A biased Gm haplotype and Gm paraprotein allotype in multiple myeloma suggests a role for the Gm system in myeloma development.

The association between a particular Gm haplotype and susceptibility to multiple myeloma (MM) is not clear. The reason is probably because no investigations have so far been carried out on the relationship between the Gm haplotype, which represents the inherited combination of IgG Gm allotypes, and the Gm allotype expressed at the IgG paraprotein (M-component), which reflects the enhanced gene expression within the haplotype in MM. We studied the incidence of Gm allotypic markers present in IgG subclasses in the serum from 52 patients with MM and in parallel with the isolated IgG paraproteins. The results showed that 84.6% of the patients were heterozygous for haplotypes Gm(a; z; n-; g;)/Gm(f; n+/n-; b1; b0; b5) and 15.3% were homozygous for Gm(f; n/n-; b1; b0; b5), while no homozygous Gm(a; z; n-; g) individuals were found among the studied patients. The incidence of these combinations in the healthy population in Serbia is 34%, 66% and < 1%, respectively. Subjects with Gm(a; z; n-; g)/Gm(f; n+/n-; b1; b0; b5) combination are over 10 times [odds ratio (OR) = 10.69; 95% confidence interval 1.67-68] as likely to be affected by the disease as the subjects with homozygous Gm(f; n+/n-; b1; b0; b5) combination (OR = 0.35, 95% confidence interval 0.06-2.23). However, despite the Gm heterozygosity, most of the Gm(a; z; n-; g;)/Gm(f; n+/n-; b1; b0; b5) positive patients with MM (86.3%) had IgG paraprotein with the allotypic marker from the Gm(f; n+/n-; b1; b0; b5) haplotype. Together with patients homozygous for this haplotype, the relative number of patients with serum IgG paraprotein carrying allotypic marker from the Gm(f; n/n-; b1; b0; b5) haplotype was 88.5%. These results suggest that the development of an M-component could be related to a disturbance on chromosome 14q32 carrying the Gm (f; n+/n-; b1; b0; b5) set of genes.

Cultured astrocytes express proteins involved in vesicular glutamate release.

Bradykinin induces receptor-mediated calcium-dependent release of glutamate from cultured astrocytes through a mechanism that is neither due to cell-swelling mechanism nor due to the reversal of the glutamate transporter. Astrocytes may thus release glutamate using a mechanism resembling the neuronal vesicular release of neurotransmitters. Synaptobrevin is a vesicular protein that together with plasma membrane proteins syntaxin and SNAP-25 participate in formation of the anchoring core complex required for initiation of exocytosis. Here, we demonstrate that synaptobrevin II is present in cultured astrocytes. Furthermore, we demonstrate that botulinus toxin type B and tetanus toxin cause a decrease in synaptobrevin II immunoreactivity and abolish bradykinin-induced release of glutamate from cultured astrocytes. While we were not able to demonstrate the presence of SNAP-25 or syntaxin immunoreactivity in cultured astrocytes, pretreatment with BoTx-A (which cleaves SNAP-25) and BoTx-C (which cleaves syntaxins) result in a decrease in the baseline release of glutamate and diminish the bradykinin-evoked release of glutamate from cultured astrocytes. These findings strongly support the notion that astrocytes may release neurotransmitters using a mechanism similar to the neuronal secretory process.

Neuroligand-evoked calcium-dependent release of excitatory amino acids from cultured astrocytes.

The release of excitatory amino acids (EAAs) from neuron-free cultures of neocortical astrocytes was monitored using HPLC. The neuroligand bradykinin caused a dose-dependent receptor-mediated increase in release of the EAAs glutamate and aspartate from type 1 astrocyte cell cultures obtained from rat cerebral cortex. Removal of calcium from the extracellular fluid prevented the bradykinin-induced release of EAAs from astrocytes. The addition of the calcium ionophore ionomycin caused a calcium-dependent release of EAAs. Inhibitors of the glutamate transporters p-chloromercuriphenylsulfonic acid, L-trans-pyrrolidine-2,4-dicarboxylate, and dihydrokainate failed to impair the ability of bradykinin to stimulate glutamate release from astrocytes. alpha-Latrotoxin, an active compound of black widow spider venom, caused a significant increase of the release of glutamate in calcium-containing saline. In calcium-depleted saline, alpha-latrotoxin produced an initial increase in the concentration of glutamate followed by a decline in the concentration of glutamate indicating stimulation of exocytosis coupled with low calcium-induced inhibition of endocytosis. Taken together, these data suggest that astrocytes may release neurotransmitter through a mechanism that is similar to the neuronal secretory process. Given the important role of glutamate in the induction of long-term potentiation, learning, memory, and excitotoxicity, it will be important to determine external signals that control both the uptake and release of glutamate by astrocytes.

[Lipoproteins and lipids of human dental plaque]. / Lipoproteini i lipidi dentalnog plaka coveka.

Host-derived lipoproteins have not yet-been detected in human dental plaque. In this microarea only lipids and lipoprotein polysaccharides known to derive from gram-positive and gram-negative bacterias, were detected. The results of this work show that in human dental plaque there are some components analogous to human serum lipoproteins. The presence of alpha-lipoproteins was established, while beta-lipoproteins could not be detected. The studies of lipids in plaque show that plaque samples contain lipid components similar of serum free cholesterol, free fatty acids, three glycerides and cholesterol esters. Phospholipids were present in extremely small amounts. The results were discussed from the aspect of the possible origin of these lipoprotein constituents as well as from the aspect of specificity and sensitivity of procedures applied in their detection.

[Immunochemical properties of dental plaque proteins. 2. Antigenic characteristics of dental plaque proteins]. / Imunohemijske osobine proteina dentalnog plaka II. Antigene karakteristike proteina dentalnog plaka.

Little is known about the antigenic properties of human dental plaque constituents. In this work an attempt to search for the antigenic properties of dental plaque proteins was made. Rabbits and guinea pigs were immunized with solubilized samples of dental plaque, and the reactivity of obtained antisera was studied. It was found that both rabbits and guinea pigs produced specific antibodies which reacted with the plaque, serum and parotid saliva. After absorption of obtained antisera specific serum or saliva this reaction disappeared, suggesting the absence of antibodies specific for dental plaque only. It was noticed that anti-plaque antisera obtained from different species have not reacted with the same intensity. The stability of formed precipitates was also different depending on antisera. The results were discussed from the aspect of immunogenetics of protein molecules present in plaque, particularly under the conditions when their structure and conformation may be altered.

[Immunochemical properties of dental plaque proteins. 1. Immunochemical similarity between proteins of human dental plaque, serum and saliva]. / Imunohemijske osobine proteina dentalnog plaka. 1. Imunohemijska slicnost proteina dentalnog plaka, seruma i pljuvacke.

The significance of human dental plaque proteins that are of endogenous origin, probably serum or saliva, is still not clear. Little is known about the physico-chemical and immunochemical properties of plaque proteins. This information, however, might be of significance for a better understanding of the possible role of plaque proteins in the aethiology of some oral diseases. The purpose of this work was to identify several proteins in dental plaque of healthy people as well as to investigate the immunochemical similarity of these proteins with appropriate serum or saliva proteins. The results showed that with the exception of IgG all the other proteins detected in plaque were immunochemically identical with the appropriate serum or saliva proteins. The presence of IgG in plaque revealed immunochemical dissimilarity with partial identity with serum IgG. It was established that IgG plaque had no Fc portion. The results were discussed from the current point of view to the problem of immunochemical similarity between proteins in general, as well as from the aspect of specificity of used antisera.

[Physicochemical properties of dental plaque proteins--electrophoretic mobility and molecular weight]. / Fizickohemijske ososbine proteina dentalnog plaka--elektroenergetska pokretiljivost i molekulska masa.

In this work electrophoretic mobility as well as molecular weight of dental plaque proteins were examined. Three types of electrophoresis and three procedures for molecular weight estimation were applied. The results showed that the electrophoretic mobility of some protein fractions present in plaque corresponded to the mobility of human serum albumin, albumin, alpha 1, alpha 2, beta and gamma globulins. The molecular weight of these proteins was estimated as to be 65,000 to 900,000 daltons approximatively. Electrophoretic mobility and molecular weight of dental plaque proteins were similar to the physicochemical properties of human serum albumins, alpha 1 anti-tripsin, transferin, some of the components of complement system, to secretory IgG and to some categories of lipoproteins, all of which we have identified immunochemically in human dental plaque samples.

Challenge with rubella virus after loss of detectable vaccine-induced antibody.

Studies were conducted of experimental challenge with rubella virus in vaccinees whose possession of vaccine-induced antibody after vaccination had been documented and whose antibody level had become undetectable or very low over time. The challenge virus was the Howell strain, which had been shown to produce typical clinical and laboratory features of rubella in susceptible persons. The challenge of the vaccinees resulted in local viral replication in all but one; in viremia, a primary immunologic response, and a secondary antibody response in some; and usually in illness without a rash or in subclinical infection. The results emphasize the importance of continuing careful clinical and laboratory surveillance of vaccinees for determining the persistence of vaccine-induced immunity and of considering methods for identifying and revaccinating the minority of vaccinees who lose such immunity.

Studies of echovirus-12 in volunteers: determination of minimal infectious dose and the effect of previous infection on infectious dose.

A two-part study of echovirus-12 was done in volunteers. In the first part the human infectious dose of the virus was determined in 149 healthy adults with undetectable serum antibody, each of whom drank 0-330,000 plaque-forming units (pfu) of virus in 100 ml of nonchlorinated water. Infection was defined as fecal shedding of virus or significant (fourfold or greater) increases in serum antibody titer. The HID50 (i.e., the dose required for infection of 50% of the volunteers) was 919 pfu. Through statistical analysis of the data by probit transformation, a 1% human-infectious dose of 17 pfu was predicted. These results were used in the second portion of the study to determine the effect of previous infection on the infectious dose. Previously infected volunteers (those with neutralizing serum antibody) were given a dose of echovirus-12 (1,500 pfu) that had been found to infect 60% of persons with undetectable serum antibody. The presence of serum antibody caused no significant change in the percentage of volunteers infected by this dose. Furthermore, the concentration of serum antibody did not affect the rate of infection or the duration of viral shedding. These results indicate that previous infection with echovirus-12 does not provide lasting protection against reinfection.