Effect of maternal and infant covariates on sibship correlation in birth weight

Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.     

Unraveling the mysteries of serum theophylline levels: a patient care report in the light of pharmacokinetics

One of our patients had trouble maintaining therapeutic and safe levels of theophylline, even though we were careful in planning and monitoring her drug regimen. This case report shows how we were able to use principles of pharmacokinetics to distinguish among plausible explanations for her experience. We discovered that she was not taking the drug consistently as prescribed and that supervised administration resolved apparent contradictions between doses and serum levels. We believe that physicians can use the same information and methods that we used to get better and safer results from theophylline therapy.     

Decision analysis: a tool for infection control

The medical world would seem to be one of increasing technology and shrinking financial resources. New tests and therapies constantly appear on the market. Most have been examined for efficacy and side effects. The real question is: where does the new test or therapy fit in with all previous products? Decision analysis is a mathematical tool adapted to assess the relative cost-effectiveness of complex diagnostic and therapeutic strategies.     

Factors affecting the toxicity of rotting carcasses containing Clostridium botulinum type E

Mice killed shortly after receiving c. 2000 spores of a type E strain of Clostridium botulinum per os were incubated at one of five chosen temperatures together with bottles of cooked meat medium seeded with a similar inoculum. After incubation the rotting carcasses were homogenized. Sterile membrane filtrates of the homogenates (10%, w/v) and pure cultures were then titrated for toxicity. Some of the main findings were confirmed with two further type E strains. Toxicity produced at 37 degrees C was poor in both carcasses and cultures (200-20,000 mouse intraperitoneal LD/g or ml). It was good in both systems at 30 and 23 degrees C, usually reaching 20,000-200,000 LD/g or ml, and in carcasses occasionally more; at 30 degrees C maximal toxicity was reached more quickly in carcasses than in cultures. Prolonged incubation (36-118 days) at 30 or 23 degrees C resulted in complete loss of toxicity in virtually all carcasses but not in cultures. At 16 degrees C the development of toxicity in carcasses was strikingly greater than in cultures. At 9 degrees C neither system produced more than slight toxicity after prolonged incubation. Trypsinization increased the toxicity of cultures but not usually of carcasses. Unfiltered carcass homogenate (10%, w/v) with maximal intraperitoneal toxicity was harmless for mice by mouth in doses of 0.25 ml. These findings differed in important respects from those made earlier with a type C strain.     

Correlation between concentrations of humoral antibodies and vitamin D nutritional status: a survey study

The vitamin D nutritional status and the plasma concentrations of IgG, IgA, IgM and total immunoglobulins were determined in 2052 Saudi subjects. It was observed that females had significantly lower 25-hydroxyvitamin D levels than males and children had lower levels than adults. The mean levels of IgG and IgM were significantly higher in females than in males and those in adults higher than in children. There was a highly significant positive correlation between the concentrations of the circulating form of vitamin D, 25-OHD, and IgG levels in the overall population, in children and in adults. When these groups were classified into males and females the correlation was significant only for females. The significance and importance of this correlation between vitamin D nutritional status and IgG is as yet unknown. The possible clinical relevance of this study's findings are discussed.     

Ocular autonomic function in progressive autonomic failure

Ocular autonomic function was assessed in 4 patients with progressive autonomic failure (PAF) and age-matched control subjects, by measurement of the pupil cycle time, and determination of autonomic denervation hypersensitivity of the iris. Pupil cycle time was abnormal in all patients with PAF; sustained pupil cycling was absent in 5 of the 8 eyes tested of the PAF patients, compared with only 16 eyes from 70 control subjects. Pupil constriction in response to 2.5% methacholine, indicative of parasympathetic denervation hypersensitivity, was significantly increased in patients with PAF (p < 0.001), whilst pupil dilation in response to 0.5% phenylephrine, indicative of sympathetic denervation hypersensitivity, was also significantly higher in the PAF patients (p < 0.001). The results suggest that ocular autonomic function may provide a sensitive early indicator of generalised autonomic dysfunction.     

Herpes zoster: a consideration in the differential diagnosis of radiculopathy

Herpes zoster probably occurs more often than generally thought. Since it produces a radicular distribution of pain, it should be included in the differential diagnosis of radiculopathy. A case is presented in which evaluating the radicular low back pain before the characteristic rash appears was misleading. Careful history-taking concerning the exact nature of the pain and sensory changes is needed to differentiate between zoster and radiculopathy, if no rash is evident.