Higher autoantibody levels and recognition of a linear NH2-terminal epitope in the autoantigen GAD65, distinguish stiff-man syndrome from insulin-dependent diabetes mellitus

The smaller form of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD65) is a major autoantigen in two human diseases that affect its principal sites of expression. Thus, destruction of pancreatic beta cells, which results in insulin-dependent diabetes mellitus (IDDM), and impairment of GABA-ergic synaptic transmission in Stiff-Man syndrome (SMS) are both characterized by circulating autoantibodies to GAD65. Anti-GAD65 autoantibodies in IDDM are predominantly directed to conformational epitopes. Here we report the characterization of humoral autoimmune responses to GAD65 in 35 SMS patients, of whom 13 (37%) also had IDDM. All SMS patients immunoprecipitated native GAD65 and the main titers were orders of magnitude higher than in IDDM patients. Furthermore, in contrast to the situation in IDDM, autoantibodies in 35 of 35 (100%) of SMS patients recognized denatured GAD65 on Western blots. Two major patterns of epitope specificity were identified on Western blots. The first pattern, detected in 25 of 35 SMS patients (71%), of whom 11 had IDDM (44%), was predominantly reactive with a linear NH2-terminal epitope residing in the first eight amino acids of GAD65. Nine of nine individuals who were HLA-haplotyped in this group carried an IDDM susceptibility haplotype and HLA-DR3, DQw2 was particularly abundant. The second pattern, detected in 10 of 35 patients (29%) of whom two had IDDM (20%), included reactivity with the NH2-terminal epitope plus strong reactivity with one or more additional epitope(s) residing COOH-terminal to amino acid 101. The second epitope pattern may represent epitope spreading in the GAD65 molecule, but may also include some cases of epitope recognition associated with IDDM resistant HLA-haplotypes. The principal NH2-terminal linear epitope in GAD65 distinguishes the reactivity of SMS and IDDM autoantibodies and may be a determinant of pathogenicity for GABA-ergic neurons. The greater magnitude and distinct specificity of the humoral response to GAD65 in SMS may reflect a biased involvement of the T helper cell type 2 (Th2) subset of CD4+ T cells and antibody responses, whereas IDDM is likely mediated by the Th1 subset of CD4+ T cells and cytotoxic T cell responses.

[Experimental study of the evaluation of efficacy of fluid replacement based on Parkland formula for burn shock]

In order to investigate the effect of fluid resuscitation of burn shock according to Parkland formula and to find out whether it leaves any damage due to hypoxia, 22 male mongrel dogs with 50% III degrees burn were divided randomly into two groups. Group 1 (14 dogs) received no fluid replacement, whereas in group 2 (8 dogs) Ringer's lactate solution was given according to Parkland formula after the injury. Swan-Ganz catheter was inserted to the pulmonary artery before burn. FAP, CVP, PAP, cardiac output and blood gas analysis were measured preburn and at 2, 6, 12, 18, 24, 36 and 48 hours postburn. The results demonstrated that group 1 dogs all died within 12 hours postburn and group 2 dogs all survived over the shock period. However, even in these survived dogs, markedly decreased cardiac output and oxygen consumption were observed over the first 18 hours postburn. This indicated that fluid replacement according to Parkland formula can not completely correct the inadequacy of tissue perfusion, and it may leave certain damage of oxygen deficiency. Therefore, further improvement in fluid resuscitation and combined treatment for early burn shock to raise cardiac output and improve tissue oxygen delivery may be needed.

[Gynecologic operations on patients with valvular heart disease or after cardiac valvular replacement surgery]

For patients with valvular heart disease or after cardiac valvular replacement surgery, the indication of gynecologic operations are remains undefine. We investigated 23 patients who undergoing gynecologic operations with valvular heart disease or after cardiac valvular replacement surgery. The current studies suggest that (1) general gynecologic operations can be performed on patients with valvular heart disease or mild cardiac dysfunction (New York Heart Association, NYHA, classification I-II) under carefully cardiovascular monitoring. (2) gynecologic operations should be done early on patients with giant gynecologic tumor which suggest malignancy and mild cardiac dysfunction (NYHA I-III). (3) on patients with repeated vaginal bleeding and anemia which induced heart failure, gynecologic operations should be performed immediately after cardiac function recovery. (4) on patients who have had mechanical cardiac valvular replacement, anticoagulant therapy should be stopped at 48 hours before gynecologic operations, and resumed at 48 hours after operations to avoid thromboembolism.

Bactericidal activity of low-dose ceftizoxime plus metronidazole compared with cefoxitin and ampicillin-sulbactam

Eighteen volunteers received ceftizoxime 1 g plus metronidazole 500 mg intravenously every 12 hours, cefoxitin 2 g intravenously every 6 hours, and ampicillin-sulbactam 3 g every 6 hours in a triple-crossover, open-label study to compare serum bactericidal titers (SBTs) against two strains of Escherichia coli and Bacteroides fragilis. Serum was analyzed for drug concentration and bactericidal activity. Ceftizoxime-metronidazole exhibited a significantly greater (p < 0.05) area under the bactericidal curve and percentage of the dosing interval with SBTs of 1:2 or above against E. coli than cefoxitin or ampicillin-sulbactam. The respective values were equal to those of ampicillin-sulbactam for one strain of B. fragilis (both greater than cefoxitin) and greater than cefoxitin and ampicillin-sulbactam for the other strain. A 1-g dose of ceftizoxime given with metronidazole 500 mg every 12 hours should be an effective alternative to standard antibiotic treatment of mixed aerobic-anaerobic bacterial infections.

Occurrence of prosaposin as a neuronal surface membrane component

Prosaposin is a precursor of four saposins that are required for the lysosomal hydrolysis of sphingolipids by specific hydrolases. Besides its precursor role, prosaposin also exists as a secreted protein. The present investigation reveals that prosaposin also exists as an integral component of the surface membranes of neuronal cells. Subcellular fractionation studies demonstrate that the membrane-bound prosaposin occurs specifically in plasma membranes of NS20Y rat neuroblastoma cells. An immunohistochemical study of the neuroblastoma cells using rat prosaposin-specific antibodies also showed that a portion of prosaposin is located on the surface of neurites as well as on cell bodies. Similar histochemical studies with antibodies that specifically recognized human prosaposin revealed the presence of prosaposin in dendrites, axons, and cell bodies of subcortical and spinal cord neurons in both human adult brain and in fetal brain (24-wk gestation). These findings suggest an important role of prosaposin in neuronal development.

Development of a method for embedded-culture of pig pancreatic islet-like cell clusters in agarose containing maltose-carrying polystyrene (HEVM) and nicotinamide

A method for embedded-culture of islet-like cell clusters (ICCs) from neonatal pig pancreas is described. The procedure is based on a sequential treatment of the pancreas with a proteolytic enzyme and ethylenediaminetetraacetate (EDTA). During the exposure to EDTA-Dispase, small pieces of pancreas were gradually digested, with gentle stirring. Under- and over-digested pancreatic cell clusters were separated from the pancreatic fragments by filtration, and formed whole islet-like cell clusters in RPMI 1640 containing 11.0 mM D-glucose and 10% fetal bovine serum (FBS). The ICCs were embedded in agarose with or without a gel containing a random copolymer hydroxethylmethacrylate-vinylbenzyl maltonamide (HEVM) of hydroxethylmethacrylate-(HEMA)-vinylbenzyl maltonamide (VMA) and nicotinamide. They remained morphologically intact and a physiological response to acute stimulation with glucose was obtained when they were embedded in the agarose containing HEVM and nicotinamide. These findings suggest that ICCs in agarose containing HEVM and nicotinamide could be a useful tool for morphological, biochemical and molecular biological studies, and also as a potential source of material for transplantation.

Differential expression of GAD65 and GAD67 in human, rat, and mouse pancreatic islets

The smaller form of the autoantigen glutamic acid decarboxylase, GAD65 (formerly the 64,000 M(r) autoantigen), is a major target of humoral autoimmunity in type I diabetes. Human autoantisera have been used extensively to characterize the GAD65 antigen in both rat and human islets, but the protein has escaped detection in mouse islets. We have now analyzed the expression of GAD65 and GAD67, the larger glutamic acid decarboxylase protein, in human, rat, and mouse islets of Langerhans and brain, using human monoclonal islet cell autoantibodies, human autoantisera, and experimentally raised antibodies to glutamic acid decarboxylase. Human monoclonal autoantibodies and experimentally raised antibodies reacted with mouse GAD65 produced in a baculovirus expression system by Western blotting and immunoprecipitation and with GAD65 in mouse brain by immunohistochemistry but failed to detect GAD65 in mouse islets by the latter two methods. However, analysis of mouse islets by Western blotting technique, using the most sensitive experimentally raised antibody, showed that mouse islets express both GAD65 and GAD67 but at levels that are severalfold lower than those in mouse brain or in human and rat islets. Furthermore, both human and rat islets predominantly express GAD65, whereas GAD67 is the major glutamic acid decarboxylase protein in mouse islets. Human islets are significantly distinct from mouse and rat islets and from brain because they only express GAD65, which is consistent with the predominant role of this form as a target of autoantibodies associated with beta-cell destruction in humans. Human as well as rat islet GAD65 are found in both membrane-bound and soluble forms. The low level of glutamic acid decarboxylase expression in mouse islets compared with human and rat islets is likely to have implications for both the development of tolerance to glutamic acid decarboxylase as well as the homing of glutamic acid decarboxylase-specific lymphocytes to the mouse beta-cell. In this context, the results suggest 1) that the mouse is ideal for studies of the consequences of an expression of high levels of glutamic acid decarboxylase in the beta-cell from a transgene and 2) that the rat may be better suited than the mouse for development of nontransgenic animal models of glutamic acid decarboxylase autoimmunity by immunization.

Study on cytomegaloviral infection in acute leukemia patients by polymerase chain reaction

Polymerase chain reaction (PCR) and blot hybridization by probe labelled with digoxin were used to detect human cytomegalovirus (HCMV) DNA in 31 patients with acute leukemia and 20 controls. The positive rate detected by PCR in acute leukemia was 74.2% and 15.0% in the controls. The difference was statistically significant. The results suggest that acute leukemia patients are the high risk population with high infection rate of HCMV. The positive rate detected by digoxin method in acute leukemia was 58.1%. Six patients showed negative results by digoxin method, but positive by PCR. It was demonstrated that PCR was superior to digoxin method in sensitivity. Anti-HCMV IgM in serum of patients was detected at the same time, the positive rate was 16.1%. Only 6 of the 23 PCR positive patients showed positive anti-HCMV IgM. It suggests that the immune response is weak in acute leukemia patients and HCMV recently infected could not be excluded in the anti-HCMV IgM negative cases.

Detection of HCV infection by cPCR in patients with acute leukemia

HCV RNA and anti-HCV were detected respectively by complemented DNA polymerases chain reaction (cPCR) and ELISA in the sera of 28 acute leukemia patients with repeated blood transfusion and changes in liver function. HCV RNA positive rate was 78.6%. Anti-HCV positive rate was 60.7%. 25 subjects showed positive results in HCV RNA or anti-HCV, or in both of them. By combined assessment, the HCV infection rate was 89.3%. Acute leukemia patients were the high risk group of HCV infection because of the lowered immune function and repeated blood transfusion. By cPCR, HCV RNA can be detected earlier and the sensitivity is higher than by anti-HCV. So cPCR is a sensitive and specific method for early diagnosis of HCV infection. The combination of HCV RNA and anti-HCV detection methods may improve the diagnostic rate of HCV infection.

Effect of external acidosis on basal and ATP-evoked calcium influx in cultured astrocytes

The effect of lactic acidosis on calcium influx, accumulation and efflux was studied in primary cultures of neonatal cortical rat astrocytes. Treatment of cultures with 20 mM sodium lactate, pH 6.0, for 10-60 min resulted in a 35% reduction of 45Ca2+ influx. The decrease in calcium influx was pH dependent because a similar reduction was observed in cultures exposed to pH 6.0 without lactate, while no difference was observed in cultures treated with sodium lactate at pH 7.4. Calcium accumulation was also decreased by lactic acidosis (20% reduction), while calcium efflux was unaffected. Studies with lanthanum, an inhibitor of calcium transport, indicated that the effect of lactic acidosis was not due to non-specific leakage of calcium. The reduction in calcium influx was reversible, thereby indicating that the cells were not permanently damaged by lactic acidosis. In addition to basal calcium influx, stimulated influx (mediated by extracellular ATP, 100 microM) was also reduced by 20 mM sodium lactate, pH 6. These findings suggest that protonization of calcium channels or other calcium entry pathways leads to a reduction in calcium influx in astrocytes. This diminished calcium entry, by affecting calcium-dependent mechanisms necessary for such processes as volume regulation, glycogen metabolism, or regulation of ionic permeability, may alter the ability of astrocytes to elicit appropriate responses following CNS injury.

Effects of electroacupuncture of "zusanli" acupoint on high blood pressure and blood hyperviscosity in stress rats

Elevation of blood pressure (BP) and blood viscosity (BV) was induced in unanesthetized Wistar rats by fixing and hanging. Electroacupuncture of "Zusanli" acupoint or microinjection of GABA (60 micrograms/10 microliters) into the IV ventricle of the brain could lower the high BP and BV induced by fixed-hanging, which could be blocked by a microinjection of GABAA receptor antagonist bicuculline (60 micrograms/10 microliters). The results showed that the depressant effect of electroacupuncture of "Zusanli" acupoint on high BP and blood hyperviscosity induced by fixed-hanging might be mediated by the activation of GABAA receptors in the brain.

[Detection of a circulating SJ 70 antigen in human schistosomiasis japonica using a monoclonal antibody]

A double antibody enzyme-linked immunosorbent assay (sandwich ELISA) was used for detection of a circulating antigen from human Schistosoma japonicum infections. This assay involves the use of poly clonal rabbit anti-schistosoma japonicum soluble egg antigen (SEA) antiserum to bind circulating antigen and a monoclonal antibody (MCAb-H4) to identify and quantify this antigen. Sera from 108 S. japonicum infected patients (acute and chronic) were tested. Sera from 93 of 95 (98%) patients with chronic infection were positive for this antigen; sera from 12 of 13 patients (93%) with acute infections were also positive. Antigen was not detectable in control human sera. Sera from 35 chronic schistosomiasis patients were collected between 6 and 12 months after paraziquantel treatment. Circulating antigen was not detectable in the sera from 33 of these patients (94%) and was dramatically reduced in the other two patients.