Immunohistochemical localization of membrane and alpha-granule proteins in human megakaryocytes: application to plastic-embedded bone marrow biopsy specimens

Using a new technique for antigen localization, we have demonstrated platelet proteins in megakaryocytes in plastic-embedded biopsy specimens of normal human bone marrow. In a series of 25 specimens, megakaryocytes showed labeling with antibodies to the integral membrane glycoproteins IIIa, IIb, and the IIb-IIIa complex; granule membrane protein 140; and five alpha-granule matrix proteins: thrombospondin, factor VIII-related antigen, beta-thromboglobulin, platelet factor 4, and fibrinogen. The antibodies to the membrane glycoproteins IIIa, IIb, and IIb-IIIa produced diffuse cytoplasmic staining and heavier staining on the plasma membrane, whereas the antibodies to the alpha-granule matrix proteins produced a distinct granular staining within the cytoplasm. Staining for granule membrane protein 140 was also granular in distribution. Rare mononuclear cells consistent with megakaryocyte precursors were labeled with these markers. Other enzyme histochemical and lectin-binding studies showed that the enzyme alpha-naphthyl acetate esterase, the lectin Ulex europaeus I, and the periodic-acid Schiff reaction were consistent, but not specific, markers of megakaryocytes. This immunohistochemical technique should facilitate the examination of qualitative and quantitative changes in megakaryocytes in a variety of physiologic and pathologic processes.     

An endogenous digitalis-factor derived from the adrenal gland: studies of adrenocortical tumor cells

The present studies demonstrate that the murine adrenocortical tumor cell line Y-1 releases a digoxin-like immunoreactive material into both serum-supplemented nutrient medium and minimal Krebs-Ringer bicarbonate medium. Release of pregnenolone into minimal medium from these cells was consistently inhibited by addition of the cholesterol side-chain cleavage inhibitor aminoglutethimide. However, release of digoxin-like immunoreactivity (DLI) was not similarly affected. To exclude the possibility that DLI could be accounted for by cross-reaction with another known adrenal steroid, aminoglutethimide inhibition was accompanied by inhibition of 17 alpha-hydroxylase with SU-10603 and inhibition of 3 beta-hydroxysteroid dehydrogenase with cyanoketone. Once again, pregnenolone release was effectively inhibited, but no similar pattern of inhibition of DLI release was observed. Increasing the time of the incubation periods from 1 to 2 h did not change the pattern of secretion of pregnenolone or DLI. HPLC analysis of DLI released over prolonged culture periods into serum-supplemented nutrient medium showed high levels of DLI in a single major and several adjacent peaks. Analysis of the ability of extracts of Y-1-conditioned medium to compete with tritiated ouabain for binding to erythrocytes indicates that conditioned medium contained highly enriched levels of ouabain-like activity. On HPLC analysis, the distribution of this activity showed partial correlation with the distribution of DLI. These observations indicate that Y-1 cells produce and release significant quantities of a material with cardiac glycoside-like properties reflected in the cross-reactivity with antidigoxin antibodies and the ability to compete with ouabain for binding to erythrocytes. In substantiation of previous findings in chopped adrenal cultures, the cardiac glycoside-like activity does not appear to result from cholesterol side-chain cleavage or pregnenolone production, since inhibition of side-chain cleavage as well as subsequent 17 alpha-hydroxylation and 3 beta-dehydrogenation did not result in consistent inhibition of DLI release.     

Blood flow distribution during hypocapnic hypoxia in Pekin ducks and bar-headed geese

The purpose of this study was to determine the effects of hypocapnic hypoxia on regional blood flow in birds. Regional blood flow was measured using the radioactive microsphere method in unanesthetized Pekin ducks (Anas platyrhynchos) and bar-headed geese (Anser indicus) breathing 21, 10 and 5% O2. In both birds, arterial PO2 was reduced from about 96 Torr during normoxia to about 28 Torr during severe hypoxia. Severe hypocapnic hypoxia produced a change in the pattern of blood flow in ducks; blood flow to some organs increased (brain, adrenal glands, heart, and eyes) while flow to other organs decreased (liver, spleen, small intestine, shell gland). Compared with ducks, bar-headed geese were able to provide higher levels of O2 delivery to their tissues since blood flow to a variety of organs and skeletal muscles was either unchanged or increased during severe hypoxia. The redistribution of blood flow in Pekin ducks during severe hypocapnic hypoxia may help to support large increases in cerebral and coronary blood flow but may also contribute to the development of a metabolic acidosis.     

Utility of diffusion-weighted MR imaging in the diagnosis of placenta accreta spectrum abnormality

Purpose

The aim of this study was to evaluate the utility of added DWI sequences as an adjunct to traditional MR imaging in the evaluation of abnormal placentation in patients with suspicion for placenta accreta spectrum abnormality or morbidly adherent placenta (MAP).

Materials and methods

The study was approved by local ethics committee. The subjects included pregnant women with prenatal MRI performed between July 2013 to July 2015. All imaging was performed on a Philips 1.5T MR scanner using pelvic phased-array coil. Only T2-weighted and diffusion-weighted imaging (DWI) series were compiled for review. Two randomized imaging sets were created: set 1 included T2-weighted series only (T2W); set 2 included T2W with DWI series together (T2W + DWI). Three radiologists, blinded to history and pathology, reviewed the imaging, with 2 weeks of time between the two image sets. Sensitivity, specificity, and overall accuracy for MAP were calculated and compared between T2W only and T2W + DWI reads. Associations between imaging findings and invasion on pathology were tested using the Chi-squared test. Confidence scores, inter-reader agreement, and systematic differences were documented.

Results

A total of 17 pregnant women were included in the study. 8 cases were pathologically diagnosed with MAP. There were no significant differences in the diagnostic accuracy between T2W and T2W + DWI in the diagnosis of MAP in terms of overall accuracy (62.7% for T2W vs. 68.6% for T2W + DWI, p = 0.68), sensitivity (70.8% for T2W vs. 95.8% for T2W + DWI, p = 0.12), and specificity (55.6% for T2W vs. 44.4% for T2W + DWI, p = 0.49). There was no significant difference in the diagnostic confidence between the review of T2W images alone and the T2W + DWI review (mean 7.3 ± 1.8 for T2W vs. 7.5 ± 1.8 for T2W + DWI, p = 0.37).

Conclusion

With the current imaging technique, addition of DWI sequence to the traditional T2W images cannot be shown to significantly increase the accuracy or reader confidence for diagnosis of placenta accreta spectrum abnormality. However, DWI does improve identification of abnormalities in the placental–myometrial interface.

     

Nondisease-Specific Problems and All-Cause Mortality among Older Adults with CKD: The REGARDS Study

Background and objectives

The term “nondisease-specific” has been used to describe problems that cross multiple domains of health and are not necessarily the result of a single underlying disease. Although individuals with reduced eGFR and elevated albumin-to-creatinine ratio have many comorbidities, the prevalence of and outcomes associated with nondisease-specific problems have not been well studied.

Design, setting, participants, & measurements

Participants included 3557 black and white United States adults ≥75 years of age from the Reasons for Geographic and Racial Differences in Stroke Study. Nondisease-specific problems included cognitive impairment, depressive symptoms, exhaustion, falls, impaired mobility, and polypharmacy. Hazard ratios for mortality over a median (interquartile range) of 5.4 (4.2–6.9) years of follow-up associated with one, two, or three to six nondisease-specific problems were calculated and stratified by eGFR (≥60, 45–59, and <45 ml/min per 1.73 m²) and separately, albumin-to-creatinine ratio (<30, 30–299, and ≥300 mg/g). Secondary outcomes included hospitalizations and emergency department visits over 1.8 (0.7–4.0) and 2.3 (0.9–4.7) years of follow-up, respectively.

Results

The prevalence of nondisease-specific problems was more common at lower eGFR and higher albumin-to-creatinine ratio levels. Within each eGFR and albumin-to-creatinine ratio strata, the risk for mortality was higher among those with a greater number of nondisease-specific problems. For example, among those with an eGFR=45–59 ml/min per 1.73 m², the multivariable adjusted hazard ratios (95% confidence intervals) for mortality associated with one, two, or three to six nondisease-specific problems were 1.17 (0.78 to 1.76), 1.95 (1.24 to 3.07), and 2.44 (1.39 to 4.27; P trend <0.001). Risk for hospitalization and emergency department visits was higher among those with more nondisease-specific problems within eGFR and albumin-to-creatinine ratio strata.

Conclusions

Among older adults, nondisease-specific problems commonly co-occur with reduced eGFR and elevated albumin-to-creatinine ratio. Identification of nondisease-specific problems may provide mortality risk information independent of measures of kidney function.