The rates of hydrolysis of thymidyl-3',5'-thymidine-H-phosphonate: the possible role of nucleic acids linked by diesters of phosphorous acid in the origins of life.

Thymidyl-3',5'-thymidine H-phosphonate undergoes acid, base, and water-catalyzed hydrolysis. The products were 3'-thymidine H-phosphonate, 5'-thymidine H-phosphonate, and thymidine in a ratio of 1:1:2. The rate constants are 1.8 x 10(-3) M-1 sec-1, 7.2 x 10(3) M-1 sec-1, and 1.5 x 10(6) sec-1 for acid, base and water catalysis, respectively. These values are comparable with previous reports for the rates of hydrolysis of simple dialkyl esters of phosphorous acids. The Arrhenius activation energy for the base-catalyzed reaction is 20 kcal/mol. and the enthalpy and entropy of activation are 19 kcal/mol and -14 eu., respectively. The Gibbs free energy of activation is 23 kcal/mol. The rate constants suggest that nucleic acids linked by diesters of phosphorous acid hydrolyze too rapidly in aqueous solution to have accumulated in useful amounts on the primitive Earth.

Primary bronchopulmonary fibrosarcoma of childhood and adolescence: reassessment of a low-grade malignancy. Clinicopathologic study of five cases and review of the literature.

In children, primary tumors of the lung constitute a unique subset of quasineoplastic and unequivocally neoplastic lesions whose benign or malignant potential is not always predictable on the basis of morphologic findings. One such neoplasm in the latter category is the primary bronchopulmonary fibrosarcoma (PBPF). This clinicopathologic, ultrastructural, and immunohistochemical study documents our experience with five PBPFs in newborns and children up to 11 years of age at diagnosis. The tumors were either endobronchial or intraparenchymal in location. A uniform population of interlacing bundles and sheets of densely arranged spindle cells with variable mitotic activity was observed microscopically in each case. Ultrastructurally, the cells had the features of fibroblasts and vimentin was the only immunohistochemical marker identified. Despite the disturbing pathologic findings, the four children with more than 1 year of follow-up have survived well 4 to 9 years after surgical resection. Our results are compared with the 21 cases of PBPF reported in the literature and the differential diagnosis is discussed.

Benign encephalopathy of pregnancy. Preliminary clinical observations.

A survey of 67 pregnancies in 51 professional women (physicians, psychologists, nurses, administrators, etc.) revealed the occurrence of symptoms of cognitive dysfunction such as forgetfulness, disorientation, confusion and reading difficulties in 28 pregnancies occurring in 21 women. These were unrelated to such factors as age of delivery, percentage weight gain, the baby's sex or birth weight, alcohol consumption, smoking, a history of migraine or allergy or other symptoms occurring during pregnancy such as sleepiness and lack of concentration, irritability, loss of interest in job or nightmares. Nor was there any correlation with hypertension, proteinuria, glycosuria, ketonuria, anemia, or morning sickness. Furthermore, these cognitive disturbances were not related to depression or sleep deprivation. Despite these symptoms, none of the women suffering from them were forced to interrupt their professional activities during pregnancy. The syndrome of benign encephalopathy of pregnancy should be recognized so that simple precautions can be taken to prevent any interference with professional or other activities. The etiology of the syndrome is unknown.

Normal pulmonary vascular resistance and left ventricular hypertrophy in young infants with bronchopulmonary dysplasia: an echocardiographic and pathologic study.

To evaluate the cardiac anatomy and functional hemodynamics in young infants with chronic lung disease, nine patients, aged 2 to 7 months, with a clinical diagnosis of bronchopulmonary dysplasia (BPD) underwent echocardiographic examination. All infants required supplemental O2 (mean FIO2 35%) to maintain adequate systemic oxygenation (Pao2 greater than 50 mm Hg). None of the infants had evidence of a patent ductus arteriosus at the time of examination. Echocardiographic measurements of left and right ventricular systolic time intervals revealed normal systolic time interval ratios suggesting pulmonary vascular resistances. However, echocardiographic evidence of left ventricular hypertrophy was found in eight of the nine infants, while right ventricular anterior wall thickness and right ventricular diastolic dimensions were not increased. Two infants died; marked left ventricular hypertrophy was noted at the time of postmortem examination while the right ventricular wall thickness was normal. The findings of left ventricular hypertrophy led to a retrospective review of autopsy material of seven patients who died with BPD over the past year. In six of seven cases examined, left ventricular posterior wall thickening was noted (range 7 to 11 mm); while the right ventricular wall thickness was normal (range 2 to 5 mm). These data suggest that (1) as assessed by echocardiography, the pulmonary vascular resistance is not significantly elevated in young infants with BPD, and (2) a hypertrophic left ventricle evolves which may assume importance in the pathogenesis of pulmonary edema in BPD, though the precise etiology remains undetermined.