The effect of gravity on the horizontal and vertical vestibulo-ocular reflex in the rat

Horizontal and vertical eye movements were recorded in alert pigmented rats using chronically implanted scleral search coils or temporary glue-on coils to test the dependence of the vestibulo-ocular reflex (VOR) upon rotation axis and body orientation. The contributions of semicircular-canal versus otolith-organ signals to the VOR were investigated by providing canal-only (vertical axis) and canal plus otolith (horizontal axis) stimulation conditions. Rotations that stimulated canals only (upright yaw and nose-up roll) produced an accurate VOR during middle- and high-frequency rotations (0.2-2 Hz). However, at frequencies below 0.2 Hz, the canal-only rotations elicited a phase-advanced VOR. The addition of a changing gravity stimulus, and thus dynamic otolith stimulation, to the canal signal (nose-up yaw, on-side yaw, and upright roll) produced a VOR response with accurate phase down to the lowest frequency tested (0.02 Hz). In order to further test the dependence of the VOR on gravitational signals, we tested vertical VOR with the head in an inverted posture (inverted roll). The VOR in this condition was advanced in phase across all frequencies tested. At low frequencies, the VOR during inverted roll was anticompensatory, characterized by slow-phase eye movement in the same direction as head movement. The substantial differences between canalonly VOR and canal plus otolith VOR suggest an important role of otolith organs in rat VOR. Anticompensatory VOR during inverted roll suggests that part of the otolith contribution arises from static tilt signals that are inverted when the head is inverted.     

Prevalence of hepatitis C virus antibody in a cohort of hemophilia patients

One hundred thirty-one patients followed at the New England Hemophilia Center (Worcester, MA) were tested for antibody to hepatitis C virus (HCV). All but two had used factor concentrate that had not undergone viral inactivation; two patients had used only cryoprecipitate. The overall prevalence of HCV antibody positivity was 76.3%. There was no significant difference in age or the amount of non-heat-treated factor concentrate used between the group that was HCV antibody positive and negative. There was also no significant difference between aminotransferase levels in the two groups. There was a positive association between HCV antibody and the presence of antibody to hepatitis B core antigen and antibody to human immunodeficiency virus. A group of 31 patients were tested twice for HCV antibody at intervals of 35 to 71 months. In this subset, 25 were repeatedly seropositive, 4 were repeatedly seronegative, and 2 went from seropositive to seronegative. These data confirm the previous impression that non-A, non-B hepatitis is a major sequela to the use of pooled coagulation factor concentrates. HCV infection may account for most of the chronic liver disease observed in this population. Anti-HCV testing of plasma donors and improved methods of viral inactivation should prevent new cases from developing.     

Human immunodeficiency virus isolation studies and antibody testing. Household contacts and sexual partners of persons with hemophilia

Virus isolation studies and human immunodeficiency virus (HIV) antibody testing were performed on 87 household contacts of 68 HIV antibody-positive hemophilic patients to determine the extent that HIV could be transmitted through heterosexual or through nonsexual, but intimate contact. Human immunodeficiency virus seropositivity was established for the 68 hemophiliacs by immunofluorescence method or enzyme-linked immunosorbent assay and confirmed by Western blot testing (for 66 patients). Fifty-one nonsexual contacts and 36 sexual partners of these hemophiliacs were tested for HIV antibody by immunofluorescence or enzyme-linked immunosorbent assay and Western blot. All sexual partners and all nonsexual household contacts were HIV antibody-negative, including six partners and nine parents of hemophiliacs from whom the virus had been isolated and seven parents and six partners of patients with AIDS. This study further demonstrates lack of transmission of HIV in intimate, but nonsexual settings, and suggests that heterosexual transmission, although well known to occur, may be relatively uncommon in hemophilic couples when the male and female partner have no other risk factors. It is hoped that intensive education and counseling programs will reduce exposure and maintain a low risk of heterosexual transmission.     

Factor IXa-factor VIIIa-cell surface complex does not contribute to the basal activation of the coagulation mechanism in vivo.

We have infused recombinant factor VIIa into patients with hereditary factor VII deficiency with marked reductions in plasma concentrations of factor IX activation peptide (FIXP), factor X activation peptide (FXP), and prothrombin activation fragment F1+2. These investigations show substantial elevations in these markers of coagulation activation and thereby demonstrate that the factor VII-tissue factor pathway is largely responsible for the activation of factor IX as well as factor X in the basal state (ie, the absence of thrombosis or provocative stimuli). We have administered a monoclonal antibody purified factor IX concentrate to individuals with hemophilia B. These studies show an increase in the plasma levels of FIXP that were initially greatly decreased, but no change in FXP or F1+2. We have also infused highly purified factor VIII concentrate into patients with hemophilia A. The data demonstrate no significant changes in the plasma concentrations of FXP and F1+2. The above observations indicate that factor IXa generated by the factor VII-tissue factor pathway is unable to activate factor X under basal conditions. Based upon the above findings, we outline a model of blood coagulation system function under basal conditions, and suggest a process by which the generation of factor Xa and thrombin might be accelerated during normal hemostasis and in the setting of thrombotic disorders.     

Conservative treatment of low velocity gunshot wounds.

A retrospective study of gunshot wounds of the extremities present 148 patients who had sufficient clinical and radiological follow-up data to assess the results. The routine treatment for this injury consisted mainly of cleansing the wound, introduction of systemic antibiotics in the emergency room followed by hospitalization. More extensive treatment and surgical debridement were done only when intraarticular or vascular injury occurred. Two patients developed infected wounds. In 6 displaced humeral shaft fractures, there were 2 non-unions and one delayed union. In 11 comminuted, displaced fractures of the femoral shaft, one non-union occurred.     

Anaphylaxis after treatment with recombinant factor VIII

BACKGROUND: Treatment of hemophilia patients with recombinant factor VIII concentrates has not previously been associated with anaphylaxis. STUDY DESIGN AND METHODS: A 5-week-old boy with severe hemophilia A developed dyspnea, cyanosis, hypotension, and a diffuse urticarial rash following treatment with a recombinant factor VIII (Recombinate). To identify the cause of anaphylaxis in this patient, the vial lot was examined for the presence of endotoxin, and a checkerboard immunoblotting technique was used to test serum and/or plasma samples from the patient and mother for the presence of antibodies (IgA, IgG, IgE, and IgM) to Recombinate-related antigens (recombinant factor VIII, von Willebrand factor, human serum albumin, Chinese hamster ovary proteins, bovine serum albumin, mouse monoclonal anti-human factor VIII, polyethylene glycol 3350), and to ethylene oxide, the agent used to sterilize the infusion equipment. RESULTS: No immune response directed against the Recombinate-related antigens or ethylene oxide that could be associated with the anaphylactic reaction was identified. Endotoxin was not present upon rabbit pyrogen testing of the therapeutic product. CONCLUSION: These studies failed to show any association between Recombinate and the onset of the allergic reaction. This seems to be the first reported case of anaphylaxis following the infusion of a recombinant form of factor VIII concentrate.