Gingival biopsies from areas characterized as clinically normal, mild gingivitis, or periodontitis were examined. Immunoglobulin (IgG, IgA, IgM, IgE and IgD) bearing cells at the sulcular and oral epithelium -lamina propria junctions as well as the central lamina propria areas were quantitated. Normal gingiva (P. I. = 0-0.2) contained few lymphocytes and plasma cells. Biopsies from areas of mild gingivitis (P.I. = 0.2-1) were infiltrated at the sulcular epithelium -lamina propria junction by lymphocytes lacking membraneassociated immunoglohulins (94 %). Few plasma cells were evident. In contrast, tissue associated with periodontitis (P. I. = 4.0-8.0) contained significant numbers of immunoglobulin hearing lymphocytes (78 %, IgG; 9 %, IgM; and 4 % IgA) and plasma cells (67 %, IgG; 24 %, IgM; and 8 % IgA) distributed throughout all three major tissue areas.These findings indicated that the nature of cellular infiltrates differed in mild gingivitis and periodontitis. The presence of predominantly IgG and IgM containing cells in periodontitis had important implications for the contribution of nonspecific effector mechanisms to the destruction of periodontal tissue. infiltrate has not been resolved. Compara-

Intact teeth were obtained from three cadavers of known age 56, 67, and 76 years, respectively. Cross-sections 100-150 micrometers thick were taken from the roots using a diamond saw. Individual sections were stained, mounted on glass slides, and photographed on a light microscope. The usual number of years for the eruption of any particular tooth were added to the annulation count to determine the estimated age for that cadaver.

Forty patients in active retention following orthodontic tooth movement into premolar extraction sites were examined for the occurrence and distribution of interdental gingival clefts, defined as an invagination of interproximal tissue with definite mesial and distal peaks having a depth of at least 1 mm. Fourteen of the forty orthodontic patients demonstrated clefts in one or more of the premolar extraction sites. No clefts were observed in premolar areas of orthodontic patients who did not require premolar extraction or in patients without previous orthodontic treatment. Interdental clefts occurred most frequently at the buccal aspect of mandibular first premolar extraction sites. The presence of the cleft appears to have clinical implications, both in terms of orthodontic relapse, and maintenance of gingival health.

Saliva and serum electrolyte concentrations were monitored in 30 patients given a course of xerostomia-producing cancer radiotherapy. The mean flow r a t e of stimulated whole saliva decreased 83.3% during a 6-week treatment period. The striking reduction in saliva o u t p u t was accompanied by significant increases in saliva Na+, C1-, Cat+, Mg" and Prot.-concentrations and by a decrease i n saliva HCO; content. The xerostomic saliva was more concentrated and had a greater salinity t h a n t h e pretreatment saliva in each instance. In contrast, none of t h e serum electrolytes measured was significantly altered by t h e subtotal salivary shutdown.Cancer 38:273-278, 1976.

A human isolate of type A Hong Kong influenza virus (H3N2) was adapted to mice by serial passage. Lung homogenates from mice who received low passage levels contained about the same quantity of virus (10 6.2−6.95 50% tissue culture infective doses/ml) as those from mice who received high passage levels (10 5.95−6.45 50% tissue culture infective doses/ml); however, death occurred only in animals given high-passage virus. Passage 3 (P3) and passage 9 (P9) viruses were selected as representative of low-passage and high-passage viruses, respectively. Although minimal differences were detected in infectivity for rhesus monkey kidney tissue cultures and mice, P9 virus was at least 10,000 times more lethal for mice (mean lethal dose = 10 4.2 ). Infection with P3 virus was accompanied by minimal bronchitis and bronchiolitis only, whereas P9-infected animals exhibited marked bronchitis, bronchiolitis, and pneumonia. Striking thymic cortical atrophy was also demonstrable in the P9-infected animals and, although virus was more commonly recovered from thymuses from these animals, immunofluorescent studies revealed only a few cells containing influenza virus antigens. To further explore the participation of thymus-derived lymphocytes in influenza, athymic nude mice and furred immunocompetent littermates were given 500 50% mouse infectious doses of P9 virus. Nude mice exhibited an increased survival time and, in contrast to the extensive lung pathology seen in furred littermates, manifested minimal cellular infiltration and no tissue destruction in lungs. Brains from nude mice exhibited encephalomalacia with lymphocytic perivascular cuffing, which was not seen in furred animals. Virus was recovered from brains of 6 of 13 nude mice and 1 of 10 furred animals. The contrasting models suggest that thymus-dependent cells play a significant role in the inflammatory response to influenza virus infection and should prove useful for probing host-virus interactions which characterize influenza virus virulence.