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Biomedical subjects

C J Richardson

Publications and source records attributed to C J Richardson.

At least 37 records · Page 2Linked to original sources
PubMed1991

Breast-feeding initiation in a triethnic population.

The influence of sociodemographic factors on the initiation of breast-feeding was evaluated in a triethnic population from Galveston, Tex. Breast-feeding rates were 44.3% among Anglo-Americans, 13.5% among blacks, and 26.6% among Mexican-Americans. Mexican ethnicity, education levels among Anglo-Americans, and marital status were associated with the initiation of breast-feeding. Odds ratios for breast-feeding were 1.94 (95% confidence interval, 1.10 to 3.43) times higher in Mexican-American compared with black women, and 1.94 (95% confidence interval, 1.34 to 2.83) times higher in married than unmarried women. Anglo-American ethnicity and education, as main effects, were not significantly associated with breast-feeding, but their interaction was. Among Anglo-American women (in comparison with black women), the odds ratios of breast-feeding increased with education level, ranging from 1.84 for those with less than an eighth grade education to 7.46 for those with some college. In contrast to recent findings suggesting that education was more important than ethnicity in predicting breast-feeding, the odds of breast-feeding among Anglo-American compared with black women depended on the level of maternal education, but the odds of breast-feeding for Mexican-American vs black women did not depend on education.

Adult↗
PubMed1991

Gentamicin population pharmacokinetic models for low birth weight infants using a new nonparametric method.

Availability of personal computer programs for control of drug regimens has stimulated interest in modeling population pharmacokinetics. In this study, we found parameter values for gentamicin in two infant populations with low birth weights. The models were developed by use of a parametric (i.e., standard two-stage algorithm) and with a new nonparametric expected maximum algorithm. Data for the two populations (i.e., infants less than or equal to 31 weeks' and greater than 31 but less than or equal to 34 weeks' gestational age) were obtained from infants admitted to the University of Texas Medical Branch intensive care nursery between August 1, 1988, and July 31, 1989. The new nonparametric method was demonstrated to be not only the equal of the standard two-stage method for population modeling but better, especially in use of sparse data sets (e.g., single serum levels). It also obviates the need for selecting proper starting conditions for the least-squares fitting procedure used in the standard two-stage method.

Computer Simulation↗
PubMed1991

Longitudinal studies of virulence factors of Pseudomonas aeruginosa in cystic fibrosis.

Among 111 strains of Pseudomonas aeruginosa from 49 children with cystic fibrosis, duration of colonization correlated with bacterial phenotype. We confirmed that P. aeruginosa from chronically colonized patients tended to be less motile, produce lower levels of protease and elastase, to be more sensitive to normal serum and to be polyagglutinating or untypable with standard antisera. We also showed that phospholipase and heat-stable hemolysin, concerned in metabolism of inorganic phosphate, and exotoxin A, were lower in these isolates. In longitudinal studies there was a decrease in virulence properties when isolates from the same patient were compared. No reversion from altered phenotype to 'wild-type' characteristics was found.

ADP Ribose Transferases↗
PubMed1991

Pyocin typing of Pseudomonas aeruginosa isolates from children with cystic fibrosis.

Pyocin typing and serotyping of 433 strains of Pseudomonas aeruginosa from children with cystic fibrosis (CF) showed that pyocin type 9 was predominant, particularly in association with polyagglutinating serotype. The common pyocin groups, 1, 5 and 10, made up only 20% of these isolates in contrast to reported rates of up to 89% in other studies using non-CF strains. No strains of pyocin type 3 were found. Polyagglutinating strains made up 72% of strains from patients colonized with P. aeruginosa for more than 12 mths. Pyocin type 9 was associated with 93% of polyagglutinating strains. The parallel between pyocin type 9 and polyagglutinating serotype suggests that these may both be characteristics acquired by P. aeruginosa colonizing patients with CF. Because of confounding between duration of colonization and exposure to cross-infection, this study does not allow definition of the role of cross-infection in determining the characteristics of these strains in most patients. In siblings, however, evidence supports a role for cross-infection either between siblings or from a common source. In 6 pairs of siblings studied, each pair had at least 1 pyocin group in common concurrently, either at entry to the study or after an interval of several months. Identical and unusual pyocin groups were recognized in samples obtained on the same day from pairs of siblings. More studies are needed to compare results of pyocin typing with methods such as genome fingerprinting to characterize these strains and determine whether the observed distribution of pyocin groups in CF isolates is related to cross-infection or whether the combination of pyocin type 9 with polyagglutinating serotype is a characteristic of CF strains.

Adolescent↗
PubMed1990

Serotype and serum sensitivity of Pseudomonas aeruginosa from children with cystic fibrosis: longitudinal studies and typing with monoclonal antibodies.

Pseudomonas aeruginosa isolated from the respiratory tract of children with cystic fibrosis from Perth, Sydney or Brisbane, were serotyped with polyclonal antisera using the International Antigenic Serotyping System. Predominant strains were untypable among isolates from Brisbane (86% of 50 strains) and Sydney (60% of 50 strains) but 64% of the 408 isolates from Perth were polyagglutinating. The frequency distributions of typable strains showed differences from those reported in clinics in the northern hemisphere, but it appears that these local differences do not affect the emergence of strains with defective lipopolysaccharide antigens. Isolates from patients studied longitudinally showed correlation between duration of colonization, appearance of untypable or polyagglutinating strains and sensitivity to normal serum. Mucoid colonies were found more commonly from patients colonized for at least 12 months but, overall, there was no significant association between serotype and mucoid colonial morphology. Commercial monoclonal antibodies did not react with polyagglutinating or untypable strains and gave identical results to the polyvalent typing system with strains classified as typable.

Antibodies, Monoclonal↗
PubMed1989

Successful separation of a conjoined biliary tract in a set of omphalopagus twins.

Omphalopagus twins were separated in the first 48 hours of life. Preoperative evaluation did not disclose either their conjoined intestines or their conjoined biliary tract; intraoperative evaluation, including an operative cholangiogram, was required to determine if separation was possible. The intestines were divided to give each infant an equal share, and an hepaticoenterostomy was constructed in each of the twins.

Bile Ducts↗
PubMed1989

Assay and Electrophoresis of Superoxide Dismutase from Red Spruce (Picea rubens Sarg.), Loblolly Pine (Pinus taeda L.), and Scotch Pine (Pinus sylvestris L.) : A Method for Biomonitoring.

This paper reports a method for extracting the antioxidant enzyme superoxide dismutase (SOD) from the needles of red spruce (Picea rubens Sarg.), loblolly pine (Pinus taeda L.), and scotch pine (Pinus sylvestris L.) with high efficiency and free from interfering compounds. The extraction employs phosphate buffer with polyvinylpolypyrrolidone and Triton X-100 followed by dialysis overnight. The isozymes of SOD in each species were separated electrophoretically and tested for their sensitivity to KCN and H(2)O(2). An isozyme resistant to these inhibitors was found in the spruce but not the pine needles. The isozymes from the spruce needles were examined for individual responses to aging and H(2)O(2) inhibition. Four of the five CuZn isozymes in spruce were found to have increased significantly but equally by October of their first year and two of those four isozymes were found to be more sensitive to H(2)O(2). The response of the SOD isozymes in loblolly pine seedlings to O(3) was also examined and the isozymes were found to be induced equally. Because the SOD activity in the young pine needles was too low to electrophorese, the SOD activity from the pines in the O(3) experiment had to be partially purified using CHCl(3) and ethanol, then concentrated.

Journal Article↗
PubMed1989

Neonatal intensive care and pediatric rehabilitation: a joint program for care of chronically ill infants.

A joint program involving a traditional neonatal intensive care unit and a pediatric rehabilitation unit was developed to care for the increasing number of infants with chronic illnesses requiring long-term specialized care. The program emphasizes provision of a more normal, age-appropriate environment, parent education, and opportunities for extended parent-child interaction.

Bronchopulmonary Dysplasia↗
PubMed1988

The effect of age on piroxicam disposition in rheumatoid arthritis.

The disposition of piroxicam in 23 patients with rheumatoid arthritis (9 males, 14 females, aged 27-79) was studied over 6 weeks using the standard oral dose of 20 mg daily. Clinical status was monitored using standard methods. The mean piroxicam steady state plasma concentration (Css) averaged 9.2 +/- 4.4 micrograms/ml, the majority of which was highly protein bound (1.4 +/- 0.5% unbound). Total plasma clearance (CL/F) of piroxicam was 1.85 +/- 0.81 ml/min and the half life (t1/2) was 53.0 +/- 24.2 h. There was wide intersubject variability in the kinetics of piroxicam and its major metabolite 5'-hydroxypiroxicam. Piroxicam CL/F, t1/2 and Css were modestly correlated with patient age. Clinical effects did not appear to be related to piroxicam plasma levels.

Adult↗
PubMed1987

Piroxicam and 5'-hydroxypiroxicam kinetics following multiple dose administration of piroxicam.

Piroxicam (20 mg once daily) was administered orally to six healthy young volunteers for 15 days. Trough steady-state levels of piroxicam and 5'-hydroxypiroxicam were 5.5 and 1.2 micrograms/ml, respectively. Piroxicam's plasma half-life (54.9 h) was significantly shorter than that of 5'-hydroxypiroxicam (70.5 h). Percent unbound piroxicam and 5'-hydroxypiroxicam in plasma at steady-state averaged 1.10 and 8.07 respectively. An average of 25.2% of the dose was recovered in urine as 5'-hydroxypiroxicam; approximately two-thirds (17.2%) in the form of the glucuronide conjugate. Average steady-state plasma levels (Css) of piroxicam (7.0 micrograms/ml) were significantly higher than predicted from a previously reported single dose study (5.3 micrograms/ml).

Adult↗
PubMed1987

Successful management of congenital tracheal stenosis in infancy.

Seven infants with congenital tracheal stenosis were evaluated and treated to assess the efficacy of current techniques of management. All had multiple congenital anomalies in addition to tracheal stenosis. Notably, three infants had imperforate anus and three had vascular rings. Each infant presented early with respiratory distress. While bronchoscopy and/or bronchography were performed in some, the diagnosis could be made from high contrast x-rays of the chest in each instance. The complexity of the tracheal lesion(s) determined the operative approach. Complicating factors included tracheomalacia, multiple stenoses, pulmonary hypoplasia, and carinal involvement. The trachea was approached through an anterolateral thoracotomy in five cases and through the neck in one. Cardiopulmonary bypass was never required. Simple resection was possible only once. Four patients received costal cartilage grafts, and one graft was created from dura. Grafts varied from 2 1/2 to 6 cm in length and extended onto the bronchi in two cases. All patients with grafts were treated with postoperative endotracheal stents and ventilatory assistance and all were extubated successfully. One patient had trisomy 16p+ detected after successful extubation and died later. One patient was treated expectantly and died. While each case must be individualized, repair of complex tracheal stenosis often results in dramatic immediate improvement and long-term success.

Child, Preschool↗
PubMed1987

Developmental features of the neonatal brain: MR imaging. Part I. Gray-white matter differentiation and myelination.

To establish the normal appearance of the neonatal brain, 51 neonates, 29-42 weeks postconception, underwent magnetic resonance (MR) imaging with a 0.6-T magnet in a prospective study. T1-weighted images were used to devise stages for the appearance of gray-white matter differentiation and extent of myelination. The results show that from 29 to 42 weeks postconception, changes in gray-white matter differentiation and myelination follow the stages in an orderly and predictable fashion. Changes in white matter intensity appear related to progressive decrease in brain water content. Myelination progresses cephalad from the brain stem at 29 weeks to reach the centrum semiovale by 42 weeks. Delayed myelination, defined as the absence of myelin in the corona radiata by 37 weeks, was seen in nine infants with complicated perinatal courses. Awareness of these developmental features should help to minimize misinterpretation of normal changes in the neonatal brain and lead to earlier detection of pathologic conditions, both with MR imaging and computed tomography.

Brain↗
PubMed1987

Developmental features of the neonatal brain: MR imaging. Part II. Ventricular size and extracerebral space.

Magnetic resonance (MR) imaging with a 0.6-T magnet was performed on 51 neonates, aged 29-42 weeks postconception. In 45 neonates, the ventricular/brain ratio (V/B) at the level of the frontal horns and midbody of the lateral ventricles ranged from 0.26 to 0.34. In six other infants a V/B of 0.36 or greater was associated with either cerebral atrophy or obstructive hydrocephalus. The width of the extracerebral space measured along specified points varied little in the neonatal period and ranged from 0 to 4 mm in 48 infants. Extracerebral space widths of 5-6 mm were seen in three other infants with severe asphyxia. Prominence of the subarachnoid space overlying the posterior parietal lobes is normal in neonates and should not be confused with cerebral atrophy. The authors conclude that V/B ratios of 0.26-0.34 and extracerebral space widths of 0-4 mm represent the normal range, and that neonates whose measurements exceed these values should be followed up.

Brain↗
PubMed1987

Abnormalities of the neonatal brain: MR imaging. Part I. Intracranial hemorrhage.

The authors prospectively evaluated 82 neonates, ranging in gestational age from 29 to 44 weeks postconception, with magnetic resonance (MR) imaging at 0.6 T. Twenty-two cases of hemorrhage in 15 infants were identified. Ultrasound (US) and computed tomography (CT) were superior to MR in the first few days after parenchymal hemorrhage, since at this time lesions were apparent on only T2-weighted images. After the first 3 days, MR was the single best modality because (a) hemorrhage on CT became imperceptible in the 2d week, whereas the high signal of hemorrhage on MR persisted for 2-11 weeks; (b) MR permitted rough dating of hemorrhage according to changes in signal intensity; and (c) MR was superior in identifying subdural or epidural hemorrhage. Because of the nonspecificity and restricted field of view of US and the inability of CT to depict hemorrhage after 7-10 days, the authors conclude that MR significantly improves the detection of intracranial hemorrhage in neonates.

Cerebral Hemorrhage↗
PubMed1987

Abnormalities of the neonatal brain: MR imaging. Part II. Hypoxic-ischemic brain injury.

Eighty-five infants, 82 of whom were 29-44 weeks postconceptional age, were imaged with a 0.6-T magnet. Eight infants had cerebral infarction. In premature neonates with very water, low-intensity white matter on T1-weighted images, ultrasound was better than both computed tomography and magnetic resonance (MR) imaging in depicting parenchymal changes of infarction or edema. However, after 37 weeks gestation, MR imaging was superior. Cerebral atrophy, present in seven infants, was consistent with subarachnoid space widths of 7 mm or more, or subarachnoid space widths of 5-6 mm with ventricular/brain ratios of 0.36 or greater. Delayed myelination was seen in a total of 18 infants with histories of hypoxic-ischemic insult. MR imaging shows promise in the neonatal period. It facilitates recognition of infarcts in full-term infants and may be used to predict abnormal neurologic outcome in infants who have initial delayed myelination.

Atrophy↗
PubMed1986

Parenteral antibiotics and carbohydrate intolerance in term neonates.

To evaluate the effects of parenteral antibiotics on carbohydrate tolerance, fecal reducing substances, stool frequency, and dietary manipulation were monitored in two groups of term neonates. The first group (n = 25) consisted of neonates receiving parenteral ampicillin sodium and gentamicin sulfate. A second group (n = 25) of matched neonates not receiving antibiotics served as controls. Most of the neonates were fed a standard lactose-containing formula and the remainder were breast-fed. Stool frequency, presence of fecal reducing substances, and requirement for dietary manipulation were significantly greater in neonates receiving antibiotics compared with controls. Infants manifesting symptomatic carbohydrate intolerance while receiving parenteral antibiotics may benefit either from receiving lactose-free formula or from decreasing the intake of lactose for the duration of antibiotic therapy.

Age Factors↗