New hepatitis B virus mutant form in a blood donor that is undetectable in several hepatitis B surface antigen screening assays

BACKGROUND: Envelope mutant forms of hepatitis B virus (HBV), impairing HBV antibody recognition, have been reported with mutations in single or multiple sites of the hepatitis B surface antigen (HBsAg) group- specific "a" determinant. Blood donors infected with such an HBsAg mutant form of HBV may escape detection by HBsAg screening assays and therefore may affect the safety of the blood supply. CASE REPORT: A repeat blood donor became HBsAg-reactive in an enzyme immunoassay. Confirmatory testing yielded negative results for HBsAg in a radioimmunoassay and in four enzyme immunoassays used in blood donor screening. The specificity of the HBsAg reactivity in the first enzyme immunoassay was confirmed by HBsAg neutralization with antibody to HBsAg. Additional HBV confirmatory test results were positive for antibody to hepatitis B core antigen and antibody to hepatitis B e antigen; negative for antibody to HBsAg and for hepatitis B e antigen; and positive for HBV DNA. DNA sequence analysis of the "a" determinant region of HBsAg revealed amino acid substitutions from Q (Gln) to R (Arg) at codon 129 and from M (Met) to T (Thr) at codon 133. CONCLUSION: This case illustrates the presence of HBsAg mutant forms of HBV in a West European blood donor population that were undetected by several HBsAg screening assays. Adaptation of HBsAg screening is indicated to overcome deficiencies in sensitivity in detecting HBsAg mutant forms of HBV. Screening for antibody to hepatitis B core antigen or HBV DNA may also detect blood donors infected with HBsAg mutant forms of HBV     

Comparative toxicities of cephalosporin antibiotics in a rabbit kidney cell line (LLC-RK1).

The rabbit kidney cell line LLC-RK1 was tested for its ability to discriminate the toxicities of six cephalosporin antibiotics according to their in vivo nephrotoxic potentials in rabbits. With the exception of cephalothin, which was markedly toxic to kidney cells in vitro, a good correlation between in vitro toxicity and in vivo nephrotoxicity was obtained, yielding the following toxicity rank order: ceftazidime less than cefazolin approximately cefoperazone less than cephaloglycin approximately cephaloridine. The addition of a kidney microsomal S9 fraction to the cell cultures desacetylated cephalothin as occurs in vivo and detoxified this antibiotic, providing it with the proper toxicity relative to the other cephalosporins. When compared with parent structures, desacetylated derivatives of other cephalosporins such as cephapirin were similarly found to be less toxic to LLC-RK1 cells. The acetylated cephalosporin cephaloglycin was not detoxified by the kidney S9 fraction and was desacetylated three to four times slower than cephalothin by renal esterases. Thus, the rate and extent of desacetylation of cephalosporins may play a role in their in vivo nephrotoxic potential. Our results further suggest that LLC-RK1 cells will provide a useful model for evaluating the potential nephrotoxicity of new cephalosporin antibiotics before in vivo studies.     

NADPH-diaphorase neurons in the retina of the hamster

NADPH-diaphorase-positive neurons have been demonstrated in the inner nuclear layer and ganglion cell layer of the retina of different mammalian species, but so far no experiments have been conducted to identify whether these cells are amacrine cells and/or retinal ganglion cells. We attempted to solve this problem by studying the NADPH-diaphorase-positive neurons in the hamster retina. From the NADPH-diaphorase histochemical reaction, two distinct types of neurons in the hamster retina were identified. They were named ND(g) and ND(i) cells. The ND(g) cells were cells with larger somata, ranging from 10 to 21 μm in diameter with a mean of 15.58 μm (S.D.= 2.59). They were found in the ganglion cell layer only. The ND(i) cells were smaller, with the somata ranging from 7 to 11 μm and having the mean diameter of 8.77 μm (S.D. = 1.24). Most of the ND(i) cells were found in the inner nuclear layer, and only very few could be observed in the inner plexiform layer. On average, there were 8,033 ND(g) and 5,051 ND(i) cells in the ganglion cell layer and inner nuclear layer, respectively. Two experiments were performed to clarify whether any of the NADPH-diaphorase neurons were retinal ganglion cells. Following unilateral optic nerve section, which leads to the retrograde degeneration of retinal ganglion cells, the numbers of both ND(g) and ND(i) cells did not change significantly for up to 4 months. In addition, when retinal ganglion cells were prelabeled retrogradely (horseradish peroxidase of flurescent microspheres) and retinas were then stained for NADPH diaphorase, no double-labeled neurons were detected. These results indicated that the NADPH-diaphorase neurons in the hamster retina were the amacrine cells in the inner nuclear layer and displaced amacrine cells in the ganglion cell layer. Dendrites of the ND(g) and ND(i) cells were found to stratify in sublaminae 1, 3, and 5 of the inner plexiform layer, with a prominent staining in the sublamina 5. The possible importance of this arrangement in the rod pathway is also discussed. © 1994 Wiley-Liss, Inc.     

Detection and molecular analysis of alpha and beta thalassaemia genes--recent developments in screening protocols.

Molecular and non-molecular techniques have been utilized for the detection and characterisation of alpha- and beta-thalassaemia genes. Non-molecular techniques example, haematological indices and haemoglobin electrophoresis allow samples to be screened rapidly without the use of radionuclides but these techniques are unable to detect mutations at the gene level. Molecular analysis of alpha- and beta-globin genes either by Southern Blotting and radionuclides or DNA amplification using the polymerase chain reaction (PCR) allows detection of specific mutations and have enabled prenatal diagnosis of the thalassaemias.     

Gracile nucleus of streptozotocin-induced diabetic rats

Summary This study reports ultrastructural changes in the gracile nucleus of male Wistar rats after streptozotocin-induced diabetes. During the acute phase (3–7 days) degenerating electron-dense dendrites and axon terminals were dispersed in the neuropil. Degenerating dendrites were characterized by an electron-dense cytoplasm, swollen mitochondria, dilated endoplasmic reticulum and scattered ribosomes. Degenerating axon terminals were characterized by an electron-dense cytoplasm and clustering of small spherical agranular vesicles. Degenerating axon terminals may form part of a synaptic glomerulus with a central electron-dense dendrite, or they may form the central element of a synaptic glomerulus. These degenerating profiles were absent in the gracile nucleus of the 3 and 7 days insulin-treated post-streptozotocin rats. Macrophages were present in the neuropil and were in the process of engulfing neuronal elements. During the medium phase (1–6 months), most of the degenerating dendrites and axon terminals had been engulfed or removed by macrophages. During the late phase (9–12 months) a second wave of degeneration occurred in the gracile nucleus, similar to the acute phase. During the medium and late phases, dystrophic axonal profiles were also significantly increased in the rats after streptozotocin treatment.It is concluded that the ultrastructural changes observed in the gracile nucleus in the present study were the result of streptozotocin-induced diabetes rather than a toxic effect of streptozotocin, even in the acute phase.     

The application of disposable contact lenses in the Navy.

With the recent advent of disposable contact lenses, many of the problems which have been hindering the military application of contact lenses have been overcome. Fifty-five myopic naval personnel with no previous contact lens experience were put through a three-week study using these contact lenses. The aim was to test the feasibility of supplying bespectacled myopic seamen with contact lenses at the outset of operational missions. Seven developed conjunctival injection which caused them to discontinue contact lens wear. Of the remaining 48, however, a vast majority showed preference for contact lenses when compared to spectacles in the work environments that they were exposed to. With contact lenses, 95.8% had comparable or better vision during the day and 85.4% during the night. No serious ocular complications were noted and only minor findings were detected in the 96 eyes at the end of three weeks of contact lens wear.     

The isolation and characterization of a mouse myeloma protein with anti-dextran activity

A myeloma protein in ascitic fluid from BALB/c mice bearing W3129 plasma cell tumors was isolated by affinity chromatography. This protein exhibits anti-dextran activity and has been obtained in highly purified form by selective adsorption on isomaltosyl-Sepharose and elution with isomaltose solution. The isomaltosyl-Sepharose was synthesized from maltose, p-aminophenyl glucoside and cyanogen bromide-activated Sepharose by a new procedure utilizing glucosyltransferase and chemical coupling reactions. Results of gel electrophoresis, isoelectrofocusing and agar diffusion experiments showed that the purified myeloma protein consisted of 6 isomeric proteins with each isomer possessing anti-dextran activity. Data from hapten inhibition studies were interpreted to show that the W3129 myeloma protein combines with terminal isomaltosyl units of branched dextrans and oligosaccharides.     

Arsenic poisoning from anti-asthmatic herbal preparations.

Arsenic poisoning, a disease of the past, was recently found in 74 patients in Singapore over a 15-month period. Most victims (70%) had a chronic form of poisoning and 64% of the cases were caused by a local anti-asthmatic herbal preparation containing 12,000 ppm of inorganic arsenic sulphide. The other patients were poisoned by six other brands of herbal preparations used for the treatment of asthma and a variety of other illnesses. Subsequent investigations revealed another 22 other brands of Chinese herbal preparations containing high concentrations of inorganic arsenic ranging from 25 to 107,000 ppm, of which most were imported. Nearly 40% of the patients had taken the medicine for less than six months, but the others had a longer history of exposure ranging from one to 15 years. Systemic involvement was confined mainly to the skin (91%), nervous system (51%), gastrointestinal system (23%) and blood (23%). Malignancy of the skin was present in six patients, and of the visceral samples, toxicological confirmation was found in half of the cases investigated. There was no correlation between the clinical status of the patients and their tissue arsenic content. The importance of arsenic poisoning by herbal preparations is discussed, as there are no known reports of their association.