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Biomedical subjects

N Macdonald

Publications and source records attributed to N Macdonald.

48 records · Page 3Linked to original sources
PubMed1984

Neonatal intracranial hemorrhage and complicating hydrocephalus.

Real-time ultrasound studies of the head were performed on 96 infants weighing 1500 g or less. This population represented all such infants admitted within the first 72 hours of life to a neonatal intensive care unit over a 9-month period. Intracranial subependymal/intraventricular hemorrhage occurred in 22 (23%) of the infants. Of these 13 (59%) developed ventricular enlargement. Four other infants, in whom hemorrhage was not identified, also developed ventricular enlargement. When it occurred, the ventricular enlargement developed within 2 weeks of the hemorrhage in 77% of cases. It reached its maximum size within 2 weeks in 65% of cases. In 9 of 16 cases the maximal ventricular enlargement was categorized as mild. Spontaneous arrest or resolution of the ventriculomegaly occurred in all but two cases, who required shunting. Clot resolution was slow. It was complete at 3 weeks in only 5 of 18 cases.

Cerebral Hemorrhage↗
PubMed1984

Neurosonographic identification of ventricular asymmetry in premature infants.

Routine head ultrasound scans have been performed on 185 consecutive infants weighing under 1500 g at birth. In 40 of these infants a significant difference in the size of the lateral ventricles was observed on one or more occasions. In 38 of these infants the left ventricle was larger than the right. The aetiology of this ventricular asymmetry is unknown. It is not believed to be due to germinal matrix or ventricular haemorrhage, hydrocephalus or the position of the infant at the time of scanning.

Cerebral Hemorrhage↗
PubMed1981

Bacterial colonization of human milk.

Because human milk is being used more and more for feeding neonates, many hospitals are struggling with the issue of culturing. The literature indicates that human milk is hardly ever sterile. Since there has been much debate concerning protocols and frequency of culturing milk specimens, we evaluated our facility's protocol, the aim of which was to assure clean collection and transportation of the mothers' milk. We studied two large sectors of patients; private and nonprivate (service). Both sectors had a similar contamination rate with the same type of organisms. Private pediatricians generally ordered more cultures per patient than did the service (nonprivate) pediatrician. We challenge the need for all these cultures, which increase the patients' cost.

Bacteria↗
PubMed1970

Origins of war.

Explore the source record for details and available documents.

Politics↗
PubMedDate not supplied

Acrylamide: review of toxicity data and dose-response analyses for cancer and noncancer effects.

Acrylamide (ACR) is used in the manufacture of polyacrylamides and has recently been shown to form when foods, typically containing certain nutrients, are cooked at normal cooking temperatures (e.g., frying, grilling or baking). The toxicity of ACR has been extensively investigated. The major findings of these studies indicate that ACR is neurotoxic in animals and humans, and it has been shown to be a reproductive toxicant in animal models and a rodent carcinogen. Several reviews of ACR toxicity have been conducted and ACR has been categorized as to its potential to be a human carcinogen in these reviews. Allowable levels based on the toxicity data concurrently available had been developed by the U.S. EPA. New data have been published since the U.S. EPA review in 1991. The purpose of this investigation was to review the toxicity data, identify any new relevant data, and select those data to be used in dose-response modeling. Proposed revised cancer and noncancer toxicity values were estimated using the newest U.S. EPA guidelines for cancer risk assessment and noncancer hazard assessment. Assessment of noncancer endpoints using benchmark models resulted in a reference dose (RfD) of 0.83 microg/kg/day based on reproductive effects, and 1.2 microg/kg/day based on neurotoxicity. Thyroid tumors in male and female rats were the only endpoint relevant to human health and were selected to estimate the point of departure (POD) using the multistage model. Because the mode of action of acrylamide in thyroid tumor formation is not known with certainty, both linear and nonlinear low-dose extrapolations were conducted under the assumption that glycidamide or ACR, respectively, were the active agent. Under the U.S. EPA guidelines (2005), when a chemical produces rodent tumors by a nonlinear or threshold mode of action, an RfD is calculated using the most relevant POD and application of uncertainty factors. The RfD was estimated to be 1.5 microg/kg/day based on the use of the area under the curve (AUC) for ACR hemoglobin adducts under the assumption that the parent, ACR, is the proximate carcinogen in rodents by a nonlinear mode of action. When the mode of action in assumed to be linear in the low-dose region, a risk-specific dose corresponding to a specified level of risk (e.g., 1 x 10-5) is estimated, and, in the case of ACR, was 9.5 x 10-2 microg ACR/kg/day based on the use of the AUC for glycidamide adduct data. However, it should be noted that although this review was intended to be comprehensive, it is not exhaustive, as new data are being published continuously.

Acrylamide↗