Sub-lethal effects on offspring of male rats treated with methadone before mating

We have observed that ingestion of methadone (METH) by male rats prior to mating greatly increased the neonatal death rate of their offspring. In this experiment male rats were allowed drinking water containing METH for 24 hrs, alone or in the presence of females, and then mated with drug-naive females. When both males and females were exposed to METH the frequency of matings was decreased. Offspring of METH males were lighter in weight at birth and at weaning, particularly if their sires had been exposed to females during the period of METH ingestion. Although the neonatal death rate of the METH offspring was more than twice that of controls this difference was not statistically significant. The enhancement of METH effects by concurrent exposure to females leads us to propose that the locus of action of METH is the developing spermatozoa.

Immune components in dental plaque

Acquired pelicle appears to contain primarily IgA and other proteins of salivary origin. With the increased time necessary for plaque formation, gingival crevicular fluid contributes proteins to the growing plaque accumulation. However, secretory IgA is still the major intact immunoglobulin in plaque samples since appreciable portions of the molecules bearing IgG determinants appear to be degraded to small fragments. Nevertheless, the amount of IgA present in plaque, which could be considered antibody, is too little to account for most of the plaque interactions. Since secretory IgA appears to be resistant to proteolytic degradation by a mixture of plaque enzymes, and IgA fragments are not prominent in plaque extracts, degradation of secretory IgA probably cannot explain the relatively low IgA levels in plaque. It has been shown that salivary IgA antibody can interfere with enzymes responsible for the plaque-forming potential of certain organisms. All the preceding evidence is consistent with our current contention that secretory IgA functions as blocking antibody to interfere with the formation of dental plaque. This could occur by direct inhibition of bacterial polymer formation or by direct or indirect inhibition of bacterial interaction with salivary constituents by secretory IgA. Less than 1% of the plaque interactions can probably be attributed to secretory IgA antibody. IgG may contribute even less since it is degraded.

Minor salivary glands as a major source of secretory immunoglobin A in the human oral cavity

Secretory immunoglobulin A is the predominant immunoglobulin in labial minor salivary gland secretions. Its mean concentration is four times higher in these secretions than in parotid gland secretion. The minor salivary glands can produce 30 to 35 percent of the immunoglobulin A that enters the oral cavity. This, together with the potential accessibility of these glands to antigenic stimulation, suggest that they may be an important source of the immune factors that are involved in the regulation of the microorganisms in the oral environment.

Aperture contrast in thick amorphous specimens using scanning transmission electron microscopy

The contrast observed in thick amorphous specimens using a scanning transmission electron microscope (STEM) can be considerably improved by the use of an optimum collector aperture angle. The size of this angle can be calculated by considering the variation of electron current transmitted through the specimen as a function both of the specimen thickness and of the angle of collection subtended at the specimen. Typically these calculations predict optimum angles to be several times the half-width of the elastic scattering distribution, often 10(-1) rad or more. Observations of biological sections of up to 2 micron in thickness using scanning attachments of commercial transmission microscopes have verifie these results at beam voltages of 50, 100 and 200 kV. Wide angle convergent beam diffraction patterns were used to give accurate values of the effective angles represented by the various collector apertures. Once the linearity of the detector-amplifier system had been established, operation in a line modulation mode enabled quantitative measurements to be made of the image contrast. Such measurements also offer a quick effective method of comparing electron beam penetrations.

Modification of prenatal stress effects in rats by adrenalectomy, dexamethasone and chlorpromazine

This study was designed as a 4 (maternal treatments) by 2 (prenatal stress) factorial. The 4 treatment groups were: chlorpromazine (CPZ) 2.1 mg/kg; dexamethasone (DEX) 38.7 mug/kg; adrenalectomy (ADX); and controls (CON). Half of the females in each group were stressed prior to mating and during gestation. Stress significantly reduced birth and weaning weights of CON offspring but did not affect the weight of CPZ, DEX or ADX offspring. At birth, DEX and ADX offsrping, as well as offspring of partially adrenalectomized females, were significantly lighter than controls; at weaning, only the DEX animals displayed a weight deficit. Stress increased open field activity of ADX offspring but decreased the activity of DEX offspring while the performance of CON and CPZ offspring was not affected. In a food deprivation test at 42 days there were significantly more deaths among male offspring of no stress (32 percent) than of stress (4 percent) females and stress offspring in all groups lost less weight than unstressed offspring in a food deprivation test at 69 days. Avoidance conditioning tests showed effects only in female offspring. Stress significantly decreased avoidances made by CON offspring and increased avoidances made by DEX offspring. Treatment with ADX, CPZ or DEX can prevent the effects of prenatal stress on some characteristics of the offspring, but in other cases the effects are potentiated by these manipulations.

Simple alkanethiol groups for temporary blocking of sulfhydryl groups of enzymes

New reagents for the temporary blocking of active or accessible sulfhydryl groups of enzymes have been developed. These reagents, which are either alkyl alkanethiolsulfonates or alkoxycarbonylalkyl disulfides, rapidly and quantitatively place various RS- groups on the sulfhydryls to generate mixed disulfides. In all cases native enzymes can be regenerated with either dithiothreitol or beta-mercaptoethanol. In general the temporary blocking groups also afford total protection against normally inhibitory thiol blocking agents. When RS- groups were attached to rabbit muscle creatine kinase (EC 2.7.3.2), a trend toward lower residual activities with increasing bulk was observed. Treatment of the native creatine kinase with 14CH3HgC1 led to incorporation of greater than 1 equiv of CH3Hg- group per subunit. This CH3Hg- blocked enzyme was fully active, and the blocking group afforded no protection against iodoacetamide. These results suggest that CH3Hg- and the RS- groups are modifying two different sulhydryl groups on the enzyme. When papain (EC 3.4.4.10) was treated with excess methyl methanethiolsulfonate. complete and rapid inhibition was observed, and 1 equiv of CH3S- was incorporated/mol of active enzyme. Complete protection against normally inhibitory 5,5'-dithiobis(2-nitrobenzoic acid) was afforded by the temporary blocking group. When rabbit muscle glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) was titrated with methyl methanethiolsulfonate, two sulfhydryl groups per subunit were found to be modified, one much more rapidly than the other. If one extrapolates the initial slope of the titration curve, the inactivation of the enzyme would be complete after modification of a single cysteinyl residue per subunit.

Isolation and immunochemical characterization of the group-specific antigen of Streptococcus mutants 6715

The group d antigen of Streptococcus mutans 6515 was isolated from a buffer (pH 7.3)-boiled extract of whole cells and analyzed immunochemically. Rabbits immunized in three different fashions with whole S. mutans 6715 each responded to the same antigenic cell surface component. This presumptive major antigen was found in culture supernatant, sonically treated supernatant, acid and buffer extracts of whole cells, and trichloroacetic acid extract of cell membranes. A crude preparation of this antigen could completely inhibit antibody-mediated cell (S. mutans 6715) agglutination in a spectrophotometric analysis. The antigen was purified from buffer-boiled extracts by gel filtration on columns of Sepharose 4B. The antigen did not migrate to the anode on electrophoresis nor did it contain appreciable quantities of phosphorus, glycerol, or ribitol. This suggested that the d antigenicity did not reside in a teichoic acid. The d antigen contained galactose and glucose as the sole saccharides, in a ratio of 5.9:1.0. Protein (9.5%) appeared to be a portion of the antigen, although Pronase-digested antigen retained the same electrophoretic mobility and could precipitate virtually all (98.6%) purified antibody directed to the intact antigen. The data obtained from hapten innvolved. Glucose also contributed to the immunodominant region. Antibody directed to the d antigen may be of importance in the inhibition of adherence phenomena manifested by S. mutans organisms of the d group.

Effects of local immunization with Streptococcus mutans on induction of salivary immunoglobulin A antibody and experimental dental caries in rats

The effect of local immunization with Streptococcus mutans on dental caries in conventional and gnotobiotic rats was studied. Injection of these animals with S. mutans strain 6715 incorporated into complete Freund adjuvant consistently resulted in the presence of antibody in saliva directed to this organism. This antibody was primarily of the immunoglobulin A class as demonstrated by specific antiglobulin augmentation and gel filtration of antibody activity. Serum antibody was also present. Five experiments have been completed in conventional rats and two in gnotobiotic animals. The immunized group of animals always had lower mean caries scores than comparably sham-immunized or nonimmunized control groups. The numbers of lesions were also always lower in the immunized animals, suggesting a possible interference with the formation of new lesions in immunized animals. The reductions in dental caries and lesions were greater on smooth surfaces than on occlusal surfaces. which might be explained as interference with adherence phenomena demonstrated by S. mutans. It is proposed that salivary immunoglobulin A antibody may be viewed as an ecological determinant in the oral cavity by affecting oral microorganisms and possibly their by-products.

The connective tissue fiber-water interface: physiological and pathological implications

Water has an important role in the maintenance of the structure and strength of collagen fibers. Lathyrism and certain corticoid hormones alter the degree of hydration of the fibers and consequently affect their strength.

Effects of oxygen tension on vascular and other smooth muscle

1. The resting tension of various isolated intestinal and vascular smooth muscle preparations varied directly with the P(O) (2) of the stream of blood used to bathe them.2. This effect was also obtained when artificial salt solution was used and was therefore not due to circulating hormones.3. The effect could not be antagonized by specific pharmacological antagonists such as hyoscine, phenoxybenzamine, hexamethonium, bromolysergic acid, diethylamide or mepyramine.4. The reactions of the isolated organs to catecholamines and 5-hydroxytryptamine (5-HT) were increased by the higher P(O) (2).5. These results support the view that oxygen tension may play a major role in autoregulation of blood flow.

Subacute and late cardiovascular sequelae to low doses of gamma radiation

A battery of in vivo and in vitro tests of cardiovascular performance were used to assess the effects of whole-body gamma radiation (cobalt-60) upon the cardiovascular system of dogs. A new method for study of the pressure-volume relations of isolated surviving arteries is described. Groups of six beagles were exposed to 30 r and 100 r 22 months before death and compared with littermate controls. No differences between irradiated and control dogs could be demonstrated. Eight mongrel dogs received 300 r 30 days before death and were compared with five mongrel controls. The only significant difference observed was in the pressure-volume curves of arteries from irradiated dogs, these vessels having a greater initial tone than control arteries. It is concluded that 30 r and 100 r of whole-body gamma radiation have no demonstrable effect upon the cardiovascular system of dogs irradiated 22 months before study, but that 300 r of gamma radiation does produce a significant abnormality of blood vessels.