Beta-amyloid deposition and other measures of neuropathology predict cognitive status in Alzheimer's disease

The relationship between progressive cognitive decline and underlying neuropathology associated with Alzheimer s disease (AD) is a key issue in defining the mechanisms responsible for functional loss. This has been a subject of much controversy, with separate studies comparing various clinical and neuropathological indices in AD. Further, it is difficult to compare studies with differences in histochemical staining protocols, brain regions examined, and data quantification criteria. There are many difficulties in designing a clinical-pathological correlative study involving AD patients. It is necessary to control for several key parameters. For example, a broad range of cognitively impaired subjects is needed, as well as short postmortem delays, brief intervals between cognitive testing and death, and the most sensitive detection and quantification techniques. In this study, we carefully controlled for each of these parameters to determine if there is a relationship between global cognitive dysfunction and multiple neuropathological indices. We selected 20 individuals representing a broad range of cognitive ability from normal to severely impaired based on the MMSE, Blessed IMC, and CDR. We counted plaque number, NFT number, dystrophic neurite number, and the relative extent of thioflavine positive plaques and neuritic involvement within plaques. We also quantified cortical area occupied by beta-amyloid immunoreactivity (A beta Load) and PHF-1 positive neuropil threads and tangles (PHF Load) using computer-based image analysis. Interestingly, we found that most pathologic measures correlated highly with the severity of dementia. However, the strongest predictor of premortem cognitive dysfunction on all three cognitive measures was the relative area of entorhinal cortex occupied by beta-amyloid deposition. In conclusion, our data show that in a carefully controlled correlative study, a variety of neuropathological variables are strongly correlated with cognitive impairment. Plaque related variables may be as strongly related to cognitive dysfunction as other established measures, including synapse loss, cell death and tau hyperphosphorylation, although no correlative study can demonstrate causality.     

Low lipid concentrations in critical illness: implications for preventing and treating endotoxemia

OBJECTIVES: To determine the prevalence and clinical significance of hypolipidemia found in critically ill patients, and whether the addition of a reconstituted lipoprotein preparation could inhibit the generation of tumor necrosis factor-alpha (TNF-alpha) in acute-phase blood taken from these patients. SETTING: Surgical intensive care unit (ICU) of a large urban university hospital. DESIGN: Prospective case series. PATIENTS: A total of 32 patients with a variety of critical illnesses had lipid and lipoprotein concentrations determined. Six patients and six age- and gender-matched control subjects had whole blood in vitro studies of the effect of lipoprotein on lipopolysaccharide mediated TNF-alpha production. INTERVENTIONS: Blood samples were drawn on admission to the ICU and over a subsequent 8-day period. MEASUREMENTS AND MAIN RESULTS: Mean serum lipid and lipoprotein values obtained from patients within 24 hrs of transfer to the surgical ICU were extremely low: mean total cholesterol was 117 mg/dL (3.03 mmol/L), low-density lipoprotein cholesterol 71 mg/dL (1.84 mmol/L), and high-density lipoprotein cholesterol 25 mg/dL (0.65 mmol/L). Only the mean triglyceride concentration of 105 mg/dL (1.19 mmol/L), and the mean lipoprotein(a) concentration of 25 mg/dL (0.25 g/L) were within the normal range. During the first 8 days following surgical ICU admission, there were trends toward increasing lipid and lipoprotein concentrations that were significant for triglycerides and apolipoprotein B. Survival did not correlate with the lipid or lipoprotein concentrations, but patients with infections had significantly lower (p = .008) high-density lipoprotein cholesterol concentrations compared with noninfected patients. Lipopolysaccharide-stimulated production of TNF-alpha in patient and control blood samples was completely suppressed by the addition of 2 mg/mL of a reconstituted high-density lipoprotein preparation. CONCLUSIONS: Patients who are critically ill from a variety of causes have extremely low cholesterol and lipoprotein concentrations. Correction of the hypolipidemia by a reconstituted high-density lipoprotein preparation offers a new strategy for the prevention and treatment of endotoxemia.     

Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. I. Linear acceleration responses during off-vertical axis rotation

1. The dynamic properties of otolith-ocular reflexes elicited by sinusoidal linear acceleration along the three cardinal head axes were studied during off-vertical axis rotations in rhesus monkeys. As the head rotates in space at constant velocity about an off-vertical axis, otolith-ocular reflexes are elicited in response to the sinusoidally varying linear acceleration (gravity) components along the interaural, nasooccipital, or vertical head axis. Because the frequency of these sinusoidal stimuli is proportional to the velocity of rotation, rotation at low and moderately fast speeds allows the study of the mid-and low-frequency dynamics of these otolith-ocular reflexes. 2. Animals were rotated in complete darkness in the yaw, pitch, and roll planes at velocities ranging between 7.4 and 184 degrees/s. Accordingly, otolith-ocular reflexes (manifested as sinusoidal modulations in eye position and/or slow-phase eye velocity) were quantitatively studied for stimulus frequencies ranging between 0.02 and 0.51 Hz. During yaw and roll rotation, torsional, vertical, and horizontal slow-phase eye velocity was sinusoidally modulated as a function of head position. The amplitudes of these responses were symmetric for rotations in opposite directions. In contrast, mainly vertical slow-phase eye velocity was modulated during pitch rotation. This modulation was asymmetric for rotations in opposite direction. 3. Each of these response components in a given rotation plane could be associated with an otolith-ocular response vector whose sensitivity, temporal phase, and spatial orientation were estimated on the basis of the amplitude and phase of sinusoidal modulations during both directions of rotation. Based on this analysis, which was performed either for slow-phase eye velocity alone or for total eye excursion (including both slow and fast eye movements), two distinct response patterns were observed: 1) response vectors with pronounced dynamics and spatial/temporal properties that could be characterized as the low-frequency range of "translational" otolith-ocular reflexes; and 2) response vectors associated with an eye position modulation in phase with head position ("tilt" otolith-ocular reflexes). 4. The responses associated with two otolith-ocular vectors with pronounced dynamics consisted of horizontal eye movements evoked as a function of gravity along the interaural axis and vertical eye movements elicited as a function of gravity along the vertical head axis. Both responses were characterized by a slow-phase eye velocity sensitivity that increased three- to five-fold and large phase changes of approximately 100-180 degrees between 0.02 and 0.51 Hz. These dynamic properties could suggest nontraditional temporal processing in utriculoocular and sacculoocular pathways, possibly involving spatiotemporal otolith-ocular interactions. 5. The two otolith-ocular vectors associated with eye position responses in phase with head position (tilt otolith-ocular reflexes) consisted of torsional eye movements in response to gravity along the interaural axis, and vertical eye movements in response to gravity along the nasooccipital head axis. These otolith-ocular responses did not result from an otolithic effect on slow eye movements alone. Particularly at high frequencies (i.e., high speed rotations), saccades were responsible for most of the modulation of torsional and vertical eye position, which was relatively large (on average +/- 8-10 degrees/g) and remained independent of frequency. Such reflex dynamics can be simulated by a direct coupling of primary otolith afferent inputs to the oculomotor plant. (ABSTRACT TRUNCATED)     

Tendon repair using flexor tendon splints: an experimental study

Mechanical strength of tendon repair using Dacron tendon splints across the laceration site were evaluated in human cadaver profundus tendons; the splints were placed both on the dorsal surface and internally within the tendon substance. Comparison was made to modified Kessler, Becker, and Savage repair techniques. Ultimate tensile strength was 2.55 kgf for the Kessler, 3.00 kgf for the Becker, 8.29 kgf for the Savage, 8.46 kgf for the internal tendon splint, and 8.10 kgf for the dorsal tendon splint; the Savage and both Tendon Splints techniques had significant higher tensile strength than the Kessler and Becker. Gap strength was 1.44 kgf for the Kessler, 2.22 kgf for the Becker, 2.45 kgf for the Savage, 2.05 kgf for internal tendon splint, and 3.15 kgf for the dorsal tendon splint. The dorsal tendon splint technique showed significant greater gap strength than the other four techniques. There was no significant difference in the magnitude of the gap during cyclic testing of these techniques; however, three of seven Kessler repairs failed and one of six Becker repairs failed. The results of these cadaver studies suggest that both tendon splint repair techniques are comparable to the Savage and may have sufficient strength to allow postoperative active motion against minimal resistance. Further in vivo testing is in order.     

The lack of NK cytotoxicity associated with fresh HUCB may be due to the presence of soluble HLA in the serum

Human bone marrow transplantation is becoming more common in the treatment of certain forms of cancer despite the scarcity of HLA matched donors. Because human umbilical cord blood (HUCB) has been used as a source for stem cells in bone marrow transplantation, and because NK cells appear to be important in graft versus leukemia response, we investigated the lytic activity of freshly isolated HUCB NK cells (HUCB-NK) against tumor targets and their ability to differentiate into LAK cells following stimulation with various cytokines. Although cytotoxicity mediated by fresh HUCB-NK was low compared to that of adult peripheral blood lymphocyte-derived NK cells (PBL-NK), the ability of HUCB-NK to bind to K562 target cells (TC) was similar to PBL-NK. In addition, the PBL-NK cytotoxicity of postpartum mothers was also low compared to that of normal adult PBL-NK. When we incubated HUCB for 18 hr in either IL-2 or IL-12, we boosted the level of HUCB-NK cytotoxicity to approximately the level observed in PBL-NK and increased the level of perforin, granzyme A, and granzyme B mRNA expression. In addition, when we incubated HUCB in IL-2, IL-4, IL-7, IL-12, TNF-alpha, IFN-alpha, IFN-gamma, or TGF-beta for 5 days, we observed that HUCB was capable of generating LAK cells only when incubated with either IL-2 or IL-12. In contrast, IL-2, IL-7, IL-12, TNF-alpha, and IFN-gamma all generated LAK cells from adult PBL. When we added to the medium low-dose IL-2 and irradiated K562 as feeder cells (mini-LAK), we were unable to generate LAK activity from HUCB-NK, whereas we could generate it with PBL-NK cells under the same conditions. Addition of serum derived from HUCB in a 4-hr 51Cr release assay with PBL-NK as the effector cells (EC) and K562 as the TC resulted in a 42% decrease in PBL-NK-mediated cytotoxicity. Although we detected no TGF-beta in HUCB serum, we did detect high concentrations of soluble class I MHC (sHLA). To our knowledge, sHLA has not previously been shown to inhibit NK cytotoxicity, although the expression of class I HLA on the surface of TC has been shown to inhibit NK cytotoxicity. To study further the effect of sHLA on cell-mediated cytotoxicity, we added various concentrations of sHLA to EC mediating NK, ADCC, and CTL activities. All were inhibited in a dose-dependent manner.(ABSTRACT TRUNCATED AT 400 WORDS)     

Differential effects of interleukin 1-alpha (IL-1 alpha) or tumor necrosis factor-alpha (TNF-alpha) on motility of human melanoma cell lines on fibronectin

Interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) induce a motogenic response in a number of benign and malignant cells. We examined the chemokinetic effects of these cytokines on the cell migration of four melanoma cell lines on fibronectin using modified Boyden chambers and video-time lapse analysis. Flow cytometry analysis of IL-1 receptors, TNF receptors, and shifts in beta 1 integrin expression were correlated with the effects of these cytokines on cell migration on fibronectin. The four melanoma cell lines exhibited heterogeneous expression of types I and II IL-1 receptors as well as p60 TNF receptors. Scant p80 TNF receptor expression was detected on only one cell line. Three of four melanoma cell lines demonstrated type I IL-1 receptors by Western blotting. IL-1 alpha and TNF-alpha induced heterogeneous modulation of beta 1 integrin expression in the four melanoma cell lines tested; downward shift of the alpha 2, alpha 3, alpha 4, and beta 1 integrin subunits was detected among three of the melanoma cell lines as were upward shifts of the alpha 4, alpha 5, and alpha 6 integrin subunits among three of the melanoma cell lines. IL-1 alpha and TNF-alpha induced enhanced migration on fibronectin in one of the melanoma cell lines and were related to an upward shift in the alpha 4 and alpha 5 integrin subunit expression. Taken together, the findings indicate that expression of a particular receptor for IL-1 or TNF does not necessarily signal a motogenic response in melanoma cells, but induces heterogeneous shifts in beta 1 integrin expression. However, upregulation in alpha 4 and alpha 5 integrin subunits appears to relate to enhanced migration on fibronectin.     

Endogenous vasodilators modulate pulmonary vascular anaphylaxis

We examined the role of endothelium-derived nitric oxide during antigen-induced contraction in pulmonary arteries isolated from actively sensitized guinea pigs. Ovalbumin (10(-2) mg/ml)-induced contraction was not sustained, and tension returned to baseline within 15 min. Pretreatment with methylene blue (10(-5) M) increased both the amplitude and the duration of the contractile response in these tissues. At 15 min, tension remained elevated and was > 70% of the peak amplitude. Removal of the endothelium with saponin (200 micrograms/ml) increased the magnitude of the contraction by > 125%; however, the duration of the response was unaffected. After pretreatment with saponin, methylene blue no longer increased the amplitude of antigen-induced contraction but its effect on the duration was unchanged. Pretreatment with nitro-L-arginine methyl ester significantly increased the magnitude of the contraction in each of the tissues. These results suggest that the response of guinea pig pulmonary arteries to antigen is modulated by two types of endogenous vasodilators, endothelium-derived nitric oxide that inhibits the initial phase of the response and an endothelium-independent relaxing factor that is guanosine 3',5'-cyclic monophosphate dependent and attenuates the duration of anaphylactic contraction.     

Antibody-mediated basophil accumulations in cutaneous hypersensitivity reactions of guinea pigs

Cutaneous basophil hypersensitivity (CBH) was studied in guinea pigs by using simplified histologic techniques. Animals immunized with oxazolone or picryl conjugates of keyhole limpet hemocyanin (KLH) emulsified with complete (CFA) or incomplete Freund's adjunvant (IFA) were found to have hapten-specific cutaneous basophil reactions when skin tested at 1 week with oxazolone or picryl chloride contant painting or intradermal injection of oxazolone or picryl-conjugated human serum albumin, respectively. Thus, hapten-specific cutaneous basophil reactions were present in guinea pigs immunized with CFA for classical delayed hypersensitivity, and in animals immunized with IFA for Jones-Mote reactions. Hapten-specific 24-hr cutaneous basophil reactions were passively transferred with immune serum from donors sensitized with conjugates of oxazolone or picryl-KLH in CFA or IFA, and with serum from oxazolone contact-sensitized animals as well. As little as 0.5 ml sera obtained from donors 1 week after immunization could systemically transfer cutaneous basophil reactions. It is likely that hapten-specific cutaneous basophil reactions are mediated by small quantities of serum antibodies. We conclude that antibody-mediated cutaneous basophil reactions may be distinctive hypersensitivity responses that can be distinguished from classical anaphylactic, Arthus, and delayed hypersensitivities. It is suggested that CBH reactions are heterogeneous and that antibody products of B lymphocytes, and factors probably derived from T lymphocytes, play a role in basophil accumulations at cutaneous hypersensitivity reactions.