Biomedical subjects

R A Brenner

Publications and source records attributed to R A Brenner.

25 records · Page 2Linked to original sources

PubMed1998

Capsular polysaccharide types of group B streptococcal isolates from neonates with early-onset systemic infection.

The distribution of serotypes of group B streptococci (GBS) isolated from 67 infants with early-onset sepsis are described. Case-infants were assembled from 13 hospitals across the United States from 15 July 1995 to 5 February 1997 through prospective active surveillance. The distribution of GBS serotypes was Ia, 40%; Ib, 9%; II, 6%; III, 27%; V, 15%; and nontypeable, 3%. Type V occurred more frequently in the northeast region (New York and New Jersey) than in other regions (29% vs. 9%, P = .06). Conversely, type III occurred significantly less frequently in the northeast region than other regions (10% vs. 35%, P = .04). GBS types Ia, III, and V accounted for 82% of the isolates. This report supports previous observations about the emergence of GBS type V, but our data caution that conclusions about serotype distributions based on one geographic location or on a small number of patients may not be generally applicable. Continued monitoring seems necessary for the design of a GBS vaccine.

Bacterial Capsules↗

PubMed1997

The role of bathtub seats and rings in infant drowning deaths.

OBJECTIVE: To describe deaths due to drowning that involve the use of an infant bathtub seat or ring. DESIGN: Case series, cases reported to the US Consumer Product Safety Commission data systems. Setting. United States, 1983-1995. MAIN OUTCOME MEASURES: Death in which an infant bathtub seat or ring was in use at the time of death and the primary cause of death was drowning. RESULTS: Thirty-two drowning deaths involving bath seats/rings were identified and investigated by the Consumer Product Safety Commission over a 13-year period. The majority of deaths (84%) occurred from 1991-1995, with more than 50% occurring in the 2 most recent years. The victims' ages at the time of the incident ranged from 5 to 15 months with a mean and median age of 8 months. In more than 90% of incidents there was a reported lapse in adult supervision, with a mean reported lapse of 6 minutes and a median lapse of 4 minutes. Focus groups with parents found that while making bathing somewhat easier, bath seats/rings are useful for a relatively short time period, as the child rapidly outgrows the product. They also suggested that care givers are more likely to leave a child unattended in the tub if one of these products is in use. CONCLUSION: Bath seats/rings are associated with an increasing number of reported infant drowning deaths. The use of such products may increase the risk of drowning among infants by increasing the likelihood that an infant will be left alone in the tub. However, in the absence of exposure data in a suitable comparison group it is difficult to assess the overall risk inherent in their use. Educational efforts reinforcing the need for continuous adult supervision of infants and children around all bodies of water should now also include a reminder that bath seats/rings are not safety items and are not a substitute for adult supervision. Infants and toddlers should never be left in the bathtub unsupervised, even for brief moments.

Accidents, Home↗

PubMed1994

Divergent trends in childhood drowning rates, 1971 through 1988.

OBJECTIVE: To examine national age-, race-, and sex-specific trends in unintentional drowning rates among US children aged 0 through 19 years. DESIGN: National mortality data published by the National Center for Health Statistics and population data from the US Bureau of the Census were used in calculating age-, race-, and sex-specific drowning rates for 1971 through 1988. Time trends were analyzed using Poisson regression techniques. SETTING: United States, 1971 through 1988. MAIN OUTCOME MEASURE: Rates of death due to unintentional, non-boat-related drowning. RESULTS: From 1971 through 1988, there were 45,680 unintentional, non-boat-related drowning deaths among 0- through 19-year-olds in the United States. Drowning rates declined sharply in older children (-5.8% per year in 10- through 14-year-olds and -5.4% per year in 15- through 19-year-olds), declined only slightly in toddlers (-1.6% per year in 1- and 2-year-olds), and actually increased in infants (+1.6% per year in those children younger than 1 year). CONCLUSION: Drowning rates in toddlers have changed little over time despite the availability of effective prevention strategies such as pool fencing. In older children, drowning rates have declined dramatically despite the lack of clear preventive initiatives. Prevention interventions targeted specifically at the infant and toddler age groups should receive priority.

Adolescent↗

PubMed1994

Cortical and trabecular bone contribute strength to the osteopenic distal radius.

Fractures of the distal radius are common, especially in postmenopausal women, and their prevalence increases with age. Knowledge of the factors that increase the risk of fracture in this metaphyseal region would have predictive and therapeutic implications. Of particular interest in this study were (a) the relative contributions of cortical and trabecular bone to the strength of the distal radius and (b) the best radiographic features to use as strength indicators. In 21 forearms from fresh cadavera (median age at the time of death, 75 years), single photon absorptiometry and quantitative computed tomography were used to determine bone mineral content (BMC), density (BMC/W), and cross-sectional properties of the radius at distal and midshaft sites. Mechanical testing of the forearms then was used to determine the ultimate force and energy to cause the type of fracture that might be caused by a fall on the outstretched hand. Twelve of the 17 tested specimens sustained a fracture of the distal radius, and five sustained a fracture of the scaphoid. In the group of fractures of the distal radius, we found the cross-sectional area and moment of inertia of the cortical shell at the metaphyseal site to be better correlates of strength than the trabecular area and trabecular moment. In contrast, strength correlated much better with trabecular density than with cortical density. Overall, the best correlates of strength were the BMC and BMC/W at either the distal or proximal site. On balance, these results suggest that the thin cortical shell contributes substantially more to the mechanical strength of the distal radius than has been commonly appreciated.

Aged↗

PubMed1982

Maturational changes in cardiac muscle myosin adenosine triphosphatase activity relative to hemodynamic alterations in newborn lambs.

We performed a chronologic investigation of left (LV) and right (RV) ventricular myosin ATPase activity and hemodynamics in newborn lambs. We found an elevation in myosin ATPase activity for the LV, which was achieved by 6 to 8 weeks of age and which correlated directly with increasing ventricular stroke work. Myosin ATPase activity did not increase with age for the RV, a finding which was associated with a postnatal decrease in ventricular stroke work. These findings may represent an important postnatal adaptation of newborn myocardium to the demands of extrauterine life.

Adenosine Triphosphatases↗

PubMed1981

Maturational Changes in Myocardial Contractile State of Newborn Lambs.

There have been no investigations of chronologic changes in postnatal contractile state of both left and right ventricles of the newborn. Thus, we determined isovolumetric indices of contractility in 32 acutely instrumented newborn lambs (1 day to 12 wk; three exteriorized near term fetuses, and four adult sheep. These studies demonstrated a marked increase in inotropic properties of both ventricles which was especially pronounced during the first 3 days of extrauterine life (group 1, left ventricle Vmax 3.2 +/- 0.27 and VCE10 3.2 +/- 0.28 Ml (muscle lengths)/sec; right ventricle Vmax 2.1 +/- 0.2 and VCE10 2.2 +/- 0.13 ML/sec); and was associated with elevated cardiac output (428 +/- 52 cc/kg/min), largely resulting from an elevated stroke volume (2.1 +/- 0.31 cc/kg). During subsequent postnatal maturation, contractility indices of both ventricles gradually declined to values intermediate between newborn and adult ((group IV, 22 to 84 days) - left ventricle Vmax 1.78 +/- 0.13 and VCE10 1.79 +/- 0.15 ML/sec; right ventricle Vmax 1.48 +/- 0.07 and VCE10 1.31 +/- 0.3 ML/sec); associated with a corresponding decline in cardiac output (group IV, 136 +/- 38 cc/kg/min), related in large measure to a decline in stroke volume (0.76 +/- 0.13) cc/kg). Simulation of birth in exteriorized fetuses was associated with a sudden increase in contractile indices for both left (Vmax 2.1 +/- .2 leads to 3.0 +/- .3 and VCE10 2.1 +/- 0.2 leads to 3.1 +/- 0.3 ML/sec) and right (Vmax 2.0 +/- 0.2 leads to 2.5 +/- 0.2 and VCE10 1.9 +/- 0.1 leads to 2.5 +/- ML/sec) ventricles. We conclude that there is a postnatal elevation of ventricular contractile state which contributes to successful postnatal adaptation of the newborn cardiovascular system.

Age Factors↗

PubMedDate not supplied

Prevalence and predictors of the prone sleep position among inner-city infants.

CONTEXT: The prone sleep position is associated with an increased risk of sudden infant death syndrome (SIDS), but few studies have assessed factors associated with the choice of infant sleep position. OBJECTIVES: To describe infant sleep position in a cohort of infants born to predominantly low-income, inner-city mothers and to identify predictors of the prone sleep position in this population. DESIGN: Prospective birth cohort study. PATIENTS AND SETTING: Three hundred ninety-four mother-infant dyads, systematically selected from 3 District of Columbia hospitals between August 1995 and September 1996. Mothers were interviewed shortly after delivery and again at 3 to 7 months postpartum. MAIN OUTCOME MEASURES: Position in which infants were placed for sleep on the night prior to the 3- to 7-month interview. RESULTS: At 3 to 7 months of age, 157 infants (40%) were placed for sleep in the prone position. Independent predictors of prone sleep position included poverty (odds ratio [OR], 1.81; 95% confidence interval [CI], 1.10-2.99), black race (OR, 2.06; 95% CI, 1.05-4.04), presence of infant's grandmother in the home (OR, 1.83; 95% CI, 1.11-3.00), and intent, as measured shortly after delivery, to place the infant in the prone position (OR, 2.28; 95% CI, 1.44-3.60). Importantly, of the 43 mothers who observed their infants in the prone sleep position while in the hospital, 40 (93%) intended to place their infants prone at home. CONCLUSIONS: A substantial proportion of infants in this predominantly low-income population were placed in the prone sleep position. Educational efforts should address both initial intentions and reinforcement of the correct sleep position, once initiated. Hospitals should ensure that healthy newborn infants are placed in the supine sleep position during the postpartum hospital stay.

Humans↗