Iris crystals in chronic uveitis.

AIMS: To analyse the unusual physical sign of iris crystals occurring in patients with uveitis. METHODS: Demographic details and clinical features were documented in 24 patients with chronic uveitis and iris crystals. Plasma immunoglobulin subclasses were measured, and a histopathological review of iridectomy specimens from 33 patients with chronic uveitis was also undertaken. RESULTS: The mean age of patients was 38 years, with a slight preponderance of females. 17 patients had Fuchs' heterochromic cyclitis although a number of other uveitis entities were represented. There was no correlation between severity of clinical signs and presence of iris crystals. Over a mean follow up period of 15 months no significant change in the number, size, or position of the crystals was seen except in four patients who underwent intraocular surgery. Only three patients had raised plasma IgG1. The review of the histology of iridectomy specimens failed to show evidence of Russell body formation in any patient. CONCLUSIONS: Iris crystals appear to be rare but may be underreported as they are small and can easily be missed. They are likely to be associated with disease processes in which there is active immunoglobulin production within the anterior chamber, such as Fuchs' heterochromic cyclitis.     

Book review

Basic Guide to Pesticides: Their Characteristics and Hazards

Shirley A. Briggs & Rachel Carson Council, 1993 Hemisphere Publishing Corporation (a member of the Taylor & Francis Group), Washington, Philadelphia and London 283 pp. ISBN 1 56032–253–5, £28.00     

D-aspartate binding to the glutamate uptake site in human brain tissue — effects of leucotomy

Summary Binding of [3 H]D-aspartate, as an indicator of glutamate uptake sites, was investigated in post-mortem human brain tissue by use of a centrifugation assay to separate free and bound ligand. Binding was displaceable, apparently saturable and to a single site, with mean K_D and Bmax values of 2.3 M and 40.3 nmol/g tissue in the frontal cortex. The method was applied to the study of tissue from frontal and temporal cortices and the caudate nucleus of five psychiatric patients who had undergone a frontal leucotomy. The effects of this neurosurgical procedure were to diminish by almost 50% the density of D-aspartate binding sites in the frontal cortex and caudate nucleus, while the temporal cortex was less affected. It is concluded that the method provides a potentially useful correlate of glutamatergic innervation in human brain tissue.     

Cation exchange contribution to the retention of specific quaternary ammonium compounds in reversed-phase high-performance liquid chromatography

The influence of electrolytes on the retention of organic cationic solutes in reversed-phase high-performance liquid chromatography (RP-HPLC) has been investigated. The effects of the nature and concentration of electrolytes and mobile phase pH on the retention of two model quaternary ammonium compounds were studied on mu-Bondapak C18 stationary phase with aqueous methanolic eluents. The nature and concentration of inorganic cations added to the mobile phase modified the retention of the solutes. The counter anion of the added electrolyte did not perceptibly influence solute retention at constant mobile phase pH, although it did significantly influence solute retention when the electrolytes were added to unbuffered mobile phases. The retention data are consistent with the inclusion of an ion exchange contribution to the retention of cationic solutes in the systems investigated.     

Estimates of radiation absorbed dose for intraperitoneally administered iodine-131 radiolabeled B72.3 monoclonal antibody in patients with peritoneal carcinomatoses

Using a newly available model for determining estimates of radiation absorbed dose of radioisotopes administered intraperitoneally, we have calculated absorbed dose to tumor and normal tissues based on a surgically controlled study of radiolabeled antibody distribution. Ten patients with peritoneal carcinomatosis received intraperitoneal injections of the murine monoclonal antibody B72.3 radiolabeled with 131I. Biodistribution studies were performed using nuclear medicine methods until laparotomy at 4-14 days after injection. Surgical biopsies of normal tissues and tumor were obtained. The marrow was predicted to be the critical organ, with maximum tolerated dose [200 rad (2 Gy) to marrow] expected at about 200 mCi (7.4 GBq). In patients with large intraperitoneal tumor deposits, the tumor itself is an important source tissue for radiation exposure to normal tissues. Local "hot-spots" for tumor-absorbed dose were observed, with maximum tumor-absorbed dose calculated at 11,000 rad (11 Gy) per 100 mCi (3.7 GBq) administered intraperitoneal; however, tumor rad dose varied considerably. This may pose serious problems for curative therapy, especially in patients with large tumor burdens.     

Extending epidural blockade for emergency caesarean section. Evaluation of 2% lignocaine with adrenaline

Pre-existing epidural analgesia was rapidly extended in 36 consecutive patients presenting for emergency caesarean section by using 20 ml of 2% lignocaine + 1/200,000 adrenaline freshly prepared given by slow bolus injection. Despite a wide range of initial analgesic sensory levels the technique produced blocks that were dense with adequate anaesthesia for surgery in all patients within 12.5 min. The plasma local anaesthetic concentrations were well below the toxic range. Neonatal condition was good.