Real-time portal monitoring to estimate dose to skin of patients from high dose fluoroscopy

Since doses to skin of patients from fluoroscopically-guided interventional procedures can be very high, real-time monitoring of skin dose is important for both patient management and quality control. The use of a scintillation detector, placed on the X-ray port to measure potential skin dose, was investigated, focusing on the uncertainties related to the technique. Sources of uncertainty include performance characteristics of the dosemeter, errors in calibration, patient set-up and changes during the procedure. Some of the largest sources of error include uncertainty in source-to-skin distance, heel effect, difficulty in identifying the area of skin principally exposed, calibration error, energy dependence of the dosemeter and the dose rate dependence of the monitor. This technique is found to be beneficial for radiation management, but users must be cognizant of the potential errors of the method and the limitations that these place on quality control and patient management. Knowing the limitations and minimizing the sources of error enhance the utility of the technique.

Notices of violation issued to Texas radioactive material licensees inspected in 1995

Notices of violation stemming from the inspection activities of the Texas Department of Health's Bureau of Radiation Control during calendar year 1995 are summarized and characterized. Although eight distinct general categories of radioactive material licenses were included in the analysis, certain general trends were noted, permitting the formulation of an objective list of the ten most frequent violations cited. In order ranked from the most frequent, these include not following operating or safety procedures, radiation surveys not being performed, inadequate personnel monitoring records, instrumentation not used or out of calibration, radioactive material inventories not performed, leak tests not performed, deficiencies in training for industrial uses, inadequate inspection and maintenance of devices, unauthorized users of radioactive material, and incomplete or absent records for receipt or transfer of radioactive material. Although the analysis was limited to a single state, the results can benefit radiation protection quality assurance programs and health physics continuing education efforts by objectively identifying areas commonly cited for being deficient. The results also reiterate the necessity for proper documentation, as at least seven of the ten most frequent violations issued appear to stem predominantly from the records of radiation protection programs.

Salivary proteolysis of histidine-rich polypeptides and the antifungal activity of peptide degradation products

Incubation of purified synthetic histidine-rich polypeptides, HRP-2, -3, -4, -5, -6 (histatins), with diluted human parotid saliva yielded a series of peptide degradation products whose structures could be determined by gas-phase sequencing of cationic polyacrylamide gel electroblots. Sequencing indicated that two and sometimes three peptides were present in the same Coomassie blue-stained band. By comparing different individuals' salivas it was observed that structural variation occurs, perhaps due to differences in the concentrations or specific activities of salivary proteases. Based on the structural data, four proteolytic enzyme activities are proposed. A trypsin-like and chymotrypsin-like enzymatic activity(s) appear to represent the most active salivary protease; however, both an alanine-lysine endopeptidase and a histidine peptidase activity are also present in parotid saliva. In comparison to HRP-4 or HRP-6, degraded products were less active as antifungal agents against Candida albicans both in blastospore and germ-tube assays.

Histatins 2 and 4 are autoproteolytic degradation products of human parotid saliva

Freshly collected human parotid saliva contains 8 cationic proteins, as demonstrated by capillary electrophoresis. These proteins include lysozyme, histatin 6 and the 6 salivary histidine-rich polypeptides (HRPs 1-6). Neither histatin 2 nor histatin 4 are present in native undegraded parotid saliva but appear only after autoproteolytic degradation of the saliva. Histatin 2 appears to arise through slow degradation of HRP-1, and histatin 4 is mainly produced as a rapid breakdown product of HRP-3.

One-step purification of histidine-rich polypeptides form human parotid saliva and determination of anti-candidal activity

Immunoadsorption affinity chromatography was used to selectively purify the family of the histidine-rich polypeptides (HRPs) from human parotid saliva. The immunoadsorbent was prepared by coupling an enriched preparation of horse anti-(HRPs 2, 3, 4, 5 and 6) IgG to protein G. Both freshly collected stimulated untreated and acidified boiled salivas (5 ml) were applied to the affinity column. When native saliva was used it appeared that all of the components of saliva, with the exception of the HRPs, were present in the fraction nonadsorbed to the affinity column; however, recovery of the HRPs with 0.2 M sodium acetate-HCl, pH 1.8, was poor. Yields of HRPs desorbed from the column with the pH 1.8 treatment were significantly improved if salivary HRP proteolysis was delayed immediately after collection by acidifying the saliva to pH 4.5 followed by a short boiling time period, which neither affected HRP quantification nor biological activity. Affinity chromatography results were checked both by cationic polyacrylamide gel and by capillary electrophoresis. Antifungal activity was found to reside only in the low pH HRP fraction of the immunoadsorbent column, suggesting that it is the histidine-rich family of polypeptides that is responsible for salivary antifungal action.

Salivary anti-candidal assays

Inhibition of Candida albicans blastospore viability by parotid, submandibular-sublingual and whole salivas could not be determined by direct assay of yeast cells in each respective saliva. Determination of antifungal activity could, however, be carried out if saliva was first preincubated with Candida cells and this was immediately followed by removal of saliva and resuspension of yeast cells in nonenriched buffers of pH 5-7 for appropriate incubation periods. To attain accurate reproducible quantitative data, parotid, submandibular-sublingual and whole salivas each required different preincubation times with C. albicans as well as prior acidification and boiling. Acidification was also necessary for optimizing the germ tube assay although, in contrast to blastospore viability, inhibition of blastospore-germ tube conversion could be determined directly in saliva. Salivary antifungal effects on blastospore division were negligible at yeast cell concentrations greater than 10(6) colony-forming units per ml and were found to be independent of pH, whereas salivary inhibition of germ tube formation was significant only at pH 5 in the assay systems employed. The requirement for acidification and an observed enhancement of antifungal activity on aqueous dilution of the saliva suggested that only a fraction of the salivary antifungal components present in saliva were available in the free form to exert their biological activity. These results open up the possibility of investigating salivary antifungal activity in human health and disease.

Antifungal activities of salivary histidine-rich polypeptides against Candida albicans and other oral yeast isolates

Twenty-six oral yeast isolates from 26 donors were tested for their susceptibility to salivary histidine-rich polypeptide-4 (HRP-4) in blastospore viability assays. HRP-4 was observed to inhibit blastospore division in all of the yeast isolates, although inhibition was variable depending upon both species and strain tested. Nine species of Candida and 2 strains of Trichosporon pullulans were included in the study. No significant differences in susceptibility to HRP-4 could be seen, irrespective of where in the oral cavity the yeast isolate was obtained.

The use of capillary electrophoresis to identify cationic proteins in human parotid saliva

Eight proteins, HRPs 1, 2, 3, 4, 5 and 6, lysozyme and histatin 6, are the major cationic components of the parotid salivas of normal healthy individuals. Histatins 2 and 4 appear to be further degradation products of the HRPs. Capillary electrophoresis separates all of these eight components, thus allowing future studies to correlate protein concentration with antimicrobial activity in health and disease.

Assessment of antimicrobial treatment of denture stomatitis using an in vivo replica model system: therapeutic efficacy of an oral rinse

Five denture stomatitis patients demonstrating Candida albicans on both maxillary dentures and palates volunteered to test the effects of Peridex oral rinse in treating their oral disease. They used Peridex rinse both as a mouthrinse and as a denture soak for a period of 24 days. Agar replicas of the tissue-fitting surfaces of the maxillary dentures revealed elimination of C. albicans. Significant decreases in palatal inflammation were also noted, although some inflammation was still evident. Several weeks after the termination of Peridex oral rinses, inflammation increased as concentrations of C. albicans on the denture surface returned to pretreatment levels. A marked similarity in the site-specific localization of this yeast species on the denture was noted before and after Peridex rinse treatment.

In vivo antifungal efficacy of salivary histidine-rich polypeptides: preliminary findings in a denture stomatitis model system

Six denture stomatitis patients, all found to have Candida albicans on their maxillary denture and palatal tissue surfaces, volunteered in this preliminary study to test the in vivo efficacy of human salivary antifungal histidine-rich polypeptides (HRPs) in treating their oral disease. The patients were equally divided among the Newton types classification and, as expected, the severity of the inflammation was greatest in the Newton type III patients and least in the Newton type I patients. Patients received sterile solutions of either HRP-3 or HRP-4, which they used both as a mouthrinse and as a denture soak for a period of 1 week. Agar replicas of the tissue-fitting surface of the maxillary dentures revealed HRP reduction and/or elimination of C. albicans from the denture; in one Newton type II individual, this finding directly correlated with a site-specific reduction in palatal inflammation. In the Newton type II and type III individuals alike, there was a significant generalized decrease in inflammation suggesting the therapeutic efficacy of the HRPs. Killing of this yeast species by the HRPs, as determined by scanning electron microscopy (SEM), was probably responsible for the observed clinical benefits noted in this investigation. In the SEM, HRP-treated blastospores appeared severely deflated, as if they had been emptied of significant quantities of intracellular material.

Sensitivity of the replica method in the detection of candidal infection among denture wearers with clinically healthy oral mucosa

To ascertain the role of Candida in denture stomatitis, the practitioner must conduct a mycologic examination of the acrylic resin denture surface, because it acts as a reservoir for continuous reinfection of the palate. Twenty-two patients were examined to compare the sensitivity of the standard technique of swabbing the denture to that of a newly developed cast agar replica technique for detecting Candida albicans. The dentures were swabbed and cast replicas of the tissue-fitting surface of the dentures were made of both study populations. The majority of cultures obtained by swabbing failed to detect the presence of Candida albicans, while all cast agar replicas grew Candida albicans. The replica method for the detection of Candida albicans in edentulous patients seemed to be a more sensitive method than currently available mycologic methods.

Role of pH in salivary histidine-rich polypeptide antifungal germ tube inhibitory activity

Purified synthetic salivary histidine-rich polypeptides (HRPs) 2, 3, 4, 5 and 6 were found to inhibit Candida albicans conversion of blastospores to germ tubes. HRP-4 was the best inhibitor within the pH 5 to 7 range tested and all of the HRPs were observed to lose potency as the pH was raised from 5 to 7. The pH pattern obtained with a synthetic homologous histidine peptide suggested that the protonated form of the histidine imidazole residues of the HRPs was important to the germ tube antifungal activity. Similar pH inhibition profiles of germ tube formation by parotid saliva and the HRPs were also observed.

Parameters affecting the inhibition of Candida albicans GDH 2023 and GRI 2773 blastospore viability by purified synthetic salivary histidine-rich polypeptides

Purified synthetic salivary histidine-rich polypeptides, HRPs 2, 3, 4, 5, and 6, were observed to inhibit Candida albicans blastospore viability at yeast cell concentrations ranging from 10(2) to greater than 10(6) colony forming units per ml. Among the HRPs, HRP-4 was the best inhibitor with significant killing activity noted at a peptide concentration of 0.5 microgram per ml. Antifungal potency under growth conditions was observed to be dependent upon pH. In contrast, killing did not vary throughout the pH range tested under non-growth conditions. Electron microscopy results demonstrated HRP damage at pH 5 which appeared to be initiated at the membrane. At pH 7.4, micrographs revealed clear evidence of intracellular destruction suggesting more extensive damage at neutral as compared to acidic pH. These results suggest that within the changing realm of the oral cavity, the HRPs would be expected to be potent killers of C. albicans.

An in vivo replica method for the site-specific detection of Candida albicans on the denture surface in denture stomatitis patients: correlation with clinical disease

A site-specific agar replica technique for detecting Candida albicans on the acrylic resin denture surface of denture stomatitis patients has been developed. The method is selective for C. albicans during a finite incubation period with a specific synthetic growth medium. C. albicans colonies can be geographically observed on the replica and their presence can be correlated with inflammatory lesions visible on the mucosa of the maxillary and mandibular residual ridges. In 12 denture stomatitis patients studied, a close clinical correlation of Newton type III patients was noted but this clinical correlation could not be observed in Newton type I and II patients. In general, the number of C. albicans colonies increased with the severity of the inflammation. The findings are discussed in light of lack of knowledge of the etiology of the stomatitis. The importance of the replica method is also discussed.

In vitro study on the inhibiting effect of different agents on the growth of Candida albicans on acrylic resin surfaces

This study evaluated at the in vitro level the antifungal effectiveness of nystatin, chlorhexidine, and a homologous histidine polypeptide on the surface of acrylic resin disks. The agents were used in a way that simulated storage of a denture by a denture wearer. Results indicated that pretreatment with poly-L-histidine was not protective against C albicans adherence and growth regardless of whether disks were stored in water or in the open air for the 8-hour period following yeast contamination. Chlorhexidine was totally effective in preventing C albicans attachment to, and growth on, the acrylic resin, even after a period of 8 days of turbidimetric monitoring. Pretreatment with Nystatin, followed by drying, was protective, yielding results similar to those obtained with chlorhexidine.

Sequence determination of low molecular weight salivary histidine-rich polypeptides from electroblots

Saliva contains six major cationic antifungal histidine-rich polypeptides (HRP) which are degraded by salivary proteases to smaller minor peptides. The primary structures of the minor peptides from one of these major HRPs, HRP-5, were elucidated in this study. Digestion of the HRP-5 substrate by human parotid saliva was followed by cationic polyacrylamide gel electrophoresis, electroblotting onto Whatman GF/C paper and gas-phase sequencing of Coomassie blue stained blots. A total of eight minor peptides were structurally analyzed. The smallest molecule characterized contained seven amino acid residues, suggesting that the technique was applicable for sequence determination of cationic peptides in the low molecular weight range.

Model system for the in vitro testing of a synthetic histidine peptide against Candida species grown directly on the denture surface of patients with denture stomatitis

The denture surface provides a nidus for the growth of microbial species that act to initiate, aggravate, and maintain clinical disease. The present investigation describes the development of a model system for the testing of the effectiveness of agents against these microbial species inhabiting the denture surface. It was observed through in vitro growth patterns that the model permitted the testing of representative samples of the microbial flora. Poly-L-histidine was observed to inhibit both Candida albicans and C. glabrata from growing from the denture surface into nutrient broth. Scanning electron microscopy of control and treated denture disks revealed that poly-L-histidine had either eliminated most microbial flora from the denture surface or had effected a noticeable distortion of those Candida blastospores still present on the surface. From microbiologic studies, it appeared that poly-L-histidine had inflicted direct but not lethal damage to the still-attached distorted blastospores because the latter were still able to promote growth in agent-free broth. The antifungal effects of poly-L-histidine were observed to be dependent on the concentration of the polypeptide. The data obtained were consistent for all of the patients regardless of their denture stomatitis classification.

A comparison of the inhibition of blastospore viability and germ-tube development in Candida albicans by histidine peptides and ketoconazole

Synthetic homologous peptides of L-histidine, ranging in length from 3 to 64 amino-acid residues, suppressed blastospore viability. Killing activity was dependent upon the peptide molecular size and concentration, and the time of cell exposure to the agent, but was independent of cell concentration in the range 10(5)-10(7) colony-forming units (c.f.u.) per ml. A 25 amino-acid residue polypeptide, similar to the human parotid salivary histidine-rich peptide (HRP-5), also affected yeast viability. Its killing effect was dependent upon the number of c.f.u. in the assay, as well as contact time with the blastospores and the final peptide concentration. HRP-5 inhibition increased with rising pH in the range 5-7.4, in contrast to poly-L-histidine and ketoconazole, which had optimal candidacidal activity at about pH 6. Poly-L-histidine, HRP-5, and ketoconazole each prevented conversion of blastospores to germ tubes, but their rank order of effectiveness varied with the assay selected. In N-acetylglucosamine-supplemented fetal calf serum, poly-L-histidine and HRP-5 were more effective inhibitors than ketoconazole, but the reverse was true in amino-acid-supplemented glucose beef-extract medium. Reduction of both germ-tube numbers and germ-tube size by HRP-5 was concentration-dependent.

Microbial caries induction in the roots of human teeth in vitro

Streptococcus mutans GS5, Lactobacillus casei DSM20011 and Actinomyces viscosus T14 produce artificial caries in the roots of extracted teeth. Roots were coated with wax leaving an 8 mm2 window exposed on the buccal surfaces, and then incubated for 8 days in the presence of the test organism, the synthetic medium being changed each day. Samples were then examined by SEM, or microradiographs were obtained from 120 microns sections. The pH at the root surface at the end of the induction averaged 4.43, 5.00 and 5.20, and the lesion depths measured on the microradiographs averaged 121, 83 and 34 microns, for Strep. mutans, L. casei and A. viscosus respectively. This relationship between pH and lesion depth confirms earlier findings. As all of these organisms can produce lesions in tooth structure, elimination of one type would probably not eliminate caries.

Inactivation of herpes simplex virus types 1 and 2 by synthetic histidine peptides

Synthetic homologous histidine peptides were found to directly and irreversibly inactivate herpes simplex virus types 1 and 2 (HSV-1 and HSV-2). The inactivation, which occurred within 1 min of virus exposure to the drug, was independent of temperature but dependent upon the pH and molecular size of the polypeptide. Poly-L-histidine consisting of 24 residues (His-24), with a molecular weight (m.w.) of 3,310, inactivated greater than 99% of the virus present at pH 6.0 and 62% at pH 5.0. Poly-L-histidine consisting of 64 (His-64; average m.w., 8,800) or 75 residues (His-75; average m.w., 10,300) inactivated greater than 99% of virus present at pH 5.0 and 6.0. However, His-24, -64, and -75 were not active against these viruses at pH 7.0 or 8.0. At the concentrations tested, poly-L-histidine of 12 (His-12; m.w., 1,665) or 18 (His-18; m.w., 2,487) residues had no effect on HSV-1 or HSV-2 at any of the pHs tested. When these studies were repeated with other basic homologous polypeptides, poly-L-arginine and poly-L-lysine, various degrees of inactivation were observed that were most pronounced in the neutral-to-alkaline pH range. Once virus was inactivated by poly-L-histidine, the effect could not be reversed in vitro by raising the pH to 7.2 or in vivo by injecting the virus into the neutral environment of an animal. These data suggest that the presence of histidine residues in a peptide of suitable structure may endow that peptide with potent antiviral capabilities.

Lysozyme-protease-inorganic monovalent anion lysis of oral bacterial strains in buffers and stimulated whole saliva

Similar to Streptococcus mutans, buffer suspensions of Lactobacillus casei, Lactobacillus plantarum, and Fusobacterium nucleatum all undergo cell lysis when treated with the lysozyme-protease-inorganic monovalent anion antibacterial system. For Lactobacillus species treated with lysozyme and proteases at pHs of 4 and 5.3, lysis resulted when a lytic activating concentration of bicarbonate anion followed enzyme treatment. Furthermore, synergistic lysis of these bacteria was noted when lysozyme-protease treatment was followed by bicarbonate anion used in combination with chloride or fluoride anions. Noteworthy, the halides were not active in promoting lysis when used by themselves in the absence of bicarbonate. For F. nucleatum suspended at pH 6.9, lysis was dependent upon the ionic strength of the buffer and resulted when lysozyme-protease treatment of the organism was followed by 100 mmol/L bicarbonate activation. When lysozyme and proteases were omitted from the incubation mixtures and replaced by stimulated whole saliva, pH 5.3, lysis was observed only with L. plantarum and S. mutans, but not with L. casei. The latter could be lysed, however, if suspended in saliva which was diluted several-fold with distilled water. In experiments where lysozyme was selectively depleted from whole saliva by immunoadsorption affinity chromatography, the great majority of the lysis capability of the saliva for L. plantarum was lost, although a significant degree of lysis appeared to be due to salivary factors other than lysozyme. F. nucleatum was also found to lyse in saliva at neutral pH, suggesting that both Gram-positive and Gram-negative oral bacteria may be susceptible to this antibacterial system in vivo.

Pulmonary paragonimiasis: diagnostic value of pleural fluid analysis

Pleural fluid studies showing a glucose value of less than 10 mg/dl, an LDH level greater than 1,000 IU/L, eosinophilia, a high protein value, and low pH are characteristic of paragonimiasis. In a patient with a pleural effusion and compatible clinical, radiologic, and serologic findings, pleural fluid analysis will allow diagnosis with reasonable certainty even in the absence of positive ova studies, and is useful in distinguishing paragonimiasis from tuberculosis.

Lysozyme-mediated aggregation and lysis of the periodontal microorganism Capnocytophaga gingivalis 2010

The ability of lysozyme to aggregate and lyse the gram-negative capnophilic periodontal microorganism Capnocytophaga gingivalis 2010 was monitored optically at 540 nm. Both hen egg white and chromatographically purified human lysozymes had significant but similar aggregation potentials for both logarithmic- and stationary-phase bacteria. In general, an increase in enzyme concentration resulted in a graded increase in both the initial and maximum changes in turbidity which occurred during the reaction period. The greatest change in turbidity occurred within the initial minutes of interaction of lysozyme and the cells, and the extent of aggregation paralleled a rapid depletion of lysozyme by the suspensions during the first minute of its incubation with the bacteria. Interestingly, the muramidase inhibitors N-acetyl-D-glucosamine and histamine did not block aggregation, whereas maleylation of lysozyme completely inhibited its aggregating ability. Demaleylation, however, restored aggregation activity comparable to the native enzyme, indicating that maleylated lysozyme retained its integrity and that aggregation was primarily dependent on charge. The addition of up to physiological concentrations of NaHCO3 and NaCl to cell aggregates resulted in varying degrees of deaggregation and lysis. Surprisingly, ultrastructural analysis of lysozyme-treated cells revealed morphological changes with or without the addition of salt. Damage appeared to occur at the blunted polar end of the cells where there was a large spherical outpouching bordered by a damaged cell envelope. Damaged cells uniformly contained dense granular cytoplasmic debris. In effect, the cationic enzyme lysed C. gingivalis 2010, which was not apparent in the spectrophotometric assay. The paradoxical finding that during bacterial aggregation there was lysis may be of significance to the further elucidation of lysozyme's antibacterial role in the gingival sulcus.

Pleuropulmonary Whipple's disease

Patients with Whipple's disease usually have gastrointestinal complaints. A broad array of extraintestinal symptoms may precede gastrointestinal complaints by years. In the patient described herein, five years of polyserositis evolved into a nearly fatal illness. Electron microscopy of an intra-abdominal lymph node biopsy led to diagnosis and successful therapy.

Lysozyme-mediated de-chaining of Streptococcus mutans and its antibacterial significance in an acidic environment

The ability of physiological amounts of lysozyme to de-chain two serotype c strains of Streptococcus mutans was determined. Both human and hen lysozymes were equally effective in chain breakage of S. mutans DPR and S. mutans DJR. De-chaining did not affect growth of cultures, but resulted in finely dispersed suspensions, at stationary phase, which were visibly different from untreated cultures. Less than 50 micrograms lysozyme per ml culture medium reduced chain length to virtually all diplococci and single cells, and this chain disruption increased total viable cell count. De-chaining required an active enzyme indicating that a degree of hydrolysis of the peptidoglycan occurred at the septae of the streptococci. De-chained S. mutans did not survive as well as streptococci of normal chain length when incubated under acidic conditions (pH 5.5), but gross cellular lysis was not apparent. The reduced aciduric property of the disrupted chains may have been due to a participation of autolysins or to a lethal triggered by the lysozyme-damaged peptidoglycan. De-chaining may be a mechanism by which lysozyme could regulate the levels of S. mutans in acidogenic plaque samples.

In vitro and in vivo studies of cellular lysis of oral bacteria by a lysozyme-protease-inorganic monovalent anion antibacterial system

Compared with anion-activated cell lysis of oral bacteria damaged with either lysozyme or trypsin, cells which were treated with both of these enzymes showed a far greater degree of lysis. This was true regardless of whether turbidimetric, DNA release, or electron microscopic assays were used to monitor the lytic process. At an acidic pH of 5.2 and an NaHCO3 concentration of 100 mM, the kinetics of lysis for two different serotype c strains of Streptococcus mutans were similar. At 0 to 100 mM bicarbonate, however, differences in the lytic susceptibilities of the two strains were evident. At pH 5.2, NaHCO3, but not NaSCN, NaCl, or NaF, was effective in promoting cell lysis of the oral bacteria. At apparent sublytic concentrations of NaHCO3, lysis was achieved by adding appropriate concentrations of NaSCN, NaCl, or NaF to the lysozyme-protease-damaged cells. In in vivo studies, hamsters given a combination of NaHCO3, NaCl, and NaSCN were found to have significantly reduced levels of S. mutans on their molar teeth compared with that found in controls or animals exposed to any one of the salts alone or to a combination of chloride and thiocyanate only. The results suggest that bicarbonate is an essential anion which, together with the other major salivary inorganic monovalent anions, plays an active role in the lysis and ultimate elimination of cariogenic bacteria.

Growth-inhibitory and bactericidal effects of human parotid salivary histidine-rich polypeptides on Streptococcus mutans

Growth inhibition and cell viability assays demonstrate that the histidine-rich polypeptides isolated from human parotid saliva are bacteriostatic and bactericidal for strains of Streptococcus mutans belonging to the serotype b and c classifications. Both inhibition of growth and cell division are enhanced by preincubation of bacteria with these polypeptides in low-ionic-strength buffers of acidic and neutral pH before dilution into enriched growth media. With prior exposure at pH 6.8, inhibition by these polypeptides of the serotype c strains, S. mutans GS5 and SB, as well as the serotype b strain, S. mutans BHT, is reversible over time under the experimental conditions selected. With similar exposure at pH 5.2, however, irreversible damage is manifested by complete inhibition of both growth and cell viability. At concentrations of 250 micrograms of the mixture of histidine-rich polypeptides per 5 X 10(5) bacterial cells per ml in the acidic preincubation buffer, bacterial lethality is maintained for a period of 48 h in the enriched growth media. At a 50-micrograms/ml concentration of these salivary agents, approximately 80% killing of S. mutans SB is noted after a 24-h incubation; however, surviving bacteria multiply and reach turbidities of untreated control cells when examined at the 48-h growth point. Similarly, hen egg white lysozyme is also found to be bactericidal for these microorganisms when preincubation is carried out under acidic conditions. However, in contrast to the histidine-rich polypeptides, lysozyme under these experimental conditions does not inhibit growth of S. mutans SB at neutral pH, although it does inhibit growth of both S. mutans BHT and S. mutans GS5 at this pH. Preexposure of S. mutans SB to the peptides in buffer at ionic strengths of 0.025 to 0.125, followed by either viability assays under nongrowing conditions or growth inhibition studies, suggests that there is very little effect of ionic strength on the antibacterial function of these peptides. In contrast to the inhibition of viability noted under growing conditions, lower concentrations of the histidine-rich polypeptides were required to elicit immediate cell death under nongrowing conditions.

Development of an enzyme-linked immunosorbent assay for determination of lysozyme in human parotid and submandibular-sublingual salivas

The specificity of lysozyme determinations in human parotid and submandibular-sublingual salivas of two subjects was assessed by comparison of lysozyme concentrations in native acidified salivas with purified enzyme obtained by immunoadsorbent fractionation of the salivas. Lysozyme concentrations were measured by the turbidimetric catalytic method and by a newly developed enzyme-linked immunosorbent assay (ELISA). The validity of the assays was established by comparing assay results with enzyme concentration values determined from optical density-extinction coefficient calculations of the purified lysozyme peak. Values for purified enzyme were found to be similar, irrespective of the assay used to determine lysozyme concentrations, and were in agreement with extinction coefficient calculations. Based on the ELISA technique, recoveries of lysozyme from both parotid and submandibular-sublingual salivas were greater than 75 and 90%, respectively. Similar recoveries were noted for parotid saliva when determinations were based on the turbidimetric assay. However, the ELISA and turbidimetric assays differed with respect to lysozyme levels in submandibular-sublingual saliva because of the apparent presence of an enhancement factor which gave rise to higher lysozyme values in the catalytic assay and therefore resulted in low recoveries of purified enzyme. This catalytic enhancement factor was present in the nonadsorbed fraction of both subjects, as higher lysozyme activities were noted when nonadsorbed fractions were added to affinity-purified lysozymes. Lysozyme levels were also determined in the parotid and submandibular-sublingual salivas of caries-resistant and -susceptible adults. In general, levels of lysozyme in parotid saliva were lower in comparison to submandibular -sublingual saliva; however, significant differences in enzyme concentration were not evident between the caries-resistant and caries-susceptible subjects.

Fungistatic and fungicidal activity of human parotid salivary histidine-rich polypeptides on Candida albicans

Human parotid saliva histidine-rich polypeptides exerted antifungal activity against Candida albicans at concentrations similar to the known antifungal activity of the imidazole antibiotics. Inhibition of both growth and viability could be demonstrated by optical density monitoring and plating assays. Inhibition of growth was observed to be greatest when the histidine-rich polypeptides were added to the inoculum before addition to the growth media. However, complete inhibition by these polypeptides was still noted during active growth at turbidities of C. albicans corresponding to 10(6) CFU/ml. At higher cell densities, growth was delayed but not halted under the experimental conditions investigated. Candidacidal activity was observed with both growing and nongrowing cells. With respect to the latter, reaction of cells in buffer with the histidine-rich polypeptides for a period of 30 min resulted in killing of greater than 90% of two different strains of C. albicans, whereas a third strain was found to be less susceptible. Moreover, the kinetics of loss of cell viability correlated with the loss of potassium from the cells. In addition to the histidine-rich polypeptides, hen egg white lysozyme, poly-L-lysine, and poly-L-histidine affected C. albicans. Both of the polyamino acids completely inhibited the growth of the yeast whereas lysozyme was not as potent. Where delays in growth were observed for all of these agents, including the histidine-rich polypeptides, turbidities reached those of untreated controls after a 24-h period. Enhanced effects were noted if C. albicans was preincubated with these agents in 0.025 2-(N-morpholino)-ethanesulfonic acid buffer, pH 5.2, before growth in the yeast synthetic medium.

Isolation of milligram quantities of a group of histidine-rich polypeptides from human parotid saliva

Freshly collected parotid saliva collected from human donors were shown by polyacrylamide gel electrophoresis to continuously secrete a group of low-molecular-weight cationic polypeptides. Up to 14 bands could be identified by Coomassie blue staining, and all bands migrated more rapidly than purified human leukemic lysozyme in cationic polyacrylamide gel electrophoresis. These peptides could be isolated as a group relatively free of other salivary components and recovered in high yields from concentrated parotid saliva by Sephadex G-25 chromatography. In sodium dodecyl sulfate gel electrophoresis, the histidine-rich polypeptide bands appeared as just two bands migrating at the tracking dye and ahead of insulin chain B. Amino acid analysis of the mixture revealed an average content of at least 48% cationic residues, of which half were histidine. When stained bands were eluted from electrophoretic gels, hydrolyzed, and subjected to amino acid analyses, they were found to be enriched in histidine. There was also a correlation of the electrophoretic mobility with the content of basic amino acids. Sephadex G-25 chromatography is a convenient, simple method for preparing milligram quantities of the histidine-rich polypeptides for chemical and biochemical studies.

Direct measurement of hepatitis B viral antibody and antigen markers in gingival crevicular fluid

Radioimmunoassay analyses of serum are widely performed to monitor the incidence of hepatitis B virus infection. As an alternative to serum analyses, the authors have explored the feasibility of using gingival crevicular fluid for the detection and quantitation of hepatitis B viral immunologic markers. The results of the study demonstrate that the hepatitis B surface antigen can be easily quantified in gingival fluid. Confirmation of the presence of the hepatitis B e antigen can also be made, but this is more difficult because of the small amounts of gingival fluid currently being assayed. Antibody to the hepatitis B surface antigen can be quantitated in high-titered persons.

Factors involved in artificial caries induction by oral streptococci in extracted human teeth

This study assesses the abilities of S. mutans GS5 and BHT and S. sanguis G9B to produce subsurface lesions on smooth surfaces of extracted human teeth and examines factors which might be responsible for any differences encountered. Teeth were incubated in Brain Heart Infusion broth containing 2% sucrose and a pure culture of the organism to be tested, the media being changed each day for eight days. Surface and media pH's were measured. The mineral content of both the surface enamel and the subsurface lesions was determined by contact microradiography. Significantly deeper and more demineralized lesions were produced by GS5 than by either BHT or G9B. GS5 also produced a lower surface and medium pH and a more dense coating on the teeth. Similar results were obtained with GS5 and G9B when the BHI broth was replaced with FMC synthetic media. It is concluded that the system described is suitable for studying cariogenic potential and will be useful in measuring the anticariogenicity of suspected therapeutic agents.

Lytic sensitivity of Actinobacillus actinomycetemcomitans Y4 to lysozyme

The ability of both human and hen egg white lysozymes to lyse Actinobacillus actinomycetemcomitans Y4 was investigated. Lysis was followed optically at 540 nm by measuring the percent reduction in turbidity of freshly harvested log-phase cells suspended in Tris-maleate buffers within a wide range of pH (5.2 to 8.5) and molarity (0.01 to 0.2 M) and containing various amounts of enzyme and EDTA. In several instances, treated microorganisms were subsequently examined in thin sections by electron microscopy. Reductions in turbidity and clearing of suspensions occurred with small amounts of lysozyme (less than 1 microgram) under relatively alkaline conditions and at low ionic strength and in the presence of small amounts of EDTA (greater than 0.01 mM). Under the most alkaline conditions, EDTA alone effected turbidity reductions similar to those observed in the presence of lysozyme, which suggested that EDTA not only increased outer membrane permeability but also caused cell lysis. Ultrastructural analysis did not always correspond to turbidimetric observations. Cell lysis was virtually complete in suspensions containing both lysozyme and EDTA. However, in contrast to turbidimetric findings, a significant percentage of cells (greater than 25%) was lysed in the presence of lysozyme alone. Furthermore, significant damage occurred in the presence of EDTA alone. Spheroplast-like cell ghosts were present which surrounded condensed cytoplasm or relatively clear spaces. These findings further support the concept of the requirement for electron microscopy to assess lytic damage in addition to turbidimetric and biochemical methods. Our results are the first to demonstrate the remarkable sensitivity of A. actinomycetemcomitans Y4 to lysozyme and to show that EDTA not only affects outer membrane permeability but effects cell lysis, possibly through activation of autolytic enzymes at the cytoplasmic membrane. The exquisite sensitivity of A. actinomycetemcomitans Y4 to lysis could be an important mechanism by which lysozyme participates in the regulation of this suspected periodontal pathogen.

Synergism of lysozyme, proteases and inorganic monovalent anions in the bacteriolysis of oral Streptococcus mutans GS5

Streptococcus mutans GS5 was grown in synthetic medium containing radioactive thymidine to monitor deoxyribonucleic acid release. At neutral pH, cell lysis of hen egg-white lysozyme- or lysozyme-protease-treated cells was dependent upon the nature and concentration of the additive inorganic anions, HCO-3, SCN-, Cl- or F-. At acidic pH, NaHCO3, but not NaSCN, NaCl or NaF, was effective in promoting cell lysis which was due not only to the change in pH but also to the new HCO-3 anion concentration at the new pH. In both pH 4 and 5.2 reaction mixtures, the lysozyme and trypsin acted synergistically with NaHCO3 and the amount of lysis produced was markedly greater than in reaction mixtures containing lysozyme and bicarbonate but no protease. At apparent sub-lytic concentrations of NaHCO3, lysis was achieved by adding an appropriate concentration of one of NaSCN, NaCl or NaF to the lysozyme-protease-damaged cells. Thiocyanate proved to be most effective among the anions requiring lower concentrations to elicit lysis compared to chloride or fluoride for a fixed sub-lytic concentration of bicarbonate. As the NaHCO3 concentration increased, the lysis in the presence of these other anions increased until maximum levels of released deoxyribonucleic acid (DNA) were attained. In addition, the higher the NaHCO3 concentration, the more marked was the change in the degree of cell lysis. At a selected concentration at which NaHCO3 was not effective with any one salt, lysis could be achieved by combining all four inorganic anions at this concentration. The results suggest that the various anions present in oral fluids may together be sufficient to trigger lysis of oral microorganisms.

Quantitative recovery, selective removal and one-step purification of human parotid and leukemic lysozymes by immunoadsorption

Immunoadsorption affinity chromatography was used to isolate and purify human lysozyme. The immunoadsorbent was prepared by coupling sheep anti-(human leukemic lysozyme) IgG to epoxy-activated Sepharose 6B. Lyophilized parotid saliva (21) was resuspended in distilled water (325 ml, 50 mg/ml, w/v) and applied to a column which had a capacity to bind 4.25 mg human enzyme. Non-adsorbed material did not contain lysozyme, as determined by enzymatic and immunological analyses. All lysozyme activity present in the applied sample (1.97 mg) bound to and was desorbed from the column by elution with 0.2 M sodium acetate HCl buffer, pH 1.8. The isolated material was homogeneous as determined by cationic and sodium dodecyl sulfate/polyacrylamide gel electrophoresis, ultracentrifugation, amino acid and amino-terminal analyses, and immunoelectrophoretic analysis. The one-step purification procedure yielded a 1370-fold increase in specific activity. Human lysozyme was also selectively purified by this method from an ammonium sulfate precipitate of the urine of a patient with chronic monocytic leukemia. Amino acid and polyacrylamide gel electrophoretic analyses indicated that the purified enzyme was identical to human lysozyme isolated from leukemic urine by classical biochemical techniques.

Bacteriolysis of Streptococcus mutans GS5 by lysozyme, proteases, and sodium thiocyanate

Streptococcus mutans GS5 was grown in a synthetic medium containing radioactive thymidine to monitor cell lysis by assay of the release of DNA. Bacteriolysis was achieved by sequential treatment of the cells with either hen egg white lysozyme and sodium thiocyanate or a combination of hen egg white lysozyme and a proteolytic enzyme followed by addition of the thiocyanate. In the absence of sodium thiocyanate, a small percentage of the total macromolecular thymidine was released in control reaction mixtures during incubation. This amount of released DNA more than doubled in trypsin-treated cells, but the inclusion of lysozyme in reaction mixtures prevented assay of the DNA. Lysis was found to be optimal in the late log phase of growth and was dependent on the concentrations of both lysozyme and protease. Concentrations of trypsin or chymotrypsin as low as 0.01 microgram/ml were found to be effective in enhancing the lytic process. The addition of protease to lysozyme-inorganic salt reaction mixtures altered both the pH and ionic strength profiles of cell lysis. At pHs of 5.5 or lower, both the lysozyme-NaSCN and the lysozyme-trypsin-NaSCN systems were inactive in mediating lysis. The loss of insoluble cell wall peptidoglycan by lysozyme treatment was pH independent and did not appear to be affected by the addition of protease. Either diluted whole saliva or neutrophil extracts could replace trypsin to enhance cell lysis further.

Effects of lysozyme and inorganic anions on the morphology of Streptococcus mutans BHT: electron microscopic examination

The effects of hen egg white lysozyme and the inorganic salt sodium thiocyanate on the integrity of Streptococcus mutans BHT were studied by transmission electron microscopy. Both control cells and cells exposed to NaSCN possessed thick outer cell walls and densely staining inner cell walls juxtaposed to the plasma membranes. In the presence of NaSCN, however, the S. mutans BHT nucleoid was coagulated into thick electron-dense filaments. Exposure of S. mutans BHT to 150 mug of hen egg white lysozyme per ml resulted in the progressive destruction of both the cell walls and the plasma membranes. The enzyme appeared to affect the region of the cell wall septum, and exposure to 150 mug of hen egg white lysozyme per ml for as short a time as 10 min resulted in visible morphological cell wall alterations. At 30 min, ultrastructural observations revealed that the majority of the cells were in the process of expelling a portion of their cytoplasmic contents from the septal and other regions of the cells at the time of fixation. After 3 h of incubation in the presence of this high lysozyme concentration, gelled protoplasmic masses, which were free from the cells, were evident. In addition, extensive damage to the outer and inner cell walls and to the plasma membranes was apparent, although the cells maintained their shape. On some areas of the cell surface, the outer cell wall and plasma membrane were completely absent, whereas at other locations the outer cell wall was either split away from the inner cell wall and plasma membrane or distended from an area free of inner cell wall and plasma membrane. Upon addition of NaSCN to the hen egg white lysozyme-treated cells, both the gelled protoplasmic masses and the damaged cells exhibited an exploded appearance and existed as membrane ghosts, cell wall fragments, or dense aggregates of cytoplasmic components. The effects of a low lysozyme concentration (22.5 mug/ml) on S. mutans morphology were less pronounced at short incubation times (i.e., 10 and 30 min) than those that were observed with a high enzyme concentration; however, breaks in the cell walls and dissolution of the plasma membranes with resulting cell lysis were visible after a prolonged (3-h) incubation and after subsequent addition of NaSCN.

Quantitation of hepatitis B viral markers in a dental school population

Ample evidence exists that dentists and dental personnel are vulnerable to hepatitis B disease. Epidemiologic studies, which provide a further understanding of the prevalence, infectious nature, and risks of transmission of the hepatitis B virus, are particularly significant in a dental school environment because of the insidious nature of the virus. Screening should be done for anti-HBs because it is the most reliable marker for hepatitis B infection and is generally believed to confer immunity. However, because no experimental data are available concerning the amount of antibody needed for protection, quantitation of anti-HBs levels in human serum or gingival crevicular fluid would be the first step in ultimately correlating antibody titers to the immune process. In this study, we present quantitative data on the relative antibody titers in a dental school population. Our findings may be of importance for monitoring the effectiveness of vaccination, for improving safety guidelines in dental clinics, and for developing new and rapid oral diagnostic screening methods. Recently, a new method using gingival crevicular fluid has been developed; it permits identification of not only antibody, but also of hepatitis B surface and e antigens (L. Andors, and associates, unpublished data).

Lysozyme binding by a polyglycerol phosphate polymer of the oral bacterium Streptococcus mutans BHT

The antibacterial properties of lysozyme for Streptococcus mutans BHT may be a function of its binding to cell components other than to peptidoglycan. Inhibitors of muramidase activity, including histamine and N-acetyl-D-glucosamine, only partially blocked the bacteriostatic effects on this strain. Greater than 20 mM histamine alone inhibited growth suggesting a bacteriostatic potential. An autoclaved saline extract was then prepared from stationary phase cultures in a chemically-defined medium. As little as 31.25 micrograms of the extract significantly blocked the effect of 50 micrograms lysozyme and complete enzyme inhibition was achieved with 62.5 micrograms. The extract was fractionated and location of potential binding components determined by a precipitin method consisting of diffusing the samples into 1.2 per cent agarose containing lysozyme. Binding components eluted in the first peak of a Sephacryl S-300 column, bound to DEAE-cellulose, but desorbed with gradient elution (0.1-1.0 M tris-HCl buffer, pH 8.0). The eluted material was then applied to an affinity column containing purified lysozyme coupled to epoxy-activated Sepharose 6B. Non-absorbed anionic material precipitated only with protamine. Lysozyme-binding fractions eluted in a sharp peak with 1.0 M tris-HCl buffer (pH 8.0), did not bind wheat-germ agglutinin, contained less than 50 micrograms protein, 95 micrograms sugar, 66.7 micrograms phosphorus, less than 0.25 mequiv lipid and no detectable nucleic acids. The peak material reacted with antiserum directed against polyglycerol phosphate, indicating that it contained acylated or, possibly, deacylated lipoteichoic acid. The findings suggest that the antibacterial properties of lysozyme for Strep. mutans BHT may, in part, be modified (or possibly regulated) by binding to molecules such as lipoteichoic acid.

Bacteriolysis of Veillonella alcalescens by lysozyme and inorganic anions present in saliva

Veillonella alcalescens subsp. dispar was grown in a synthetic medium containing either radiolabeled thymidine or uridine to monitor cell lysis by assay of the release of deoxyribonucleic acid or ribonucleic acid (RNA), respectively. Biochemical analyses demonstrated that, although human or hen egg white lysozymes alone did not release deoxyribonucleic acid or RNA, the nucleic acids were liberated in equal amounts from lysozyme-treated cells by the addition of low concentrations of the sodium salts of HCO-3, SCN-, Cl-, and F-, RNA release was dependent on enzyme and anion concentration. Human lysozyme was more potent than hen egg white lysozyme, and bicarbonate was the most effective anion in promoting bacteriolysis. Surprisingly, ultrastructural analyses differed from biochemical results. Lysozyme alone caused lysis in approximately 40% of the cell population. Detailed ultrastructural examination revealed aggregated cytoplasmic components which appeared as small clumps, explaining why nucleic acids were not measurable in the biochemical assays. In reaction mixtures containing lysozyme plus inorganic salts, electron microscopy results were compatible with biochemical data. Ultrastructural studies demonstrated that the addition of inorganic salts to lysozyme-treated cells resulted in the solubilization of the protoplasmic aggregates of lysed cells, presumably freeing the complexed RNA, and in the rapid lysis of the remaining cells (approximately 60%). These data suggest that electron microscopy must be used in conjunction with biochemical assays to assess lytic damage of bacterial cells.

Peptidoglycan loss during hen egg white lysozyme-inorganic salt lysis of Streptococcus mutans

Streptococcus mutans BHT was grown in Todd-Hewitt dialysate medium containing N-acetyl[(14)C]glucosamine for 6 to 11 generations. After treatment with cold and hot trichloroacetic acid and trypsin, 52 to 65% of the radioactivity remained present in insoluble peptidoglycan-containing residues. Hen egg white lysozyme or mutanolysin treatment of the peptidoglycan residues resulted in the release of 80 and 97%, respectively, of the (14)C label to the supernatant fraction. Hydrochloric acid hydrolysates of such supernatants showed that essentially all of the radioactivity present in insoluble peptidoglycan fractions was present in compounds that comigrated on paper chromatography with glucosamine ( approximately 60%) or muramic acid ( approximately 30%). Treatment of whole cells with low and high concentrations of lysozyme alone resulted in losses of 45 and 70% of the insoluble peptidoglycan, respectively, yet release of deoxyribonucleic acid from cells was not detected. Sequential addition of appropriate concentrations of selected inorganic salts after lysozyme treatment did result in the liberation of deoxyribonucleic acid. Deoxyribonucleic acid release was correlated with a further release of peptidoglycan from the insoluble fraction. However, the total amount of peptidoglycan lost effected by the low concentration of lysozyme and NaSCN (lysis) was significantly less than the amount of peptidoglycan hydrolyzed by high concentrations of lysozyme alone (no lysis), suggesting that the overall amount of peptidoglycan lost did not correlate well with cellular lysis. The total amount of insoluble peptidoglycan lost at the highest salt concentrations tested was found to be greater than could be accounted for by lysozyme-sensitive linkages of the peptidoglycan, possibly implicating autolysins. The results obtained suggested that hydrolysis of peptidoglycan bonds in topologically localized, but strategically important, sites was a more significant factor in the sequence that results in loss of cellular integrity (lysis).

Lysis of Streptococcus mutans by hen egg white lysozyme and inorganic sodium salts

Streptococcus mutans BHT was grown in a synthetic medium containing radioactive thymidine to monitor deoxyribonucleic acid release. Kinetic experiments demonstrated that although lysozyme alone could not liberate deoxyribonucleic acid, cellular deoxyribonucleic acid was liberated from lysozyme-treated cells by addition of low concentrations of inorganic sodium salts. When the salts were tested for their ability to dislodge cell-bound tritiated lysozyme, the extent of the initial release of enzyme by individual anions correlated with the anion potency for deoxyribonucleic acid liberation (SCN- greater than ClO4- greater than I- greater than Br- greater than NO3- greater than Cl- greater than F-), although the total amount of lysozyme dislodged did not correspond directly with cell lysis. Differences in the effectiveness of anions (SCN-, HCO3-, Cl- and F-) in potentiating cell lysis could be enhanced or minimized by varying the lysozyme, anion, and bacterial cell concentrations. As the anion concentration was increased for each enzyme concentration and cell concentration, the lysis increased, in some cases markedly, until maximum levels of released deoxyribonucleic acid were attained. The maximum levels of lysis of SCN- and HCO3- were similar and were greater than those for Cl- and F-. In addition, the maximum levels were observed to increase for each of the anions as the concentration of lysozyme increased.

Selective antibacterial properties of lysozyme for oral microorganisms

The antibacterial properties of lysozyme were investigated with oral microorganisms representing the seven serotypes (a through g) of Streptococcus mutans, Veillonella alcalescens, and the virulent (V) and avirulent (AV) strains of Actinomyces viscosus T14. Growth of bacteria in defined medium was monitored spectrophotometrically after the addition of various amounts (25 mug to 5 mg/ml) of enzyme. No growth inhibition of V. alcalescens was observed. Inhibition of A. viscosus T14(V) and A. viscosus T14(AV) occurred with 160 mug of lysozyme per ml. Of the S. mutans cultures tested, the serotype a and b strains were inhibited with as little as 25 mug of enzyme per ml, whereas e and f strains were most resistant to the bacteriostatic activity of lysozyme. The presence of dl-threonine or sucrose in growth medium did not significantly affect the results. A lysoplate assay was developed to rapidly survey the bacterial cultures for their susceptibility to the lytic ability of the enzyme. Lysis, as a measure of a zone of clearing in agarose plates, occurred for all microorganisms in the presence of lysozyme after the subsequent addition of NaCl or detergent. The bactericidal activity of lysozyme was determined on S. mutans BHT and S. mutans LM-7 by the pour plate technique. Preincubation of S. mutans LM-7 with as much as 1 mg of enzyme for 90 min did not affect viability or growth, whereas preincubation of S. mutans BHT with 1 mg of lysozyme resulted in no recoverable colony-forming units. An antigen containing extract of S. mutans LM-7 blocked the growth inhibitory property of lysozyme. Human lysozyme was a more effective antibacterial factor than hen egg white lysozyme. Total growth inhibition of S. mutans BHT was effected with 40 mug of human enzyme, and as little as 10 mug of human enzyme inhibited growth for greater than 20 h. The data presented indicate that different mechanisms may be responsible for the bacteriostatic, lytic, and bactericidal properties of the enzyme and that lysozyme is a selective but effective antibacterial factor for oral microorganisms.

Cleft palate following prenatal food restriction in mice: association with elevated maternal corticosteroids

Following food restriction of pregnant CD-1 mice, the maternal serum corticosteroid levels and incidence of skeletal and visceral abnormalities of the progeny were determined. Dams from the groups receiving restricted food on gestation days 6 to 15 had increased resorptions, and the progeny had delayed ossification of the skeleton with cleft palate accompanied by delayed ossification of the presphenoid bone. The incidence and intensity of these changes was correlated with the level of food restriction. The incidence of cleft palate for progeny from dams receiving 4.0 to 2.5 g of feed per day ranged from 6.3% to 100.0%, respectively. Serum corticosteroid levels of pregnant control and food restricted dams were similar on gestation day 10, but the levels of food restricted dams were 6 to 10 times greater than controls on gestation day 15. Thus cleft palate, delayed skeletal ossification, and increased resorptions are predictably produced by food restriction of CD-1 mice and were highly correlated with the elevated endogenous serum corticosteroid levels.