278 The biochemical and antibiotic susceptibility tests were done with media supplemented with 0.001% pyridoxal hydrochloride. Therefore, these strains of Strep. mitior should be referred
EFFECT OF COMPONENTS OF INFLUENZA VIRUS VACCINE ON HUMAN
PLATELETS*
to as
"pyridoxal-dependent" not "pyridoxine-dependent". e
School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, U.S.A.
ROBERTA B. CAREY
CEREBRAL VENTRICULAR SIZE IN CHRONIC SCHIZOPHRENIA
*Human platelet suspension in ’Tyrode’ solution containing 0.35% albumin and apyrase.’ Platelets were prelabelled with 14C-serotonin for measurement of release of amine storage granule contents3and with 51Cr for measurement of loss of cytoplasmic constituents.9 Aggregation was recorded with a Payton aggregation module (Payton As-
sociates, Rexdale, Ontario). Concentrations listed the platelet suspension.
are
final concentrations after all additions
to
[thiomersal]). The preservative itself caused platelet aggregation and the release of 40-50% of the contents of the amine storage granules (see table). Leone et a1.8 have also reported that a concentration of thimerosal as low as 20 fLmol/l causes platelet aggregation in human platelet-rich plasma. Since the concentration of thimerosal in the aggregation experiments of Rivard and Potier would have been 25 mol/1 it seems likely that the aggregation they observed was, at least in part, caused by the preservative. It is also possible that other impurities in the vaccine may be capable of causing or contributing to platelet aggregation or that the strains of influenza virus in the vaccine may act like Newcastle disease virus and have several effects on the platelets. It is unlikely that the neuraminidase activity of the vaccine is responsible for its platelet-aggregating effects. It also seems improbable, in our opinion, that subcutaneous or intramuscular injection of 0.5 ml of vaccine would cause sufficient virsemia to produce platelet aggregates in the circulation. S. SCOTT J. F. MUSTARD Department of Pathology, M. CHERNESKY McMaster University, R. L. KINLOUGH-RATHBONE Hamilton, Ontario L85 4J9, Canada Department of Biochemistry,
University ofToronto
SiR,—The correspondence which followed the report of Johnstone et at.’ that the ventricular size of chronic institutionalised schizophrenic patients was larger than that found in a control group included several explanations of the result and highlighted the need for further studies.3.4 During the past three years, eleven patients with a clinical diagnosis of schizophrenia have been examined by computerised tomography (c.T.) at the National Hospital and an assessment of the Evans index2 was made. These patients were referred either from a psychiatric hospital where they were resident or from a general practitioner and the main reason for referral was to exclude organic disease. The diagnosis of schizophrenia was made either by a referring psychiatrist or by psychiatrists at’the National Hospital. Details of these patients and the results of their c.T. scans are given in the table. In each case the Evans index fell within the normal range (
EFFECT OF COMPONENTS OF INFLUENZA VIRUS VACCINE ON HUMAN
PLATELETS*
to as
"pyridoxal-dependent" not "pyridoxine-dependent". e
School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, U.S.A.
ROBERTA B. CAREY
CEREBRAL VENTRICULAR SIZE IN CHRONIC SCHIZOPHRENIA
*Human platelet suspension in ’Tyrode’ solution containing 0.35% albumin and apyrase.’ Platelets were prelabelled with 14C-serotonin for measurement of release of amine storage granule contents3and with 51Cr for measurement of loss of cytoplasmic constituents.9 Aggregation was recorded with a Payton aggregation module (Payton As-
sociates, Rexdale, Ontario). Concentrations listed the platelet suspension.
are
final concentrations after all additions
to
[thiomersal]). The preservative itself caused platelet aggregation and the release of 40-50% of the contents of the amine storage granules (see table). Leone et a1.8 have also reported that a concentration of thimerosal as low as 20 fLmol/l causes platelet aggregation in human platelet-rich plasma. Since the concentration of thimerosal in the aggregation experiments of Rivard and Potier would have been 25 mol/1 it seems likely that the aggregation they observed was, at least in part, caused by the preservative. It is also possible that other impurities in the vaccine may be capable of causing or contributing to platelet aggregation or that the strains of influenza virus in the vaccine may act like Newcastle disease virus and have several effects on the platelets. It is unlikely that the neuraminidase activity of the vaccine is responsible for its platelet-aggregating effects. It also seems improbable, in our opinion, that subcutaneous or intramuscular injection of 0.5 ml of vaccine would cause sufficient virsemia to produce platelet aggregates in the circulation. S. SCOTT J. F. MUSTARD Department of Pathology, M. CHERNESKY McMaster University, R. L. KINLOUGH-RATHBONE Hamilton, Ontario L85 4J9, Canada Department of Biochemistry,
University ofToronto
SiR,—The correspondence which followed the report of Johnstone et at.’ that the ventricular size of chronic institutionalised schizophrenic patients was larger than that found in a control group included several explanations of the result and highlighted the need for further studies.3.4 During the past three years, eleven patients with a clinical diagnosis of schizophrenia have been examined by computerised tomography (c.T.) at the National Hospital and an assessment of the Evans index2 was made. These patients were referred either from a psychiatric hospital where they were resident or from a general practitioner and the main reason for referral was to exclude organic disease. The diagnosis of schizophrenia was made either by a referring psychiatrist or by psychiatrists at’the National Hospital. Details of these patients and the results of their c.T. scans are given in the table. In each case the Evans index fell within the normal range (
