Additive neuroprotective effects of dextrorphan and cycloheximide in rats subjected to transient focal cerebral ischemia

Previous studies have implicated both excitotoxicity and apoptosis in the pathogenesis of cerebral infarction induced by focal ischemic insults. Here we tested the possibility that the NMDA antagonist, dextrorphan, and the protein synthesis inhibitor, cycloheximide, would produce additive protective effects in a rodent model of focal ischemia-reperfusion. Transient focal cerebral ischemia was induced by a 90 min period of ligation of the right middle cerebral artery and both common carotid arteries. Administration of either 30 mg/kg dextrorphan or 0.5 mg/kg cycloheximide, given i.p. 15 min before ischemia, reduced infarct volume by about 65%. When optimal concentrations of each drug were given together, infarct volume was reduced by 87% as measured 14 days later. These observations support the idea that both excitotoxicity, and apoptosis dependent on new protein synthesis, contribute to cerebral infarction after transient focal ischemia in the rat.

Dextrorphan reduces infarct volume, vascular injury, and brain edema after ischemic brain injury

Focal cerebral ischemia confined to the cerebral cortex in the right middle cerebral artery (MCA) territory was induced by temporary ligation of the MCA and both common carotid arteries (CCAs). Reperfusion was initiated by releasing all three arterial occlusions after 90 min of ischemia. Infarct volume was morphometrically measured after triphenyltetrazolium chloride staining 24 h postischemia. Blood-brain barrier breakdown was assessed 4 h postischemia by measuring vascular permeability to fluorescein isothiocyanate-conjugated dextran (FITC-D), a macromolecule tracer. Ischemic brain edema was measured based on percent water content, 24 h postischemia. Dextrorphan (DX) 20-10 mg/kg given ip 15 min before ischemia reduced infarct volume in a dose-dependent manner with an apparent U-shaped dose-response curve; best protection was observed at 30 mg/kg. Posttreatment at 30 min, but not 60 min, was still effective. DX (30 mg/kg, given 15 min before ischemia) also reduced the postischemic increase in vascular permeability and brain edema in the right MCA cortex. Results from this study support the idea that NMDA receptor activation contributes to blood-brain barrier breakdown and brain edema after ischemic insults

Very delayed infarction after mild focal cerebral ischemia: a role for apoptosis?

The temporal evolution of cerebral infarction was examined in rats subjected to transient occlusion of both common carotid arteries and the right middle cerebral artery. After severe (90-min) ischemia, substantial right-sided cortical infarction was evident within 6 h and fully developed after 1 day. After mild (30-min) ischemia, no cortical infarction was present after 1 day. However, infarction developed after 3 days; by 2 weeks, infarction volume was as large as that induced by 90-min ischemia. These data suggest that infarction after mild focal ischemia can develop in a surprisingly delayed fashion. Some evidence of neuronal apoptosis was present after severe ischemia, but only to a limited degree. However, 3 days after mild ischemia, neurons bordering the maturing infarction exhibited prominent TUNEL staining, and DNA prepared from the periinfarct area of ischemic cortex showed internucleosomal fragmentation. Furthermore, pretreatment with 1 mg/kg cycloheximide markedly reduced infarction volume 2 weeks after mild ischemia. These data raise the possibility that apoptosis, dependent on active protein synthesis, contributes to the delayed infarction observed in rats subjected to mild transient focal cerebral ischemia.

Epidemiology of incident spinal fracture in a complete population

STUDY DESIGN

Cross-section observational study of incident spinal fractures using an administrative data-base.

OBJECTIVES

To identify and define all patients who have spinal fractures within a complete population.

SUMMARY OF BACKGROUND DATA

The true incidence of spinal column and cord injury is not known. Previous studies have been institutional or practice based. Accurate information concerning the magnitude of the spinal injury population and their characteristics may provide more rational basis for public health decision making and resource allocation.

METHODS

The study dates were April 1, 1981 to March 31, 1984. Using the Manitoba Health Services Insurance Plan database, all patients with ICD-9-CM coding of 805.x and 806.x (spinal column fracture with and without spinal cord injury) were identified. Incidence rates, age and gender distribution, and ambulatory and hospital contracts were identified. Hospital discharge abstracts were used to classify mechanisms of injury, associated injuries, and length of stay.

RESULT

The annual incidence rate of spinal fracture was 64 per 100,000. Two thousand sixty-three patients were identified, with 944 being admitted to the hospital. There were two peaks of incidence occurring in young men and elderly women. Of the hospitalized patients, 182 had cervical injury, 286 had thoracic fracture, and 403 had injury in the lumbosacral spine Associated injuries occurred in 38% of hospitalized patients. Length of stay was an average of 38.5 days. Overall mortality was 41%. Neurologic injury occurred in 122 patients.

CONCLUSIONS

Ambulatory care of spine injuries is more common than hospital care. Two peaks of incidence occur-in young men and elderly women. Future decisions for research, public health policy, and resource allocation can be based on these data.

Determining the duration of Ixodes scapularis (Acari: Ixodidae) attachment to tick-bite victims

The duration of tick attachment is one factor associated with risk for human infection caused by several tick-borne pathogens. We measured tick engorgement indices at known time intervals after tick attachment and used these indices to determine the length of time that ticks were attached to tick-bite victims in selected Rhode Island and Pennsylvania communities where the agents of Lyme disease and human babesiosis occur. The total body length and width as well as the length and width of the scutum were measured on nymphal and adult female Ixodes scapularis Say removed from laboratory animals at 0, 12, 24, 36, 48, 60, and 72 h after their attachment. Three engorgement indices were calculated at each time interval. In addition, engorgement indices measurements were recorded for 504 ticks submitted to a commercial laboratory for pathogen detection testing between 1990 and 1992. No detectable change was observed in the average engorgement indices for either nymphal or adult ticks between 0 and 24 h of attachment using any of the engorgement indices. After 24 h of tick attachment, all engorgement indices continuously increased: average indices for nymphs attached 36, 48, and 60 h were significantly different from those attached < or = 24 h and from each other. Similarly, average engorgement indices for adult ticks attached < or = 36 h were significantly different from those attached for 48 h or more. More than 60% of tick-bite victims removed adult ticks by 36 h of attachment, but only 10% found and removed the smaller nymphal ticks within the first 24 h of tick feeding. The duration of tick attachment may serve as a useful predictor of risk for acquiring various infections, such as Lyme disease and babesiosis, transmitted by I. scapularis. Regression equations developed herein correlate tick engorgement indices with duration of feeding. A table containing specific engorgement index prediction intervals calculated for both nymphs and adults will allow the practitioner or clinical laboratory to use easily measured tick engorgement indices to predict transmission risk by determining the duration of feeding by individual ticks.

mRNA expression of vimentin gene in lens of transgenic mouse and DNA amplification in human cataracts

PURPOSE

To investigate the role of vimentin gene in cataractogenesis.

METHODS

The 12.7kb chicken vimentin genes were microinjected into the male pronuclei of 918 fertilized mice eggs. 841 injected embryos were transferred into oviducts of pseudopregnant recipient females, of which 12 pregnant mice gave birth to 49 offspring mice. The integration and expression of exogenous gene in the offspring were analysed by Southern and Northern blot hybridizations. In the human senile cataract, the lens vimentin gene was analyzed with the chicken vimentin gene probe.

RESULTS

It showed that four of F1 offspring were transgenic mice in which the chicken vimentin gene was integrated in their genomes. The transgenic band was 12kb, similar to the 12.7kb chicken vimentin fragment injected. One 2kb vimentin mRNA was visualized on E2 mouse lens blot, which revealed that the chicken vimentin gene was efficiently expressed in this transgenic mouse. In the human senile cataract lens, 12kb BamHI-restricted vimentin fragments displayed a stronger hybridization signal than that of the control lens in Southern blot analysis. It implies that the formation of human senile cataract may be associated with the amplification of vimentin gene.

CONCLUSIONS

We have successfully developed four transgenic mice bearing chicken vimentin gene and having mRNA expression which can be used for further study. It is to be observed if the normal lens cell function is affected by the expressed product and cataract occurs in our transgenic mice. The cause of the gene amplification in human cataract remains for further investigation.

HIV gp120 inhibits T cell activation by interfering with expression of costimulatory molecules CD40 ligand and CD80 (B71)

One mechanism of the immune suppression in HIV infection has been postulated as being caused by the interaction of HIV envelope glycoprotein gp120 with CD4 molecules. Thus, pretreatment of purified peripheral blood T cells or CD4+ T cell clones with gp120 (or an anti-CD4 mAb) results in inhibition of anti-CD3 mAb-induced proliferative responses. In this study, we have analyzed the role of the interacting pairs of costimulatory molecules, CD28-B71 (CD80) and CD40 ligand (CD40L)-CD40, to elucidate further the mechanism of HIV gp120-induced inhibitory effects on T cell functions. Interactions between CD28-B71 and CD40L-CD40 were found to be essential for the anti-CD3 mAb-induced T cell proliferation, as demonstrated by up-regulation of B71 and CD40L and the ability of anti-B71 and anti-CD40L mAbs to inhibit this response. Pretreatment of CD4+ T cells with gp120 before CD3 ligation with anti-CD3 mAb resulted in failure of up-regulation of CD40L on T cells and B71 on APC. Exogenous addition of anti-CD28 mAb overcame the inhibitory effect of gp120 on anti-CD3 mAb-induced T cell proliferation. We conclude that binding of gp120 to CD4 molecules on T cells may interrupt the sequential cascade of intercellular interaction involving 1) Ag/MHC class II-TCR/CD4, 2) CD40L-CD40, and 3) B71-CD28. These studies indicate that the CD4-gp120 interaction results in dysregulation of expression of costimulatory molecules, CD40L, and B71 expression on T cells and APC, respectively, thereby contributing to the T cell hyporesponsiveness in HIV infection.

HIV gp120 inhibits T cell activation by interfering with expression of costimulatory molecules CD40 ligand and CD80 (B71)

One mechanism of the immune suppression in HIV infection has been postulated as being caused by the interaction of HIV envelope glycoprotein gp120 with CD4 molecules. Thus, pretreatment of purified peripheral blood T cells or CD4+ T cell clones with gp120 (or an anti-CD4 mAb) results in inhibition of anti-CD3 mAb-induced proliferative responses. In this study, we have analyzed the role of the interacting pairs of costimulatory molecules, CD28-B71 (CD80) and CD40 ligand (CD40L)-CD40, to elucidate further the mechanism of HIV gp120-induced inhibitory effects on T cell functions. Interactions between CD28-B71 and CD40L-CD40 were found to be essential for the anti-CD3 mAb-induced T cell proliferation, as demonstrated by up-regulation of B71 and CD40L and the ability of anti-B71 and anti-CD40L mAbs to inhibit this response. Pretreatment of CD4+ T cells with gp120 before CD3 ligation with anti-CD3 mAb resulted in failure of up-regulation of CD40L on T cells and B71 on APC. Exogenous addition of anti-CD28 mAb overcame the inhibitory effect of gp120 on anti-CD3 mAb-induced T cell proliferation. We conclude that binding of gp120 to CD4 molecules on T cells may interrupt the sequential cascade of intercellular interaction involving 1) Ag/MHC class II-TCR/CD4, 2) CD40L-CD40, and 3) B71-CD28. These studies indicate that the CD4-gp120 interaction results in dysregulation of expression of costimulatory molecules, CD40L, and B71 expression on T cells and APC, respectively, thereby contributing to the T cell hyporesponsiveness in HIV infection.

Binding of human plasminogen and urokinase-type plasminogen activator to the Lyme disease spirochete, Borrelia burgdorferi

Many bacteria that spread in the skin produce enzymes that digest extracellular matrix components. Borrelia burgdorferi spreads from a skin inoculation site to form the characteristic erythema migrans skin lesion. It was determined that B. burgdorferi does not produce collagenase, elastase, hyaluronidase, or other enzymes that digest extracellular matrix components. However, B. burgdorferi bound human plasmin, plasminogen (Pgn), and urokinase-type plasminogen activator (uPA). When spirochetes were sequentially incubated with Pgn and uPA, bioactive plasmin was generated on the surface of B. burgdorferi. B. burgdorferi did not produce an endogenous Pgn activator. Fluorochrome-conjugated uPA and Pgn colocalized to the terminus of the spirochete. In a mouse model, uPA-treated B. burgdorferi were more infectious than control spirochetes. Binding of host uPA and Pgn to form a bioactive extracellular matrix protease on B. burgdorferi represents a mechanism that could facilitate dissemination and localization of spirochetes to sites of vascular injury.

Bone graft harvest site as a determinant of iliac crest strength

Bone graft harvest site fracture can occur after removal of bone from the anterior iliac crest. No biomechanically proven guidelines for safe removal of bone exist. Cadaveric hemipelves were tested in a materials testing system machine, with the harvest site occurring 15-mm posterior to the anterosuperior iliac spine in 8 specimens and 30-mm posterior in 7 specimens. These pelves were then tested to failure by simulating avulsion fractures caused by the forces of the flexors of the hip. Average force at failure was 783 N (standard deviation, +/- 333 N) in the 15-mm group and 1917 N (standard deviation, +/- 735) in the 30-mm group. This study provides objective data which demonstrate that harvest 30 mm posterior to the anterosuperior iliac spine weakens the iliac crest less than harvest 15 mm posterior to the anterosuperior iliac crest. To minimize the possibility of iliac crest fracture after bone graft harvest, bone should be removed at least 30 mm from the anterior superior iliac spine.

Mechanism of apoptosis in peripheral blood mononuclear cells of HIV-infected patients

Lymphocytes from patients with HIV-infection have been shown to undergo accelerated spontaneous apoptosis. Binding of CD4 molecules by HIV envelope protein gp120 and anti-gp120 antibodies can lead to crosslinking of CD4 molecules (CD4XL) in vitro and conceivably in vivo. We have recently shown that CD4XL in vitro, when performed in unfractioned peripheral blood mononuclear cells (PBMC) on normal HIV seronegative donors, is by itself sufficient to induce T cell apoptosis (Blood 82:3392, 1993). To further examine the mechanisms involved in apoptosis, we have examined the expression of Fas antigen (Fas) using 3 color flow cytometry. Fas is a cell surface molecule known to mediate apoptosis-triggering signals. We induced CD4XL in PBMC obtained from normal donors, either by anti-CD4 mAb Leu3a or by HIV-1 envelope protein gp160. PBMC subpopulations were examined for Fas Ag expression and for apoptosis induction by flow cytometry. CD4XL was found to result in increased Fas expression as well as Fas mRNA in lymphocytes and the up-regulated Fas Ag was closely correlated with apoptotic cell death. CD4XL in PBMC also resulted in induction of the cytokines INF-tau and TNF-alpha in the absence of IL-2 and IL-4 secretion. Both these cytokins contributed to Fas Ag up-regulation and antibodies to TNF-alpha and INF-tau abrogated CD4XL-induced Fas up-regulation and T-cell apoptosis. These findings suggest that CD4XL occurring in vivo might play an important role in inducing an abberant cytokine profile (which has been observed in HIV infected individuals) and also in triggering of T-cell apoptosis.

HIV-1 gp160 as a modifier of Th1 and Th2 cytokine response: gp160 suppresses interferon-gamma and interleukin-2 production concomitantly with enhanced interleukin-4 production in vitro

Disease progression in HIV-1 infection is reported to be associated with a gradual shift in CD4+ T cell function from a Th type 1 to a Th type 2 of response, but the underlying mechanism remains unclear. In this study, the effect of HIV-1 envelope glycoprotein gp160 on secretion of cytokines IFN-gamma/IL-2 (Th1 type) and IL-4 (Th2 type) was analyzed using freshly isolated unfractioned peripheral blood mononuclear cells (PBMC), CD4+ T cell lines, and PBMC depleted of CD8+ cells (CD8- PBMC) as target cells. Pretreatment of these cells with HIV gp160 significantly reduced PHA-induced secretion of IFN-gamma and IL-2 but augmented IL-4 production. This effect of gp160 was not observed when the target cells consisted of PBMC depleted of either CD4+ cells (CD4- PBMC) or of CD2+ cells (CD2- PBMC). Pretreatment of gp160 with soluble CD4-immunoglobulin chimeric molecules abrogated the observed effects of gp160, suggesting that CD4-gp120 interaction is required for modification of the cytokine secretion profile. Our results suggest that exposure of CD4+ T cells to HIV-1 envelope proteins may modify the responses evoked by additional stimuli in favor of a Th2-type dominant response.

Cross-linking of CD4 molecules upregulates Fas antigen expression in lymphocytes by inducing interferon-gamma and tumor necrosis factor-alpha secretion

We have recently shown that, in unfractioned peripheral blood mononuclear cells (PBMCs), the cross-linking of CD4 molecules (CD4XL) is sufficient to induce T-cell apoptosis. However, the underlying mechanism for the CD4XL-mediated T-cell apoptosis is largely unknown. Several recent studies have shown that Fas antigen (Ag), a cell-surface molecule, mediates apoptosis-triggering signals. We show here that cross-linking of CD4 molecules, induced either by anti-CD4 monoclonal antibody (MoAb) Leu3a or by human immunodeficiency virus-1 (HIV-1) envelope protein gp160, upregulates Fas Ag expression as well as Fas mRNA in normal lymphocytes. Addition of the tyrosine protein kinase inhibitor genistein or of the immunosuppressive agent cyclosporin A abrogated these effects. The upregulation of Fas Ag closely correlated with apoptotic cell death, as determined by flow cytometry. In addition, CD4XL resulted in the induction of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in the absence of interleukin-2 (IL-2) and IL-4 secretion in PBMCs. Both INF-gamma and TNF-alpha were found to contribute to Fas Ag upregulation and both anti-IFN-gamma and anti-TNF-alpha antibodies blocked CD4XL-induced Fas Ag upregulation and lymphocyte apoptosis. These findings strongly suggest that aberrant cytokine secretion induced by CD4XL and consequent upregulation of Fas Ag expression might play a critical role in triggering peripheral T-cell apoptosis and thereby contribute to HIV disease pathogenesis.

A comparative analysis of distraction rods versus Luque rods in thoracic spine fractures

The findings of this study emphasize the importance of distraction in obtaining and maintaining reduction in upper thoracic fractures that are unstable and collapsing into kyphosis. It also shows that a Luque rectangle construct cannot fulfill this function adequately in this type of fracture. Thirty-four consecutive cases of surgically treated upper thoracic spine fractures were reviewed. Two patients died, and 4 were lost to follow-up, so after a minimum 6-month clinical and radiographic follow-up there were 11 patients in the Luque group and 17 in the distraction rod group. Preoperatively, there was no significant difference in age, sex, level of injury or severity of kyphosis between the two groups. The Luque stabilization took an average of 1 h longer. There was no difference in local, general or neurological complications between the groups. Pain at the final follow-up was the same according to analgesic use. The kyphosis in the Luque group increased progressively from preoperative to postoperative values continued and to increase. In the distraction rod group the postoperative kyphosis was improved compared with the preoperative values. At final follow-up the kyphosis had returned nearly to the preoperative values. The difference in the adequacy of the reduction as measured by percentage of anterior collapse between the two groups is highly statistically significant: distraction rod better postoperatively, P = 0.0114 (Student's t-test); distraction rod better at final follow-up, P = 0.0054 (Student's t-test).

Envelope glycoproteins of HIV-1 interfere with T-cell-dependent B cell differentiation: role of CD4-MHC class II interaction in the effector phase of T cell help

T-cell-dependent B cell differentiation involves two phases: an inductive phase of T cell activation followed by an effector phase, which involves stimulation of B cells by activated T cells. We have previously demonstrated that anti-CD3 mAb and antigen-induced T-cell-dependent B cell functions are inhibited by HIV-1 envelope glycoprotein, gp120, at the inductive phase of T-cell-dependent B cell response. In this study we have investigated whether gp120 also inhibits the effector phase of interactions involved in T-cell-dependent-B cell differentiation response. For these studies, CD4+ T cells were first activated with antigen or pokeweed mitogen, cultured with soluble HIV-gp120 or medium for 2 hr, and washed. Coculture of gp120-treated preactivated T cells with autologous B cells resulted in impairment of IgG secretion, but did not affect IgM secretion significantly. The IgG secretion was restored by the addition of PMA (activator of protein kinase C) or forskolin (activator of adenylate cyclase), but not by the addition of ionomycin (inducer of intracellular calcium) to the T plus B cell cultures. A similar pattern of Ig secretion (IgM, no IgG) was observed with B cells of a patient with bare lymphocyte syndrome, indicating a requirement for MHC class II molecule interaction with T cells. These studies suggest that the effector phase of T-B cell interactions are impaired by gp120, and that the mechanism involves a signal transducing event(s), which is dependent upon cyclic AMP and/or protein kinase C. Furthermore, these latter reactions occur subsequent to T-B cell contact-dependent interactions at the effector phase, which involve MHC class II molecules on B cells and CD4 molecules on T cells.

Severe spinal degeneration in Wilson's disease

This case report is the first to report severe spinal degeneration and destruction in Wilson's disease. The presentation, assessment, and decision making for treatment are discussed. This condition should be considered in patients with Wilson's disease who present with back pain.

L-phenylalanine and UVA irradiation in the treatment of vitiligo

In order to evaluate the efficacy of L-phenylalanine (L-Phe) in combination with UVA therapy for vitiligo an open trial (149 patients, 18 months) and a small double-blind trial (32 patients, 6 months) were conducted. Oral L-Phe loading resulted in peak plasma levels of L-Phe after 30-60 min and a slight increase in the plasma tyrosine level. Response to L-Phe plus UVA irradiation was positive, and various grades of repigmentation not exceeding 77% in the open and 60% in the blind trial were observed. An increased L-Phe dose resulted in increased L-Phe plasma levels but not in improved clinical results. The optimal L-Phe dose appears to be lower than 50 mg/kg/day. Although it is difficult to draw firm conclusions from the present investigation, we think that L-Phe may have a place in the treatment of vitiligo and its role merits further investigation.