Biomedical subjects

J S Schreiber

Publications and source records attributed to J S Schreiber.

5 recordsLinked to original sources

PubMed2001

Parents worried about breast milk contamination. What is best for baby?

Breast milk contamination may concern parents who are worried about their infant's exposure to environmental or occupational chemicals. This article examines the risks posed by chemicals in breast milk compared to the risks of formula feeding. In addition, this article provides guidance to health care professionals about how to evaluate maternal exposures that may influence breast milk quality. A guide to assessing potential exposures at home and in the workplace is provided.

Breast Feeding↗

PubMed1993

The role of the dura in cranial bone regeneration in the immature animal.

In an animal model, the effect of transferring mature pericranial tissues to immature animals with cranial bone defects was tested. Isogeneic guinea pigs of different ages were used: "infants" (3-4 weeks) and "adults" (> 18 months). Bilateral parietal cranial defects were made in infant guinea pigs and the guinea pigs were divided into three groups. In group 1 (n = 6), the infant periosteum was resected and replaced as an autograft on one side (control), and adult periosteum was transplanted as an isograft on the other (experiment). In group 2 (n = 5), dura was used as the variable. In group 3 (n = 5), combined dura and periosteum were the variables. After 8 weeks, there was complete or near complete bone regeneration in all animals in which infant dura was present. There was minimal to no bone regeneration in defects in which adult dura was present. Unlike dura, periosteum had little influence on the capacity of the bone to regenerate.

Animals↗

PubMed1993

Predicted infant exposure to tetrachloroethene in human breastmilk.

Based on a variety of maternal occupational and residential inhalation exposure scenarios, estimates of infant exposure to the dry-cleaning solvent tetrachlorothylene (perchloroethylene, PCE) in breastmilk were made. Physiologically based pharmacokinetic (PBPK) modeling indicates that infants may be exposed to elevated levels of PCE in breastmilk due to their mothers' inhalation of PCE. The PBPK-predicted breastmilk PCE concentrations agree very well with measured concentrations, where available. Based on this analysis, infants may be exposed to this workplace chemical via breastmilk at doses corresponding to rather high levels of risk. Predicted breastmilk doses provide the infant with little margin of exposure to doses associated with adverse health effects. In addition, the estimated increased cancer risks associated with these infant exposures are large under certain exposure scenarios. The actual concentrations of PCE in breastmilk of exposed mothers can only be known with certainty if monitoring is conducted. Due to the widespread exposure potential, monitoring studies should be undertaken so that the appropriate risk management alternatives can be better evaluated.

Adult↗

PubMed1993

An investigation of indoor air contamination in residences above dry cleaners.

An investigation of residences located above dry cleaning facilities was conducted to determine whether indoor and outdoor air concentrations of the dry cleaning solvent tetrachloroethene (perchloroethylene, PCE) were elevated compared to residences not near a dry cleaning facility. Data were also collected on the dry cleaners' operating conditions and equipment. Significantly elevated levels of PCE were found in the indoor air of each of six apartments located above dry cleaners compared to control residences for both day and night samples. The PCE concentrations in outdoor air near the dry cleaners were also significantly elevated compared to control locations and were lower than the concentrations measured indoors. The type of dry cleaning machine was significantly associated with the concentration of PCE found in the apartment above. A strong correlation was also found between the day and night PCE levels in the study apartments.

Air Pollutants, Occupational↗

PubMed1992

Membranous bone lengthening: a serial histological study.

Bone lengthening using the process of corticotomy and gradual distraction of callus is applicable to the membranous bone of the canine mandible. In this study the precursors to bone formation, in the area between the distracted bone edges, are analyzed in an attempt to determine the mechanism of bone formation. Ten mongrel dogs 5 months of age were studied. A unilateral, periosteal-preserving angular corticotomy was performed, and an external bone-lengthening device was fixed to the mandible. After 10 days of external fixation, the mandible was lengthened 1 ml per day for 20 days and then held in external fixation for 8 weeks. The dogs were killed for histological and microradiographic study at 10 and 20 days of distraction, and at 14, 28, and 56 days after the completion of distraction. It was observed that the gap between the distracted bone edges is first occupied by fibrous tissue. As distraction proceeds, the fibrous tissue becomes longitudinally oriented in the direction of distraction. Early bone formation advances along the fibrous tissue, starting from the cut bone ends. Eventually the area is converted to mature cortical bone. Bone is formed predominantly by intramembranous ossification. This mechanism is similar to that of bone formation during long bone lengthening.

Animals↗