Ultrastructure of lingual enamel epithelium in rabbit permanent incisors

The recent observation thai the lingual surface of the permanent rabbit incisor, in contrast to the rodent incisor, is covered with enamel near the initially formed tip, initiated a histologic study of the enamel epithelium in this region. Tooth buds from fetal New Zealand white rabbits aged 27 and 30 days in utero were processed for transmission electron microscopy. Examination of longitudinal and cross-sections revealed a transition of secretory ameloblasts to postsecretory amelobasts on the facial aspect of the enamel organ. Incisally. the facial ameloblast layer was continuous with postsecretory ameloblasts on the lingual aspect. More apically on the lingual surface, a gradual transition between postsecretory and reduced ameloblasts occurred. This study shows that by day 27 in utero., the ameloblasts on the lingua] aspect of the tooth are in the postsecretory and degenerative stages and that, by day 30, the enamel epithelium lingually has been replaced by cementum on the prismatic enamel and by connective tissue.     

Ten Years of Infective Endocarditis: A Clinicopathologic Study

ABSTRACT The records of 46 patients with infective endocarditis diagnosed either clinically or postmortem were analyzed. Twenty-six patients were over 60 years of age. S. aureus was the predominant organism, almost exclusively found in patients with acute endocarditis. Thirty-six patients had pre-existing heart disease, the most common being non-rheumatic valvular calcification and congenital defects. Two thirds of the patients, especially those with aortic valve regurgitation, developed new or progressive heart failure. A correct clinical diagnosis was established in only 30 patients. Twenty-three patients died, the mortality being 71% in acute and 32% in subacute disease. Only one of eight patients with prosthetic valve infection died. Four patients required urgent valve replacement. Early surgical intervention should be considered in patients with uncontrolled heart failure.     

HLA-B27-Negative Arthritis Related to Campylobacter Jejuni Enteritis in Three Children and Two Adults

ABSTRACT. Five out of 37 patients with proven Campylobacter jejuni enteritis developed arthritis. Two adult patients presented with classical Reiter's syndrome. One of the three children had reactive arthritis, and clinical suspicion of septic arthritis could not be confirmed in two. The acute synovitis subsided usually without treatment in all patients within 3–7 days, while arthralgia persisted longer in 4 patients. HLA-B27 was not present in the 5 patients with arthritis, but was found in 4 others. In Northern Norway, Campylobacter fetus ssp. jejuni is more frequently isolated from stool specimens than Salmonella, Shigella and Yersinia enterocolitica. Synovial fluid should be cultured following Campylobacter jejuni enteritis in arthritis patients.     

Effect of salivary proteins on calcification of oral bacteria

abstract — The calcification of Bacterionema matruchotii (Strain 13 and Strain 14266 ATCC) in vitro was studied by electron microscopy. The microorganisms were incubated for 4 weeks in a medium consisting of an inorganic calcifying solution to which was added filter sterilized concentrated saliva. Calcification occurred in both strains, mainly in the extra-cellular space. In some regions crystal formation occurred in close association with the surface of cell walls or vesicular particles derived from the cells. In other locations, crystals were deposited in a matrix of organic material separate from the bacteria. The latter pattern of calcification was seen also when the medium was incubated without bacteria. When the observations were compared with those of a previous study in which the same strains of B. matruchotii had been incubated in a calcifying solution, it appeared that the addition of salivary proteins to the in vitro system had two major effects: (1) reduced amounts of intra-cellular calcification, as a consequence of the added nutrients which prevented cellular degeneration, and (2) increased intercellular calcification, due to the presence of increased amounts of organic material with affinity for calcium and phosphate. Thus, it appears that the pattern of calcification of oral microorganisms—either intracellularly or extracellularly - is not exclusively a characteristic of each bacterial species or strain, but may be influenced by nutritional factors as well.     

On the chromaffin system of the African lungfish,Protopterus aethiopicus1

The distribution of chromaffin tissue was studied in the African lungfish using Falck-Hillarp fluorescent histochemistry together with quantitative analysis of catecholamines in plasma and tissue extracts. Intensely fluorescent cells form chromaffin tissue in the wall of the atrium, the wall of the most anterior part of the left cardinal vein and the walls of the segmentally arranged intercostal arteries. The arrangement thus appears to be a combination of the situations in cyclostomes, elasmobranchs and teleosts. Adrenaline is present in larger quantities than noradrenaline in the intercostal arteries and the cardinal vein, while noradrenaline dominates in the atrium. During “stress” induced by physical disturbance of the animals, a strong increase in especially the noradrenaline concentration of the plasma was detected.     

Cardiovascular Risk Factors in Type I (Insulin-dependent) Diabetic Patients with and without Proteinuria

ABSTRACT. In diabetes mellitus cardiovascular mortality among patients with increased urinary albumin excretion seems to be higher than in patients with normal urinary albumin excretion. Therefore we investigated blood pressure, total cholesterol, fibrinogen and in vivo platelet adhesion in 61 patients with type I (insulin-dependent) diabetes, 39 without complications, such as retinopathy or proteinuria and 22 with proteinuria and slightly elevated serum creatinine. The two groups had similar age, sex, diabetes duration and glucose control. Blood pressure, total cholesterol, fibrinogen and in vivo platelet adhesion were all significantly elevated in patients with proteinuria (p<0.01), whereas these parameters were normal in the uncomplicated diabetic patients, independent of diabetes duration. The mortality of cardiovascular disease during 20 years' follow-up was significantly higher among patients with proteinuria compared with patients without proteinuria (p<0.001), indicating that these risk factors contribute to the increased cardiovascular mortality in patients with clinical nephropathy.     

Location and ultrastructure of the first cementum formed in rabbit incisors

Abstract The morphology of the continuously erupting rabbit incisor differs characteristically from that of the rodent incisor and is incompletely known. In this study, permanent incisors from fetal New Zealand white rabbits aged 26–30 days in utero were processed for transmission electron microscopy. Examination of longitudinal and cross-sections revealed that disintegration of the epithelial sheath on root analog surfaces was followed by cementogenesis. The first layer of cementum matrix was seen on the mesial aspect and consisted of a finely granular ground substance and a few embedded collagen fibrils which extended to the cementodentinal junction. Within the period 27–30 days in utero, acellular cementum was formed on all root-analog surfaces and, in addition, formed a fine coating over the enamel. Although the initially formed cementum layer contained fewer collagen fibrils than subsequent layers, a layer of so-called intermediate cementum was not observed.