The Spleen in Type I Hyperlipoproteinemia: Histochemical, Biochemical, Microfluorometric and Electron Microscopic Observations

Histochemical, biochemical, microfluorometric and electron microscopic studies were made of the spleen of a patient with type I hyperlipoproteinemia. Foam cells were observed that contained a material identified as ceroid on the basis of its autofluorescence, acid-fastness, sudanophilia, PAS-positivity and insolubility in organic solvents. Electron microscopy showed that the ceroid was organized in the form of granules with concentric lamellae of irregular periodicity. The process of formation of these granules is described in detail. The ceroid was considered to represent nondigestible end products of the metabolism of chylomicrons taken up by macrophages in splenic sinusoids.     

Endocarditis with ruptured cerebral aneurysm caused by Cardiobacterium valvarum sp. nov

A fastidious gram-negative bacterium was isolated from the blood of a 37-year-old man who had insidious endocarditis with a sudden rupture of a cerebral aneurysm. Characterization of the organism through phylogenetic and phenotypic analyses revealed a novel species of Cardiobacterium, for which the name Cardiobacterium valvarum sp. nov. is proposed. C. valvarum will supplement the current sole species Cardiobacterium hominis, a known cause of endocarditis. Surgeries and antibiotic treatment cured the patient's infection and associated complications. During cardiac surgery, a congenital bicuspid aortic valve was found to be the predisposing factor for his endocarditis.     

Quantitative analysis of the velocity characteristics of optokinetic nystagmus and optokinetic after-nystagmus

1. Velocity characteristics of optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) induced by constant velocity full field rotation were studied in rhesus monkeys. A technique is described for estimating the dominant time constant of slow phase velocity curves and of monotonically changing data. Time constants obtained by this technique were used in formulating a model of the mechanism responsible for producing OKN and OKAN.2. Slow phase velocity of optokinetic nystagmus in response to steps in stimulus velocity was shown to be composed of two components, a rapid rise, followed by a slower rise to a steady-state value. Peak values of OKN slow phase velocity increased linearly with increases in stimulus velocity to 180 degrees /sec. Maximum slow phase eye velocities in the monkey are 2-3 times as great as in humans.3. At the onset of OKAN, slow phase velocity falls by about 10-20%, followed by a slower decline to zero. Peak OKAN slow phase velocities were linearly related to optokinetic stimulus velocities up to 90-120 degrees /sec. Above 120 degrees /sec OKAN slow phase velocity saturated although OKN slow phase velocity continued to increase.4. The charge and discharge characteristics of OKAN were studied. The OKAN mechanism charged in 5-10 sec and discharged over 20-60 sec in darkness. The time constants of decay in OKAN slow phase velocity decreased as stimulus velocities increased. They also decreased on repeated testing. In several monkeys there was a consistent difference in the rate of decay of OKAN slow phase velocity to the right and left.5. Extended visual fixation discharged the activity responsible for producing OKAN. Short fixation times caused only a partial discharge of the OKAN mechanism. Following brief periods of fixation, OKAN resumed but with depressed slow phase velocities.6. A model based on a state realisation of a peak detector was formulated which approximately reproduces the salient characteristics of OKN and OKAN. This model predicts the three dominant characteristics of OKAN: (1) charge over 5-7 sec, (2) slow discharge in darkness, and (3) rapid discharge with visual fixation. With the addition of direct fast forward pathways, it also correctly predicts the rapid and slow rise in OKN. We postulate that OKAN is produced by a central integrator which is also active during OKN. Presumably this integrator acts to maximize velocities during OKN and to smooth and stabilize ocular following during movement of the visual surround.     

p53-Regulated Apoptosis Is Differentiation Dependent in Ultraviolet B-Irradiated Mouse Keratinocytes

Previous studies from our laboratory, using p53 transgenic mice, have suggested that ultraviolet (UV) light-induced keratinocyte apoptosis in the skin is not affected by overexpression of mutant p53 protein. To further elucidate a possible role for p53 in UV-induced keratinocyte cell death, we now examine apoptosis in skin and isolated keratinocytes from p53 null (−/−) mice and assess the influence of cell differentiation on this process. In vivo, using this knockout model, epidermal keratinocytes in p53−/− mice exhibited only a 5.2-fold increase in apoptosis after 2000 J/m² UVB irradiation compared with a 26.3-fold increase in normal control animals. If this p53-dependent apoptosis is important in elimination of precancerous, UV-damaged keratinocytes, then it should be active in the undifferentiated cells of the epidermal basal layer. To test this hypothesis, we examined the effect of differentiation on UV-induced apoptosis in primary cultures of murine and human keratinocytes. Apoptosis was p53-independent in undifferentiated murine keratinocytes, which exhibited relative resistance to UVB-induced killing with only a 1.5-fold increase in apoptosis in p53+/+ cells and a 1.4-fold increase in p53−/− cells. Differentiated keratinocytes, in contrast, showed a 9.4-fold UVB induction of apoptosis in p53+/+ cells, almost three times the induction observed in p53−/− cells. This UV-induced difference in apoptosis was observed when keratinocytes were cultured on type IV collagen substrate, but not on plastic alone. Western blotting of UV-irradiated, differentiated keratinocytes did not support a role for either Bax or Bcl-2 in this process. In support of these findings in mice, cell death in human cultured keratinocytes also occurred in a differentiation-associated fashion. We conclude that p53-induced apoptosis eliminates damaged keratinocytes in the differentiated cell compartment, but this mechanism is not active in the basal, undifferentiated cells and is therefore of questionable significance in protection against skin cancer induction.     

Hemodynamic and hormonal responses to lower body negative pressure in men with varying profiles of strength and aerobic power

Hemodynamic, cardiac, and hormonal responses to lower-body negative pressure (LBNP) were examined in 24 healthy men to test the hypothesis that responsiveness of reflex control of blood pressure during orthostatic challenge is associated with interactions between strength and aerobic power. Subjects underwent treadmill tests to determine peak oxygen uptake ( O_2max) and isokinetic dynamometer tests to determine knee extensor strength. Based on predetermined criteria, subjects were classified into one of four fitness profiles of six subjects each, matched for age, height, and body mass: (a) low strength/average aerobic fitness, (b) low strength/high aerobic fitness, (c) high strength/average aerobic fitness, and (d) high strength/high aerobic fitness. Following 90 min of 0.11 rad (6°) head-down tilt (HDT), each subject underwent graded LBNP to –6.7 kPa or presyncope, with maximal duration 15 min, while hemodynamic, cardiac, and hormonal responses were measured. All groups exhibited typical hemodynamic, hormonal, and fluid shift responses during LBNP, with no intergroup differences between high and low strength characteristics. Subjects with high aerobic power exhibited greater (P < 0.05) stroke volume and lower (P < 0.05) heart rate, vascular peripheral resistance, and mean arterial pressure during rest, HDT, and LBNP. Seven subjects, distributed among the four fitness profiles, became presyncopal. These subjects showed greatest reduction in mean arterial pressure during LBNP, had greater elevations in vasopressin, and lesser increases in heart rate and peripheral resistance. Neither O_2max nor leg strength were associated with fall in arterial pressure or with syncopal episodes. We conclude that interactions between aerobic and strength fitness characteristics do not influence responses to LBNP challenge.     

Platelet interactions with calcium-phosphate-coated surfaces

Many studies have shown that calcium-phosphate (CaP)-coated endosseous implants exhibit more peri-implant bone formation and bone contact at early healing times than uncoated implants. Since the rate of healing is influenced by blood/implant interactions and possibly the degree of blood platelet activation, the aim of this study was to determine whether the topography, microtopography, or the presence of calcium (Ca) and phosphate (PO(4)) ions in the implant surface plays a predominant role in platelet activation. We define the threshold between topography and microtopography as the limit of the scale range of platelets themselves; thus, a microtopographic surface is defined by one which exhibits features 3mum. With the help of four international collaborating laboratories, we prepared 11 titanium and CaP-modified titanium surfaces each with different (micro)topographies and interrogated these surfaces with both platelet adhesion (lactate dehydrogenase activity) and platelet activation (microparticle formation and P-selectin expression) assays. Our results show that: calcium (Ca)- and phosphate (PO(4))-containing surfaces of increasing surface microtopographical complexity exhibit increasing platelet activation; surfaces with similar surface microtopographies show similar levels of platelet activation regardless of the presence of Ca and PO(4) in the surface; and that surface microtopography is responsible for platelet activation rather than the presence of Ca and PO(4) in the surface.     

Production of anti-NC1 antibody by affected male dogs with X-linked hereditary nephritis: A probe for assessing the NC1 domain of collagen type IV in dogs and humans with hereditary nephritis

Summary Some patients with hereditary nephritis (HN) who have received a renal transplant have been shown to form antibody with specificity for the NC1 domain of collagen type IV, a major constituent of glomerular basement membranes (GBM). We attempted to duplicate this phenomenon in a family of dogs with X-linked HN, a model for human X-linked HN, by immunizing affected male dogs with normal dog NC1 domain. A collagenase digest was prepared from normal dog GBM, the NC1 domain was separated into dimer (50 kDa) and monomer (24 kDa and 26 kDa) components by SDS-PAGE, and injected into two affected male dogs. Antisera obtained from both dogs contained antibody which reacted with the NC1 domain of dog and human GBM by a plate-binding radioimmunoassay, bound to the dimer and 26 kDa monomer bands by Western blotting, and staining dog and human GBM by immunofluorescence (IF). The affected male dog antiserum reacted equally by radioimmunoassay with the NC1 domain isolated from GBM of unaffected, affected male, and carrier female dogs in the family with X-linked HN, and bound by Western blotting to dimers and the 26 kDa monomer band of the NC1 domain of GBM in each group of dogs. However, the affected male dog antiserum differentiated these dogs by IF; it produced global staining of GBM of unaffected dogs, failed to stain GBM of affected male dogs, and produced segmental staining of GBM of carrier female dogs. Absorption of the affected male dog antiserum with normal dog NC1 domain eliminated the staining of dog GBM by IF, whereas staining persisted after absorption with affected male dog NC1 domain. The abnormal staining patterns of GBM seen by IF in the affected male and carrier female dogs and the results of the absorption studies imply an abnormality of one or more determinants in the 26 kDa monomer band of the NC1 domain of their GBM. Amino acid sequencing of this band identified the 1(IV) chain of collagen type IV, a finding that has implications for the pathogenesis of canine X-linked HN. Absent and segmental staining respectively were also seen by IF in GBM of a male and female patient with HN, using the affected male dog antiserum. Thus, the results obtained in affected male and carrier female dogs with X-linked HN may also be relevant to patients with this disease.     

Predictive value of early HCV RNA quantitation for sustained response in nonresponders receiving daily interferon and ribavirin therapy

The prognostic value of early hepatitis C virus (HCV)-RNA load was evaluated among nonresponder patients to previous interferon (IFN) therapy treated with daily IFN and ribavirin. One hundred-six nonresponders (83 men), mean age 44.8 +/- 11 years, were treated with IFN-alpha 2b 3 MU/day for 24 weeks, followed by 3 MU x 3/week for 24 weeks plus ribavirin 1-1.2 g/day for 48 weeks. HCV RNA was quantified by Versant HCV RNA 3.0 assay (Bayer). The predictive values of the baseline and the change in viral load at week 1, 4, and 12 for sustained virological responses were analyzed using receiver operating characteristic (ROC) curves, as well as predictive values of >2 log(10) drop from baseline by weeks 1, 4, and 12 in combination with undetectable HCV RNA for sustained virological response. Thirty-two patients (30.2%) were sustained virological responders. The highest area under the curve was obtained at week 4. The unquantifiable HCV RNA level, in combination with at least a 2 log(10) drop in viral load by week 4 and week 12, had a negative predictive value of 96% and 97%, respectively. Nonresponse can be predicted as early as week 4 or week 12 in nonresponders treated with daily IFN and ribavirin.