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Biomedical subjects

M A Becker

Publications and source records attributed to M A Becker.

101 records · Page 6Linked to original sources
PubMedDate not supplied

Hip involvement in ankylosing spondylitis.

Hip involvement in ankylosing spondylitis (AS) is a common and disabling problem. The clinical and x-ray records of 87 patients with definite AS (Rome criteria) were examined to define and characterize their hip disease. Clinical hip disease was present in 33 cases (38%), was usually bilateral (91%), and tended to begin early in the disease course; it was the cause of 50% of the Class III and IV disability in the entire study group. Typical findings included regional pain, limitation of motion, muscle atrophy, and flexion contractures. Radiologic hip abnormalities occurred in 42 cases (48%). The radiographic pattern was distinctive when compared to that in two control groups and included axial migration of the femoral head (63%), concentric joint space narrowing (50%), rufflike femoral osteophytosis (36%), and protrusio acetabuli (30%). Eight patients required bilateral hip surgery. Para-articular ossification occurred in 8 of 16 replaced hips; in 5 of 8 hips it caused clinical immobility. This potentially serious complication may limit the usefulness of hip arthroplasty in some AS patients.

Adult↗
PubMedDate not supplied

Recent advances in the identification of enzyme abnormalities underlying excessive purine synthesis in man.

Work is continuing in the attempt to increase knowledge of the regulation of the rate of purine synthesis in man by means of an analysis of biochemical alterations leading to purine overproduction among patients with gout. The authors are now assessing the frequency of kinetic mutations in enzymes whose alterations already have been associated with increased purine synthesis. Efforts in this regard have been rewarded by the identification of a new form of alteration leading to partial deficiency of HGPRT and a kinetic variant of PRPP synthetase with increased affinity for ribose-5-phosphate. In order to identify new forms of enzyme abnormalities associated with excessive purine synthesis, the value of a proposed classification scheme requiring measurement of PRPP and ribose-5-phosphate concentration and generation is being assessed in cultured fibroblasts. It is hoped that the results of these measurements will lead to the identification of additional kinetic variants of presently known enzyme abnormalities and will help to identify new classes of mutants in the regulation of human purine metabolism. The excessive purine synthesis that underlies the hyperuricemia of a substantial number of patients with gouty arthritis reflects alterations in the normal mechanism regulating the rate of purine nucleotide synthesis. The study of such purine "overproducers" has provided insight into the nature of this regulatory mechanism and has underscored the diversity of specific genetic and biochemical aberrations affecting it. Despite these advances, however, less than 10% of all patients with gout and excessive purine production can presently be accounted for by known enzyme abnormalities (1). Recognition that current knowledge of the regulation of the rate of purine nucleotide synthesis in man is incomplete has provided the authors impetus leading to the studies described here, which are preceded by a brief review of background.

Adult↗
PubMedDate not supplied

Flow-synchronized ventilation of preterm infants with respiratory distress syndrome.

Asynchrony of delivered and spontaneous breaths in mechanically ventilated infants may impair gas exchange and prolong the need for assisted ventilation. We conducted a randomized, controlled trial of a patient-triggered, flow-synchronized ventilator on 30 preterm infants with respiratory distress syndrome who weighed between 1100 and 1500 gm at birth. Entry criteria included radiographic evidence of respiratory distress syndrome and the need for mechanical ventilation and surfactant replacement therapy. Patients were assigned to either conventional time-cycled, pressure-limited ventilation or patient-triggered, flow-synchronized ventilation in an assist/control mode. Otherwise clinical management was identical. Time to extubation was the primary outcome measure. Patients treated with flow-synchronized ventilation were weaned more rapidly and had a significantly shorter mean time to extubation than those treated with time-cycled, pressure-limited ventilation, 119 versus 271 hours, p = 0.0152. In addition, there was no difference in the rate of complications between the two groups. There were, however, considerable reductions in patient charges of $4344 per patient in the flow-synchronized ventilation group.

Female↗
PubMedDate not supplied

Comparison of two methods of surfactant administration and the effect on dosing-associated hypoxemia.

OBJECTIVE: The purpose of our study was to test the hypothesis that surfactant dosing through a proximal sideport adapter on an endotracheal tube leads to more dosing-associated hypoxemia compared with a method of dosing that uses a double-lumen endotracheal tube. STUDY DESIGN: Using adequate sample size to compare significant changes in O2 saturation (power > 0.8, alpha < 0.05) we enrolled 36 infants with respiratory distress syndrome in this randomized trial. A 10% change in O2 saturation was considered clinically significant. Nineteen infants received 38 doses of surfactant through the sideport adapter. Seventeen infants received 31 doses of surfactant through the nonventilation lumen of a double-lumen endotracheal tube. Two main outcome measures were assessed: time-averaged O2 saturation values 30 minutes after dosing and the largest absolute fall in O2 saturation for each patient. RESULTS AND CONCLUSIONS: Time-averaged O2 saturation measures were higher in the proximal sideport group (p = 0.02), but the magnitude of difference was probably not clinically significant. No significant difference was detected between groups when we compared largest absolute drop in O2 saturation. Secondary analyses found no effect of birth weight or dose number (second vs third dose) on either outcome measure.

Administration, Inhalation↗
PubMedDate not supplied

Spontaneous minute ventilation predicts readiness for extubation in mechanically ventilated preterm infants.

OBJECTIVE: We designed an observational study to test the hypothesis that a comparison of two methods of minute ventilation, spontaneously generated with mechanically generated, would be a useful predictor of readiness for extubation in preterm infants, weighing <2000 gm, who require mechanical ventilation for >24 hours. STUDY DESIGN: This observational study of 35 infants weighing < or = 2000 gm evaluated the comparison of spontaneously generated minute ventilation with mechanically generated minute ventilation to successfully predict readiness for extubation. After reaching entry criteria, infants were extubated if their spontaneously generated minute ventilation (while receiving endotracheal CPAP) was > or = 50% of the mechanically generated minute ventilation during assist/control ventilation. RESULTS: Of the 35 infants who had a successful trial and were extubated, 30 (86%) remained extubated for at least 24 hours. Of the five infants who failed extubation, four developed apnea and one developed stridor. Thus, a spontaneous minute ventilation of > or = 50% of mechanically generated minute ventilation predicted readiness for extubation in 86% of the patients in this observation. CONCLUSION: A spontaneously generated minute ventilation that is > or = 50% of the mechanically generated minute ventilation is an objective predictor of the readiness for extubation in low birth weight infants who have been weaned to modest ventilatory support.

Birth Weight↗