n = 14), glucogenic precursors (glucogenic, n = 14), or lipids (lipogenic, n = 15). On d 3 before dry-off, total feed allowance was restricted to 50% in half of the animals of each dietary group, whereas feed allowance remained unchanged in the other animals. Performance parameters (milk yield, milk composition, and dry matter intake) were recorded, and daily blood and milk samples were taken and analyzed for various metabolic and endocrine parameters. Additionally, activity and mRNA abundance of several genes in leukocytes were measured at selected time points before and after feed restriction and dry-off, respectively. Feed restriction immediately resulted in a negative energy balance and decreased milk production. Concomitantly, concentrations of nonesterified fatty acids increased, whereas insulin, insulin-like growth factor-1, and glucagon decreased. After dry-off, energy balance turned positive and plasma nonesterified fatty acids decreased. Plasma glucose, insulin, and insulin-like growth factor-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were higher in nonrestricted compared with restricted animals after dry-off. The experimental concentrate types marginally affected the investigated metabolic and endocrine factors, with the exception of elevated milk and plasma urea concentrations in cows fed the nitrogenic concentrate. Chemotactic and phagocytic activity of leukocytes were not affected by diets, feed restriction, or dry-off. Likewise, blood leukocyte mRNA abundance encoding for tumor necrosis factor α (TNF), heat shock protein family A (HSP70), and the glucose transporters (GLUT) 1 and 3 remained unchanged throughout the study period. Overall, the short-term negative energy balance induced by feed restriction was temporarily accompanied by metabolic adaptations, but did not alter the studied factors related to the immune system. Metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood.

Risk of Potentially Inappropriate Medications in Adults With CKD: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study

RATIONALE & OBJECTIVE

Adults with chronic kidney disease (CKD) may be at increased risk of adverse effects from use of potentially inappropriate medications (PIMs). Our objective was to assess whether PIM exposure has an independent association with CKD progression, hospitalizations, mortality, or falls.

STUDY DESIGN

Retrospective observational study.

SETTING & PARTICIPANTS

Chronic Renal Insufficiency Cohort (CRIC) study; 3,929 adults with CKD enrolled 2003-2008 and followed prospectively until December 2011.

EXPOSURE

PIM exposure was defined as prescriptions for any medications to be avoided in older adults as defined by the 2015 American Geriatrics Society Beers Criteria.

OUTCOME

Hospitalization count, death, a composite kidney disease end point of CKD progression or initiation of kidney replacement therapy (KRT), KRT, and fall events assessed 1 year after PIM exposure.

ANALYTICAL APPROACH

Logistic regression and Poisson regression to estimate the associations of PIM exposure with each outcome.

RESULTS

The most commonly prescribed PIMs were proton pump inhibitors and α-blockers. In unadjusted models, any PIM exposure (compared to none) was associated with hospitalizations, death, and fall events. After adjustment, exposure to 1, 2, or≥3 PIMs had a graded association with a higher hospitalization rate (rate ratios of 1.09 [95% CI, 1.01-1.17], 1.18 [95% CI, 1.07-1.30], and 1.35 [95% CI, 1.19-1.53], respectively) and higher odds of mortality (odds ratios of 1.19 [95% CI, 0.91-1.54], 1.62 [95% CI, 1.21-2.17], and 1.65 [95% CI, 1.14-2.41], respectively). In a cohort subset reporting falls (n=1,109), prescriptions for≥3 PIMs were associated with an increased risk of falls (adjusted OR, 2.85 [95% CI, 1.54-5.26]). PIMs were not associated with CKD progression or KRT. Age did not modify the association between PIM count and outcomes.

LIMITATIONS

Measurement bias; confounding by indication.

CONCLUSIONS

Adults of any age with CKD who are prescribed PIMs have an increased risk of hospitalization, mortality, and falls with the greatest risk occurring after more than 1 PIM prescription.

Electric cigarette-related lung injury and cardiovascular insult

The cardiovascular effects of electronic cigarette use are unknown. Here we present a case describing a young, previously healthy patient without prior cardiopulmonary comorbidities who developed severe, acute cardiac dysfunction in the setting of e-cigarette use, in addition to the more commonly encountered respiratory symptoms. While pulmonary manifestations are characteristic of e-cigarette or vaping product use-associated lung injury (EVALI), the acute and reversible cardiomyopathy seen here has not been previously described in association with either EVALI or e-cigarette use.

Associations of Performance-Based Functional Assessments and Adverse Outcomes in CKD

Background

The comparative utility of performance-based functional assessments in predicting adverse outcomes in CKD is unknown. To examine their relative utility, we examined three performance-based functional assessments in an observational cohort of patients with CKD.

Methods

We recruited 350 participants with stage II-V, predialysis CKD. Participants were administered three performance-based functional assessments: Short Physical Performance Battery (SPPB), Modified Mini-Mental Status Exam (M3SE), and Lawton Instrumental Activities of Daily Living (IADL). Scores were dichotomized on the basis of the median and combined into a summary score. Outcomes included 50% GFR reduction, ESKD, and death. We used Cox proportional hazards to assess the association of performance-based functional assessments with outcomes.

Results

Compared with high performers, low SPPB performers had the highest adjusted rate of death, ESKD, or 50% reduction in GFR (HR, 1.96; 95% CI, 1.28 to 2.99). Low SPPB had the strongest association with death when adjusted for multiple covariates (HR, 2.43; 95% CI, 1.36 to 4.34). M3SE performance was not associated with any adverse outcome. None of the performance-based functional assessments were associated with ESKD, but a low IADL score was associated with a lower hazard ratio for ESKD or 50% decline GFR (HR, 0.49; 95% CI, 0.24 to 1.00).

Conclusions

Low SPPB score was the strongest predictor of death and all adverse outcomes as a composite. Future trials should determine if outcomes for patients with CKD who have poor physical performance and low SPPB scores are improved by targeted interventions.

Clinical Trial registry name and registration number

Safe Kidney Care Cohort Study, NCT01407367.

Association of Opioids and Nonsteroidal Anti-inflammatory Drugs With Outcomes in CKD: Findings From the CRIC (Chronic Renal Insufficiency Cohort) Study

RATIONALE & OBJECTIVE

Safe analgesic choices are limited in chronic kidney disease (CKD). We conducted a comparative analysis of harm from opioids versus nonsteroidal anti-inflammatory drugs (NSAIDs) in CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

3,939 patients with CKD in the Chronic Renal Insufficiency Cohort (CRIC) Study.

EXPOSURES

30-day analgesic use reported at annual visits.

OUTCOMES

A composite outcome of 50% glomerular filtration rate reduction and kidney failure requiring kidney replacement therapy (KRT), as well as the outcomes of kidney failure requiring KRT, hospitalization, and pre-kidney failure death.

ANALYTICAL APPROACH

Marginal structural models with time-updated exposures.

RESULTS

Participants were followed up for a median of 6.84 years, with 391 (9.9%) and 612 (15.5%) reporting baseline opioid and NSAID use, respectively. Time-updated opioid use was associated with the kidney disease composite outcome, kidney failure with KRT, death (HRs of 1.4 [95% CI, 1.2-1.7], 1.4 [95% CI, 1.1-1.7], and 1.5 [95% CI, 1.2-2.0], respectively), and hospitalization (rate ratio [RR], 1.7; 95% CI, 1.6-1.9) versus opioid nonusers. Similar results were found in an analysis restricted to a subcohort of participants reporting ever using other (nonopioid and non-NSAID) analgesics or tramadol. Time-updated NSAID use was associated with increased risk for the kidney disease composite (HR, 1.2; 95% CI, 1.0-1.5) and hospitalization (RR, 1.1; 95% CI, 1.0-1.3); however, these associations were not significant in the subcohort. The association of NSAID use with the kidney disease composite outcome varied by race, with a significant risk in blacks (HR, 1.3; 95% CI, 1.0-1.7). NSAID use was associated with lower risk for kidney failure with KRT in women and individuals with glomerular filtration rate<45mL/min/1.73m² (HRs of 0.63 [95% CI, 0.45-0.88] and 0.77 [95% CI, 0.59-0.99], respectively).

LIMITATIONS

Limited periods of recall of analgesic use and potential confounding by indication.

CONCLUSIONS

Opioid use had a stronger association with adverse events than NSAIDs, with the latter's association with kidney disease outcomes limited to specific subgroups, notably those of black race.

Ensuring Patient Safety During the Transition to ESRD

Patients with chronic kidney disease (CKD) are at risk for complications both inherent to the disease and as a consequence of its treatment. The dangers that CKD patients face change across the spectrum of the disease. Providers who are well-versed in these safety threats are best poised to safeguard patients as their CKD progresses.

Adverse safety events in patients with Chronic Kidney Disease (CKD)

INTRODUCTION

Chronic kidney disease (CKD) confers a higher risk of adverse safety events as a result of many factors including medication dosing errors and use of nephrotoxic drugs, which can cause kidney injury and renal function decline. CKD patients may also have comorbidities such as hypertension and diabetes for which they require more frequent care from different providers, and for which standard, but countervailing treatments, may put them at risk for adverse safety events. Areas covered: In addition to the well-known agents such as iodinated radiocontrast, antimicrobials, diuretics and angiotensin converting enzyme (ACE) inhibitors which can directly affect renal function, safety considerations in the treatment of common CKD complications such as anemia, diabetes, analgesia and thrombosis will also be discussed. Expert opinion: Better outcomes in CKD may be achieved by alerting care providers to the special care needs of kidney patients and encouraging patients to self-manage their disease with the decision support of multidisciplinary patient care teams.

Chiropractic care and ochronotic arthropathy

OBJECTIVE

To discuss the case of a patient with ochronotic arthropathy whose symptoms were treated with chiropractic care. An emphasis is placed on this condition's radiographic features.

CLINICAL FEATURES

A 59-year-old woman with pain in her low back, right knee, and left ankle sought chiropractic evaluation. Black pigmentation was found in the sclera of both eyes, and homogentisic acid was present in the urine. Orthopedic evaluation revealed uncomplicated, nonspecific joint pain, and radiographs demonstrated characteristic spinal changes.

INTERVENTION AND OUTCOME

The patient was treated with chiropractic manipulation, physiotherapy modalities, bracing, and exercises. This type of therapy was successful in reducing the symptoms and helped decrease the severity and frequency of acute exacerbations.

CONCLUSION

Ochronotic arthropathY is a rare metabolic disorder that can be diagnosed from spinal radiographs. Chiropractic care is an appropriate tool for reducing its symptomatology.

The keratinocyte-derived cytokine IL-7 increases adhesion of the epidermal T cell subset to the skin basement membrane protein laminin-5

Human epidermis contains a subset of epidermal T cells that can mount an immune response by migrating through the skin and into the peripheral lymphnodes to proliferate before re-entering the epidermis. The cytokine IL-7 is shown to be localized to the basement membrane of normal human skin. Furthermore, culturing in the presence of IL-7 causes increased adhesion of epidermal T cells but not peripheral blood T cells to the major epidermal basement membrane protein, laminin-5. The mechanism for increased T cell adhesion to laminin-5 is due, at least in part, to an increase in the cell surface expression of the integrin alpha3beta1. Epidermal T cells cultured in IL-7 that are strongly adherent to laminin-5 are shown by flow cytometry to consist of a variety of subsets; therefore, the increase in cell adhesion is not due to an outgrowth of one T cell subset during culturing. We hypothesize that in vivo, exposure to IL-7 is required for epidermal T cell adhesion to laminin-5.

Intraocular pressure measurement in the conscious rat

PURPOSE

To develop a method for measurement of intraocular pressure in conscious, unsedated rats. METHODS. The animal was gently held with a thick fabric mitten, topical anesthetic drops were instilled and the Tono-Pen was applied to the cornea.

RESULT

Measurements in a total of 51 animals did not differ significantly among four strains studied: the overall mean intraocular pressure+/-standard deviation was 13.0+/-1.2 mm Hg. Several intraocular pressure tolerance limits were calculated from this conscious rat data to provide a baseline estimate for future studies.

CONCLUSIONS

This measurement method in conscious rats may contribute to making this widely used laboratory animal available for intraocular pressure research.

Preoperative predictors of cost in Medicare-age patients undergoing coronary artery bypass grafting

BACKGROUND

Identification of preoperative factors that contribute to the cost of coronary artery bypass grafting could aid in predicting the procedure's expense. In this study, 30 sociodemographic and clinical preoperative factors were examined with "survival analysis" techniques to determine characteristics related to total hospital cost.

METHODS

Characteristics of all patients age 65 or older undergoing isolated coronary artery bypass grafting from July 1993 to April 1995 (n = 757) were recorded. Software was developed within the hospital's Transitions Systems, Inc, database to calculate the outcome variable of total cost. Nonparametric methods were used for the univariate analysis of the data, and the Cox proportional hazards model was used for the multivariable analysis, censoring 25 patients who died in the hospital.

RESULTS

Median hospital cost from the day of the operation until discharge was $15,198. Median length of stay after the operation was 6 days. Multivariable analysis revealed that age, preoperative renal failure, history of cerebrovascular accident, low ejection fraction, and surgical urgency were independent predictors of total cost.

CONCLUSIONS

This study, using an accurate representation of true hospital cost and a modeling technique that accounts for the confounding effect of in-hospital death on cost, provides a template for analysis of cost in other patient groups.

The relation of pneumothorax and other air leaks to mortality in the acute respiratory distress syndrome

BACKGROUND

In patients with the acute respiratory distress syndrome, pneumothorax and other air leaks - any extrusion of air outside the tracheobronchial tree - have been attributed to high ventilatory pressures or volumes and linked to increased mortality.

METHODS

We analyzed data from a prospective trial of aerosolized synthetic surfactant in 725 patients with the acute respiratory distress syndrome induced by sepsis. We compared the ventilatory pressures and volumes in the patients without any air leaks (the highest values during the five-day study) with the pressures and volumes in those with pneumothorax or with any air leaks (the highest values during the 16- and 24-hour periods before the complication developed).

RESULTS

Fifty patients (6.9 percent) had pneumothorax and 77 (10.6 percent) had pneumothorax or other air leaks. There were no significant differences between patients with air leaks and those without air leaks in any pressure or volume examined. Overall mortality at 30 days was 40.0 percent (95 percent confidence interval, 36.4 to 43.6); among the patients with pneumothorax, it was 46.0 percent (95 percent confidence interval, 32.2 to 59.8), and among those without pneumothorax, it was 39.3 percent (95 percent confidence interval, 35.6 to 43.0; P=0.35). The mortality rate was 45.5 percent (95 percent confidence interval, 34.4 to 56.6) in the group with any air leaks and 39.0 percent (95 percent confidence interval, 35.3 to 42.8) in the group without air leaks (P=0.28).

CONCLUSIONS

In patients with sepsis-induced acute respiratory distress syndrome who were receiving mechanical ventilation with conventional pressures and volumes, there were no significant correlations between high ventilatory pressures or volumes and the development of pneumothorax or other air leaks. Pneumothorax or other air leaks were not associated with a significantly increased mortality rate.

During development, 17alpha-estradiol is a potent estrogen and carcinogen

Neonatal administration of estradiol-17beta (E2-17beta) increases the nuclear DNA content in the mouse reproductive tract. Similar responses have been demonstrated for synthetic estrogens such as diethylstilbestrol. One of the questions raised regarding environmental estrogens such as organochlorines is whether they are potent enough to result in abnormal changes such as those demonstrated by both natural and synthetic estrogens. To test this hypothesis, female BALB/c mice were treated neonatally (days 1-5) with either E2-17beta or estradiol-17alpha (E2-17alpha), an inactive stereoisomer in adult reproductive tissues. We also proposed whether neonatal administration of (E2-17alpha) was tumorigenic and whether the effects were age dependent. To answer these questions, one set each of 10 day-old treated and control mice received short-term secondary administration of E2-17beta, E2-17alpha, or cholesterol. Cervicovaginal tracts from intact BALB/c mice were examined histologically and by flow cytometry at 70 days of age and by histology alone at 18 to 22 months of age. The results include several important findings: a) like E2-17beta, neonatal E2-17alpha treatment induced persistent vaginal cornification, hypospadias, vaginal concretions, and hyperproliferation in nearly 100% of the animals regardless of the secondary treatment for most groups; b) neonatal E2-17alpha treatment increased the nuclear DNA content of cervicovaginal epithelium at one-half both the level (mean DNA index of 1.02 vs 1.04) and incidence (22 vs 46% of the animals) of E2-17beta; c) short-term secondary treatment with E2-17alpha, unlike E2-17beta, did not significantly augment the increase in DNA content (13% for E2-17alpha vs 37 and 56% for control and E2-17beta, respectively); and d) neonatal administration with E2-17alpha induced adenosquamous tumors in the reproductive tract in 25% of the animals. Therefore, the biological effects (estrogenic potency) of E2-17alpha may be age dependent.

Human, canine and murine BRCA1 genes: sequence comparison among species

Five to ten percent of breast cancer in the western world may be attributed to the inheritance of highly penetrant mutations in the breast and ovarian cancer susceptibility gene, BRCA1. The biological function of BRCA1 and factors affecting expressivity, such as gene-environment and gene-gene interactions, may be more effectively studied in appropriate animal models. We report the cloning and sequencing of the canine and murine BRCA1 genes and contrast the sequences with human BRCA1. The amino terminal 120 residues of the gene are > 80% identical among the three species. The C-terminus is also highly conserved, containing an 80 amino acid stretch that is over 80% identical. Motifs of likely functional significance are maintained, including the amino terminal RING finger motif (amino acids 24-64) and the granin consensus sequence (1214-1223). The distribution of missense mutations and neutral polymorphisms identified in BRCA1-linked breast cancer suggests that disease associated missense mutations occur at highly conserved residues whereas polymorphisms are in regions of lower conservation. Among eighteen missense mutations with unknown consequences, seven occur in amino acids that are identical across species. Four of these seven (E1219D, A1708E, P1749R and M1775R) are also within conserved domains. Taken together, these data predict regions of the gene which may be critical for normal function.

An efficient Shine-Dalgarno sequence but not translation is necessary for lacZ mRNA stability in Escherichia coli

The 5' ends of many bacterial transcripts are important in determining mRNA stability. A series of Shine-Dalgarno (SD) sequence changes showed that the complementarity of the SD sequence to the anti-SD sequence of 16S rRNA correlates with lacZ mRNA stability in Escherichia coli. Several initiation codon changes showed that an efficient initiation codon is not necessary to maintain lacZ mRNA stability. A stop codon in the 10th codon of lacZ increased mRNA stability. Therefore, ribosomal binding via the SD sequence but not translation of the coding region is necessary to maintain lacZ mRNA stability.

Transcriptional slippage occurs during elongation at runs of adenine or thymine in Escherichia coli

A run of 11 adenine or thymine residues at the 5' end of an out-of-frame lacZ gene causes a high level of beta-galactosidase expression in E. coli. This effect was not observed for a run of guanine residues. Reverse transcription of mRNA isolated from E. coli containing the run of 11 A's reveals heterogeneity of transcript length while reverse transcription of mRNA isolated from S. cerevisiae containing the same gene shows no heterogeneity. Protein sequencing of the beta-galactosidase molecules derived from the out-of-frame construct containing a run of adenines reveals the addition of a lysine at the run. A new method was developed where messages small enough to allow resolution of single nucleotide differences on an acrylamide gel are electrophoresed, electroblotted onto nylon and probed. This confirmed the reverse transcription results and showed that additional residues can be added to transcripts derived from DNA containing 10 or 11 thymine residues. A mechanism for slippage is discussed where the A-U rich RNA-DNA hybrid can denature during elongation and rehybridize in an offset position, causing the addition of extra residues to the transcript.

Demonstration of IL-1 alpha, and IL-1 beta secretion by the monocytic leukemia cell line, THP-1

This study examined the secretion of IL-1 alpha and IL-1 beta by THP-1 leukemia cells following activation with mezerein and promotion of synthesis by interferon (IFN-gamma). Interleukin-1 (IL-1) was not detected by co-mitogenic thymocyte assays of crude supernates. Isoelectrofocusing of concentrated medium showed that all biologically active IL-1 migrated at a pH of 6.8-7.2, indicating that the major secreted form was IL-1 beta. Double antibody ELISA confirmed the presence of IL-1 beta, but failed to detect IL-1 alpha in isofocused fractions. Although it appeared that THP-1 cells do not secrete IL-1 alpha; an inhibitor of thymocyte response to IL-1 was present in conditioned medium, migrated in an acidic pH range and masked the expression of biologically active rIL-1 alpha and rIL-1 beta. In contrast, IL-1 alpha was detected using a cell blotting assay. This technique permitted visualization of subpicogram levels of IL-1 when secreted by cells attached to an immunoblotting paper. Cell blotting showed that a greater proportion of attached cells incubated for 24 h in medium containing mezerein and IFN-gamma secreted IL-1 than cells in control medium. In conclusion, the amount of immunoreactive or biologically active IL-1 alpha secreted by stimulated THP-1 cells appeared to be much lower than that reported for human peripheral blood monocytes.

Studies on the mechanism of captopril induced hypotension in rats

The mechanism of the hypotensive response to captopril was investigated in pithed and urethane anesthetized rats. Cumulative intravenous doses of captopril produced dose-dependent hypotensive responses which were correlated with blockade of the pressor response to angiotensin I. Angiotensin II responses were unaffected. Infusions of saralasin, an angiotensin receptor antagonist, inhibited the hypotensive action of captopril, the degree of antagonism being correlated with inhibition of angiotensin II pressor responses. Bilateral nephrectomy lowered blood pressure to approximately the same level as captopril and completely abolished the hypotensive effect of captopril. No evidence was obtained for the involvement of endogenous bradykinin or prostaglandins in the hypotensive action of captopril. It is concluded that in pithed and urethane anesthetized rats, captopril mediates its hypotensive response by removing the renal renin-angiotensin system, most probably via inhibition of angiotensin I - converting enzyme. The results contrast with similar studies conducted in anesthetized dogs. In this species, the mechanism of action of captopril remains for further resolution.

Rapid paper chromatographic separation of [14C] angiotensen II from some metabolites: application to organ distribution

A rapid, inexpensive method for the separation of 5-1-isoleucyl[14C] angiotensin II (A-II) from its various metabolites has been devised. A-II was extracted from tissues with absolute methanol (recovery 96%) and paper chromatographed in a butanol-acetic acid-water (18:2:5) medium for two ascents at 60 degrees C. The resulting RF for A-II of 0.45 was then compared with the RF values of three A-II metabolites produced by enzymatic degradation of the 14C-A-II and [14C]isoleucine. Trypsin degradation produced the [14C]hexapeptide metabolite, chymotryptic degradation produced the [14C]tetrapeptide metabolite and carboxypeptidase A degradation produced the [14C]heptapeptide. Increases in temperature produced a continuous increase in RF values for all the substances examined but the resolution decreased above 60 degrees C. Similarly, increases in the temperature caused the appearance of secondary peaks with some but not all peptides. The tryptic digest (hexapeptide) and the chymotryptic digest (tetrapeptide) are apparently acid- and heat-stable under the experimental conditions. All of the peptides examined failed to produce secondary peaks when heated at neutral pH. The method was used to study the tissue distribution of 14C-A-II after intravenous injection.

Localization of 14C-angiotensin in rat brain after intravenous injection

14C-angiotensin II (14C-AII) was infused into rats which were sacrificed 5, 15, 30, 60 min post infusion. Blood and brain samples were extracted and chromatographed on paper with standards of authentic 14C-AII and metabolites produced by the enzymatic degradation of the 14C-AII. Blood levels of both total radioactivity and 14C-angiotensin declined rapidly at first and slowly thereafter. Similarly total brain radioactivity also declined with time but 14C-angiotensin levels increased over the 60 min resulting in a large increase in the percentage of angiotensin found in the brain. Examination of the brain/blood ratio for 14C-angiotensin at each time point indicates that the brain reaches equilibrium with the blood (brain/blood = 1) at 30 min and remains unchanged at 60 min. This data suggests that intravenously injected 14C-angiotensin II can cross the blood brain barrier by a passive mechanism resulting in the binding of the hormone at central sites.

The relation between the subcellular distribution of [3H]resperpine and its proposed site of action

The amount of [3H]reserpine retained after injection is greater in the heart, a tissue with a high density of adrenergic innervation than in femoral muscle. Subcellular distribution studies emphasized that 15 and 60 min after injection of [3H]reserpine it could not be shown to be uniquely associated with the noradrenaline-containing granules. The possibility existed that the large amount of reserpine bound to cellular lipids at these times might mask a more specific binding. A reduction in the dose and a lengthening of the time between drug administration and tissue measurement to 18 h revealed a small amount of [3H]reserpine to be bound more firmly to the microsomal or amine granule-containing fraction. Prior saturation of tissue binding sites by treatment with large amounts of unlabelled reserpine or tetrabenazine decreased the retention of subsequently injected [3H]reserpine. This decreased tissue retention resulted in an increase in the formation of [3H]trimethoxybenzoic acid.

A model is proposed relating tissue distribution and binding to reserpine's mechanism of action.