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Biomedical subjects

M Van Allen

Publications and source records attributed to M Van Allen.

12 recordsLinked to original sources
PubMed1992

The Diabetes in Early Pregnancy Study: changes in cholesterol, triglycerides, body weight, and blood pressure. The National Institute of Child Health and Human Development--the Diabetes in Early Pregnancy Study.

This study examined changes in cholesterol, triglycerides, body weight, and blood pressure during pregnancy in 312 diabetic and 356 control women recruited within 21 days after conception. Cholesterol values rose in both groups but were significantly lower in diabetic women at each time point (166 vs 178 mg/dl at week 12, p = 0.0004). Triglyceride values also rose in both groups. Triglyceride levels did not differ between groups up to week 8 of gestation, but by weeks 10 to 12 they were significantly lower in diabetic women than in controls (75 vs 89 mg/dl at week 12, p = 0.0004). Although they were no heavier at entry, diabetic women gained significantly more weight between weeks 6 and 8 (p less than 0.001), resulting in a mean difference between groups of 1 kg. Systolic blood pressure increased steadily and significantly in the diabetic but not the control women (115.8 +/- 16.2 SD vs 109.3 +/- 11.8 mm Hg, p = 0.0006 at term). Diastolic blood pressure was higher in diabetic women on entry (70.7 vs 67.3 mm Hg, p = 0.0006) and throughout gestation. Significant correlations were found in the diabetic group between maternal blood pressure and lipids and infant birth weight. These newly found differences in cholesterol and triglyceride levels, weight gain, and blood pressure between type I diabetic and control women during gestation may have long-term cardiovascular implications.

Adult↗
PubMed1992

Computed tomography-guided fixation of unstable posterior pelvic ring disruptions.

Open reduction and internal fixation (ORIF), the current treatment of choice of posterior pelvic ring disruptions with instability, has significant disadvantages. These include relatively "blind" placement of the fixation screws, infection, exsanguinating hemorrhage, and high wound complication rates. We feel fluoroscopy does not offer significant clarity in defining the posterior structure. Advantages of computed tomography (CT)-guided sacral fixation are direct visualization of the course of the screws and absence of significant wound complications. This technique provides superior visualization of the nerve roots and sacral canal compared to fluoroscopic methods. Thirteen patients (10 unilateral and 3 bilateral) with unstable but reducible sacral fractures or sacroiliac joint (SIJ) disruptions underwent CT-guided posterior pelvic ring fixation using a cannulated screw system. Skeletal traction was required intraoperatively in one case by a traction-counteraction pulley system in the CT scanner. All other reductions were performed by preoperative skeletal traction or manually by the surgeons after anesthesia in the scanner or after push-pull films demonstrated instability. The guide pin, using depth and angulation measurements derived from the scout CT scans, was positioned across the fracture or SIJ. Following CT confirmation of the position of the pin, the screw tract was drilled and the cannulated screw was placed into position. Radiographic and clinical follow-up observation (7-24 months) showed healing with no significant complications in all 13 patients. Computed tomography-guided sacral fixation is a safe alternative to ORIF in selected patients with reducible unstable pelvic fractures.

Adolescent↗
PubMed1990

Pharmacokinetics of anticonvulsants in pregnancy: alterations in plasma protein binding.

Anticonvulsant levels decline as pregnancy progresses, even in the face of constant and, in some cases, increased dosages of medications. It has been suggested that this decline is responsible for the increase in seizure frequency seen in approximately one-third of the women with epilepsy who become pregnant. Changes in plasma protein binding may explain the declines in anticonvulsant concentrations during pregnancy. A prospective cohort study was designed to test this hypothesis. Carbamazepine, phenytoin and phenobarbital were studied. The mean total concentrations of all 3 drugs declined as pregnancy progressed, rising in the postpartum period. Free concentrations also declined, but did so significantly only for phenobarbital. The free fraction for all anticonvulsants studied rose significantly throughout pregnancy. Protein binding is significantly altered during pregnancy for all 3 drugs studied and appears to account for much of the decline in anticonvulsant concentrations seen in this condition. It is suggested that free rather than total drug concentrations be monitored in pregnant women with epilepsy.

Adult↗
PubMed1989

Drug ingestion during pregnancy: infrequent exposure in a contemporary United States sample. National Institute of Child Health and Human Development Diabetes in Early Pregnancy Study Group.

Drug ingestion in a cohort of United States women proved consistently lower than in prior United States populations. Participating were 342 insulin-dependent diabetic and 387 control subjects who were enrolled before conception (76%) or no later than 21 days after conception (24%). Drug exposures were then recorded at entry and periodically throughout organogenesis (gestational weeks 6, 8, 10). During gestational weeks 1 to 10, approximately two thirds of the subjects were exposed to no agent other than oral iron, oral vitamins, or insulin (diabetic subjects). The mean exposures in gestational weeks 1 to 10 were 0.72 +/- 1.05 (SD) for diabetic women and 0.54 +/- 0.96 for control subjects; throughout pregnancy, the mean exposures were 1.26 +/- 1.66 and 1.58 +/- 1.78, respectively. The low exposure frequency in this contemporary United States population is highly encouraging. However, it follows that collaborative cohort efforts may be necessary in order to assess teratogenicity of drugs because relatively few women are now exposed.

Abnormalities, Drug-Induced↗
PubMed1988

Incidence of spontaneous abortion among normal women and insulin-dependent diabetic women whose pregnancies were identified within 21 days of conception.

Whether pregnant women with insulin-dependent diabetes mellitus have an increased risk of spontaneous abortion is controversial. To address this question, we enrolled 386 women with insulin-dependent diabetes and 432 women without diabetes before or within 21 days after conception and followed both groups prospectively. Sixty-two diabetic women (16.1 percent) and 70 control women (16.2 percent) had pregnancy losses (odds ratio, 0.99; 95 percent confidence interval, 0.67 to 1.46). After adjustment for known risk factors for spontaneous abortion, the rate was still not significantly higher in the diabetic group (odds ratio, 0.91; 95 percent confidence interval, 0.59 to 1.40). Nonetheless, among the diabetic women, most of whom had good metabolic control, those who had spontaneous abortions had higher fasting and postprandial glucose levels in the first trimester than those whose pregnancies continued to delivery (P = 0.01 for fasting glucose levels and P = 0.005 for postprandial levels). In the small subgroup of diabetic women with poor control, who had elevated values for glycosylated hemoglobin in the first trimester, each increase of 1 SD above the normal range was associated with an increase of 3.1 percent in the rate of pregnancy loss (95 percent confidence interval, 0.6 to 5.6). We conclude that diabetic women with good metabolic control are no more likely than nondiabetic women to lose a pregnancy, but that diabetic women with elevated blood glucose and glycosylated hemoglobin levels in the first trimester have a significantly increased risk of having a spontaneous abortion.

Abortion, Spontaneous↗
PubMed1986

Limb-body wall complex: in utero sonographic diagnosis of a complicated fetal malformation.

Limb-Body Wall Complex is a complicated fetal malformation with the essential features of neural-tube defects, body-wall disruption, and limb abnormalities. This complex should be distinguished from other body-wall defects including omphalocele and gastroschisis since the prognosis for limb-body wall complex is uniformly poor. For 13 cases of this unusual fetal anomaly, sonographic, radiologic, and pathologic findings were correlated. Thoracic or abdominal body-wall defects, neural-tube abnormalities, severe scoliosis, positional deformities, and abnormalities of fetal membranes were consistently demonstrated on in utero sonograms. Results show that the diagnosis of limb-body wall complex can be made by prenatal sonography.

Abdominal Muscles↗
PubMed1985

Neuropsychologic detection of abnormal mental decline in older persons.

We conducted comprehensive neuropsychologic assessment in normal 60- to 88-year-old persons and in patients with dementia of various causes, matched for age and sex. Patients with dementia performed significantly poorer on tests of short-term memory, temporal orientation, visual perception, and language. Further data analysis, including multivariate classification procedures, identified a combination of three tests (Visual Retention, Controlled Oral Word Association, and Temporal Orientation) that in a cross-validation study correctly classified 89% of cases with a high degree of probability. Only 6.5% of cases were misclassified, while 4.5% were in a questionable, borderline category. The battery constituted by these three discriminating tests provides a brief, easily administered neuropsychologic screening instrument that may be used by a variety of health professionals for the detection of abnormal mental decline in older persons.

Aged↗
PubMed1983

A spectrum of gyral anomalies in Miller-Dieker (lissencephaly) syndrome.

Four unrelated patients who had the clinical appearance of Miller-Dieker syndrome, also called lissencephaly syndrome, were studied. All four had a typical clinical course with failure to thrive, severe psychomotor retardation, opisthotonos, seizures, and death early in life. None of these children had lissencephaly, the anticipated central feature of this disorder. One of the four had pachygyria, one had polymicrogyria, and two had both pachygyria and polymicrogyria. The brain weights were normal to decreased. The ventricles were dilated in all cases. The cerebral cortex was thickened in each, with decreased white matter and diminution or distortion of the cellular layers, and there were neuroglial heterotopias. The corpus callosum was partially absent in one and thinned in three. The neuropathy found in these children with Miller-Dieker syndrome suggests a spectrum of gyral anomalies resulting from a single type of embryonic error.

Agenesis of Corpus Callosum↗
PubMed1980

Neurology.

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Humans↗