A sequence-specific polymerase chain reaction assay for mitochondrial DNA polymorphisms in human platelets and white cells

BACKGROUND: Because mitochondria are abundant in white cells and are also present in platelets, polymorphic sequences in mitochondrial DNA (mtDNA) represent a unique target for polymerase chain reaction (PCR)- based detection of donor material. STUDY DESIGN AND METHODS: A PCR assay was developed that uses sequence-specific primers (SSP) focused on two continent-specific mtDNA polymorphisms. Results were validated by the use of informative restriction endonucleases. Three commercially available methods to extract mtDNA from white cell-reduced human platelets was compared. In preparation for in vivo studies, in vitro mixing studies designed to mimic transfusion were conducted to investigate the performance of the SSP-PCR assay. RESULTS: The gene sequences of two representative examples of amplicons obtained with the new SSP-PCR matched the sequence expected from the published genetic code. Fifteen individuals were classified as either positive (n = 6) or negative (n = 9) for the Asian polymorphism by the use of published primers known to flank the polymorphic site followed by digestion with appropriate restriction enzymes. Results with SSP-PCR were nearly perfectly concordant with those of restriction enzyme analysis. Although the use of three DNA extraction methods allowed the preparation of mtDNA that was suitable for PCR, large and consistent differences (ranging from 10- to 1000-fold) in endpoint sensitivity were found. In vitro mixing studies reproducibly documented that the SSP-PCR assay could detect as little as 1 percent of donor platelets mixed with recipient blood. CONCLUSION: PCR-SSP can be reliably used to identify human mtDNA polymorphisms. By optimization of the method of mtDNA extraction, the sensitivity of PCR-SSP assay was greatly increased. This assay should prove useful in investigations of allogeneic platelet transfusions without cell labeling. It may also be applied to studies of the donor cell microchimerism that follows transfusion or transplantation.     

Roxatidine versus ranitidine in the treatment of duodenal ulcers: A randomized double-blind controlled multicentre study in Singapore

Roxatidine acetate, a new H₂ receptor antagonist, was compared with ranitidine in the treatment of duodenal ulcers in a double-blind multicentre study. Eighty-four patients with endoscopically proven duodenal ulcer were randomized to receive 150 mg roxatidine acetate or 300 mg ranitidine at bedtime. Repeat endoscopy was performed after 4 weeks (25–33 days) and if the ulcer had not healed, another endoscopy was performed after a further 4 weeks of treatment. Using per protocol analysis 73.6% of ulcers treated with roxatidine healed at 4 weeks compared to 72.2% of ulcers treated with ranitidine (P=NS). The healing rates at 8 weeks were 92% with roxatidine and 83.3% with ranitidine (P=NS). Using equivalence tests, the healing rate of roxatidine was found to be equivalent to that of ranitidine within a 20% region. Roxatidine users took significantly less antacids than ranitidine users (P < 0.05). There were no significant adverse effects due to roxatidine or ranitidine. Roxatidine is a safe effective drug in the treatment of duodenal ulcers with a healing rate comparable to that of ranitidine.     

A Proposal for the Structure of the Drosophila Genome

We propose a structure for the genome of Drosophila melanogaster in which each chromatid of each chromomere (band) consists on the average of about 30-35 different sequences of single-copy (unique) DNA, each on the average about 750 base pairs in length. These are separated from one another by stretches of the middle repetitive (reiterated) DNA, which in D. melanogaster makes up about 15% of the genome. These stretches are about 100-150 base pairs in length and are all of the same sequence or family in each individual chromomere and of a different family (sequence) in each different chromomere. Our proposed structure of the Drosophila genome is in accord with all of the known facts concerning the physical chemistry and molecular biology of Drosophila DNA.     

Extremely high levels of natural killer cells in angioimmunoblastic lymphadenopathy

Analysis of peripheral blood leukocytes from a patient with angioimmunoblastic lymphadenopathy using monoclonal antibodies and the fluorescence-activated cell sorter showed an unusually high proportion of cells that were OKT10+OKM1+63D3-. Since a large proportion of the large granular lymphocytes associated with natural killing in humans bears this surface phenotype, both blood and lymph node cells were subsequently tested for cell-mediated cytotoxicity in natural killer (NK)-cell assays. Following chemotherapy, both cells bearing the NK surface phenotype and the NK cytotoxicity disappeared and a population of cells, bearing none of the typical lymphocyte or monocyte markers, became dominant. At this point the patient was diagnosed as having immunoblastic sarcoma and shortly thereafter succumbed to his disease. In the few cases where extremely high levels of NK activity have been reported, the tumor cells themselves have been responsible for cell-mediated cytotoxicity. In this case, the final tumor population had no NK activity. Thus either a subpopulation of cytotoxic tumor cells was destroyed by chemotherapy or the patient had expanded numbers of NK cells reacting against his tumor prior to therapy.     

The epidemiology and natural history of asthma

Medically and economically asthma is an extremely important disease that affects about 4 per cent of the United States population every year. Most cases require treatment and many individuals are forced to limit their activities. Asthma is most prevalent in childhood and among older adults and the disease can begin or remit at any age. There is an unexplained predominance of boys among childhood asthmatics. Studies involving skin tests, bronchial challenges, aerometric sampling, and clinical examination have established allergy as important in the etiology of both adult-onset and childhood-onset asthma. Allergen sensitivity is particularly important in childhood-onset disease. The efficacy of allergy immunotherapy in the treatment of asthma is not well established. Seasonal excerbations of asthma suggest sensitivity to pollens, molds, or dusts but may also occur in individuals with nonallergic asthma and may be related to climatic conditions or outbreaks of respiratory infection. Asthma patients often have a history of allergic rhinitis or eczema and these conditions are also frequent in the families of asthmatics. These atopic diseases usually occur at the same time and allergic rhinitis in children should not be considered a harbinger of asthma. Asthmatic attacks are frequently initiated by viral infections, and asthmatic patients appear to have an increased susceptibility to viruses. Bacterial infections are not frequently associated with asthmatic attacks, and the routine use of antibiotics for such episodes is not warranted. Breast-feeding of infants appears to reduce the incidence of atopic disease and infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

Thoracic wall involvement by Hodgkin disease and non-Hodgkin lymphoma: CT evaluation

Thoracic computed tomographic (CT) scans of 250 patients with newly diagnosed or recurrent lymphoma revealed thoracic wall involvement in 24 patients (11 with Hodgkin disease, 13 with non-Hodgkin lymphoma). Thoracic wall involvement occurred without contiguous mediastinal or parenchymal involvement in 17 patients. Of these, 13 patients had masses beneath the pectoralis muscles or within the breast, and four had masses arising from the ribs. Five additional patients had mediastinal masses with thymic involvement and parasternal extension through the thoracic wall. Pulmonary parenchymal lymphoma with thoracic wall invasion was noted in the remaining two patients. In five of nine patients receiving radiation therapy, treatment plans were modified by CT demonstration of thoracic wall lymphoma.