Studies of the mechanism by which chronic metabolic acidosis augments urinary calcium excretion in man

We carried out clearance studies in nine healthy adults and four patients with hypoparathyroidism before and after inducing stable metabolic acidosis with either NH₄Cl or acetazolamide. Clearances were repeated in seven normal subjects and three of the patients 3 days after stopping these agents.     

Thy-L antigen expression on rat brain cell lines.

Cell lines derived from the central nervous system of rats were screened serologically for the presence of Thy-1 (theta), a cell surface differentiation antigen shared by brain and thymus of rats and mice. Both cytotoxicity absorption and indirect immunofluorescence assays were performed using a rabbit anti-rat thymocyte serum (ATS) with Thy-1 specificity. The complement-dependent cytotoxicity of ATS detected a mouse-rat cross-reacting determinant of the molecule bearing the Thy-1 antigen. Of 20 lines tested, 1 of 6 neuronal and 7 of 14 non-neuronal lines expressed Thy-1, as judged by their capacity to absorb ATS cytotoxicity for a Thy-1 positive thymoma line. Similar results were obtained in quantitative absorption assays of these lines employing a mouse anti-Thy 1.1 alloantiserum, but the xenoantiserum (ATS) was more sensitive for detecting the rat molecule bearing Thy-1. Indirect immunofluorescence, which was performed on several of the lines, yielded results in complete agreement with the cytotoxicity absorption assays, and revealed a generalized distribution of antigen in a speckled or patchy pattern over the membrane of cell bodies and processes.     

The B cell IgM Fc receptor: further evidence for the B cell origin of "null" chronic lymphocytic leukemia

Fifty-three cases of chronic lymphocytic leukemia (CLL) were studied for the presence of the B cell IgM Fc receptor (Fc microR) using an aggregated IgM reagent. Restricted surface immunoglobulin, using conventional immunofluorescent techniques and FACS analysis, was detected in 43 cases (81%). The cells in the remaining ten cases (19%) expressed negligible surface immunoglobulin (slg-) and did not form E rosettes (E-), but this "null" subset clearly expressed the B cell Fc microR. The coincident membrane expression of the B1 antigen and the la- like antigen, as well as serial studies showing surface membrane light chain acquisition (in one patient), provided additional evidence for the B cell origin of this slg-E- subset. This subgroup of CLL appears to correspond phenotypically to a normal counterpart at a stage of B cell differentiation between the pre-B cell and the slgM+ early B cell. The B cell Fc microR appears to be a consistent and potentially useful marker for sl gE ("null") CLL.     

Osteoporosis with vertebral compression fractures, retropulsed fragments, and neurologic compromise

Osteoporosis frequently affects the vertebral column and causes compression fractures, biconcave ("fish-mouth") vertebrae, kyphosis, and pain. The cases are reported of three postmenopausal osteoporotic women who had neurologic symptoms of the lower extremities because of vertebral body fractures with a retropulsed fragment narrowing the spinal canal. None of the women had experienced trauma. The fractures resembled burst-type fractures that result from axial loading with major trauma. The retropulsed fragments could be seen best on computed tomographic or magnetic resonance images and were very subtle on conventional radiographs, on which an abnormal posterior vertebral body line was the only abnormality detected. This complication of osteoporosis of the spine is important to recognize so that appropriate treatment can be instituted.     

Prevalence and distribution of alveolar bone loss in a population of 15-year-old schoolchildren

Abstract The prevalence and distribution of bone loss, as assessed by the measurement of loss of attachment, was determined in a group of 15-year-old schoolchildren living in an industrial area in the North-West of England. A total of 46% of the population had loss of attachment ≥ 1 mm, including 11% who had loss of attachment ≥ 2 mm, on at least one tooth. Children of West Indian or Indo-Pakistani origin were most severely affected. Among children of European origin, those attending non-grammar schools showed the higher prevalence. Diagnostic criteria may explain some of the differences between this and previous reports on British teenage populations. The presence of early destructive periodontal disease may represent a useful measure of the need for periodontal treatment in such populations.     

Detection of Prevotella intermedia in subgingival plaque of adult periodontitis patients by polymerase chain reaction

A PCR assay was developed that could specifically amplify DNA from the periodontal pathogen Prevotella intermedia. A pair of primers was selected from regions of the 16S rRNA gene of P. intermedia that were both divergent in sequence at their 3' ends with respect to the corresponding regions of the 16S rRNA gene of P. nigreseens , its most closely related species, and used in the PCR assay. Positivity was indicated by amplification of an 855 bp product. Using purified genomic DNA from these 2 species, assay conditions were determined under which only P. intermedia DNA and not P. nigrescens DNA was amplifiable. Absolute specificity of the assay was confirmed by the fact that no amplification products were obtained when using DNA from several other important periodontal organisms. The optimized PCR assay was used to identify P. intermedia in subgingival plaque samples of patients with adult periodontitis. Confirmation of amplification of P. intermedia DNA was achieved by digestion of PCR products with the restriction endonuclease R sal, which gives different restriction patterns for P. intermedia and P. nigrescens. Of the 97 samples analysed, 38 (39%) were positive for P. intermedia. The results obtained confirm P. intermedia as a possible aetiological agent of adult periodontitis. Additionally, PCR primers targeting the corresponding region of the 16S rRNA gene of P. nigrescens were shown to be specific for the organism when used in a PCR assay, although P. nigrescens was not detectable in any of the subgingival plaques analysed.